KR100754382B1 - Backlight unit - Google Patents

Abstract

The disclosed backlight unit includes a light guide plate and a light source for irradiating light to an edge of the light guide plate, the backlight unit being immersed at the edge of the light guide plate so that the light source can be inserted, and having a light incident surface and both sides to which light is incident. And a concave portion and an elastic member for pushing the light source toward the light incident surface.

Description

Backlight unit

6 is a schematic side view showing one embodiment of a backlight unit according to the present invention;

Figure 2 is an exploded perspective view showing a first example of the coupling structure of the LED.

3 is a plan view of a first example of the coupling structure of the LED shown in FIG.

4 is a plan view showing a second example of the coupling structure of the LED.

5 is a plan view showing a third example of the coupling structure of the LED.

6 is an exploded perspective view showing a fourth example of the coupling structure of the LED.

7 is a plan view of a fourth example of the coupling structure of the LED shown in FIG.

8 is an exploded perspective view showing a fifth example of the coupling structure of the LED.

9 is a plan view of a fifth example of a coupling structure of the LED shown in FIG. 8;

<Description of the symbols for the main parts of the drawings>

10 ...... Light guide plate 11 ...... Optical path converting means

12 ...... Edge 20 ...... Reflector

40 ...... LED 41 ...... Light Emitting Chip

42 ...... Frame 43 ...... Elastic Arm

44.Uneven portion 50 ......

51 ... incident surface 52, 53 ... side wall

54 ...... Support groove 55 ...... Regulator

56 ...... Prism pattern 57 ......

60 ...... Elastic member

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit, and more particularly, to an edge emitting backlight unit for injecting light into an edge of a light guide panel (LGP).

In general, flat displays are classified into light emitting and light receiving types. The light emitting type includes a cathode ray tube, a plasma display device, an electroluminescent device, a fluorescent display device, and the like. The light-receiving type includes a liquid crystal display. Among them, since the liquid crystal display itself emits light and does not form an image, and light is incident on the outside to form an image, there is a problem in that an image cannot be observed in a dark place. In order to solve this problem, a back light unit is installed on the back of the liquid crystal display to irradiate light. Accordingly, an image can be realized even in a dark place. The backlight unit is used in surface light source devices such as lighting signs as well as light receiving displays such as liquid crystal displays.

The backlight unit includes a direct light type (LGP) and a light guide panel (LGP) in which a plurality of lamps installed directly below the liquid crystal display directly irradiate light to the liquid crystal panel according to the arrangement of the light source. Lamps installed at the edges are classified as edge light types that irradiate light and transmit it to the liquid crystal panel.

The edge emitting type can use a line light source and a point light source as a light source. Representative line light sources include cold cathode fluorescent lamps (CCFLs) in which electrodes at both ends are installed in a tube, and light emitting diodes (LEDs) as point light sources. CCFLs have the advantage of being able to emit strong white light, achieve high brightness and high uniformity, and allow for large-area designs, but they are operated by high frequency AC signals and have a narrow operating temperature range. LEDs have lower performance than CCFLs in terms of brightness and uniformity, but are driven by direct current signals, have a long lifetime and a wide operating temperature range. In addition, since it has the advantage of being thin, it is widely used as an illumination unit of a small liquid crystal display device.

In installing the light source at the edge of the light guide plate, the position of the light source must be precisely regulated. If the position of the light source is not stable and shakes, the luminance of light emitted from the light guide plate becomes uneven due to the light loss.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide an edge-emitting backlight unit capable of effectively fixing a light source to a light guide plate.

The backlight unit of the present invention for achieving the above object, in the backlight unit having a light guide plate and a light source for irradiating light to the edge of the light guide plate, is formed immersed in the edge of the light guide plate so that the light source can be inserted A concave portion having a light incident surface on which light is incident and both sides; And an elastic member for pushing the light source toward the light incident surface.

In one embodiment, the backlight unit further includes a support groove immersed from both side surfaces of the concave portion, wherein the elastic member is supported by the support groove to push the light source.

In one embodiment, the light source includes a frame in which the light emitting chip is accommodated, and the elastic member includes an elastic arm extending from the frame so that an end thereof is supported by the support groove. As a result, the elastic member may be integrally formed with the LED.

In one embodiment, the light incident surface may be provided with a control unit for contacting the front end of the light source to regulate the position of the light source.

The backlight unit of the present invention for achieving the above object, in the backlight unit having a light guide plate and a light source for irradiating light to the edge of the light guide plate, is formed immersed in the edge of the light guide plate so that the light source can be inserted A concave portion having a light incident surface on which light is incident and both sides; A coupling part formed on both side surfaces in a sawtooth shape, and having its vertex facing toward the light incident part; It is formed in the sawtooth shape on both sides of the light source, and the uneven portion coupled to the coupling portion.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view showing an embodiment of a backlight unit according to the present invention. 1, the LED 40 is provided as a light source at the edge 12 of the light guide plate 10. On the bottom of the light guide plate 10 is provided an optical path changing means 11 for changing the traveling path of the light emitted from the LED (40). As the optical path changing means, for example, a hologram pattern, a scattering pattern, or the like can be applied. Since the type and principle of hologram pattern and scattering pattern are well known to those skilled in the art, further description thereof will be omitted. The hologram pattern and the scattering pattern are formed by a printing method or a machining method. The reflecting plate 20 reflects light passing through the bottom of the light guide plate 10 upward. An optical member 30 such as a prism sheet or a diffusion sheet may be further provided on the upper surface of the light guide plate 10 to improve luminance uniformity of light.

The light guide plate 10 is made of a light-transmissive material that can transmit light. Acrylic transparent resins, such as PMMA and PC having a refractive index of 1.49 and a specific gravity of about 1.19, are mainly used. Is also used. The size of the light guide plate 10 depends on the size of an image display device (not shown), for example, a liquid crystal display (LCD), installed on the light exit surface 112 side.

The LED 40 refers to a light emitting diode as an example of a point light source. Light irradiated from the LED 40 is incident on the edge 12 of the light guide plate 10. Among the light incident on the light guide plate 10, light having an incident angle with respect to the top surface of the light guide plate 10 smaller than the critical angle is emitted to the top surface of the light guide plate 10. Light whose incidence angle is larger than the critical angle is spread throughout the light guide plate 10 while repeating total reflection. At this time, the optical path changing means converts the incident angle with respect to the upper surface of the light guide plate 10 by changing the direction of travel of the light by diffracting or scattering the light. As described above, light incident through the edge 12 of the light guide plate 10 is emitted in the form of surface light through the upper surface of the light guide plate 10. A plurality of LEDs 40 may be installed, and may be installed at other edges as well as the left edge 12 of the light guide plate 10.

Japanese Patent Application Laid-Open No. 1998-199315 discloses a light source coupling structure using a snap-fit, but the coupling structure of the document serves to prevent the light source from being separated, but to close the light source to the light guide plate or to prevent shaking. It is difficult to do In addition, the snap-fit must have a rib shape that is very thin in order to have elasticity. In the case where the shape of the snap fit is manufactured integrally with the light guide plate, it is difficult to manufacture the light guide plate. In addition, in the case of a backlight unit for a small display device, since the light guide plate is very thin, for example, about 1 mm, it is difficult for the snap fit to have a strength sufficient to firmly fix the light source, and there is a high possibility of damage. In installing the LED 40 to the edge 12 of the light guide plate 10, its installation position must be precisely regulated. When the LED 40 is shaken in the plane including the optical axis and / or the optical axis, the luminance of light emitted from the light guide plate 10 becomes uneven due to the light loss.

2, an example of an installation structure of the LED 40 using the elastic member 60 is disclosed. A recess 50 immersed from the edge 12 of the light guide plate 10 is shown. The LED 40 is inserted into the recess 50. The light incident surface 51 on the front side is a surface on which light is incident. Both sides 52 and 53 of the light incident surface 51 guide both sides of the LED 40 to regulate the LED 40 from being shaken. The elastic member 60 is for pushing the LED 40 toward the light incident surface 51 so as not to shake. The light guide plate 10 is provided with support grooves 54 immersed from both side surfaces 52 and 53 of the recess 50. The elastic member 60 may be manufactured by injection molding a material having elasticity such as plastic or rubber. In addition, the elastic member 60 may be made of spring steel or the like having elasticity. Both ends 61 of the elastic member 60 are supported by the support groove 54. By the above configuration, as shown in FIG. 3, the LED 40 is pushed in the optical axis direction to be inserted into the recess 50, and then the elastic member 60 is coupled to the support groove 54. The elastic member 60 is deformed from the state shown by the dotted line of FIG. 3 to the state shown by the solid line, and pushes the rear surface of the LED 40 toward the light incident surface 51. Therefore, the LED 40 can be firmly coupled to the light guide plate 10 without shaking. The light guide plate 10 is manufactured by injection molding or extrusion molding using a light transmitting material. Since the coupling structure of the recess 50 or the like may be formed directly in the manufacturing process of the light guide plate 10, no separate manufacturing process is required. The vertical movement of the LED 40 may be supported by the reflective plate 20, the optical member 30 provided on the upper surface of the light guide plate 10, or an external structure for packaging the backlight unit. In addition, since the LED 40 may be coupled to a substrate (not shown) for power supply, in the present embodiment, a coupling structure for preventing shaking in a plane including the optical axis direction and the optical axis of the LED 40 is provided. Explained.

As shown in FIG. 4, the light incident surface 51 may be provided with a restriction unit 55 for regulating the position of the LED 40. When the LED 40 is pushed toward the light incident surface 51 by the elastic force of the elastic member 60, the tip portion of the LED 40 is in contact with the restricting portion 55. Thereby, the LED 40 can be positioned at a desired position by appropriately selecting the protruding amount of the restricting section 55. The restricting unit 55 may be provided at the front end of the LED 40. Of course, if the LED 40 is in close contact with the light incident surface 51, the restriction unit 55 will be unnecessary.

As shown in FIG. 5, the light incident part 51 may be provided with a prism pattern 56 for diffusing light as necessary. In this case, the vertex of the prism pattern 56 may take the role of the restricting portion 55. In addition, when the LED 40 needs to be located at a position spaced apart from the apex of the prism pattern 56 by a predetermined distance, the restricting portion 55 protruding from the apex of the prism pattern 56 may be provided.

The elastic member 60 may be integrally formed with the LED 40. Referring to FIG. 6, the LED 40 has a shape in which a light emitting chip 41 for irradiating light to the frame 42 is accommodated. Frame 42 is typically made of plastic. In view of this, the elastic arm 43 may be formed in the frame 42 of the LED 40. When the LED 40 is pushed in the optical axis direction to be inserted into the recess 50, the ends of the elastic arm 43 are deformed inward while contacting both side surfaces 52 and 53 of the recess 50. When the end of the resilient arm 43 is supported by the support groove 54, the resilient arm 43 tends to be restored to its original state by the restoring force. By this restoring force, as shown in FIG. 7, the LED 40 is elastically biased toward the light incident surface 51 and is firmly positioned at a predetermined position. By such a configuration, the LED 40 can be firmly fixed to the light guide plate 10 by using the shape of the LED 40 itself. Therefore, the number of parts can be reduced, and the ease of assembly of the backlight unit can be improved.

Referring to FIG. 8, another embodiment for coupling an LED to a light guide plate is shown. Referring to FIG. 8, serrated coupling portions 57 are provided on both side surfaces 52 and 53 of the recess 50. As for the coupling part 57, it is preferable that the tooth-shaped vertex faces the light incident surface 51 side. On both sides of the LED 40, serrated uneven portions 44 are provided. It is preferable that the tooth | gear shape of the uneven part 44 is a direction opposite to the tooth | gear shape of the engaging part 57. As shown in FIG. When the LED 40 is pushed in the optical axis direction by such a configuration, the coupling portion 57 and the uneven portion 44 are elastically deformed little by little, and the LED 40 is inserted into the recess 50. Then, as shown in FIG. 9, the coupling portion 57 and the uneven portion 44 mesh with each other like a wedge so that the LED 40 is firmly fixed to the light guide plate 10. The embodiment described above is that the light guide plate 10 and the frame 42 of the LED 40 are generally manufactured by injection molding, and the material of the light guide plate 10 and the frame 42 typically has some elasticity. As an idea, it has the advantage of not requiring a separate manufacturing process in forming the coupling portion 57 and the uneven portion 44. In addition, once the LED 40 is coupled to the light guide plate 10, the LED 40 may not be separated well by the conventional force, and since the plurality of tooth shapes are interlocked with each other, the LED 40 may be very firmly attached to the light guide plate ( 10) can be fixed.

As described above, according to the backlight unit according to the present invention, the following effects can be obtained.

First, by using the elastic member to firmly fix the light source to the light guide plate, it is possible to reduce the light loss due to the displacement or shaking of the light source.

Second, by forming the elastic member integrally with the LED can reduce the number of parts and simplify the assembly process.

Third, by combining the LED and the light guide plate using a sawtooth shape, it is possible to firmly combine the LED and the light guide plate without adding a separate component.

It is to be understood that the invention is not limited to that described above and illustrated in the drawings, and that more modifications and variations are possible within the scope of the following claims.

Claims (5)

In the backlight unit having a light guide plate and a light source for irradiating light to the edge of the light guide plate, A concave portion immersed at an edge of the light guide plate to allow the light source to be inserted therein, and having a light incident surface and both sides of which light is incident; And an elastic member for pushing the light source toward the light incident surface. The light incident surface is a backlight unit, characterized in that the control unit for contacting the front end of the light source to regulate the position of the light source. The method of claim 1, And a support groove immersed from both side surfaces of the recess. And the elastic member is supported by the support groove and pushes the light source. The method of claim 2, The light source includes a frame in which a light emitting chip is accommodated. And the elastic member extends from the frame and includes an elastic arm whose end portion is supported by the support groove. delete In the backlight unit having a light guide plate and a light source for irradiating light to the edge of the light guide plate, A concave portion immersed at an edge of the light guide plate to allow the light source to be inserted therein, and having a light incident surface and both sides of which light is incident; A coupling part formed on both side surfaces in a sawtooth shape, and having its vertex facing toward the light incident part; And a concave-convex portion which is formed in a sawtooth shape on both side portions of the light source, and is coupled to the coupling portion.

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