KR20070025861A - Light emitting unit and direct light type back light apparatus using the same - Google Patents

Abstract

A light-emitting unit and a direct light type back light unit employing the light-emitting unit are provided to improve brightness and prevent a dark part from being generated at the center of an LCD(Liquid Crystal Display) panel. A light-emitting unit includes a base(31), a light-emitting diode(40), a cup member(35), and a lens(50). The light-emitting diode is mounted on the base and emits light. The cup member is formed with a predetermined height on the base around the light-emitting diode. The lens is located on the base and includes a light-receiving part, a first refracting part(53) for refracting and transmitting incident light, and a second refracting part for refracting and transmitting the incident light. The first refracting part is flat and is formed at the center of the backside of the light-receiving part. The second refracting part is formed around the first refracting part and has a predetermined curvature. The light emitted from the light-emitting diode is uniformly projected over a wide range through the lens.

Description

Light emitting unit and direct light type back light apparatus using the same

1 is a schematic cross-sectional view showing a conventional edge-emitting backlight device.

Figure 2 is a schematic cross-sectional view showing a light emitting unit according to an embodiment of the present invention.

3 is a schematic view for explaining another embodiment of the incidence part of FIG. 2;

FIG. 4 is a diagram illustrating a path of propagation of light L1 and L2 emitted from a light emitting diode when the refractive index of the dispensing member is greater than the refractive index of the lens. FIG.

 FIG. 5 is a diagram showing a traveling path of the light L3 when the refractive index of the dispensing member is smaller than the refractive index of the lens and the difference in the value thereof is large, and a path of the light L4 when the refractive index is the same.

6 and 7 illustrate a light emitting unit structure according to a comparative example.

FIG. 8 is a diagram illustrating a case in which the diameter w of the first refractive portion has a value equal to or greater than 1/3 of the diameter R of the lens, and FIGS. 9, 10A, and 10B are diagrams illustrating the case where the diameter w of the first refractive portion passes through the lens. Figure showing luminance distribution of light.

FIG. 11 is a diagram illustrating a case in which the diameter w of the first refraction portion has a value equal to or less than one third of the diameter R of the lens, and FIGS. 12A and 12B are luminance distributions of light transmitted through the lens in FIG. 11. The figure showing.

13 is a view showing an air layer formed between the lens and the dispensing member.

14 is a schematic cross-sectional view showing a light emitting unit according to another embodiment of the present invention.

15 is a schematic cross-sectional view showing a light emitting unit according to another embodiment of the present invention.

Figure 16a is a graph showing the yellowing phenomenon when the lens is composed of an epoxy resin.

Figure 16b is a graph showing whether yellowing occurs when the lens is composed of a silicone resin.

17 is a schematic cross-sectional view showing a light emitting unit according to another embodiment of the present invention.

18A and 18B show the directivity angle distribution and uniformity of illumination light when polishing a lens surface.

19A and 19B are diagrams showing a direction angle distribution and uniformity of illumination light when the lens surface is matted;

20A is a view showing a distribution of directivity angles of a general light emitting unit having a maximum luminance value of 0 degrees.

Fig. 20B is a view showing a distribution of directivity angles of the light emitting unit according to the present invention, wherein the maximum luminous intensity value has a distribution of +/- 75 degrees.

Fig. 21 is a graph showing actual values of lumen values in the case of polishing and matting of the lens according to the embodiment of the present invention.

22 is a graph showing a cross-sectional curve in a model to explain the degree of surface roughness.

Figure 23 is a schematic cross-sectional view showing a direct-emitting type backlight device according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

31 ... base 33, 35 ... cup member

40 ... Light Emitting Diode 50, 150 ... Lens

51, 52 ... input 53, 153 ... first refraction

55, 155 ... second refraction 61, 161 ... dispensing member

63, 65 Adhesive 71 Reflector

73.Diffusion Plate 75 ... Prism Sheet

77 ... LCD panel

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting unit using a light emitting diode and a backlight device employing the same, and more particularly, to a light emitting unit having a structure capable of increasing luminance and removing dark phenomenon at the center of a lens, and direct light emitting employing the same. It relates to a type backlight device.

In general, the liquid crystal display device, which is a kind of light receiving type flat panel display, does not have its own light emitting capability, and thus forms an image by selectively transmitting illumination light emitted from the outside. To this end, a backlight device for illuminating light is provided on the back of the liquid crystal display.

The backlight device is classified into a direct emission type and an edge emission type according to the arrangement of the light sources. The direct emission type is a method in which a lamp installed directly below the liquid crystal panel directly irradiates light directly onto the liquid crystal panel. On the other hand, the edge emitting type is a method in which a lamp installed at an edge of a light guide panel (LGP) irradiates light and transmits the irradiated light to the liquid crystal panel through the light guide plate.

1 is a schematic cross-sectional view showing a conventional edge-emitting backlight device. Referring to the drawings, cold cathode fluorescent lamps (CCFLs) are provided at both edges of the light guide plate 3. The bottom of the light guide plate 3 is formed with a reflector 9 for emitting light incident from the CCFL 1 toward the liquid crystal display device (hereinafter referred to as LCD) panel 10. Therefore, the light irradiated from the CCFL 1 is incident on the light guide plate 3 through the edge. The incident light is converted into surface light by the light guide plate 3 and the reflecting plate 9 and is emitted to the upper surface of the light guide plate 3.

The diffusion plate 5 and the optical prism sheet 7 are disposed on the upper surface of the light guide plate 3. Therefore, the light emitted to the upper surface of the light guide plate 3 is diffused by the diffuser plate 5, and then travels toward the LCD panel 10 with the path corrected by the optical prism sheet 7. .

On the other hand, the conventional backlight device has the advantage that by adopting the CCFL (1) as a light source, it is possible to obtain a strong white light of high brightness, high uniformity, it is possible to design a large area. However, since the CCFL 1 uses mercury as the discharge gas, it cannot be free from environmental problems. In addition, since the light guide plate 3 and the optical prism sheet 7 are used to change the light illuminated at the edge in the vertical direction and to correct the path of the illumination light, the number of parts is high and the space occupied by these optical elements needs to be secured. The disadvantage is that there is a limit to reducing the overall thickness of the device. In addition, there is a problem that the color reproduction rate is very low at about 74% level compared to the standard of the National Television System Committee (NTSC).

On the other hand, as a light source replacing the above-described CCFL, a light emitting unit using a light emitting diode (LED) is emerging. Unlike the CCFL, which is a linear light source, the light emitting diode is a point light source, and has the advantages of longer life, wider operating temperature range, environmental friendliness, and high color reproducibility than the CCFL. In addition, there is an advantage that it is possible to illuminate the light of a high luminance depending on the structure.

However, when the backlight unit is configured by arranging such a high brightness light emitting unit at the edge of the light guide plate, light is not sufficiently transmitted to the center portion of the LCD panel in illuminating light over the entire large area of the LCD panel. Accordingly, there is a problem in that a dark portion is formed in the portion. In addition, since the backlight device having such a structure employs both the light guide plate and the optical prism sheet, there is a limit in thickness reduction compared to the case where the CCFL is used as the light source.

Accordingly, an object of the present invention is to provide a light emitting unit having a structure in which a dark phenomenon is not generated in the upper center of the light emitting device while increasing the brightness.

In addition, another object of the present invention is to provide a direct light emitting backlight device capable of implementing thinner and larger screen illumination by excluding a light guide plate by employing the light emitting unit described above.

In order to achieve the above object, a light emitting unit according to the present invention includes a base; A light emitting diode mounted on the base and emitting light; A cup member formed at a predetermined height around the light emitting diode on the base; It is provided on the base, disposed on the light emitting diode side, the incident portion to which light is incident, the first refractive portion for refracting and transmitting the incident light to be formed flat in the center of the back surface of the incident portion, and around the first refractive portion And a lens having a second refraction portion configured to refractively transmit incident light to be formed at a predetermined curvature. The light emitted from the light emitting diode is uniformly emitted through a wide area through the lens.

In addition, the direct-emitting type backlight device according to the present invention in order to achieve the above another object, and a reflecting plate for reflecting the incident light; A light source including a plurality of light emitting units on the reflecting plate to illuminate light; A diffuser plate disposed on the light source and configured to diffuse light illuminated by the light emitting unit; And a prism sheet for converting the propagation path by refracting the light diffused through the diffusion plate.

Hereinafter, a light emitting unit and a direct light emitting backlight device employing the same according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 2, a light emitting unit according to an exemplary embodiment of the present invention includes a base 31, a light emitting diode 40 mounted on the base 31, and the light emitting diode 40 on the base 31. Cup member 33 formed in the periphery, and the lens 50 is installed on the base 31 to change the emission direction of the light illuminated from the light emitting diode (40).

The light emitting diode 40 is a point light source and illuminates light having a predetermined wavelength on the surface facing the lens 50. Here, the base 31 is provided with a lead frame 35 for supplying power to the light emitting diode 40, the light emitting diode 40 is mounted on the lead frame 35 or a lead frame by a wire It is electrically connected to (35).

The cup member 33 is formed at a predetermined height around the light emitting diode 40 on the base 31. The cup member 33 is provided to surround the light emitting diode 40 with a dispensing member 61 which will be described later, and to install the lens 50. The height of the cup member 33 should be formed at a height that does not interfere with the path of the light traveling through the lens 50. In this case, when a part of the light irradiated from the light emitting diode 40 is incident on the cup member 33, the incident light is reflected by the cup member 33 and is directed to a path other than a desired traveling path. Causes performance degradation. In view of this, the height of the cup member 33 is formed equal to or slightly higher than the height of the light emitting diode 40.

The lens 50 has a structure in which the light emitted from the light emitting diode 40 is able to deflect laterally the light illuminated in a direction perpendicular to or near to an upper surface of the base 31. That is, when the lens 50 is used as a light source of the direct-emitting backlight device, the maximum intensity of the directivity angle is approximately +/- 75 degrees so that the light source has a constant brightness in the liquid crystal display panel, and the intensity of the center portion is maximum. It is lower than the intensity to have a constant luminance as a whole.

To this end, the lens 50 includes an incident part 51 through which light is incident, a first refractive part 53 formed flat in the center of the back surface of the incident part 51, and the first refractive part 53. The second refractive portion 55 is formed around the predetermined curvature.

The incidence part 51 is disposed on the light emitting diode 40 side, through which light is incident on the lens 50. Referring to FIG. 2, the incidence part 51 according to the exemplary embodiment may have a planar structure parallel to the light exit surface of the light emitting diode 40.

Referring to FIG. 3, the incident part 52 according to another exemplary embodiment may be formed of a protruding surface protruding toward the light emitting diode 40 at a predetermined curvature. In this case, the incident part 52 has a predetermined curvature so that the incident part 52 together with the first and second refraction parts 53 and 55 may perform a substantial function as a control element for the light beam passing through the lens 50. Can be. Therefore, it is possible to efficiently manage the rays in the lens design.

2 and 3, it is preferable that the dispensing member 61 is further provided in the inner space of the cup member 33.

The dispensing member 61 is made of a transparent material and is positioned between the light emitting diode 40 and the lens 50 to protect the light emitting diode 40. In addition, the heat generated during the illumination of the light emitting diode 40 may be blocked from being directly transmitted to the lens 50, thereby preventing a yellowing phenomenon in which the lens 50 is yellowed by heat.

4 illustrates a traveling path of the light L ₁ and L ₂ emitted from the light emitting diode 40 when the refractive index of the dispensing member 61 ′ is greater than the refractive index of the lens 50. Referring to the drawings, the light L ₁ having an incident angle smaller than the critical angle θ c [= sin ⁻¹ (n _d1 / n _d2 )] at the interface between the lens 50 and the dispensing member 61 ′ is incident part 51. It can be seen that the light L ₂ having an angle of incidence larger than the critical angle θc is totally reflected at the incident part 51 while refracting the light. Where n _d1 and n _d2 represent the d-line refractive indices of the lens 50 and the dispensing member 61, respectively.

That is, since total reflection occurs when a material having a high refractive index is incident at an angle greater than a critical angle, the dispensing member 61 is made of the same material as that of the lens 50 or the lens to fundamentally prevent this. It is preferable to be made of a transparent material having a relatively low refractive index compared to (50).

FIG. 5 shows a traveling path of the light L ₃ when the refractive index of the dispensing member 61 ″ is smaller than the refractive index of the lens 50 and the difference in the value thereof is large, and the light when the refractive index is the same ( L ₄ ) shows the progress path.

Referring to the drawings, in both cases, the light emitted from the light emitting diode 40 passes through the lens 50. On the other hand, the light L ₃ is primarily refracted at the incident surface 51, while the light L ₄ passes straight through the incident surface 51. Therefore, when comparing the paths of the light transmitted through the lens 50, it can be seen that L ₃ is directed above the lens compared to L ₄ . That is, when the difference in refractive index between the lens 50 and the dispensing member 61 ″ is small or the same, the light propagates at a larger refractive angle, so that the light spreads widely.

In addition, as the refractive index of the lens 50 increases, the refractive angle of the light emitted from the lens 50 finally increases. Therefore, in view of the foregoing, it is preferable that the lens 50 and the dispensing member 61 " have the same refractive index and have a large value.

More preferably, the lens 50 is made of a material satisfying the condition of Equation (1).

Examples of the transparent material constituting the lens 50 include an epoxy resin having a d-line refractive index n _d1 of 1.54, polymethyl methacrylate (PMMA), polycarbonate (PC), acrylic resin, and silicone resin.

In addition, the dispensing member 61 is made of a material satisfying the equation (2).

An example of the dispensing member 61 may be a silicone resin having a d-line refractive index n _d2 of 1.41.

Referring to FIG. 2, the first refraction portion 53 has a flat structure formed flat in the center of the rear surface of the incident portion 51. As described above, when the first refraction portion 53 is formed in a flat structure, the dark phenomenon at the luminance measurement position can be eliminated as the angle of refraction emitted from the lens 50 increases proportionally as a whole. Hereinafter, the advantages obtained by the first refraction portion 53 having a flat structure will be described in detail while comparing with the lens structure according to the comparative example as shown in FIGS. 6 and 7.

6 and 7 are light emission disclosed in Patent Application No. 10-2004-0113927 filed by the present applicant on December 28, 2004 The unit structure is shown.

Referring to the drawings, the lens 20 has a first refractive portion 21 of the structure formed in the conical groove shape in the upper portion of the center and the second refractive portion 23 formed with a predetermined curvature in the periphery thereof. When the lens is configured in this way, when looking at the distribution (A) (B) of the light transmitted through each of the first and second refractive portions 21 and 23, It can be seen that the distribution (B) is uniformly distributed without relatively spacing. On the other hand, it can be seen that the distribution of light transmitted through the first refraction portion 21 toward the second refraction portion 23 from the center becomes wider. This is because the angle of incidence increases rapidly as the incident angle changes with distance. In the case of having such a light distribution and the number of incident light rays per unit area is smaller than that of the second refractive portion 23, as shown in FIG. 7, the first refractive portion 21 and the second refractive portion ( It can be seen that a ring-shaped dark portion occurs at the boundary portion between 23).

The present invention is characterized in that the first refraction portion 53 has a flat structure in order to eliminate the above-described dark portion phenomenon. The dark phenomenon at the luminance measurement position (the position of the liquid crystal display element when employed as the light source of the backlight unit) can be eliminated.

 In addition, the diameter w of the first refraction portion 53 preferably satisfies the condition of Equation 3 in relation to the overall diameter R of the lens 50.

FIG. 8 illustrates a case in which the diameter w of the first refraction portion 53 has a value equal to or greater than 1/3 of the diameter R of the lens 50. FIGS. 9, 10A, and 10B illustrate FIG. 8. In this case, the luminance distribution of the light transmitted through the lens is shown.

Referring to the drawings, it can be seen that the luminance distribution C of the light transmitted through the first refraction portion 53 has a larger value than the luminance distribution of the light transmitted through the surroundings. This is due to the fact that the refractive angle is not large because the first refraction portion 53 has a flat structure, and thus the number of light rays that proceed straight to the center increases. In this way, since the light transmitted through the lens does not achieve uniformity as a whole, it is difficult to utilize the light emitting unit as a light source such as a backlight unit.

FIG. 11 illustrates a case in which the diameter w of the first refractive portion 53 has a value equal to or less than 1/3 of the diameter R of the lens 50. FIGS. 12A and 12B illustrate a lens in FIG. It shows the luminance distribution of the light passing through.

Referring to the drawings, in the above-described configuration, the central refraction portion can be eliminated by making the first refraction portion 53 flat. In addition, since the number of light rays that proceed straight to the center can be reduced by forming the diameter w of the first refractive portion 53 relatively narrow, it is possible to suppress the sudden increase in luminance at the first refractive portion 53. . Therefore, the light transmitted through the lens 50 can be made to have a uniform distribution as a whole.

Therefore, when the light emitting unit according to the present embodiment is applied as a light source of the backlight unit for a display, it is possible to illuminate the light with a constant luminance as a whole for a certain area.

The second refraction portion 55 has a predetermined curvature so that the light incident from the light emitting diode 40 can be refracted and transmitted laterally. Here, the second refractive portion 55 is preferably a spherical surface having a radius of curvature of 2mm to 10mm. In this case, when the radius of curvature is greater than 10 mm, the angle of refraction of light illuminated by the light emitting diode 40 and incident on the second refraction portion 55 is reduced. Therefore, there arises a problem that the illumination area of light is narrowed.

On the other hand, when the curvature of the refracting portion 55 is less than 2mm, it is difficult to secure a sufficient size of the refracting portion 55, there is a problem that the normal arrangement of the first refraction portion 53 is difficult.

The lens 50 configured as described above may be molded through injection molding, injection molding, transfer molding, or diamond turning.

In addition, the installation of the lens 50 on the base 31 may be performed using the adhesive 63. Here, examples of the adhesive 63 include the same epoxy resin or silicone resin as the medium of the lens 50.

On the other hand, in the case of bonding the lens 50 on the base 31 as shown in Figure 2, as shown in Figure 13, the interface between the lens 50 and the dispensing member is separated between, Problems may occur in which an air layer is formed.

In particular, when the lens 50 and the adhesive 63 are made of an epoxy resin or a silicone resin, and the dispensing member 61 is made of a silicone resin, the air layer has no adhesiveness between the epoxy resin and the silicone resin. Problems are more likely to occur. In this case, in more detail, as the heat is generated when the LED 40 is driven, the dispensing member 61 made of a silicone resin is thermally expanded. At this time, the lens 50 is naturally lifted up. Meanwhile, when the light emitting diode 40 is turned off, the dispensing member 61 is contracted while being cooled, thereby forming an air layer at an interface between the dispensing member 61 and the lens 50. As such, when the air layer is formed, the light ray may be abnormally refracted at the interface, which may cause a problem of uneven brightness distribution.

In consideration of this point, it is preferable that the light emitting unit according to another embodiment of the present invention has a junction structure as shown in FIG. 15.

Referring to FIG. 14, the lens 50 is installed on the base 31 by attaching a portion of the lens 50 to the cup member 35. At this time, the first bonding portion 57 formed on the lens 50 and the second bonding portion 35a formed on the cup member 35 are formed in a concave-convex shape corresponding to each other so as to have a large area facing each other. 65 are mutually joined. Here, the adhesive 65 is preferably made of an epoxy material of the same material as the lens 50.

As described above, in the case where the bonding structure is improved, the lens 50 is strongly bonded to the cup member 35 even though the lens 50 and the dispensing member 61 are not bonded to each other due to material characteristics, and thus the light emitting unit 40 The thermal expansion of the dispensing member 61 generated during the operation can be suppressed. Therefore, since the external air does not flow into the cup member 35 during the on / off operation of the light emitting unit 40, it is possible to fundamentally block the formation of the air layer.

In addition, as shown in FIG. 3, when a curvature is applied to the incidence portion 52, the space between the incidence portion 52 and the dispensing member 61 becomes narrow, and thus the thermal expansion of the dispensing member 61 is performed. Can be suppressed more effectively.

15 is a schematic cross-sectional view showing a light emitting unit according to another embodiment of the present invention.

Referring to the drawings, the light emitting unit according to the present embodiment includes a base 31, a light emitting diode 40 mounted on the base 31, and a light emitting diode 40 formed on the base 31. And a lens 150 and a dispensing member 161 which are installed on the cup member 35 and the base 31 to change the emission direction of the light illuminated by the light emitting diode 40. The lens 150 includes a first refractive portion 153 having a flat structure and a second refractive portion 155 having a predetermined curvature. The description will be omitted.

The present embodiment is characterized in that the lens 150 and the dispensing member 161 are made of a silicone resin and are integrally formed by a direct molding process. As such, when the lens 150 and the dispensing member 161 are integrally formed by the direct molding process, the number of assembly processes can be reduced.

In addition, when the lens 150 and the dispensing member 161 are integrally formed of a silicone resin, it is to prevent yellowing that may occur when the epoxy resin is formed and a decrease in luminous flux.

That is, when direct molding with an epoxy resin in the lens configuration of the light emitting unit, the performance is exhibited at low current. On the other hand, at a high current, the temperature of the light emitting diode is increased, which causes yellowing of the epoxy resin itself, which causes the lens to turn yellow, thereby causing a decrease in luminous flux. FIG. 16A is a graph illustrating yellowing when the lens is formed of an epoxy resin. FIG. Looking at the graph, it can be seen that the initial transmittance of about 80% or more for light in the wavelength region of about 350 nm or more. On the other hand, as the seal passes, the wavelength band having a transmittance of about 80% or more is gradually shifted, and after day 14, only light in a wavelength region of about 450 nm or more has a transmittance of 80% or more. Therefore, as indicated by the area D, yellowing phenomenon occurs in which the lens changes to yellow.

On the other hand, when the lens is composed of a silicone resin, as shown in Fig. 16b, even after 14 days have passed, about 80% or more of the light in the wavelength region of about 350 nm or more as the initial stage shows that yellowing does not occur. Able to know.

17 is a schematic cross-sectional view showing a light emitting unit according to another embodiment of the present invention.

Referring to the drawings, the light emitting unit according to the present embodiment includes a base 31, a light emitting diode 40 mounted on the base 31, and a light emitting diode 40 formed on the base 31. And a lens 250 and a dispensing member 61, which are installed on the cup member 35 and the base 31 to change the emission direction of the light illuminated by the light emitting diode 40. The lens 250 includes a first refractive portion 253 having a flat structure and a second refractive portion 255 having a predetermined curvature, and is characterized in that the lens surface 250a is matted. . Here, since the configuration except for the Matt surface treatment of the lens surface 250a is substantially the same as the configuration described above, a detailed description thereof will be omitted.

In the surface treatment of a lens, in the case of a conventional light emitting unit, it is common to treat the lens surface by polishing in consideration of the brightness. On the other hand, in the case where the polishing process is performed as shown in FIG. 18A, since the direction angle is not smooth as shown in FIG. 18B, a ring-shaped bright line appears as shown in FIG. 18B, which causes the uniformity of illumination light to be reduced. Can act as

In consideration of this, when a matte treatment is performed on the surface 250a of the lens 250, the light passing through the lens 250 is transmitted to the first and second refractive portions 253 and 255. Scattered, as shown in FIGS. 19A and 19B, it is possible to obtain illumination light having a uniform light distribution without a ring-shaped bright line.

Here, in the case of a general lens, during the matting process, the total luminous flux is reduced. On the other hand, in the case of the light emitting unit having the maximum luminous intensity value of approximately +/- 75 degrees as in the present invention, the luminous flux does not greatly decrease. Looking more specifically as follows.

FIG. 20A illustrates a distribution of directivity angles of a general light emitting unit having a maximum luminance value of 0 degrees. FIG. In the case of such a light emitting unit, when the surface is matte, many of the scattered light rays act as portions indicated by the dotted lines in the drawing. The luminous intensity value shown in the dotted line is the luminous intensity value position of 0.5 times or less than the maximum luminous intensity value, and the light rays of the dotted line portion act as light that disappears instead of being illuminated when the light emitting unit is driven. As a result, the luminous flux value is lowered.

FIG. 20B shows the distribution of the directivity angle of the light emitting unit according to the present invention, wherein the maximum luminous intensity value has a distribution of +/- 75 degrees. In this case, since the light illuminated in the entire area of the light emitting unit is used as the illumination light, the scattered light acts as the effective illumination light even when scattering is generated by the matt surface treatment. Therefore, luminous flux fall does not occur largely.

FIG. 21 shows measured values of lumen values in the case of polishing and matting of the lens according to the exemplary embodiment of the present invention. As shown, in both cases it can be seen that the lumen value does not differ significantly even when the current value applied to the light emitting diode is increased.

Here, matting of the lens surface 250a means processing the lens surface so that the lens surface has a predetermined roughness. Here, surface roughness means the degree of unevenness which shows the precision of a surface.

22 is a graph showing a cross-sectional curve modelically. Here, the cross-sectional curve refers to the shape of the cross section when the processing surface is cut vertically. In the figure, Rmax represents the maximum roughness, and Ra represents the centerline average value, that is, the average roughness. Here, Rmax is the distance between the two parallel lines that take the reference length from the roughness cross-section curve and are parallel to the center line of the cross-section curve and contact the highest peak and the lowest valley.

In the present embodiment, it is preferable that the average roughness Ra of the surface of the lens has a value in the range of about 0.8 μm to 1.8 μm. Here, if the value is less than 0.8㎛ close to the case of the polishing treatment, the ring-shaped bright line appears, if the value is out of the 1.8㎛ range there is a problem that the light flux is reduced due to excessive scattering.

23 is a schematic cross-sectional view showing an edge-emitting backlight device according to an embodiment of the present invention. Referring to the drawings, the reflection plate 71, the light source 100 for illuminating the light provided on the reflection plate 71, the diffusion plate 73 disposed on the light source 100, and the illumination light LCD It includes a prism sheet 75 for refraction transmission in the panel 77 direction. The reflector 71 reflects the light incident from the light source to the diffuser 73.

The light source 100 includes a plurality of light emitting units described with reference to FIGS. 2 to 22, and each light emitting unit illuminates most of light at a luminance value of +/− 75 °. Since the structure itself of this light emitting unit is as described above, its detailed description will be omitted.

The diffusion plate 73 diffuses and transmits the light illuminated by the light source 100. The prism sheet 75 is directed toward the LCD panel 77 by refracting the light transmitted by the diffusion plate 73.

The backlight device configured as described above can illuminate the LCD panel 70 with light having a constant luminance even by eliminating the use of the light guide plate (3 in FIG. 1) by disposing a light source in a direct light emission type.

The light emitting unit according to the present invention configured as described above uses a lens including a first refraction portion having a flat structure and a second refraction portion having a predetermined curvature to change the path of light irradiated in the vertically upward direction of the light emitting diode, It is possible to illuminate a light whose value has a direction angle distribution in the range of +/- 75 °. Therefore, when employed as a light source of the backlight device of the LCD panel, it is possible to prevent the bright light lines appearing brighter than the peripheral portion of the light emitting diode installation, and to remove the dark portion that may be generated when the conical inlet is formed in the center of the lens. In addition, the light emitting unit according to the present invention improves the bonding structure between the lens and the base to block the formation of the air layer between the lens and the dispensing member, thereby fundamentally preventing the decrease in light uniformity due to the air layer formation. In addition, the light emitting unit according to the present invention has an advantage of reducing the occurrence of ring-shaped bright lines caused by the polishing process of the lens surface by scattering the light emitted from the lens surface by matting the lens surface.

In addition, the backlight device according to the present invention can be provided with a plurality of light emitting units having the above-described structure to illuminate the light from below the LCD panel. Therefore, there is an advantage that it can be applied to a large display according to the alignment position and the number of light emitting units. In addition, since uniform light having a desired luminance can be obtained without the use of a light guide plate, it is possible to reduce the thickness, reduce the manufacturing cost, and reduce the production time.

The above embodiments are merely exemplary, and various modifications and equivalent other embodiments are possible from those skilled in the art. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the invention described in the claims below.

Claims (22)

A base; A light emitting diode mounted on the base and emitting light; A cup member formed at a predetermined height around the light emitting diode on the base; It is provided on the base, disposed on the light emitting diode side, the incident portion to which light is incident, the first refractive portion for refracting and transmitting the incident light to be formed flat in the center of the back surface of the incident portion, and around the first refractive portion Including a lens having a second refractive portion that is formed with a predetermined curvature to refractively transmit incident light, including, And the light emitted from the light emitting diode is uniformly emitted through a wide area through the lens. The method of claim 1, And a dispensing member installed inside the cup member to protect the light emitting diode. The method of claim 2, wherein the dispensing member, A light emitting unit comprising a material having a refractive index relatively lower than the refractive index of the lens, or substantially the same refractive index as the lens. The method of claim 3, The dispensing member is a light emitting unit, characterized in that made of a material satisfying the following conditional expression. Here, n _d2 represents the d-line refractive index of the dispensing member. <Conditional expression>

The method of claim 4, wherein The dispensing member is a light emitting unit, characterized in that made of a silicone resin. The method of claim 2, And the lens and the dispensing member are made of a silicone resin and are integrally formed by a direct molding process. The method of claim 1, wherein the incident portion of the lens, A light emitting unit comprising a protruding surface protruding from a plane or a predetermined curvature. The method according to any one of claims 1 to 7, Wherein the diameter of the first refraction portion is approximately 1/3 or less of the total diameter of the lens. The method according to any one of claims 1 to 7, The first refractive unit is a light emitting unit, characterized in that the spherical surface having a radius of curvature of 2mm to 10mm. The method according to any one of claims 1 to 6, The lens is a light emitting unit, characterized in that made of a transparent material satisfying the following conditional expression. Where n _d1 represents the d-line refractive index of the lens. <Conditional expression>

The method of claim 10, The lens is a light emitting unit, characterized in that made of any one material selected from epoxy resin, polymethyl methacrylate, polycarbonate, acrylic resin and silicone resin. The method according to any one of claims 1 to 7, The lens is installed on the base by a portion thereof is bonded to the cup member, A light emitting unit, characterized in that the junction of the lens and the junction of the cup member is formed in a concave-convex shape corresponding to each other so that the area facing each other. The method of claim 12, A light emitting unit, characterized in that the bonding portion of the lens and the bonding portion of the cup member are bonded to each other by an adhesive made of epoxy or silicone resin. The method according to any one of claims 1 to 7, And the surface of the lens is matted so that light passing through the lens is scattered at the first and second refractive portions. The method of claim 14, And the average roughness Ra of the lens surface is in the range of about 0.8 μm to 1.8 μm. A reflector for reflecting incident light; A light source provided with a plurality of light emitting units according to any one of claims 1 to 7 on the reflecting plate to illuminate light; A diffuser plate disposed on the light source and configured to diffuse light illuminated by the light emitting unit; And a prism sheet for converting the propagation path by refracting and transmitting the light diffused through the diffusion plate. The method of claim 16, And the diameter of the first refractive portion is about 1/3 or less of the total diameter of the lens. The method of claim 16, And the first refraction portion is a spherical surface having a radius of curvature of 2 mm to 10 mm. The method of claim 16, The lens is a direct-emitting type backlight device, characterized in that made of a transparent material satisfying the following conditional expression. Where n _d1 represents the d-line refractive index of the lens. <Conditional expression>

The method of claim 16, The lens is installed on the base by a portion thereof is bonded to the cup member, And a junction portion of the lens and a junction portion of the cup member are formed in a concave-convex shape corresponding to each other so that an area facing each other is wide. The method of claim 20, The junction of the lens and the junction of the cup member is a direct-emitting backlight device, characterized in that bonded to each other with an adhesive made of epoxy or silicone resin. The method of claim 16, Direct light emission, characterized in that the surface of the lens has an average roughness value in the range of about 0.8 μm to 1.8 μm by Matte treatment so that the light passing through the lens is scattered at the first and second refractive portions. Type backlight device.

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