KR100609592B1 - Side emitting led and lens suitable for the same - Google Patents

Abstract

Side emitting light emitting diodes and lenses suitable therefor are disclosed. The lens includes: a lower surface comprising alternating incidence surfaces and lower total reflection surfaces connected to each other at an angle relative to a central axis; An upper total reflection surface having a constant slope with respect to the central axis; And an emission surface connecting the upper total reflection surface and the lower surface. Light entering the lens through the incident surfaces directly from the light emitting diode die is refracted from the respective incident surfaces to the lower total reflection surface adjacent to the respective entrance surfaces, and is totally reflected from the lower total reflection surface to the upper total reflection surface, It is then totally reflected from the upper total reflection surface to the exit surface and discharged to the outside through the exit surface in a direction substantially perpendicular to the central axis. In addition, at least a portion of the light incident on the incident surfaces and reflected from the incident surfaces enters the lens through another lower total reflection surface adjacent to each of the incident surfaces. Accordingly, the light extraction efficiency can be improved.

Light emitting diodes, light guide plates, lenses, total internal reflection, refraction

Description

Side emitting light emitting diode and suitable lens {SIDE EMITTING LED AND LENS SUITABLE FOR THE SAME}

1 is a front view illustrating a conventional light emitting diode for backlight.

FIG. 2 is a cross-sectional view for describing a side light guide plate using the light emitting diode of FIG. 1.

3 is a perspective view of the light guide plate of FIG. 2 equipped with the light emitting diodes of FIG. 1.

4 is a cross-sectional view illustrating a conventional side-emitting light emitting diode.

FIG. 5 is a perspective view illustrating a light guide plate using the side emission light emitting diode of FIG. 4.

6 is a cross-sectional view of the light guide plate of FIG. 5 mounted with the side emission light emitting diode of FIG. 4.

7 is a cross-sectional view illustrating a lens according to an embodiment of the present invention.

8 is a partial cross-sectional view for describing the lower surface of the lens according to an embodiment of the present invention.

FIG. 9 is a partial cross-sectional view illustrating an upper total reflection surface and an emission surface of a lens according to an exemplary embodiment of the present invention. FIG.

10 is a cross-sectional view illustrating a light emitting diode according to an embodiment of the present invention.

Explanation of reference numerals for the main parts of the drawing

110: light emitting diode die, 116: center axis of the lens,

120: lens, 121a, 122a, 123a: incident surfaces,

121b, 122b, 123b: lower total reflection surfaces, 121d, 122d, 123d: corners,

127: convex, 128: total top reflection,

129: exit surface

The present invention relates to a side light emitting diode and a lens suitable therefor, and more particularly, to a side light emitting diode and a lens suitable therefor that can improve light extraction efficiency by using total reflection characteristics of light.

Passive display devices, such as liquid crystal displays, can reflect or absorb ambient sunlight or room light to produce an image. Thus, ambient sunlight or room light is required to view the displayed image. However, there is a problem in that the displayed image cannot be viewed when the intensity of ambient sunlight or room light is not sufficient to illuminate the display panel. As an alternative to this problem, a backlight panel for backlighting the display panel is generally adopted.

In general, a backlight panel includes a light guide plate and a light source such as an incandescent lamp, a fluorescent lamp, or a light emitting diode (LED). After the light emitted from the light source is incident on the light guide plate and mixed into uniform light, the image is realized by illuminating the LCD panel. On the other hand, LED is often used as a backlight light source due to its excellent color reproduction, and it is expected to increase its use in the future as it is environmentally friendly.

FIG. 1 is a front view for explaining a conventional light emitting diode 10 for backlight, and FIG. 2 is a cross-sectional view for explaining a side light guide plate 20 using the light emitting diode of FIG. 1, and FIG. 3 is light emission of FIG. FIG. 2 is a perspective view of the light guide plate 20 of FIG. 2 mounted with the diodes 10.

Referring to FIG. 1, the light emitting diode 10 has a hemispherical lens 12. In addition, the light emitting diode 10 has a reflective cup (not shown), and a light emitting diode die (not shown) is mounted inside the reflective cup. Light emitted from the LED die is emitted to the outside by the reflective cup and the lens 12 at a predetermined angle. The light emitted from the light emitting diode 10 to the outside has a constant light output pattern 14 along the central axis 16 of the lens. The light output pattern 14 emitted from the light emitting diode 10 having the hemispherical lens 12 is formed on the hemispherical lens 12 as shown, and has a predetermined width.

As shown in FIG. 2, the conventional light emitting diode 10 is coupled to a side surface of the light guide plate 20. Light emitted from the light emitting diode 10 is incident on the light guide plate 20 and propagates in the length direction of the light guide plate 20. Meanwhile, as shown in FIG. 3, a plurality of light emitting diodes 10 are mounted along the side surface of the light guide plate 20.

When the conventional light emitting diode 10 is used, a plurality of light emitting diodes 10 are mounted on the side surface of the light guide plate 20 to enable uniform backlighting. However, combining the conventional light emitting diode 10 and the light guide plate 20 is inefficient because it requires a plurality of light emitting diodes 10. In addition, since the light output pattern 14 of the light emitting diode 10 has a predetermined width, as the width of the light guide plate 20 decreases, the coupling efficiency of the light emitting diode 10 and the light guide plate 20 decreases. . That is, the ratio of light incident on the light guide plate 20 in the light emitted from the light emitting diode 10 is reduced.

A light emitting diode and a lens for solving the above problems has been disclosed by West et al. In US Pat. No. 6,679,621 entitled "side emitting LED and lens."

FIG. 4 is a cross-sectional view of the side emitting LED 30 disclosed in US Pat. No. 6,679,621. FIG. 5 is a perspective view illustrating a light guide plate 42 using the side emitting light emitting diode 30 of FIG. Is a cross-sectional view of the light guide plate 42 of FIG. 5 mounted with the side emitting light emitting diode 30 of FIG.

Referring to FIG. 4, the side emitting LED 30 includes a body 32, a light emitting diode die 36, and a lens 34. The light emitting diode die 36 is mounted on an upper surface of the main body 32. The lens 34 is coupled to the body 32 and positioned above the light emitting diode die 36.

The lens 34 includes a funnel-shaped total internal reflection surface (TIR surface) 40 and a refractive surface 38 symmetrical about the central axis 43 of the lens. The total reflection surface 40 reflects light from the lens 34 so that the light exits in a direction perpendicular to the central axis 43. On the other hand, the refracting surface 38 is formed in a sawtooth shape is refracted in the direction perpendicular to the central axis 43 to emit.

That is, the light that reaches the total reflection surface 40 through the lower surface of the lens 34 in the light emitting diode die 36 is totally reflected at the total reflection surface 40, and is refracted by the refractive surface 38 to provide the It is emitted in a direction perpendicular to the central axis 43. In addition, the light reaching the refracting surface 38 through the lower surface of the lens 34 in the LED die 36 is refracted by the refracting surface 38 and outward in a direction perpendicular to the central axis 43. Is released.

As shown in FIG. 5, the light emitting diodes 30 are mounted inside the light guide plate 42. In order to mount the light emitting diodes 30, holes 46 are formed in the light guide plate 42. Meanwhile, in order to prevent light from being emitted to the outside through the side of the light guide plate 42, a reflective coating 44 is formed on the side of the light guide plate 42. As shown in FIG. 6, the light emitted from the light emitting diode 30 is emitted to the side of the lens 34 and is incident on the light guide plate 42.

According to the U.S. Patent No. 6,679,621, by adopting the side emitting light emitting diodes 30, the number of light emitting diodes 30 can be reduced, and the coupling efficiency of the light emitting diodes 30 and the light guide plate 42 can be increased. have. However, when light emitted from the light emitting diode die 36 enters the lens 34, some of it is reflected at the bottom surface of the lens 34. The light reflected from the lower surface may be re-reflected from the main body 32 to be incident on the lens 34, but the intensity of the light due to the re-reflection decreases. Therefore, the intensity of light incident on the lens 34 is reduced, and as a result, the extraction efficiency of the light emitted from the light emitting diode 30 is reduced.

An object of the present invention is to provide a lens for a side-emitting light emitting diode that can improve the light extraction efficiency.

Another object of the present invention is to provide a side emitting light emitting diode which can improve light extraction efficiency.

In order to achieve the above technical problem, the present invention provides a side emitting light emitting diode and a lens suitable therefor. A lens suitable for a side emitting light emitting diode according to an aspect of the present invention comprises: a lower surface comprising alternating incidence surfaces and lower total reflection surfaces connected to each other at an angle relative to a central axis; An upper total reflection surface having a constant slope with respect to the central axis; And an emission surface connecting the upper total reflection surface and the lower surface.

At this time, light entering the lens through the incident surfaces directly from the LED die is refracted from the respective incident surfaces to the lower total reflection surface adjacent to the respective entrance surfaces, and totally reflected from the lower total reflection surface to the upper total reflection surface. And then totally reflected from the upper total reflection surface to the exit surface and discharged outward through the exit surface in a direction substantially perpendicular to the central axis. In addition, at least a portion of the light incident on the incident surfaces and reflected from the incident surfaces enters the lens through another lower total reflection surface adjacent to each of the incident surfaces. Accordingly, the light emitted from the light emitting diode die can be emitted side by side through the lens, and the light extraction efficiency can be improved.

On the other hand, the emission surface may be formed of a diffusion surface for emitting light emitted through the emission surface at a predetermined diffusion angle. The diffusion surface may emit light emitted at a diffusion angle of 0.2 to 3 °.

In one embodiment of the present invention, at least some of the light that is reflected at the incident surfaces and enters the lens through another lower total reflection surface adjacent to each of the incident surfaces is transferred from the other lower total reflection surface to the other lower total reflection surface. It is refracted to a neighboring incident surface, reflected from the neighboring incident surface to the upper total reflection surface, and then totally reflected at the upper total reflection surface, and is emitted to the outside through the side surface. The light emitted to the outside may be emitted in a direction substantially perpendicular to the central axis.

In addition, the incident surfaces and the lower total reflection surfaces may both be concave or convex toward the central axis. More preferably, both the incident surfaces and the lower total reflection surfaces are concave surfaces toward the central axis.

A side emitting light emitting diode according to another aspect of the present invention includes a lens and at least one light emitting diode die positioned below the bottom surface of the lens. The lens includes: a lower surface including alternating incidence surfaces and lower total reflection surfaces connected to each other at an angle relative to the central axis; An upper total reflection surface having a constant slope with respect to the central axis; And an emission surface connecting the upper total reflection surface and the lower surface.

At this time, the light entering the lens directly from the light emitting diode die through the incidence surfaces is refracted from the incidence surfaces to the lower total reflection surface adjacent to the incidence surfaces, and from the lower total reflection surface to the upper total reflection surface. Totally reflected, and then totally reflected from the upper total reflection surface to the exit surface and discharged outwardly through the exit surface in a direction substantially perpendicular to the central axis. In addition, at least a portion of the light incident on the incident surfaces and reflected from the incident surfaces enters the lens through another lower total reflection surface adjacent to each of the incident surfaces. Accordingly, light emitted from the light emitting diode die may be emitted side by side through the lens, and light extraction efficiency may be improved.

On the other hand, the emission surface may be formed of a diffusion surface for emitting light emitted through the emission surface at a predetermined diffusion angle. The diffusion surface may emit light emitted at a diffusion angle of 0.2 to 3 °.

In one embodiment of the present invention, at least some of the light that is reflected at the incident surfaces and enters the lens through another lower total reflection surface adjacent to each of the incident surfaces is transferred from the other lower total reflection surface to the other lower total reflection surface. It is refracted to a neighboring incident surface, reflected from the neighboring incident surface to the upper total reflection surface, and then totally reflected at the upper total reflection surface, and is emitted to the outside through the side surface. The light emitted to the outside may be emitted in a direction substantially perpendicular to the central axis.

In addition, the incident surfaces and the lower total reflection surfaces may both be concave or convex toward the central axis. More preferably, both the incident surfaces and the lower total reflection surfaces are concave surfaces toward the central axis.

The at least one light emitting diode may be positioned on a central axis of the lens or symmetrically with respect to the central axis.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided as examples to sufficiently convey the spirit of the present invention to those skilled in the art. Accordingly, the invention is not limited to the embodiments described below and may be embodied in other forms. In the drawings, lengths, thicknesses, and the like of layers and regions may be exaggerated for convenience. Like numbers refer to like elements throughout.

7 is a cross-sectional view illustrating a lens 120 according to an embodiment of the present invention.

Referring to FIG. 7, the lens 120 has a lower surface, an upper total reflection surface 128 and an emission surface 129 connecting the lower surface and the upper total reflection surface symmetric with respect to the central axis 116. It includes. The lens 120 is a cyclic olefin copolymer (cyclic olefin copolymer; COC), polymethylmethacrolate (PMMA), polycarbonate (PC), PC / PMMA, silicone (silicone), fluoro It may be made of a fluorocarbon polymer or polyetherimide (PEI), or the like, and may be manufactured using various techniques such as injection molding or casting.

The convex surface 127 is positioned in the central region of the lower surface. The convex surface 127 refracts light incident at a small angle with respect to the central axis 116 into light substantially parallel to the central axis 116. Thus, the convex surface 127 is not limited to a single convex surface as shown, and may be formed of multiple convex surfaces, such as a fresnel surface. The incidence surfaces 121a, 122a, 123a, and the like and the lower total reflection surfaces 121b, 122b, 123b, and the like are alternately connected to the outside from the convex surface 127. The incident surfaces 121a, 122a, 123a, etc., and the lower total reflection surfaces 121b, 122b, 123b, etc., form an angle with respect to the central axis and cross each other to form corners 121d, 122d, 123d, and the like. . Meanwhile, the incident surfaces 121a, 122a, 123a, etc., and the lower total reflection surfaces 121b, 122b, 123b, etc. may be rotation planes surrounding the central axis 116, or surfaces that traverse the ground vertically. have.

The upper total reflection surface 128 has a constant slope with respect to the central axis. The upper total reflection surface 128 is designed such that light incident in parallel to the central axis 116 is totally reflected in a direction perpendicular to the central axis 116. The upper total reflection surface 128 may be coated with a reflective material such as aluminum. The upper total reflection surface 128 is a rotation surface surrounding the central axis 116 in correspondence with the incident surfaces 121a, 122a, 123a, etc. and the lower total reflection surfaces 121b, 122b, 123b, or the like. It may be faces that traverse the ground vertically. When the upper total reflection surface 128 is a rotating surface surrounding the central axis 116, the upper total reflection surface 128 is a funnel shape.

The emission surface 129 is designed to be parallel to the central axis 116 such that the light totally reflected by the upper total reflection surface 128 is emitted in a direction perpendicular to the central axis 116. In addition, the emission surface 129 may be formed as a diffusion surface to improve the light extraction efficiency. The diffusion surface will be described later with reference to FIG. 9.

Light emitted from the light emitting diode die 110 enters the lens by directly entering the convex surface 127 and the incident surfaces 121a, 122a, 123a, and the like, and enters the incident surfaces 121a, 122a, 123a. Etc.) is prevented from directly entering the lower total reflection surfaces 121b, 122b, 123b, etc.). Light incident on the convex surface 127 proceeds to light parallel to the central axis 116 to reach the upper total reflection surface 128, and from the upper total reflection surface 128 to the emission surface 129. After total reflection, the light is emitted to the outside through the emission surface 129 in a direction perpendicular to the central axis 116. In addition, the light directly incident on the incident surfaces 121a, 122a, 123a, and the like is refracted by the incident surfaces and proceeds to adjacent lower total reflection surfaces 121b, 122b, 123b, and the like, and the lower total reflection surface Fields 121b, 122b, 123b, etc., are totally reflected in a direction parallel to the central axis 116 to the upper total reflection surface 128. Thereafter, the total reflection from the upper total reflection surface 128 to the exit surface 129 is emitted to the outside in a direction perpendicular to the central axis 116. In addition, a part of the light incident on the incident surfaces 121a, 122a, 123a, and the like is reflected at the incident surfaces. At least some of the reflected light enters the lens through another lower total reflection surface adjacent to each of the incident surfaces 121a, 122a, 123a, and the like.

As described above, the curvature and the slope of the incident surfaces 121a, 122a, 123a, etc. and the lower total reflection surfaces 121b, 122b, 123b, etc., are used to determine the center of the light emitted from the LED die 110. It is organically related to each other to face the upper total reflection surface 128 parallel to the axis 116. Hereinafter, relative relations between the incident surfaces 121a, 122a, 123a, etc. and the lower total reflection surfaces 121b, 122b, 123b, etc. will be described in detail with reference to FIG. 8.

FIG. 8 is an enlarged partial cross-sectional view of the incident surfaces 122a and 123a and the lower total reflection surfaces 122b and 123b to explain the lower surface of the lens 120 according to the exemplary embodiment.

Referring to FIG. 8, a part of light incident on the incident surface 123a in the LED die 110 is refracted by the incident surface 123a and proceeds to the lower total reflection surface 123b. The refractive angle of the incident surface 123a is determined by the refractive index of the lens 120 and the incident angle of the light. On the other hand, a part of the light incident on the incident surface 123a is reflected from the incident surface 123a and proceeds to the lower total reflection surface 122b. In this case, the reflection angle at the incident surface 123a is determined by the incident angle of the light. Here, the case where the said incident surface 123a is concave surface toward the said central axis 116 is considered as shown. However, the present invention is not limited to the case where the incident surfaces are concave surfaces, and may be convex or planar as long as the object of the present invention can be achieved.

First, when looking at the light 111 incident to the incident surface 123a closest to the edge 122d, the light 111 is refracted and reflected at the incident surface 123a to light 112 and the light ( 113). The light 112 is refracted from the incident surface 123a to the lower total reflection surface 123b and totally reflected at the lower total reflection surface 123b. In this case, the lower total reflection surface 123b has an inclination for total reflection of the light 112 in a direction parallel to the central axis 116. Meanwhile, the reflected light 113 enters the lens 120 through the lower total reflection surface 122b. Subsequently, the light 113 is totally reflected at the incident surface 122a. In this case, the light 113 may be totally reflected in a direction parallel to the central axis 116 according to the inclination of the incident surface 122a.

On the other hand, when the light 117 is incident on the incident surface 123a adjacent to the edge 123d, the light 117 is refracted and reflected at the incident surface 123a, so that the light 118 and the light 119 Separated by). The light 118 is refracted from the incident surface 123a to the lower total reflection surface 123b and totally reflected at the lower total reflection surface 123b. In this case, the lower total reflection surface 123b has an inclination for total reflection of the light 118 in a direction parallel to the central axis 116. Meanwhile, the reflected light 119 enters the lens 120 through the lower total reflection surface 122b. Subsequently, the light 119 is totally reflected at the incident surface 122a. In this case, the light 119 may be totally reflected in a direction parallel to the central axis 116 according to the inclination of the incident surface 122a.

On the other hand, light incident on the incident surface 123a in the LED die 110 is incident between the light 111 and the light 117. When such light is refracted at the incident surface 123a, it is refracted to diverge between the light 112 and the light 118. Therefore, when the lower total reflection surface 123b has a constant curvature as shown, the refracted light is totally reflected at the lower total reflection surface 123b to the upper portion between the light 112 and the light 118. It runs parallel to the axis 116. In addition, the light incident on the incident surface 123a is reflected between the light 113 and the light 119 when reflected from the incident surface 123a and is a path between the light 113 and the light 119. Proceed along.

9 is a partial cross-sectional view for describing the upper total reflection surface 128 and the exit surface 129 of the lens 120 according to an embodiment of the present invention.

Referring to FIG. 9, as described with reference to FIGS. 7 and 8, total reflection in parallel with the central axis 116 in the light and lower total reflection surfaces 121b, 122b, 123b, etc., refracted at the convex surface 127. The lights R1, R2, R3, etc. reach the upper total reflection surface 128. On the other hand, the upper total reflection surface 128 has a constant slope with respect to the central axis (116). Accordingly, the lights R1, R2, R3, and the like are totally reflected in the same direction at the upper total reflection surface 128. In this case, when the total reflection surface 128 has an inclination of 45 ° with respect to the central axis, the lights R1, R2, R3, etc. are totally reflected in the direction perpendicular to the central axis 116. In this case, the emission surface 129 is designed to be parallel to the central axis 116 so that the light totally reflected in the direction perpendicular to the central axis 116 is emitted in the same direction. Preferably, the exit surface 129 may be a diffusion surface. The diffuse surface emits emitted light at a predetermined diffuse angle. In this case, the diffusion angle may be 0.2 ~ 3 °.

10 is a cross-sectional view illustrating an embodiment of a light emitting diode according to another aspect of the present invention.

Referring to FIG. 10, the light emitting diode includes a light emitting diode die 110 and a lens 120 described with reference to FIGS. 7 to 9. The light emitting diode die 110 is positioned below the lens 120 and is positioned on the central axis 116 of the lens. Meanwhile, the LED die 110 may be two or more LED dies. In this case, the LED dies are symmetrically positioned with respect to the center axis 116 line of the lens 120.

Meanwhile, the light emitting diode die 110 is mounted on the main body 130. A reflective cup (not shown) may be provided on the main body 130, and the LED die 110 may be mounted inside the reflective cup. In addition, the body 130 is provided with electrodes for connecting the LED die 110 to an external power source. The light emitting diode die 110 is electrically connected to the electrodes.

The lens 120 may be coupled to the main body 130 using various coupling members (not shown). For example, a hook may be integrally formed on the lens 120 to be coupled to the main body 130, and the lens 120 may be bonded to the main body 130 using a bonding material.

Meanwhile, the space between the lens 120 and the main body 130 may be in an air state or a vacuum state, and may be filled using a molding member such as resin, silicon, epoxy, or the like. The molding member has a refractive index, and the refractive index of the molding member is preferably smaller than the refractive index of the lens 120. The molding member may contain a phosphor.

According to the present invention, it is possible to provide a lens for a side emitting light emitting diode which can improve the light extraction efficiency by increasing the intensity of light emitted from the light emitting diode die and entering the lens, compared to the prior art, and using the lens It is possible to provide a side emitting light emitting diode that can improve extraction efficiency.

Claims (6)

A lens suitable for a side emitting light emitting diode, A lower surface comprising alternating incidence surfaces and lower total reflection surfaces connected to each other at an angle relative to a central axis; An upper total reflection surface having a constant slope with respect to the central axis; And And a light emitting surface connecting the upper total reflection surface and the lower surface. The method according to claim 1, The emission surface is a lens, characterized in that consisting of a diffusion surface for emitting light emitted through the emission surface at a diffusion angle of 0.2 ~ 3 °. The method according to claim 1, Light entering the lens through the incident surfaces directly from the light emitting diode die is refracted from the respective incident surfaces to the lower total reflection surface adjacent to the respective entrance surfaces, and is totally reflected from the lower total reflection surface to the upper total reflection surface, And then totally reflected from the upper total reflection surface to the emission surface and discharged to the outside through the emission surface in a direction substantially perpendicular to the central axis, At least a portion of the light incident on the incident surfaces and reflected from the incident surfaces enters the lens through another lower total reflection surface adjacent to each of the incident surfaces. The method according to claim 3, At least a portion of the light reflected from the incident surfaces and entering the lens through another lower total reflection surface adjacent to each of the incident surfaces is refracted from the other lower total reflection surface to an incident surface neighboring the other lower total reflection surface, And reflecting from the neighboring incident surface to the upper total reflection surface, and then totally reflecting at the upper total reflection surface and emitting to the outside through the side surface. The method according to claim 1, And the incident surfaces and the lower total reflection surfaces are both concave toward the central axis. The lens of any one of claims 1 to 5; And At least one light emitting diode die positioned below the bottom surface of the lens.

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