KR20090032864A - Light emitting diode package having asymmetric lens - Google Patents

Abstract

A light-emitting diode package having lens is provided to prevent the reduction of the luminous efficiency by forming the lens into the curved surface along the second direction. A light-emitting diode package comprises a package body(11), the first and second leads(13a,13b), a light emitting diode die, and a lens(33). The light-emitting diode package comprises a heat sink and a molding unit. The package body supports the first and second leads. The package body has the opening exposing the parts of leads. The leads expose the package body to the outside. The heat sink emits the heat generated from the light emitting diode die to the outside. The light emitting diode die is mounted to the package body. The light emitting diode die is electrically connected to the first and second leads. The lens covers the light emitting diode die and bonding wires.

Description

Light emitting diode package with lens {LIGHT EMITTING DIODE PACKAGE HAVING ASYMMETRIC LENS}

The present invention relates to a light emitting diode package, and more particularly to a light emitting diode package having a lens of a specific shape for increasing the directional angle in the uniaxial direction.

In general, the light emitting diode package includes a package body and a light emitting diode mounted on the package body. Light emitting diodes have the advantages of small size, long life and low power over incandescent, fluorescent and discharge light sources.

1 is a perspective view illustrating a light emitting diode package according to the related art, and FIG. 2 is a schematic cross-sectional view of FIG. 1.

1 and 2, the light emitting diode package includes a package body 11 having a first lead 13a and a second lead 13b, a light emitting diode die 17, and a lens 23. . The light emitting diode package may include a heat sink 15 for dissipating heat generated in the light emitting diode die 17 for high power. In addition, the molding part 21 containing the phosphor may cover the LED die 17.

The light emitting diode die 17 is electrically connected to the first and second leads 13a, 13b, for example, via bonding wires 19a, 19b. The leads are connected to an external power source to drive the LED die 17 to emit light.

On the other hand, the lens 23 has a generally hemispherical shape and is formed by a molding technique. The light emitted from the light emitting diode die 17 by this lens 23 is emitted at a high light output within a certain direction angle.

However, a light emitting diode package having a hemispherical lens according to the prior art emits light symmetrically about its center within a certain direction angle. Such a light emitting diode package emits symmetrical light and can be used in various applications. However, the conventional LED package has a disadvantage in that the number of LEDs needs to be increased when used in applications requiring rectangular light emission, such as a rectangular backlight unit or an LED channel letter. The increase in the number of LEDs thus leads to an increase in the elements necessary for heat dissipation, such as heat sinks and means for thermally bonding them externally, thus increasing the final product cost.

On the other hand, in order to increase the directivity of the light emitting diode package to replace the hemispherical lens, various shapes of lenses, such as Fresnel (Fresnel) lens, concave lens and the like have been studied. However, these lenses have a disadvantage in that luminous efficiency is reduced compared to hemispherical lenses due to the light loss therein.

An object of the present invention is to provide a light emitting diode package suitable for applications requiring a rectangular light output.

SUMMARY OF THE INVENTION An object of the present invention is to provide a light emitting diode package having a lens capable of increasing the directional angle in the uniaxial direction while preventing a decrease in luminous efficiency.

To solve the above problems, the present invention provides a light emitting diode package including a lens covering the light emitting diode die. According to embodiments of the present invention, the lens has a vertical cross section taken to cross its center along a first direction compared to a vertical cross section taken to cross its center along a second direction perpendicular to the first direction. It has a relatively rectangular shape, and the vertical cross section taken to cross its center along the second direction is formed to have a semi-ellipse shape relative to the vertical cross section taken to cross its center along the first direction.

Here, the vertical cross sections refer to some vertical cross sections from the top surface of the lens of the lens, rather than the entire vertical cross sections from the top surface to the bottom surface of the lens.

According to embodiments of the present invention, the lens forms a convex curved surface along the second direction to prevent the luminous efficiency from decreasing and increases the directivity angle of the light emitted in the first direction.

Meanwhile, the vertical cross section taken to cross the center along the first direction may have a quadrangular shape. In other words, the upper edge of the vertical cross-section and both edges subsequent thereto may be a straight line.

In addition, the vertical cross-section taken to cross its center along the second direction may be hemispherical. That is, the semi-elliptic shape may be hemispherical.

On the other hand, the lens can be symmetrical about a vertical cross section taken to cross its center. Such lenses exhibit symmetrical luminescent properties in either direction.

Further, the vertical cross section taken away from the center of the lens and parallel to the first direction may have a smaller height and width than the vertical cross section taken to cross the center thereof. In addition, the vertical cross-section taken parallel to the first direction may become smaller in height and width as it moves away from the center of the lens. Accordingly, the hemispherical lens can be easily replaced with the lens of the present invention which can increase the directivity angle in the first direction in the LED package employing the conventional hemispherical lens.

Meanwhile, the center of the lens may be positioned above the LED die, so that the LED package emits symmetrical light in a first direction and a second direction about the LED die.

The LED package may further include a package body having first and second leads, and the LED die is mounted on the package body and electrically connected to the first and second leads.

According to embodiments of the present invention, it is possible to provide a light emitting diode package suitable for an application requiring a rectangular light output by increasing the direction angle along the first direction. In addition, it is possible to provide a light emitting diode package capable of preventing a reduction in luminous efficiency by forming a curved surface along the second direction of the lens.

Hereinafter, with reference to the accompanying drawings will be described embodiments of the present invention; The following embodiments are provided as examples to ensure that the spirit of the present invention can be fully conveyed to those skilled in the art. Accordingly, the invention is not limited to the embodiments described below and may be embodied in other forms. And, in the drawings, the width, length, thickness, etc. of the components may be exaggerated for convenience. Like numbers refer to like elements throughout.

3 is a perspective view illustrating a light emitting diode package having a lens according to an embodiment of the present invention, and FIGS. 4 and 5 are cross-sectional views taken along a first direction and a second direction to cross the center of the lens, respectively. admit.

3 to 5, the light emitting diode package includes a package body 11, first and second leads 13a and 13b, a light emitting diode die 17, and a lens 33. In addition, the LED package may include a heat sink 15 and a molding part 21.

The package body 11 supports the first and second leads 13a and 13b. The package body 11 has an opening that exposes portions of the leads 13a and 13b, and the leads extend from portions exposed to the opening to protrude out of the package body 11. Leads 13a and 13b protruding to the outside may be bent to allow surface mounting, as shown. The package body may be formed using an insert molding technique after positioning the first and second leads 13a and 13b.

The heat sink 15 transfers heat generated from the light emitting diode die 17 to the outside and releases the heat. In order to promote heat dissipation, the heat sink 15 may have a wide bottom surface, and may have a protrusion for mounting the light emitting diode 17 at the center thereof. The heat sink 15 may be insert molded together with the leads 13a and 13b to be supported by the package body 11, but the heat sink 15 is not limited thereto. After the package body 11 is formed, the package body 11 is formed. It may be inserted in (11).

The LED die 17 is mounted on the package body 11 and electrically connected to the first and second leads 13a and 13b. As shown, the LED die 17 may be mounted on the heat sink 15 and electrically connected to the first and second leads 13 and 13b through the bonding wires 19a and 19b. .

The light emitting diode 17 has two electrodes. The two electrodes may be located on the upper side of the light emitting diode 17 as shown, in which case bonding wires 19a and 19b are connected to the two electrodes, respectively. Alternatively, the two electrodes may be located on both sides of the light emitting diode 17, that is, the upper and lower portions, respectively. In this case, one electrode may be electrically connected to the heat sink 15 by a conductive adhesive, and the other electrode may be electrically connected to the first lead 13a through the bonding wire 19a. In this case, the second lead 13b is electrically connected to the heat sink 15 through a bonding wire or directly. In addition, the light emitting diode 17 may have a flip chip structure. In this case, a submount (not shown) is interposed between the light emitting diode 17 and the heat sink 15, and the bonding wires are submounted. And leads 13a and 13b may be connected. The LED 17 may have various structures, and a method of electrically connecting the LED die and the leads may be variously selected.

On the other hand, the upper surface of the light emitting diode 17, as shown, may be located below the upper surface of the package body 11, but is not limited to this, it is located above the package body 11 can do. When the upper surface of the light emitting diode 17 is located above the upper surface of the package body 11, the light emitted from the light emitting diode 17 may be prevented from being reflected from the inner wall of the opening of the package body 11.

On the other hand, a lens 33 covers the light emitting diode die 17 and the bonding wires. The lens 33 may be formed by molding epoxy or silicon on the package body 11. The lens 33 protects the light emitting diode die 17 and the bonding wires 19a and 19b from the external environment, that is, moisture and external force, and adjusts the direction or emission direction of the light.

The lens 33 according to the embodiments of the present invention is taken to cross its center along a first direction (direction perpendicularly across the leads 13a, 13b in FIG. 3), as shown. The vertical cross section (see FIG. 4) has a rectangular shape and is taken vertically across the center along a second direction (the direction of the leads 13a and 13b) orthogonal to the first direction (see FIG. 5). It is formed to have a semi-elliptic shape, for example, a hemispherical shape.

Here, the center of the lens 33 may be located above the LED die 17, but is not limited thereto. The center of the lens 33 may be located off the top of the LED die 17. In addition, the lens 13 may be symmetrical with respect to the vertical cross section taken to cross the center thereof, but is not limited thereto. However, as shown in FIG. 3, the lens 33, which is symmetrical with respect to the vertical cross section crossing the center of the lens 33, may exhibit symmetric light emission characteristics in any direction.

According to the exemplary embodiments of the present invention, the upper surface of the lens 33 forms a semi-elliptic curved surface in the second direction, thereby reducing the luminous efficiency of the light emitted from the LED die 17. The light can be emitted to the outside. In addition, since the upper surface of the lens 33 has a linear shape in the first direction, the directivity angle of the light emitted in the first direction is increased.

In addition, the vertical cross section taken out of the center of the lens 33 and parallel to the first direction may have a smaller height and width than the vertical cross section taken to cross the center thereof. Such a lens 33 means that the height and width of the vertical cross section taken to cross the center thereof are the largest compared to the vertical cross section taken at another part. This lens 3 also includes having a partially flat surface on its upper surface.

In addition, the vertical cross section taken parallel to the first direction may become smaller in height and width as it moves away from the center of the lens. Such a lens shape means that a portion where the side surfaces and the upper surface of the lens meet as shown in FIG. 3 goes downward from the first direction to the second direction. Accordingly, it is possible to easily form a lens having a generally circular shape with a lower surface such that the first direction and the second direction have different shapes, and as a result, a hemispherical shape in a light emitting diode package employing a conventional hemispherical lens. The lens of the image can be easily replaced with the lens of the present invention which can increase the directivity angle in the first direction.

Meanwhile, the molding part 21 may be interposed between the light emitting diode 17 and the lens 33. The molding part 21 is formed to cover the light emitting diode 17 before molding the lens 33. As shown in FIG. 4 or 5, the molding part 21 may be defined on the upper surface of the heat sink 15, but is not limited thereto and may be formed to fill the opening. The molding part 21 may be formed of epoxy or silicon, and may be formed of the same material as the lens 33.

Meanwhile, the molding part 21 and / or the lens 33 may include a phosphor for wavelength converting a part of the light emitted from the light emitting diode 17. Accordingly, it is possible to implement multicolor light, for example white light, using the light emitting diode 17 emitting light of a single wavelength.

In the present embodiment, it has been described that the vertical cross section of the lens 33 has a quadrangular shape so as to cross its center taken along the first direction, but the vertical cross section of the lens 33 is not limited to a quadrangular shape of a straight line. That is, the vertical cross section of the lens 33 taken to cross its center along the first direction has a quadrangle shape relative to the vertical cross section of the lens 33 taken to cross its center along the second direction. Can be. Further, the vertical cross section of the lens 33 taken to cross its center along the second direction has a semi-ellipse shape relative to the vertical cross section of the lens 33 taken to cross its center along the first direction. It may be.

In addition, in the present embodiment, the package in which the light emitting diode die 17 is mounted on the package body 11 having the first and second leads 13a and 13b has been described, but is not limited thereto. It can be applied to all kinds of packages adopting 33, for example, chip-type LEDs, top-view LEDs, and lamp LEDs.

6 is a graph simulating light emission intensity in a first direction and a second direction with respect to a light emitting diode package according to an embodiment of the present invention.

Here, the light emitting diode package was set under the same conditions except for the shape of the lens in the first direction and the second direction. On the other hand, the lens was set to have the shape shown in FIG. That is, a simulation was performed on a lens formed to have a rectangular shape in which a vertical cross section parallel to the first direction is smaller as the distance from the center of the lens 33 becomes smaller, and the center of the lens 33 is along the first direction. The vertical cross section taken to cross is square and the vertical cross section taken to cross the center of the lens 33 along the second direction is set to have a hemispherical shape.

Referring to FIG. 6, the light output 43 along the second direction showed the maximum light emission intensity at the center thereof, similarly to the general light output graph of the hemispherical lens. On the other hand, the light output 41 along the first direction showed the maximum light emission intensity at a predetermined angle away from the center thereof. On the other hand, the angular range representing the luminescence intensity of 1/2 or more with respect to the maximum luminescence intensity, that is, the direction angle range, is wider than the graph of the light output 41 along the first direction than the graph of the light output 43 along the second direction. It can be seen that. This indicates that the directivity angle distribution of the light output 41 in the first direction is further increased compared to the directivity angle distribution of the light output 43 in the second direction having a hemispherical shape.

1 is a perspective view illustrating a light emitting diode package according to the prior art.

2 is a schematic cross-sectional view of FIG. 1 for explaining a light emitting diode package according to the prior art.

3 is a perspective view illustrating a light emitting diode package having a lens according to an embodiment of the present invention.

4 and 5 are schematic cross-sectional views taken along a first direction and a second direction to cross the center of the lens of FIG. 3, respectively.

6 is a graph simulating light emission intensity in a first direction and a second direction with respect to a light emitting diode package according to an embodiment of the present invention.

Claims (8)

A light emitting diode package comprising a lens covering a light emitting diode die, The lens has a relatively rectangular shape compared to a vertical cross section taken such that a vertical cross section taken to cross its center along a first direction crosses its center along a second direction perpendicular to the first direction. A light emitting diode package formed such that a vertical cross section taken to cross its center along two directions has a semi-ellipse shape relative to a vertical cross section taken to cross its center along the first direction. The method according to claim 1, The light emitting diode package of claim 1, wherein the vertical cross-section taken to cross its center along the first direction has a rectangular shape. The method according to claim 1, A light emitting diode package having a hemispherical vertical cross section taken across the center along the second direction. The method according to claim 1, And the lens is symmetrical about a vertical cross section taken to cross its center. The method according to claim 1, And a vertical cross section taken away from the center of the lens and parallel to the first direction has a smaller height and width than the vertical cross section taken to cross the center thereof. The method according to claim 5, The vertical cross-section taken parallel to the first direction is smaller in height and width as the distance away from the center of the lens. The method according to claim 1, The center of the lens is a light emitting diode package located above the light emitting diode die. The method according to claim 1, Further comprising a package body having first and second leads, The LED die is mounted on the package body and electrically connected to the first and second leads.

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