KR20150037220A - Lighting unit having remote phosphor - Google Patents

Abstract

The present invention relates to a light emitting device including a remote fluorescent substance with improved light emitting efficiency. A light emitting device according to the present invention includes: a light emitting diode chip; And a phosphor film disposed apart from the light emitting diode chip and including phosphors dispersed in the phosphor film, wherein the refractive index of the phosphor film is decreased as the distance from the light emitting diode chip is increased.

Description

TECHNICAL FIELD [0001] The present invention relates to a light emitting device including a remote fluorescent material,

The present invention relates to a light emitting device. More particularly, the present invention relates to a light emitting device including a remote fluorescent material.

A light emitting device including a phosphor refers to a light source that converts a wavelength of intrinsic luminescent color using a phosphor powder to obtain a desired luminescent color. In particular, a light emitting device including a phosphor for white implementation has been actively developed as a high power, high efficiency light source that can replace a backlight of a lighting device or a display device.

In order to manufacture a high-efficiency white light emitting device, it is necessary to uniformly coat the phosphor on the blue or ultraviolet light emitting diode chip. Accordingly, various methods of applying the phosphor on the light emitting diode chip have been taken into consideration. Typical examples thereof include a slurry method, a conformal method, and a remote method.

The slurry method is the most convenient but currently widely used method of applying phosphors. Though the slurry method is simple, unevenness of color occurs due to irregularities of the thickness of the phosphor film, deterioration of the phosphor occurs due to high temperature, and the light conversion efficiency of the phosphor is lowered. In addition, since the phosphor hermetically closes the light emitting diode chip, the light emitted from the light emitting diode chip is reflected again into the light emitting diode chip, thereby further reducing the light conversion efficiency. Therefore, it is not suitable for a long-life light emitting device because it reduces phosphor extraction efficiency and lifetime.

The conformal method is a method of uniformly applying a phosphor film to all surfaces of a light emitting diode chip. In the case of such a coating method, the uniformity of light is excellent. However, application of the phosphor according to the conforma method is not applied to the upper and side portions of the phosphor film with the same thickness, but the thickness of the phosphor film must be applied differently depending on the amount of emitted light. Therefore, the manufacturing cost of the light emitting device increases. Also in this method, deterioration of the phosphor is still problematic.

In the remote method, the phosphor is not disposed on the surface of the light-emitting diode chip, but spaced apart from the light-emitting diode chip. That is, a phosphor layer or a phosphor layer is formed on the substrate including the light emitting diode chip or the substrate including the light emitting diode chip. Therefore, as compared with other methods, there is little phenomenon of reduction in light conversion efficiency due to the deterioration of the phosphor and high color stability makes it possible to provide a white light source of uniform color.

U.S. Patent No. 5959316 discloses a semiconductor device having a light-emitting diode covered with a transparent spacer that separates the LED from a phosphor layer of uniform thickness. Referring to Figure 3 of that application, there is shown a lead frame with a reflector that supports the LED. The transparent separator encapsulates the LED, and the phosphor is disposed on the transparent separator.

However, since there is a difference between the refractive index of the phosphor film or the phosphor layer including the phosphor used in the light emitting diode package and the refractive index of the atmosphere, a method of increasing the total reflection critical angle and improving the luminous efficiency of the light emitting device has been desired.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a light emitting device including a remote fluorescent substance with improved luminous efficiency.

Disclosure of Invention Technical Problem [8] The present invention provides a light emitting device including a remote fluorescent material having improved luminous efficiency by reducing a refractive index difference between a phosphor film included in a light emitting device and the atmosphere.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a light emitting device including a remote fluorescent material capable of preventing deterioration of a phosphor included in a light emitting device.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a light emitting device having improved luminous efficiency in all directions of a light emitting device.

A light emitting device according to an embodiment of the present invention includes a light emitting diode chip; And a phosphor film disposed apart from the LED chip and including phosphors dispersed therein, the refractive index of the phosphor film being smaller as the distance from the LED chip is decreased. Therefore, deterioration of the phosphors dispersed in the phosphor film can be prevented, and the luminous efficiency can be improved.

The phosphors included in the light emitting device according to an embodiment of the present invention may be dispersed so that the scattering angle decreases as the distance from the light emitting diode chip increases.

The phosphors included in the light emitting device according to an exemplary embodiment of the present invention may be dispersed so as to have a larger diameter as the distance from the light emitting diode chip increases.

The phosphor film included in the light emitting device according to an exemplary embodiment of the present invention may have a lower density as the distance from the light emitting diode chip increases.

The diameters of the phosphors included in the light emitting device according to an embodiment of the present invention may be in the range of 5 to 20 mu m.

The phosphor film included in the light emitting device according to an embodiment of the present invention may have a laminated structure in which at least two phosphor films are laminated.

The phosphor film included in the light emitting device according to another embodiment of the present invention includes a first phosphor film disposed closest to the light emitting diode chip and dispersed by the first phosphors, a second phosphor film disposed farthest from the light emitting diode chip, And a second phosphor film disposed between the first phosphor film and the third phosphor film and in which the second phosphors are dispersed.

The first phosphors dispersed in the first phosphor film included in the light emitting device according to another embodiment of the present invention have a smaller size than the second and third phosphors dispersed in the second and third phosphor films, The second phosphors dispersed in the second phosphor layer may have a smaller size than the third phosphors dispersed in the third phosphor layer.

The density of the first phosphor film included in the light emitting device according to another embodiment of the present invention may be greater than the density of the second and third phosphor films and the density of the second phosphor film may be greater than the density of the third phosphor film. Through this, the refractive index of the phosphor film can be decreased stepwise.

The first to third phosphors included in the light emitting device according to another embodiment of the present invention may have a diameter of 5 to 20 탆.

The first phosphors included in the light emitting device according to another embodiment of the present invention may be red phosphors, the second phosphors may be green or yellow phosphors, and the third phosphors may be blue phosphors.

The phosphors included in the light emitting device according to one embodiment of the present invention may include at least one of a silicate-based fluorescent material, a YAG-based fluorescent material, a nitride-based fluorescent material, and a TAG-based fluorescent material.

The light emitting device according to an embodiment of the present invention may further include a support film, and the phosphor film may be disposed on the support film.

The phosphor film included in the light emitting device according to an embodiment of the present invention includes at least one transparent material of silicon, epoxy, glass, and plastic, and the phosphors may be dispersed in the transparent material.

The phosphor film included in the light emitting device according to an embodiment of the present invention may surround the front surface of the LED chip.

The phosphor film included in the light emitting device according to an embodiment of the present invention may be spherical.

The light emitting diode chip included in the light emitting device according to an embodiment of the present invention may be a blue light emitting diode chip or an ultraviolet light emitting diode chip.

A light emitting device according to another embodiment of the present invention includes a light emitting diode chip; And a phosphor film disposed between the light emitting diode chip and the phosphor dispersed therein, wherein the scattering angle of the phosphor film is reduced as the distance from the light emitting diode chip increases.

The phosphors included in the light emitting device according to another embodiment of the present invention may be dispersed so as to have a larger diameter as the distance from the light emitting diode chip increases.

The diameter of the phosphors included in the light emitting device according to another embodiment of the present invention may be in the range of 5 to 20 mu m.

The light emitting device according to the present invention can prevent deterioration of the phosphor and prevent reduction in the light conversion efficiency of the phosphor. Further, the difference in refractive index between the phosphor film included in the light emitting element and the atmosphere can be reduced, and the luminous efficiency can be improved. Since the refractive index of the phosphor film can be decreased stepwise or continuously, the total reflection critical angle at the time of light extraction can be increased stepwise or continuously. In addition, the luminous efficiency can be improved by distributing the phosphors having a small scattering angle and high strength to the phosphor film disposed farthest from the LED chip.

1 is a perspective view illustrating a light emitting device according to an embodiment of the present invention.
2 is a cross-sectional view illustrating a light emitting device according to an embodiment of the present invention.
3 is a cross-sectional view illustrating a portion of a light emitting device according to an embodiment of the present invention.
4 is a cross-sectional view illustrating a portion of a light emitting device according to another embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to designate the same or similar components throughout the drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. In addition, the preferred embodiments of the present invention will be described below, but it is needless to say that the technical idea of the present invention is not limited thereto and can be variously modified by those skilled in the art.

1 and 2 are a perspective view and a cross-sectional view illustrating a light emitting device according to an embodiment of the present invention. 1 and 2, the light emitting device may include a light emitting diode chip 110, a substrate 120, a support 130, a phosphor film 140, and a phosphor 150.

The light emitting diode chip 110 may be mounted on the substrate 120. The light emitting diode chip 110 may be a blue light emitting diode chip or an ultraviolet light emitting diode chip.

The light emitting diode chip 110 has a shape in which a basic light emitting diode chip composed of one active layer for emitting light and two cladding layers surrounding it, and a basic type light emitting diode chip are turned upside down and fixed on a silicon submount, Emitting diode chip and a basic type light emitting diode chip, which are structures that emit a light emitting diode chip, and a vertical type light emitting diode chip in which electrodes are formed without removing a laminated part. The light emitting device according to the present invention is not limited to the above-described types and shapes of the LED chip, and various LED chips may be used according to the purpose of the present invention.

The substrate 120 may supply current to the light emitting diode chip 110. Although not shown, depending on the type of light emitting diode chip 110, the substrate 120 may include electrodes, bumps, wires, and the like. The substrate 120 may be a ceramic substrate, a metal substrate, a PCB substrate, or a plastic substrate. When the light emitting diode chip 110 is grown on the substrate 120, the substrate 120 may be a nitride substrate or a sapphire substrate. Although not shown, the substrate 120 may be configured to include a recess, and the light emitting diode chip 110 may be disposed in the recess. In this case, the concave portion included in the substrate 120 may have a reflecting portion, the reflecting portion may reflect upward the light emitted from the side surface of the LED chip 110, and the fluorescent film covering the LED chip 110 (140) may be in planar or hemispherical form.

The support member 130 may support the substrate 120 on which the light emitting diode chip 110 is mounted. The support 130 may be electrically or physically connected to the substrate 120.

When the support 130 is electrically connected to the substrate 120, the support 130 may supply current to the substrate 120. The support base 130 may be formed of various thicknesses and materials in consideration of the shape and weight of the substrate 120 to be supported. For example, the support 130 may comprise metal, ceramic or plastic.

The phosphor film 140 may be spaced apart from the light emitting diode chip 110. The shape of the phosphor film 140 may be spherical to surround the LED chip 110 and / or the substrate 120. In the light emitting device of FIGS. 1 and 2, the phosphor film 140 is shown surrounding the LED chip 110 and the substrate 120, but the shape of the phosphor film 140 is not limited thereto. For example, the phosphor film 140 is disposed apart from the light emitting diode chip 110, but both ends thereof may be in contact with the substrate 120. That is, in the form of a hemisphere surrounding the front surface and the side surface of the light emitting diode chip 110.

The phosphor film 140 may include a transparent material. The phosphor film 140 may include at least one of silicon, epoxy, glass, plastic, and resin.

The phosphor film 140 may be formed as a single layer or a multilayer. The phosphor film 140 may be formed by a method of spin coating or laminating a film.

The phosphors 150 may be distributed in the phosphor film 140. The phosphor 150 may be a silicate-based fluorescent material, a YAG-based fluorescent material, a nitride-based fluorescent material, and a TAG-based fluorescent material. The phosphor 150 is not limited to the above-described phosphors, and may include various kinds of phosphors depending on the type of the LED chip 110 to be disposed. The phosphor 150 may be red, yellow, green, and blue phosphors.

The diameter of the phosphor 150 may be 5 to 20 占 퐉. When the shape of the phosphor 150 is not spherical, the longest length of the phosphor 150 may be 5 to 20 占 퐉.

In the light emitting device according to an embodiment of the present invention, the phosphors 150 may be disposed with a certain purpose. The arrangement of the phosphors 150 will be described later in detail in Fig.

3 is a cross-sectional view illustrating one region of a light emitting device according to an embodiment of the present invention. Referring to FIG. 3, the light emitting device may include a light emitting diode chip 110, a substrate 120, a phosphor film 140, and a phosphor 150. Since the same constituent elements have been described in the light emitting element of Fig. 2, redundant explanations are omitted.

The phosphor 150 may be dispersed so as to have a larger diameter as the distance from the light emitting diode chip 110 increases. Accordingly, the phosphors 150 dispersed in the phosphor film 140 closest to the LED chip 110 have the smallest diameter and the phosphor 150 dispersed in the phosphor film 140 farthest from the LED chip 110, May have the largest diameter.

Since the phosphors 150 included in the light emitting device according to an embodiment of the present invention have a diameter of 5 mu m or more, the Fraunhofer theory and the mie optical theory are applied to the diffraction and scattering characteristics of the particles . Specifically, the Fraunhofer theory can be applied when the diameter of the phosphor is about 10 탆 or more, and the mie optical theory can be applied when the diameter is about 10 탆 or less. According to the Fraunhofer theory, the scattering intensity is proportional to the particle size, and the diffraction angle is inversely proportional to the particle size. Accordingly, in the case of the phosphors 150 having a small particle size disposed close to the LED chip 110, the light irradiated to the phosphors 150 increases scattering, but the intensity is small. In addition, in the case of the phosphors 150 having a large particle size disposed at a distance from the light emitting diode chip 110, the light irradiated to the phosphors 150 reduces the scattering, but the intensity thereof is high. The light emitting device according to an embodiment of the present invention is characterized in that phosphor particles having a large scattering angle and relatively low scattering intensity are disposed near the light emitting device and the phosphor particles having a small scattering angle and high scattering strength are scattered away from the light emitting device, And the emission efficiency is improved by using the size distribution of the phosphor particles.

That is, when phosphors are precipitated and distributed in the molding resin portion according to the related art, among the phosphors of various sizes, relatively large-sized phosphors are rapidly precipitated and distributed near the LED chip. In contrast, according to embodiments of the present invention, phosphors having a relatively small particle size are distributed near the light emitting diode chip.

Further, the phosphor film 140 may have a lower density as the distance from the light emitting diode chip 110 increases. Although not shown, when the size of the phosphors 150 is the same, the number of the phosphors 150 distributed per unit volume in the region adjacent to the LED chip 110 may be large. In a region apart from the LED chip 110, The number of phosphors 150 distributed per unit volume may be small. When the size of the phosphor 150 is different, that is, the phosphor 150 having a relatively large particle size is disposed outside the phosphor film 140, and the phosphor 150 having a relatively small particle size is disposed on the phosphor film 150 The mass of the fluorescent material 150 distributed per unit volume in the region adjacent to the light emitting diode chip 110 may be heavy and the fluorescent material 150 distributed in the region separated from the light emitting diode chip 110 150 may be small in mass.

If the density of the phosphor film 140 becomes smaller toward the outside, the refractive index may also become smaller toward the outside. The smaller the difference between the outermost refraction index of the phosphor film 140 and the refraction index of air, the higher the critical angle for total reflection, and thus the luminous efficiency can be improved.

Therefore, the light emitting device according to the present invention can reduce the density of the phosphor film 140 as the distance from the light emitting diode chip 110 increases, thereby improving the luminous efficiency.

4 is a cross-sectional view illustrating a portion of a light emitting device according to another embodiment of the present invention. Referring to FIG. 4, the light emitting device includes a light emitting diode chip 110, a substrate 120, a phosphor film 140, and a phosphor 150. The phosphor film 140 includes a first phosphor film 140a, a second phosphor film 140b, and a third phosphor film 140c. The phosphor 150 includes a first phosphor 150a, a second phosphor 150b, and a third phosphor 150c.

The first phosphor film 140a may be disposed closest to the light emitting diode chip 110. The third phosphor film 140c can be packed farthest from the light emitting diode chip 110. [ The second phosphor film 140b may be disposed between the first and second phosphor films 140a and 140c. The first fluorescent material 150a may be distributed to the first fluorescent material layer 140a, the second fluorescent material 150b may be distributed to the second fluorescent material layer 140b, and the third fluorescent material 150c may be distributed to the third fluorescent material layer 140c have.

The density of the phosphor film 140 can be reduced in the order of the first phosphor film 140a, the second phosphor film 140b, and the third phosphor film 140c. That is, the phosphor film 140 of the light emitting device according to another embodiment of the present invention may have a stepwise lower density. In this case, the effect of lowering the refractive index can be obtained similarly to the above. However, in the case of this embodiment, the refractive index can be lowered stepwise.

The sizes of the phosphors 150 may be larger in the order of the first phosphor 150a, the second phosphor 150b, and the third phosphor 150c. That is, since the size of the phosphors 150 included in the light emitting device according to another embodiment of the present invention increases stepwise, the scattering angle also decreases stepwise.

The diameter of the phosphor 150 may be 5 to 20 占 퐉. When the shape of the phosphor 150 is not spherical, the longest length of the phosphor 150 may be 5 to 20 占 퐉. For example, in the case of this embodiment, the first phosphor 150a may be 5 to 10 占 퐉, the second fluorescent material 150b may be 10 to 15 占 퐉, and the third fluorescent material 150c may be 15 to 20 占 퐉. However, the sizes of the first, second, and third phosphors 150a, 150b, and 150c are not limited thereto.

The first fluorescent material 150a may be a red fluorescent material, the second fluorescent material 150b may be a green or yellow fluorescent material, and the third fluorescent material 150c may be a blue fluorescent material. The red phosphor is disposed nearest to the LED chip 110 to prevent red light emitted from the red phosphor from being reabsorbed to other phosphors before being emitted to the outside. Thus, the color rendering property and the luminous efficiency can be improved.

In this embodiment, the phosphor film 140 included in the light emitting device is shown as three films, but the present invention is not limited thereto. That is, the phosphor film 140 may be a single layer, or may be a laminated structure in which at least two phosphor films are laminated.

For example, when the light emitting diode chip 110 is an ultraviolet light emitting diode chip, the phosphor film 140 includes a first phosphor film 140a including a red phosphor, a second phosphor film 140b including a green phosphor, And a third phosphor film 140c including a blue phosphor layer. When the light emitting diode chip 110 is a blue light emitting diode chip, the phosphor film 140 may have a three-layer structure including a first phosphor film 140c including a red phosphor, Layer structure including a phosphor film 140a and a second phosphor film 140b including a yellow phosphor.

Although not shown in FIGS. 1 to 4, the light emitting device may further include a support film. The phosphor film 140 may be disposed on the support film. The support film may be a transparent material such as glass, plastic, epoxy and resin. Although not shown, the light emitting device according to the present invention may not be an empty space between the phosphor film 140 and the LED chip 110. In other words, a resin such as epoxy or silicon may be included in the void space due to the separation between the phosphor film 140 and the LED chip 110. The light emitting diode chip 110 may be protected with a molding part.

1 to 4, the phosphors 150 are somewhat exaggerated to facilitate understanding. Further, the components included in the light emitting device of Figs. 1 to 4 do not represent the original size and the ratio.

It will be apparent to those skilled in the art that various modifications, substitutions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. will be. Therefore, the embodiments disclosed in the present invention and the accompanying drawings are intended to illustrate and not to limit the technical spirit of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments and the accompanying drawings . The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

110: Light emitting diode chip.
120: substrate.
130: Support.
140: Phosphor film.
140a: First phosphor film.
140b: second phosphor film.
140c: Third phosphor film.
150: Phosphor.
150a: first phosphor.
150b: second phosphor.
150c: third phosphor.

Claims (20)

A light emitting diode chip; And
And a phosphor film disposed apart from the light emitting diode chip and including phosphors dispersed therein,
And the refractive index of the phosphor film decreases as the distance from the light emitting diode chip increases. The method according to claim 1,
Wherein the phosphors are dispersed so that the scattering angle decreases as the distance from the light emitting diode chip increases. The method according to claim 1,
And the phosphors are dispersed so as to have a larger diameter as the distance from the light emitting diode chip increases. The method according to claim 1,
Wherein the phosphor film has a lower density as the distance from the light emitting diode chip increases. The method of claim 3,
Wherein the phosphor has a diameter ranging from 5 to 20 mu m. The method according to any one of claims 1 to 5,
Wherein the phosphor film has a laminated structure in which at least two phosphor films are laminated. The method of claim 6,
The phosphor film includes a first phosphor film disposed closest to the light emitting diode chip and dispersed by the first phosphors, a third phosphor film disposed farthest from the light emitting diode chip and having the third phosphors dispersed therein, And a second phosphor film disposed between the films and having the second phosphor dispersed therein. The method of claim 7,
The first phosphors dispersed in the first phosphor layer have a smaller size than the second and third phosphors dispersed in the second and third phosphor layers,
And the second phosphors dispersed in the second phosphor film have a smaller size than the third phosphors dispersed in the third phosphor film. The method of claim 8,
Wherein the first to third phosphors have a diameter of 5 to 20 mu m. The method of claim 7,
Wherein the first phosphors are red phosphors, the second phosphors are green or yellow phosphors, and the third phosphors are blue phosphors. The method of claim 7,
Wherein a density of the first phosphor film is larger than a density of the second and third phosphor films and a density of the second phosphor film is greater than a density of the third phosphor film. The method according to claim 1,
Wherein the phosphors include at least one of a silicate-based fluorescent material, a YAG-based fluorescent material, a nitride-based fluorescent material, and a TAG-based fluorescent material. The method according to claim 1,
Further comprising a support membrane,
And the phosphor film is disposed on the support film. The method according to claim 1,
Wherein the phosphor film comprises at least one of a transparent material of silicon, epoxy, glass and plastic, and the phosphors are dispersed in the transparent material. The method according to claim 1,
And the phosphor film surrounds a front surface of the light emitting diode chip. 16. The method of claim 15,
Wherein the phosphor film is spherical. The method according to claim 1,
Wherein the light emitting diode chip is a blue light emitting diode chip or an ultraviolet light emitting diode chip. A light emitting diode chip; And
And a phosphor film disposed apart from the light emitting diode chip and including phosphors dispersed therein,
Wherein the phosphor film has a smaller scattering angle as the distance from the light emitting diode chip increases. 19. The method of claim 18,
And the phosphors are dispersed so as to have a larger diameter as the distance from the light emitting diode chip increases. The method of claim 19,
Wherein the phosphor has a diameter ranging from 5 to 20 mu m.

Images