Light emitting diode lens and backlight apparatus having the same

The present invention relates to an LED lens, in which a planar bottom has a pair of halves symmetrically connected with each other about a reference line and narrowed in the vicinity of the reference line. A pair of substantially semicircular reflecting surfaces are extended from both edges of the bottom connected with both ends of the reference line. A radiating surface is connected with remaining edges of the bottom and semicircular edges of the reflecting surfaces. The reflecting surfaces reflect light beams are introduced from the LED chip through the bottom toward the radiating surface. The radiating surface radiates the light beams to the outside when the light beams are introduced to the radiating surface through reflection from the reflecting surfaces and directly through the bottom, so that the light beams are radiated to the outside in a predetermined beam angle.

RELATED APPLICATION

The present application is based on, and claims priority from, Korean Application Number 2004-6321, filed Aug. 11, 2004, the disclosure of which is hereby incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a lens, and more particularly, to a Light Emitting Diode (LED) lens for radiating light from an LED chip in a predetermined beam angle to the outside and a backlight apparatus incorporating the same.

2. Description of the Related Art

A Liquid Crystal Display (LCD) is gaining attention as a next generation display according to the development of the electronic industry. The LCD is generally equipped with a backlight apparatus for illuminating an LCD panel from behind since the LCD panel does not light spontaneously.

FIG. 1is a cross-sectional view illustrating a conventional LED which is proposed in U.S. Pat. No. 6,679,621 as a light source of a side emitting LCD backlight apparatus. Referring toFIG. 1, an LED10includes a plastic package11containing a heat conductive material therein, a pair of leads12for the input/output of electric signals, an LED chip14installed within the plastic package11and a lens13placed on the frame11. The lens13functions to redirect light beams generated from the LED chip14to horizontal directions.

The lens16is optically designed so that the light beams, which are generated from the LED chip14and propagate in all directions, are refracted horizontally. WhileFIG. 1illustrates the lens13having a generally mortar-shaped structure, the lens13may have more sophisticated structure according to angles of light emitted from the LED chip14. There is a problem in that some of the light beams maybe uncontrollably directed in a vertical direction rather than being horizontally refracted.

In addition, when an LCD backlight apparatus is realized by using LEDs10as above, the LEDs10functioning as point light sources are mounted in line on PCBs of a predetermined length to form LED arrays20functioning as linear light sources as shown inFIG. 2. The LED arrays20are arranged in parallel with each other at a predetermined distance and reflectors31are attached to both sides of the LED arrays20to form a backlight apparatus30, in which the reflectors31are designed to reflect light beams from the LED arrays20in vertical directions.

In the backlight apparatus30using the conventional LEDs as described above, since the light beams generated from the light sources or the LED chips14are refracted horizontally by the lens13and then reflected vertically by the reflectors31, the light beams change their paths for several times. Therefore, the complicated paths cause light loss.

In addition, since the light beams emitted from the LED chips14spread for 360° about optical axes having vertical direction as shown inFIG. 1, their brightness reduces significantly in proportion to the distance from the light sources or the LED chips14. Therefore, it is required to arrange the LED arrays20adjacent to each other in order to prevent brightness reduction.

SUMMARY OF THE INVENTION

The present invention has been made to solve the foregoing problems of the prior art and it is therefore an object of the present invention to provide an LED lens for radiating light from an LED chip in a predetermined beam angle to the outside.

It is another object of the present invention to provide an LED lens which can reduce the number of LED array modules when applied to a backlight apparatus.

It is yet another object of the present invention to provide an LCD backlight apparatus incorporating the above LED lens.

According to an aspect of the invention for realizing the object, there is provided an LED lens for radiating light emitted from an LED chip to the outside comprising: a planar bottom having a pair of halves symmetrically connected with each other about a reference line, and narrowed in the vicinity of the reference line; a pair of substantially semicircular reflecting surfaces extended from both edges of the bottom connected with both ends of the reference line; and a radiating surface connected with remaining edges of the bottom and semicircular edges of the reflecting surfaces, wherein the reflecting surfaces reflect light beams introduced from the LED chip through the bottom toward the radiating surface, and the radiating surface radiates the light beams to the outside, the light beams being introduced to the radiating surface through reflection from the reflecting surfaces and directly through the bottom, whereby the light beams are radiated to the outside in a predetermined beam angle.

Preferably, the reflecting surfaces are curved. Alternatively, each of the reflecting surfaces may include a curved portion connected with the bottom and a planar portion connected with the radiating surface.

Preferably, the pair of reflecting surfaces are symmetric or asymmetric with each other.

Preferably, at least one of the reflecting surfaces is extended from one of the ends of the reference line into the form of a half funnel.

Preferably, the radiating surface has a cross-sectional configuration of a concave curve. Alternatively, the radiating surface may comprise a pair of first linear portions connected with the reflecting surfaces, a pair of opposed second linear portions extended from the first linear portions at a predetermined angle toward the reference line and a convex portion connected with the second linear portions.

Preferably, the radiating surface further comprises linear or curved connecting portions formed between the second linear portions and the convex portion.

Preferably, the second linear portions are substantially parallel with the reference line or inclined at a predetermined angle with respect to the reference line.

Preferably, the bottom is narrowed in the vicinity of the reference line to form a reduced diameter portion, and comprises linear or curved portions at both ends of the reduced diameter portion.

According to an aspect of the invention for realizing the object, there is provided a backlight apparatus provided in a rear part of an LCD for radiating light beams perpendicularly into an LCD panel, comprising: a substantially box-shaped housing opened toward the LCD panel; a reflector inclined slowly upward within the housing; and an LED array including a board extended across the housing and erected on the reflector and at least one LED lens attached on the board for radiating light emitted from an LED chip to the outside. The LED lens comprises: a planar bottom having a pair of halves symmetrically connected with each other about a reference line, and narrowed in the vicinity of the reference line; a pair of substantially semicircular reflecting surfaces extended from both edges of the bottom connected with both ends of the reference line; and a radiating surface connected with remaining edges of the bottom and semicircular edges of the reflecting surfaces, wherein the reflecting surfaces reflect light beams introduced from the LED chip through the bottom toward the radiating surface, and the radiating surface radiates the light beams to the outside, the light beams being introduced to the radiating surface through reflection from the reflecting surfaces and directly through the bottom, whereby the light beams are radiated to the outside in a predetermined beam angle.

Herein the terminology “reflecting surface” represents a lens surface for reflecting light emitted from a light source through total internal reflection obtained by its refractivity and configuration, but does not mean a surface which can reflect all light. The terminology “radiating surface” represents a lens surface for outwardly radiating light which is introduced thereto directly from the light source or as reflected from the reflecting surface. In addition, the terminology “optical axis” represents a specific optical path in a cross section of the lens which is taken along the light source, and the entire lens has optical axes extended in the form of a semicircle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

First Embodiment

FIGS. 3 to 8illustrate the structure of an LED lens according to a first embodiment of the present invention, in whichFIG. 3is a perspective view of an LED lens according to a first embodiment of the present invention,FIG. 4is a plan view of the LED lens shown inFIG. 3,FIG. 5is a side elevation view of the LED lens shown inFIG. 3,FIG. 6is a front elevation view of the LED lens shown inFIG. 3,FIG. 7is a bottom view of the LED lens shown inFIG. 3, andFIG. 8is a cross-sectional view of the LED lens shown inFIG. 3taken along the line I—I.

Referring toFIGS. 3 to 8, an LED lens100according to the first embodiment of the present invention is made of transparent material, and so configured to radiate light from an underlying LED chip120in a specific beam angle to the outside.

The LED lens100of this embodiment has a peanut-shaped planar bottom102, a pair of reflecting surfaces110extended upward from the bottom102and a radiating surface116formed between the bottom102and the reflecting surfaces110. The LED lens100also has first edges104between the bottom110and the reflecting surfaces110, second edges108between the bottom102and the radiating surface116and third edges112between the reflecting surfaces110and the radiation surface116. The LED lens100has an overall configuration as is drawn by rotating a cross section S shown inFIG. 8for 180° around a base line A thereof.

The cross section S shown inFIG. 8is constituted of the straight base line A, a pair of convex arc-shaped side lines B, which are opposed to each other and extended upward from both ends of the base line A, and a concave arc-shaped top line C drawn between top ends of the side lines B. Herein vertices a formed by the base line A and the side lines B will be referred to as first connecting points whereas vertices b formed by the side lines B and the top line C will be referred to as second connecting points for the convenience's sake of description. In addition, the reference symbol b indicates outermost points on the side lines B which are drawn between the connecting points b and c.

The cross section S ofFIG. 8is taken along the line I—I ofFIG. 3so that the LED lens100ofFIG. 3is cut along a straight line drawn between a pair of connecting points106. The LED lens100has a cross-sectional configuration the same as that inFIG. 8as long as it is taken along the straight line between the connecting points106, that is, the base line A inFIG. 8, regardless of a radial position which the cross section S passes by.

Hereinafter the structure of the LED lens100according to the first embodiment of the present invention will be described in conjunction with the cross-sectional configuration inFIG. 8.

First, as illustrated more specifically inFIG. 7, the bottom102is delineated by the pair of first edges104, which are opposed to each other and extended along the length of the bottom102, and the pair of opposed second edges108, which are extended to connect both ends of the first edges104. The second edges108are formed shorter than the first edges104. The bottom102is configured the same as that obtained by coupling two cross sections S as shown inFIG. 2together about the base line A. The respective first edges104have a configuration obtained by connecting a pair of convex arcs together in an opposed way about the connecting point106. Each first edge104is produced by connecting two side lines B as shown inFIG. 8together. On the contrary, the second edges108have a concave configuration the same as the top line C ofFIG. 8.

The reflecting surfaces110have a configuration the same as that drawn by the opposed side lines B when the cross section S ofFIG. 8is rotated for 180° about the base line A. That is, the reflecting surfaces110are formed between the first edges104and the third edges112drawn by the second connecting points c. When seen along the x axis inFIG. 3, the reflecting surfaces110have a semicircular configuration (as more specifically illustrated inFIG. 5). Also, when seen along the y axis inFIG. 3, arcs114of dotted lines, which are drawn by the outermost connecting points b of the cross section S, are positioned at the top and the third edges112and the connecting points106are positioned at the bottom of the reflecting surfaces110. In this case, regions of the reflecting surfaces110between the arcs114and the connecting points106are generally shaped as the half of a funnel.

In addition, the radiating surfaces116are delineated by the second edges108and the third edges112, respectively, and correspond to a locus drawn by the top line C of the cross section S inFIG. 8.

While it has been described that the lens100has an integral solid structure, a portion of the lens100over the LED chip120may be filled with transparent resin such as silicone that has a refractivity substantially the same as or similar to that of the lens100.

As described above, the LED lens100is designed to radiate light from the LED chip120in a predetermined beam angle to the outside, as will be described hereinafter with reference toFIGS. 9 to 11, in whichFIG. 9illustrates beam angle characteristics in the cross section S of the LED lens100according to the first embodiment of the present invention,FIG. 10is a plan view illustrating beam angle characteristics of the LED lens100according to the first embodiment of the present invention, andFIG. 11illustrates beam angle characteristics in the bottom102of the LED lens100according to the first embodiment of the present invention.

ReferringFIG. 9first, light beams L emitted from the LED chip120, which is expressed as a point light source for the convenience's sake, are radiated in part directly through the radiating surfaces116to the outside. Parts of the light beams L are reflected from the reflecting surfaces110, and then radiated to the outside through the radiating surfaces116. Herein a light path Aodirected perpendicularly forward from the LED chip120will be referred to as “optical axis” for the convenience's sake. Since the cross-sectional configuration as inFIG. 9exists for 180° about a line between the connecting points106or the base line A in the entire LED lens100, the optical axis Aoalso exists for about 180° and therefore draws a semicircle.

In this case, partial regions of the reflecting surfaces110from the first connecting points a to the second connecting points b (hereinafter will be referred to as “first reflecting surface regions”) are so designed to reflect beams L from the LED chip120through total internal reflection. The configuration of the reflecting surfaces110between the first and second connecting points a and b is determined based upon the refractivity of the lens100and that of the external environment (i.e., the air in general). In the meantime, partial regions of the reflecting surfaces110from the second connecting points b to the third connecting points c (hereinafter will be referred to as “second reflecting surface regions”) are not necessarily required to reflect the entire light beams L. The second reflecting surface regions may be optionally configured to radiate the light beams L by refracting the same toward the optical axis Ao.

Alternatively, the second reflecting surface regions between the connecting points b and c may be formed in parallel with the optical axis Ao.

This configuration is designed on the basis of the fact that those surfaces extended from the second connecting points b in parallel with the optical axis Aocan reflect the light beams L through total internal reflection as long as the light beams L from the LED chip120are reflected from the second connecting points b through total internal reflection.

The radiating surface116outwardly radiates the beams L that are incident to the radiating surface116directly from the LED chip120and through reflection from the reflecting surfaces110. In this case, since the radiating surface116is concave, the beams L tend to spread out rather than to converge toward the optical axis Aowhen they are radiated to the outside. The beams L are radiated to the outside in the range of a predetermined beam angle with respect to the optical axis, the beam angle is determined by the configuration of the lens100, and more particularly, the configuration of the reflecting and radiating surfaces110and116and the refractivity of the lens100.

When seen in the x-axial direction ofFIG. 3, the beams L emitted from the LED chip120propagate radially from the light source as shown inFIG. 10. Since the radiating surface116is configured the same as the locus drawn by the top line C when the cross section S ofFIG. 8is rotated for 180° about the base line A as described hereinbefore, respective points of the radiating surface116on the same plane are spaced equally from the point light source of the LED chip120. In this case, the LED chip120is placed at the center of a circle, and the radiating surface116draws a semicircle. Therefore, when seen on a plane, the beams L emitted from the LED chip120are perpendicularly incident into the radiating surface116and therefore radiated to the outside without reflection or refraction.

Referring toFIG. 11, the reflection and radiation at the bottom102of the LED lens100is substantially the same as that inFIG. 9. The reflection and radiation at the bottom102of the LED lens100is substantially the same as that inFIG. 9. In addition, since the bottom102has a configuration obtained by coupling two of the cross section S together about the base line A, the light beams L are radiated to the right and left in the drawing from the LED chip120that is a point light source.

Accordingly, when the LED lens100of this embodiment radiates the light beams L emitted from LED chip120to the outside, the LED lens100radiates y- and z-axial components of the light beams in radial directions as they are but redirects x-axial components thereof in y- and/or z-axial directions. As a result, when radiated to the outside through the radiating surface116of the LED lens100, the light beams L are refracted within the predetermined beam angle about the optical axis Aowhile spreading in the radial directions. The range of beam angle is determined by the configuration and refractivity of the LED lens100. For example, shaping the reflecting surfaces110asymmetrical may create an asymmetric beam angle.

The LED lens100of this configuration forms simpler optical paths compared to the conventional LED lens10so as to reduce light loss.

Hereinafter a backlight apparatus incorporating LED lenses of the present invention will be described with reference toFIG. 12.

As shown inFIG. 12, a backlight apparatus140is designed to radiate light perpendicularly to an LCD panel (not shown) from a rear part of an LCD (not shown). The backlight apparatus140includes a substantially box-shaped housing144opened toward the LCD panel, a reflector142extended along a slow upward inclination within the housing144and an LED array130extended across the housing and erected on the reflector142. The reflector142is extended along the plane of the housing144, that is, the x-axial direction in the drawing. The reflector142is also inclined slowly upward in a vertical direction, that is, the z-axial direction. The LED array130is placed in a lowermost part of the reflector142, and includes a number of LED chips (not shown) attached to both sides of a bar-shaped board (e.g., typically PCB), a number of LED lenses100surrounding the LED chips, respectively, and a bracket132for fixing the LED array130to the reflector142.

This causes light beams L radiated from the LED array130propagate inside the backlight apparatus140in a predetermined beam angle. That is, the light beams L spread out in the plane direction of the backlight apparatus140but do not spread out beyond a predetermined vertical angle. The beams L are mixed together while propagating along the plane of the backlight apparatus140, and then the mixed beams reflect from the reflector142toward the LCD panel so as to backlight the LCD panel.

This structure allows one LED array130to be mounted with more LED lenses and chips, which are doubled compared to the foregoing prior art, thereby increasing light quantity radiated from the LED array130. Accordingly, this structure can reduce the number of LED arrays130, thereby simplifying the structure of the backlight apparatus140.

FIG. 13is a plan view of a modification to the LED lens according to the first embodiment of the present invention. Referring toFIG. 13, an LED lens100A according to this modification has linear portions112A formed in partial regions of third edges112opposed to an LED chip120. The linear portions112A have a length the same as that of the LED chip120. Also, a linear region of an equal configuration is formed in a corresponding portion of a radiating surface (not shown). The LED lens100A of this configuration can be suitably applied especially if the LED chip120is long.

FIG. 14is a bottom view of another modification to the LED lens according to the first embodiment of the present invention. Referring toFIG. 14, an LED lens100B according to this modification is substantially the same as the LED lens as shown inFIGS. 3 to 8except that linear connecting parts106B are formed in the middle of first edges, respectively. The linear connecting parts106B facilitate the fabrication of a mold for forming the lens100B. Alternatively, the connecting parts may be curved.

The LED lens according to the first embodiment of the present invention are not limited to the afore-described illustrative structures100,100A and100B. For example, the radiating surfaces are not necessarily symmetric. In this case, the foregoing connecting point106or the connecting part106B may be formed only in one of the reflecting surfaces110so that the opposite one of the reflecting surfaces110may not be half funnel shaped.

Second Embodiment

FIGS. 15 to 20illustrate the structure of an LED lens according to a second embodiment of the present invention, in whichFIG. 15is a perspective view of the LED lens according to the second embodiment of the present invention,FIG. 16is a plan view of the LED lens shown inFIG. 15,FIG. 17is a front elevation view of the LED lens shown inFIG. 15,FIG. 18is a side elevation view of the LED lens shown inFIG. 15,FIG. 19is a bottom view of the LED lens shown inFIG. 15, andFIG. 20is a cross-sectional view of the LED lens shown inFIG. 15taken along the line II—II.

Referring toFIGS. 15 to 20, an LED lens200according to the second embodiment of the present invention is made of transparent material, and so configured to radiate light from an LED chip220, which is placed in the bottom thereof, in a specific beam angle to the outside.

The LED lens200of this embodiment includes a planar bottom202in the form of opposed crowns, a pair of first and second reflecting surfaces204and206extended upward from the bottom202, first and second radiating surfaces210and214and intermediate surfaces212. The radiating surfaces210and214and the intermediate surfaces212are formed between the bottom202and the second reflecting surfaces206. The LED lens200has a general configuration the same as that drawn by rotating a cross section S shown inFIG. 20for 180° around a base line A thereof.

The cross section S shown inFIG. 20is constituted of the straight base line A, a pair of convex arc-shaped first side lines B1extended upward from both ends of the base line A in an opposed fashion, a pair of straight second side lines B2extended upward from the first side lines B1, a pair of straight first top lines C1extended inward from top ends of the second side lines B2, a pair of straight second top lines C2extended downward from inner ends of the first top lines C1and a convex arc-shaped third top line connecting between bottom ends of the second top lines C2. Herein, for the convenience's sake of description, vertices a formed by the base line A and the first side lines B1will be referred to as first connecting points, vertices b formed by the first and second side lines B1and B2will be referred to as second connecting points, vertices c formed by the second side lines B2and the first top lines C1will be referred to as third connecting points, vertices d formed be the first top lines C1and the second top lines C2will be referred to as fourth connecting points, and vertices e formed by the second top lines C2and the third top line C3will be referred to as fifth connecting points.

The cross section S ofFIG. 20is taken along the line II—II ofFIG. 15so that the LED lens200ofFIG. 15is cut along a straight line drawn between a pair of connecting points208. The LED lens200has a cross-sectional configuration the same as that inFIG. 20as long as it is taken along the straight line between the connecting points208, that is, the base line A inFIG. 20, regardless of a radial position which the cross section S passes by.

Hereinafter the structure of the LED lens200according to the second embodiment of the present invention will be described in conjunction with the cross-sectional configuration inFIG. 20.

As described above, the LED lens200has a configuration the same as a locus drawn by rotating the cross section S ofFIG. 20about the base line A for 180°.

First, the bottom202as specifically shown inFIG. 19has a configuration the same as that obtained by rotating the cross section S ofFIG. 20, that is, coupling two cross sections S together about the base line A.

The reflecting surfaces204and206have a configuration the same as a locus drawn by the opposed first and second side lines B1and B2when the cross section S ofFIG. 20is rotated about the base line A for 180°. That is, the first reflecting surfaces204correspond to loci drawn by the first side lines B1between the first and second connecting points a and b of the cross section S ofFIG. 20, the second reflecting surfaces206correspond to loci drawn by the second side lines B2connecting between the second and third connecting points b and c. Accordingly, the respective first reflecting surfaces204have an overall configuration corresponding to the half of a funnel, and the connecting points208correspond to vertices of funnels.

Further, the radiating surfaces210and214and the intermediate surfaces212are drawn by the top lines C1, C2and C3of the cross section S ofFIG. 20, respectively.

While it has been described that the lens200has an integral solid structure, a portion of the lens200over the LED chip220may be filled with transparent resin such as silicone that has a refractivity substantially the same as or similar to that of the lens200.

As described above, the LED lens200is designed to radiate light from the LED chip220in a predetermined beam angle to the outside, as will be described hereinafter with reference toFIGS. 21 and 22, in whichFIG. 21is a cross-sectional view illustrating beam angle characteristics in the cross section S of the LED lens200according to the second embodiment of the present invention, andFIG. 22is a bottom view illustrating beam angle characteristics in the bottom202of the LED lens according to the second embodiment of the present invention.

Referring toFIG. 21first, light beams L emitted from the LED chip220, which is expressed as a point light source for the convenience's sake, are radiated in part directly through the first and second radiating surfaces210and214to the outside. Parts of the light beams L-are reflected from the reflecting surfaces204and206, and then radiated to the outside through the radiating surfaces210and214. In this case, a light path Aodirected perpendicularly forward from the LED chip220will be referred to as “optical axis” for the convenience's sake.

In this case, partial regions of the reflecting surfaces204and206are so configured that the first reflecting surfaces204between the first and second connecting points a and b reflect the light beams L emitted from the LED chip220via total internal reflection. The configuration of the first reflecting surfaces204is determined based upon the refractivity of the lens200and that of the external environment (i.e., the air in general). In the meantime, the second reflecting surfaces206from the second connecting points b to the third connecting points c are not necessarily required to reflect the entire light beams L. The second reflecting surfaces206maybe optionally configured to radiate the light beams L by refracting the same toward the optical axis Ao.

The radiating surfaces210and214outwardly radiate a light beam L1reflected from the reflecting surfaces204and a light beam L2introduced directly from the LED chip220. The second radiating surface214outwardly radiates the light beam L2directly introduced from the LED chip220, and owing to its convex geometry, serves to focus the light beam L2toward the optical axis Ao. In the entire LED200, since the cross section S as shown inFIG. 21exists for 180° about the base line A or a straight line between the connecting points208, the optical axis Aoalso forms a semicircle of 180°.

The light beams L are radiated to the outside in a predetermined beam angle with respect to the optical axis, and the beam angle is determined by the refractivity of the lens200and the configuration of the lens200such as the reflecting surface204and206, the radiating surfaces210and214and the intermediate surfaces212.

Referring toFIG. 22, the reflection and radiation at the bottom202of the LED lens200is substantially the same as that inFIG. 21. In addition, since the bottom202has a configuration obtained by coupling two of the cross section S together about the base line A, the light beams L are radiated to the right and left in the drawing from the LED chip220that is a point light source.

As not shown in the drawings, when emitted from the LED chip220in a radial direction of the LED diode200, that is, the y- and z-axial directions ofFIG. 15, the light beams propagate radially from the light source as previously described in the first embodiment with reference toFIG. 10. As shown inFIG. 18, since the LED lens200has a semicircular configuration in a plane seen in the x-axial direction, the light beams emitted from the LED lens220are radiated to the outside without reflection or refraction in the y- or z-axial direction.

Accordingly, when the LED lens200of this embodiment radiates the light beams L emitted from LED chip220to the outside, the LED lens200radiates y- and z-axial components of the light beams in radial directions as they are but redirects x-axial components thereof in y- and/or z-axial directions. As a result, when radiated to the outside through the radiating surfaces210and214of the LED lens200, the light beams L are refracted within the predetermined beam angle about the optical axis Aowhile spreading in the radial directions. The range of the beam angle is determined by the configuration and refractivity of the LED lens200.

A number of LED lenses200of this structure are arrayed in both sides of an LED array substantially the same as shown inFIG. 12, which is mounted on an LCD backlight apparatus. Then, light emitted from LED chips can backlight the LCD panel in a substantially same fashion as inFIG. 12.

This structure also allows one LED array to be mounted with more LED lenses and chips which are doubled compared to the foregoing prior art, thereby increasing light quantity radiated from the LED array. Accordingly, this structure can reduce the number of LED arrays, thereby simplifying the structure of the backlight apparatus.

FIGS. 23 to 25are cross-sectional views of various modifications to the LED lens according to the second embodiment of the present invention.

Referring toFIG. 23, an LED lens200A has substantially the same structure as the afore-described LED lens200of the second embodiment except that connecting surfaces216are formed at those regions where intermediate surfaces212are connected with a second radiating surface214. The connecting surfaces216facilitate the fabrication of a mold for forming the lens200A.

Referring toFIG. 24, an LED diode lens200B has substantially the same structure as the LED lens200A inFIG. 24except that first radiating surfaces210B are so inclined that outer portions thereof are projected beyond inner portions thereof. The inclined first radiating surfaces210B can focus passing light beams further toward the optical axis. The first radiating surfaces210B have an angle preferably about 30 to 60° about intermediate surfaces212inFIG. 24. The inclined first radiating surfaces210B can be applied to the LED lens200of the second embodiment.

Referring toFIG. 25, an LED lens200C has curved connecting surfaces216C formed between intermediate surfaces212and a second radiating surface214. The curved connecting surfaces216C also facilitate the fabrication of a mold for forming the lens200C.

FIG. 26is a bottom view of a still another modification to the LED lens according to the second embodiment of the present invention. Referring toFIG. 26, an LED lens200D has a bottom configuration substantially the same as that of LED lens200of the second embodiment inFIG. 19except that curved connecting portions208D are formed around converging points of first reflecting surfaces204and curved connecting surfaces216D are formed between intermediate surfaces212and a second radiation surface214. The curved connecting portions208D and surfaces216D can further facilitate the fabrication of a mold for forming the lens200D.

FIG. 27is a graph illustrating the intensity of light beams radiated through radiating surfaces210and214of the LED lens200D as shown inFIG. 26. InFIG. 27, the intensity of light is marked in candela according to radial angles in lateral directions of the LED lens200D with respect to the optical axis, i.e., the normal line passing through an LED chip220as the light source. As can be seen fromFIG. 27, radiating light is concentrated within the range of about ±15° with respect to the x-axis (ofFIG. 15). The radiating light in this beam angle corresponds to about at least 70% of the entire light quantity.

The LED lens200D ofFIG. 26was taken in this experiment, since it is easiest to realize this structure. For example, the LED lens200inFIGS. 15 to 20can further enhance the efficiency.

The LED lens according to the first embodiment of the present invention are not limited to the afore-described illustrative structures200,200A to200D. For example, the radiating surfaces204and206are not necessarily symmetric. In this case, the foregoing connecting points208or the connecting portions208D may be formed only in one of the reflecting surfaces204so that the opposite one of the reflecting surfaces110may not be half funnel shaped. In addition, the second reflecting surfaces206may be inclined at a predetermined angle with respect to the optical axis Aorather than being parallel with the same. Alternatively, the second reflecting surfaces may be formed at different angles.

As described hereinbefore, the LED lens of the present invention radiates light beams generated from the LED chip to the outside in a predetermined beam angle to simplify the optical path thereby reducing optical loss.

In addition, the backlight apparatus of the present invention can double the light quantity radiated from the LED array by mounting LED lenses and chips on both sides of the array module. This can reduce the number of LED arrays and thereby simplifying the backlight apparatus structure.