U.S. patent application number 17/652181 was filed with the patent office on 2022-06-09 for lens for wide diffusion light.
The applicant listed for this patent is HL OPTICS CO., LTD. Invention is credited to Ho Kyung KI, Kang Hyun LEE.
Application Number | 20220179134 17/652181 |
Document ID | / |
Family ID | 1000006156797 |
Filed Date | 2022-06-09 |
United States Patent
Application |
20220179134 |
Kind Code |
A1 |
KI; Ho Kyung ; et
al. |
June 9, 2022 |
LENS FOR WIDE DIFFUSION LIGHT
Abstract
Disclosed herein is a light diffusion lens. The light diffusion
lens according to one embodiment of the present disclosure includes
a bottom surface, an incidence surface concavely formed inward the
bottom surface from one area (an incidence hole) thereof, and an
exit surface from which light incident through the incidence
surface is emitted, wherein at least two protrusions are formed on
the incidence surface symmetrically in relation to an optical axis
or at least two second dimples are formed on the exit surface
symmetrically in relation to the optical axis.
Inventors: |
KI; Ho Kyung; (Cheonan-si,
KR) ; LEE; Kang Hyun; (Pyeongtaek-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HL OPTICS CO., LTD |
Hwaseong-si |
|
KR |
|
|
Family ID: |
1000006156797 |
Appl. No.: |
17/652181 |
Filed: |
February 23, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16680821 |
Nov 12, 2019 |
|
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17652181 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 3/08 20130101; G02B
5/0278 20130101 |
International
Class: |
G02B 5/02 20060101
G02B005/02; G02B 3/08 20060101 G02B003/08 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 12, 2018 |
KR |
10-2018-0138515 |
Claims
1. A light diffusion lens comprising: a bottom surface; an
incidence surface concavely formed inward the bottom surface from
one area (an incidence hole) thereof; and an exit surface from
which light incident through the incidence surface is emitted,
wherein at least two protrusions are formed on the incidence
surface symmetrically in relation to an optical axis.
2. The light diffusion lens of claim 1, wherein each of the at
least two protrusions is disposed within a predetermined divergence
angle based on the optical axis, and the divergence angle is less
than or equal to 50 degrees.
3. The light diffusion lens of claim 1, wherein each of the at
least two protrusions is convexly formed from the incidence surface
toward the optical axis.
4. The light diffusion lens of claim 3, wherein an edge at which
the at least two protrusions and the incidence surface meet has a
circular shape.
5. The light diffusion lens of claim 1, wherein the sum of areas of
the at least two protrusions is less than or equal to 30% of an
entire area of the incidence surface.
6. The light diffusion lens of claim 1, wherein any point on each
of the at least two protrusions corresponds to the center of the
height of the incidence surface.
7. The light diffusion lens of claim 1, wherein at least two
dimples are formed on the exit surface symmetrically in relation to
the optical axis.
8. The light diffusion lens of claim 7, wherein each of the at
least two dimples is disposed within a predetermined divergence
angle based on the optical axis, and an angle between the optical
axis and a center of each of the at least two dimples ranges from
about 36 degrees to about 40 degrees.
9. The light diffusion lens of claim 7, wherein each of the at
least two dimples has an elliptical shape.
10. A light diffusion lens comprising: a bottom surface having an
elliptical shape; an incidence surface concavely formed inward the
bottom surface from one area (an incidence hole) thereof; and an
exit surface from which light incident through the incidence
surface is emitted, wherein at least two dimples are disposed on
the exit surface symmetrically in relation to an optical axis.
11. The light diffusion lens of claim 10, wherein each of the at
least two dimples is disposed within a predetermined divergence
angle based on the optical axis, and an angle between the optical
axis and a center of each of the at least two dimples ranges from
about 36 degrees to about 40 degrees.
12. The light diffusion lens of claim 10, wherein each of the at
least two dimples has an elliptical shape.
Description
BACKGROUND
Field
[0001] The present disclosure relates to a light diffusion
lens.
Discussion of Related Art
[0002] Recently, the demands for flat panel display devices having
more improved performance while being smaller in size and lighter
in weight are explosively increasing around the rapidly developing
semiconductor technology.
[0003] Among these flat panel display devices, since liquid crystal
display (LCD) devices, which are recently getting attention, have
advantages such as miniaturization, weight reduction, and low power
consumption, and the like, the LCD devices are gradually getting
attention as alternatives to overcome disadvantages of the
conventional cathode ray tube (CRT). Currently, the LCD devices are
installed and used in many information processing devices which
need a display device.
[0004] Since LCD panels in the LCD devices are light receiving
elements which do not emit light by itself, the LCD panels have
backlight units for providing light to the LCD panels therebelow.
Here, the backlight unit may include a lamp, a light guiding panel,
a reflective sheet, an optical sheet, and the like.
[0005] The lamp employs a cold cathode fluorescent lamp generating
relatively low heat, generating white light near natural light, and
having a long service life, or a light emitting diode (LED) type
lamp having excellent color reproducibility and low power
consumption. The cold cathode fluorescent lamp was conventionally
used. However, since the LED type lamp has advantages of excellent
color reproducibility and low power consumption, products of LED
type lamps have begun to be employed.
[0006] The disclosure of this section is to provide background
information relating to the invention. Applicant does not admit
that any information contained in this section constitutes prior
art.
SUMMARY
[0007] The present disclosure is directed to a light diffusion lens
which minimizes a dark portion formed in light diffused through a
lens using a dimple formed on an incidence surface or an exit
surface.
[0008] The present disclosure is also directed to a light diffusion
lens which is capable of securing light diffusivity and light
uniformity by changing an optical path of a part of light having
directivity in a specific direction using a dimple formed on an
incidence surface or an exit surface.
[0009] The present disclosure is also directed to a light diffusion
lens which is capable of preventing or minimizing a dark portion,
which may be formed in diffused light, by proposing a shape or a
position of a dimple formed on an incidence surface, a shape or a
position of a dimple formed on an exit surface, and a relationship
between the dimple formed on the incidence surface and the dimple
formed on the exit surface in terms of design.
[0010] In one general aspect, there may be provided a light
diffusion lens comprising: a bottom surface; an incidence surface
concavely formed inward the bottom surface from one area (an
incidence hole) thereof; and an exit surface from which light
incident through the incidence surface is emitted, wherein at least
two protrusions are formed on the incidence surface symmetrically
in relation to an optical axis.
[0011] In some exemplary embodiment of the present invention, each
of the at least two protrusions may be disposed within a
predetermined divergence angle based on the optical axis, and the
divergence angle is less than or equal to 50 degrees.
[0012] In some embodiment of the present invention, each of the at
least two protrusions may be convexly formed from the incidence
surface toward the optical axis.
[0013] In some embodiment of the present invention, an edge at
which the at least two protrusions and the incidence surface meet
may have a circular shape.
[0014] In some embodiment of the present invention, the sum of
areas of the at least two protrusions may be less than or equal to
30% of an entire area of the incidence surface.
[0015] In some embodiment of the present invention, any point on
each of the at least two protrusions may correspond to the center
of the height of the incidence surface.
[0016] In some embodiment of the present invention, at least two
dimples may be formed on the exit surface symmetrically in relation
to the optical axis.
[0017] In some embodiment of the present invention, each of the at
least two dimples may be disposed within a predetermined divergence
angle based on the optical axis, and an angle between the optical
axis and a center of each of the at least two dimples may range
from about 36 degrees to about 40 degrees.
[0018] In some embodiment of the present invention, each of the at
least two dimples may have an elliptical shape.
[0019] In other general aspect of the present invention, there may
be provided a light diffusion lens comprising: a bottom surface
having an elliptical shape; an incidence surface concavely formed
inward the bottom surface from one area (an incidence hole)
thereof; and an exit surface from which light incident through the
incidence surface is emitted, wherein at least two dimples are
disposed on the exit surface symmetrically in relation to an
optical axis.
[0020] In some embodiment of the present invention, each of the at
least two dimples may be disposed within a predetermined divergence
angle based on the optical axis, and an angle between the optical
axis and a center of each of the at least two dimples may range
from about 36 degrees to about 40 degrees.
[0021] In some embodiment of the present invention, each of the at
least two dimples may have an elliptical shape.
[0022] In another general aspect of the present invention, there
may be provided a light diffusion lens comprising: a bottom surface
having an elliptical shape; an incidence surface concavely formed
inward the bottom surface from one area (an incidence hole)
thereof; and an exit surface from which light incident through the
incidence surface is emitted, wherein a first dimple of an
elliptical shape is formed on the exit surface at a position of a
predetermined first radius from an optical axis, at least two
second dimples having an elliptical shape are formed on the exit
surface at a position of a second radius that is smaller than the
first radius, and a third dimple having an elliptical shape is
formed on the exit surface at a position of a third radius that is
smaller than the second radius.
[0023] In some embodiment of the present invention, a long axis of
the bottom surface may be disposed to correspond to short axes of
the first and third dimples.
[0024] In some embodiment of the present invention, length of long
axis of each of the at least two second dimples may be smaller than
that of long axis of the first dimple and may be greater than that
of long axis of the third dimple.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The above and other aspects, features and advantages of the
present disclosure will become more apparent to those of ordinary
skill in the art by describing embodiments thereof in detail with
reference to the accompanying drawings, in which:
[0026] FIG. 1 is a perspective view illustrating a light diffusion
lens according to a first embodiment;
[0027] FIG. 2 is a bottom view illustrating the light diffusion
lens according to the first embodiment;
[0028] FIG. 3 is a plan view illustrating the light diffusion lens
according to the first embodiment;
[0029] FIG. 4 is a side view illustrating the light diffusion lens
according to the first embodiment;
[0030] FIG. 5 is a cross-sectional view illustrating the light
diffusion lens according to the first embodiment;
[0031] FIG. 6 is an enlarged view illustrating area A of FIG.
5;
[0032] FIG. 7 is a diagram illustrating an arrangement relationship
between a light source and the light diffusion lens according to
the first embodiment;
[0033] FIG. 8 is a diagram illustrating an optical path due to a
first protrusion of the light diffusion lens according to the first
embodiment;
[0034] FIG. 9 shows photographs illustrating light distribution
before and after application of the first protrusion in the light
diffusion lens according to the first embodiment;
[0035] FIG. 10 is a diagram illustrating a light source for
emitting light to an incidence surface of the light diffusion lens
according to an embodiment;
[0036] FIG. 11 is a perspective view illustrating a light diffusion
lens according to a second embodiment;
[0037] FIG. 12 is a bottom view illustrating the light diffusion
lens according to the second embodiment;
[0038] FIG. 13 is a plan view illustrating the light diffusion lens
according to the second embodiment;
[0039] FIG. 14 is a side view illustrating the light diffusion lens
according to the second embodiment;
[0040] FIG. 15 is a cross-sectional view illustrating the light
diffusion lens according to the second embodiment;
[0041] FIG. 16 is an enlarged view illustrating area B of FIG.
15;
[0042] FIG. 17 is a diagram illustrating an arrangement
relationship between a light source and the light diffusion lens
according to the second embodiment;
[0043] FIG. 18 is a diagram illustrating an optical path due to a
second dimple of the light diffusion lens according to the second
embodiment;
[0044] FIG. 19 shows photographs illustrating light distribution
before and after application of the second dimple in the light
diffusion lens according to the second embodiment;
[0045] FIG. 20 is a perspective view illustrating a light diffusion
lens according to a third embodiment;
[0046] FIG. 21 is a bottom view illustrating the light diffusion
lens according to the third embodiment;
[0047] FIG. 22 is a plan view illustrating the light diffusion lens
according to the third embodiment;
[0048] FIG. 23 is a side view illustrating the light diffusion lens
according to the third embodiment;
[0049] FIG. 24 is a cross-sectional view illustrating the light
diffusion lens according to the third embodiment;
[0050] FIG. 25 is an enlarged view illustrating area D of FIG.
24;
[0051] FIG. 26 is a diagram illustrating an arrangement
relationship between a light source and the light diffusion lens
according to the third embodiment;
[0052] FIG. 27 is a diagram illustrating an optical path due to a
first protrusion and a second dimple of the light diffusion lens
according to the third embodiment;
[0053] FIG. 28 is a perspective view illustrating a light diffusion
lens according to a fourth embodiment;
[0054] FIG. 29 is a bottom view illustrating the light diffusion
lens according to the fourth embodiment;
[0055] FIG. 30 is a plan view illustrating the light diffusion lens
according to the fourth embodiment;
[0056] FIG. 31 is a front view illustrating the light diffusion
lens according to the fourth embodiment;
[0057] FIG. 32 is a side view illustrating the light diffusion lens
according to the fourth embodiment;
[0058] FIG. 33 is a cross-sectional view in a long axis direction
based on an exit surface of the light diffusion lens according to
the fourth embodiment;
[0059] FIG. 34 is a cross-sectional view in a short axis direction
based on the exit surface of the light diffusion lens according to
the fourth embodiment;
[0060] FIG. 35 is an enlarged view illustrating area E of FIG.
33;
[0061] FIG. 36 is a diagram illustrating an arrangement
relationship between a light source and the light diffusion lens
according to the fourth embodiment;
[0062] FIG. 37 shows photographs illustrating light distribution
before and after application of a third protrusion in the light
diffusion lens according to the fourth embodiment;
[0063] FIG. 38 is a perspective view illustrating a light diffusion
lens according to a fifth embodiment;
[0064] FIG. 39 is a bottom view illustrating the light diffusion
lens according to the fifth embodiment;
[0065] FIG. 40 is a plan view illustrating the light diffusion lens
according to the fifth embodiment;
[0066] FIG. 41 is a front view illustrating the light diffusion
lens according to the fifth embodiment;
[0067] FIG. 42 is a side view illustrating the light diffusion lens
according to the fifth embodiment;
[0068] FIG. 43 is a cross-sectional view in a long axis direction
based on an exit surface of the light diffusion lens according to
the fifth embodiment;
[0069] FIG. 44 is a cross-sectional view in a short axis direction
based on the exit surface of the light diffusion lens according to
the fifth embodiment;
[0070] FIG. 45 is an enlarged view illustrating area F of FIG.
43;
[0071] FIG. 46 is a diagram illustrating an arrangement
relationship between a light source and the light diffusion lens
according to the fifth embodiment;
[0072] FIG. 47 shows photographs illustrating light distribution
before and after application of a third protrusion in the light
diffusion lens according to the fifth embodiment;
[0073] FIG. 48 is a perspective view illustrating a light diffusion
lens according to a sixth embodiment;
[0074] FIG. 49 is a bottom view illustrating the light diffusion
lens according to the sixth embodiment;
[0075] FIG. 50 is a plan view illustrating the light diffusion lens
according to the sixth embodiment;
[0076] FIG. 51 is a front view illustrating the light diffusion
lens according to the sixth embodiment;
[0077] FIG. 52 is a side view illustrating the light diffusion lens
according to the sixth embodiment;
[0078] FIG. 53 is a cross-sectional view in a long axis direction
based on an exit surface of the light diffusion lens according to
the sixth embodiment;
[0079] FIG. 54 is a cross-sectional view in a short axis direction
based on the exit surface of the light diffusion lens according to
the sixth embodiment;
[0080] FIG. 55 is an enlarged view illustrating area G of FIG. 53;
and
[0081] FIG. 56 is a diagram illustrating an arrangement
relationship between a light source and the light diffusion lens
according to the sixth embodiment.
DETAILED DESCRIPTION OF EMBODIMENTS
[0082] The present disclosure may be applied with various changes,
and may be included with various embodiments, and particular
embodiments will be exemplified by drawings and explained in the
Detailed Description. However, the present disclosure will not be
limited to the particular embodiments, and the described aspect is
intended to embrace all such alterations, modifications, and
variations that fall within the scope and novel idea of the present
disclosure.
[0083] Accordingly, in some embodiments, well-known processes,
well-known device structures, and well-known techniques are not
illustrated in detail to avoid unclear interpretation of the
present disclosure.
[0084] Hereinafter, embodiments of the present disclosure will be
described in detail with reference to the accompanying
drawings.
[0085] Light emitted from an LED may have strong directivity and
tends to concentrate in a front direction of the LED. Therefore, in
some instances light is not uniformly distributed throughout the
LCD panel and a front portion of the LED becomes brighter and a
portion away from the front portion thereof becomes darker. Thus,
the demands for technology to effectively and uniformly diffuse the
light of LED are increasing.
[0086] In particular, in real life, a size of the LCD panel is
increased due to high brightness and high efficiency of the LED,
and the LED emits light through four or five surface-emission
instead of one surface-emission so that the demands for technology
to effectively and uniformly diffuse the light of the LED are
increasing.
[0087] Therefore, the demands are also increasing for lens
technology for designing an incidence surface on which light is
incident and an exit surface from which the light is emitted so as
to allow the LED to implement surface emission and, on the basis of
the design, minimizing a dark portion which is locally generated
due to a lens such that uniformity of the light can be
improved.
First Embodiment
[0088] FIG. 1 is a perspective view illustrating a light diffusion
lens according to a first embodiment, FIG. 2 is a bottom view
illustrating the light diffusion lens according to the first
embodiment, FIG. 3 is a plan view illustrating the light diffusion
lens according to the first embodiment, FIG. 4 is a side view
illustrating the light diffusion lens according to the first
embodiment, FIG. 5 is a cross-sectional view illustrating the light
diffusion lens according to the first embodiment, FIG. 6 is an
enlarged view illustrating area A of FIG. 5, and FIG. 7 is a
diagram illustrating an arrangement relationship between a light
source and the light diffusion lens according to the first
embodiment. Here, FIG. 5 is a cross-sectional view taken along line
A1-A1 of FIG. 1. In FIGS. 4 and 5, an R direction indicates a
radial direction, and a Z direction indicates an axial direction or
an optical axis direction.
[0089] Meanwhile, an optical axis C may be a center of light
emitted from a light source 10 and may coincide with a center of a
light diffusion lens 1.
[0090] The light diffusion lens 1 according to the first embodiment
may be used in a liquid crystal display device. In this case, the
liquid crystal display device may include a substrate and a
plurality of light sources 10 which are mounted on the substrate.
The light diffusion lens 1 may be disposed to cover the light
source 10 to diffuse the light emitted from the light source 10. In
this case, the light diffusion lens 1 may diffuse the light using a
protrusion or bulge formed on an aspherical-shaped incidence
surface 200, thereby improving light uniformity.
[0091] Referring to FIGS. 1 to 7, the light diffusion lens 1
according to the first embodiment may include a bottom surface 100,
the incidence surface 200 on which light is incident, an exit
surface 300 from which the light incident through the incidence
surface 200 is emitted, and first protrusions or bulges 400
convexly formed on the incidence surface 200. Here, the exit
surface 300 may include a top surface 310 and a side surface 320.
In this case, the top surface 310 may be convexly formed toward an
upper side. Here, the "upper side" and a "lower side" are relative
expressions. Unless otherwise defined below, a direction from the
bottom surface 100 to the top surface 310 is determined as the
upper side (upward side), and, conversely, a direction from the top
surface 310 to the bottom surface 100 is determined as the lower
side (downward side).
[0092] Therefore, the light diffusion lens 1 may diffuse the light
emitted from the light source 10 using the aspherical-shaped
incidence surface 200, the exit surface 300, and the first
protrusions 400 formed on the incidence surface 200.
[0093] In embodiments, in the light diffusion lens 1, since an
optical path of the light emitted from the light source 10 is
changed due to shapes of the incidence surface 200 and the exit
surface 300 and the first protrusions 400, the incidence surface
200 which is formed in the aspherical shape, the shape of the exit
surface 300, and arrangements, shapes, and sizes of the first
protrusions 400 act as largest factors of light distribution
according to the change of the optical path of the light.
[0094] The light diffusion lens 1 may be formed using a material of
polycarbonate or polymethmethylacrylate. Here, a refractive index
of polycarbonate is 1.58, and a refractive index of
polymethmethylacrylate is 1.49.
[0095] Referring to FIG. 3, the bottom surface 100 may be formed in
a circular shape in which an incidence hole 210 is disposed at a
center thereof.
[0096] Further, the bottom surface 100 may be formed in a
downwardly convex shape or a flat surface shape.
[0097] The downwardly convex-shaped bottom surface 100 may be a
curved surface having a curvature that is greater than that of a
central portion of the top surface 310.
[0098] An example of the bottom surface 100 includes a bottom
surface formed of a curved surface having a downwardly convex
shape, but the present disclosure is not necessarily limited
thereto. For example, in the bottom surface 100, a flat surface may
be formed from an edge to a predetermined length in a center
direction, and a lower convex surface may be formed from a position
at which the flat surface ends to a center side. In embodiments,
the bottom surface 100 may have a shape of which curvature is zero
from the edge to a predetermined length in the center direction and
increases and then decreases again to the center of the bottom
surface 100 from the predetermined length.
[0099] When compared with a bottom surface comprised of only the
flat surface, the bottom surface 100 having the lower convex
surface may totally reflect more light, which is emitted to the
lower side, toward the upper side among lights emitted from the
light source 10.
[0100] Here, in order to preferentially totally reflect the light
due to the lower convex surface, the flat surface may be disposed
outside the lower convex surface.
[0101] Further, the bottom surface 100 of a flat surface shape may
be formed to be inclined from an end portion of a lower side of the
side surface 320 toward the optical axis C. Referring to FIG. 4,
the bottom surface 100 of a flat surface shape may be a flat
surface which is formed to be inclined with respect to an imaginary
horizontal surface at a predetermined angle based on the end
portion of the lower side of the side surface 320. Accordingly, the
bottom surface 100 may totally reflect more light, which is emitted
to the lower side, toward the upper side among lights emitted from
the light source 10.
[0102] The incidence surface 200 is a surface portion through which
the light emitted from the light source 10 located in the incidence
hole 210 is incident into the light diffusion lens 1.
[0103] As shown in FIGS. 1 and 5, the aspherical-shaped incidence
surface 200 may be formed to be concave inward the bottom surface
100 from the center thereof. Accordingly, the incidence hole 210
may be formed in the center of the bottom surface 100.
[0104] A vertical cross section of the incidence surface 200 may be
formed in a semi-elliptical shape, a semi-rugby ball shape, or a
parabolic shape. Accordingly, the incidence surface 200 may be
formed of an aspherical surface. In this case, the incidence
surface 200 may be formed to have a predetermined height H1 from
the bottom surface 100 based on the optical axis direction.
[0105] Referring to FIGS. 1, 3, and 5, a horizontal cross section
of the incidence surface 200 may have a circular shape which is
formed to have a predetermined radius. In this case, since the
vertical cross section of the incidence surface 200 is formed in a
semi-elliptical shape, a semi-rugby ball shape, or a parabolic
shape, a radius of the horizontal cross section of the incidence
surface 200 may be decreased toward the upper side. Accordingly,
the incidence surface 200 may have a maximum radius R1.
[0106] The incidence hole 210 may be formed in a circular shape
which is formed with a predetermined radius. In this case, since
the incidence hole 210 is disposed below the incidence surface 200,
the incidence surface 200 may be formed with the maximum radius R1
in the incidence hole 210. Here, the maximum radius R1 of the
incidence surface 200 may be called a first radius.
[0107] A center of the incidence hole 210 may be disposed on the
optical axis C, and the light source 10 may be disposed at the
center of the incidence hole 210. Accordingly, an air layer may be
disposed between the light source 10 and the incidence surface 200.
Thus, light emitted from the light source 10 to the air layer may
be refracted at the incidence surface 200 of the light diffusion
lens 1 having a different refractive index.
[0108] The exit surface 300 may be a surface of the light diffusion
lens 1 from which the light incident through the incidence surface
200 is emitted and may be formed to be rotationally symmetrical
based on the optical axis C. Accordingly, as shown in FIG. 3, when
the exit surface 300 is viewed from the optical axis direction, the
exit surface 300 may be formed in a circular shape so as to have a
predetermined radius R2. Here, the radius R2 of the exit surface
300 may be called a second radius.
[0109] A height H2 of the exit surface 300 may be smaller than the
radius R2 of the exit surface 300.
[0110] Referring to FIG. 4, the exit surface 300 may include the
convex-shaped top surface 310 and the side surface 320 disposed
between the top surface 310 and the bottom surface 100. In this
case, the side surface 320 may be disposed parallel to the optical
axis C. Further, some of lights incident into the light diffusion
lens 1 through the incidence surface 200 is refracted through the
top surface 310 to be emitted to the outside.
[0111] The top surface 310 may be convexly formed in a
hemispherical shape or a rotationally symmetrical shape. For
example, the top surface 310 may be convexly formed in the optical
axis direction (the Z direction).
[0112] In this case, the top surface 310 may be symmetrically
formed based on an imaginary vertical flat surface passing through
the optical axis C. Accordingly, the top surface 310 may implement
a symmetrical optical path based on the optical axis C.
[0113] The top surface 310 may be formed in a convex shape of which
curvature is gradually increased from a central portion of an
uppermost end of the top surface 310 toward an edge portion
thereof. Alternatively, the central portion of the uppermost end of
the top surface 310 may be flatter than the edge portion
thereof.
[0114] The first protrusion 400 may be convexly formed toward the
optical axis C. Accordingly, the first protrusion 400 may be called
a first protruding portion or a first protrusion.
[0115] A plurality of first protrusions 400 may be formed on the
incidence surface 200, and the sum of the plurality of first
protrusions 400 may be 30% or less of an entire area of the
incidence surface 200.
[0116] In embodiments, the plurality of first protrusions 400 are
formed to have an area of 30% or less of the entire area of the
incidence surface 200. When the first protrusions 400 have an area
exceeding 30% of the entire area of the incidence surface 200, the
first protrusions 400 affect overall image quality of the light
diffusion lens 1. For example, since paths of reflected light and
returned light are changed when the entire area of the plurality of
first protrusions 400 increases, when the plurality of first
protrusions 400 are applied, the sum of the entire area of the
plurality of first protrusions 400 are less than or equal to 30% of
the entire area of the incidence surface 200.
[0117] Referring to FIG. 7, since some of the lights emitted from
the light source 10 may be emitted at a predetermined divergence
angle .theta. based on the optical axis C, the first protrusion 400
is disposed within the divergence angle .theta. so that the light
is refracted to the top surface 310 of the exit surface 300 and
then emitted. Accordingly, the light diffusion lens 1 may secure
light diffusivity and light uniformity by changing the optical path
of some of the lights, which have directivity in a specific
direction, through the first protrusion 400. In this case, the
divergence angle .theta. may be 50 degrees or less based on the
optical axis C. In embodiments, the first protrusion 400 is
disposed within 50 degrees based on the optical axis C.
[0118] Referring to FIGS. 5 and 6, the first protrusion 400 may be
formed of a first curved surface 410 having a predetermined
curvature in a vertical cross section. Thus, the first curved
surface 410 may convexly be formed on the incidence surface 200
toward the optical axis C.
[0119] A center C1 of the first curved surface 410 may be disposed
in the light diffusion lens 1. In this case, the center C1 of the
first curved surface 410 may be disposed on an imaginary line L
passing through a center C2 of the height H1 of the incidence
surface 200 in a horizontal direction based on the optical axis
direction. In this case, the line L may be disposed above the side
surface 320.
[0120] Referring to FIG. 5, two first protrusions 400 may be
symmetrically disposed based on the optical axis C in the vertical
cross section. Accordingly, the light diffusion lens 1 may improve
light uniformity in the radial direction. Here, in consideration of
the light emitted from the light source 10, two or more or three or
more first protrusions 400 may be disposed. Additionally, in
consideration of light uniformity in the radial direction, two or
more even numbers of first protrusions 400 may be symmetrically
disposed based on the optical axis C.
[0121] Alternatively, the first protrusion 400 may be formed in a
hemispherical shape to protrude from the incidence surface 200.
Here, a cross section of the first protrusion 400 may be formed in
a circular shape.
[0122] Referring to FIG. 1, an edge at which the first protrusion
400 and the incidence surface 200 meet may be formed in a circular
shape. Here, the edge at which the first protrusion 400 and the
incidence surface 200 meet may be called a first edge.
[0123] Accordingly, as shown in FIG. 5, the edge may be formed to
have a predetermined diameter D1. Further, the diameter D1 may be
formed to be smaller than the first radius R1 which is the maximum
radius from the optical axis C to the incidence surface 200.
[0124] The edge may include one point P1 at a lower end and one
point P2 at an upper end based on the optical axis direction. Here,
the one point P1 at the lower end may be called a first point, and
the one point P2 at the upper end may be called a second point.
[0125] Referring to FIG. 6, in embodiments, the first protrusion
400 is disposed within a predetermined available range based on the
radial direction. Here, the available range may indicate a range
between a distance R3 from the optical axis C to the one point P1
at the lower end of the edge in the radial direction and a distance
R4 from the optical axis C to the one point P2 at the upper end of
the edge in the radial direction. In one embodiment, the available
range may be a factor which indicates how far the first protrusion
400 is away from the optical axis C in the radial direction.
[0126] Therefore, when the first protrusion 400 is disposed outside
the available range, a dark portion and a bright portion are
generated in an image due to internal reflection of the light
diffusion lens 1 such that light uniformity may be degraded. Here,
the dark portion may mean an area that is darker than a periphery
of light formed using a light diffusion lens. Further, the bright
portion may mean an area that is brighter than the periphery of the
light formed using the light diffusion lens.
[0127] Consequently, the light diffusion lens 1 may secure the
light uniformity by locating the first protrusion 400 within the
available range.
[0128] As shown in FIG. 5, the distance R3 from the optical axis C
to the one point P1 at the lower end of the edge may be formed to
be greater than the distance R4 from the optical axis C to the one
point P2 at the upper end of the edge. The distance R3 from the
optical axis C to the one point P1 at the lower end of the edge may
be formed to be smaller than the first radius R1 which is the
maximum radius.
[0129] Therefore, the light diffusion lens 1 may define the
distance R3 from the optical axis C to the one point P1 at the
lower end of the edge and the distance R4 from the optical axis C
to the one point P2 at the upper end of the edge based on the first
radius R1, thereby presenting an arrangement position of the first
protrusion 400.
[0130] Here, the first radius R1 may be 6.1 to 6.2 times a
difference R3-R4 between the distance R3 from the optical axis C to
the one point P1 at the lower end of the edge and the distance R4
from the optical axis C to the one point P2 at the upper end of the
edge. Specifically, the first radius R1 may be 6.12 times the
difference R3-R4 between the distance R3 from the optical axis C to
the one point P1 at the lower end of the edge and the distance R4
from the optical axis C to the one point P2 at the upper end of the
edge.
[0131] Further, the diameter D1 of the edge may be formed to be
greater than the difference R3-R4 between the distance R3 from the
optical axis C to the one point P1 at the lower end of the edge and
the distance R4 from the optical axis C to the one point P2 at the
upper end of the edge.
[0132] Therefore, the light diffusion lens 1 may define the
distance R3 from the optical axis C to the one point P1 at the
lower end of the edge and the distance R4 from the optical axis C
to the one point P2 at the upper end of the edge based on the
diameter D1 of the edge, thereby presenting a size of the first
protrusion 400.
[0133] Here, the diameter D1 of the edge may be 3.3 to 3.4 times
the difference R3-R4 between the distance R3 from the optical axis
C to the one point P1 at the lower end of the edge and the distance
R4 from the optical axis C to the one point P2 at the upper end of
the edge. Specifically, the diameter D1 of the edge may be 3.37
times the difference R3-R4 between the distance R3 from the optical
axis C to the one point P1 at the lower end of the edge and the
distance R4 from the optical axis C to the one point P2 at the
upper end of the edge.
[0134] FIG. 8 is a diagram illustrating an optical path due to a
first protrusion of the light diffusion lens according to the first
embodiment, and FIG. 9 shows photographs illustrating before and
after application of the first protrusion. Here, FIG. 9A is a
photograph illustrating light formed by a light diffusion lens in
which a first protrusion is omitted from the light diffusion lens
according to the first embodiment, and FIG. 9B is a photograph
illustrating light formed by the light diffusion lens, to which the
first protrusion is applied, according to the first embodiment.
[0135] Referring to FIG. 8, lights incident into the first
protrusion 400 may be refracted by the first protrusion 400 to
improve light uniformity of the light diffusion lens 1. For
example, the lights incident into the first protrusion 400 may be
collected by the first protrusion 400 and refracted to the top
surface 310. For example, the first protrusion 400 may serve as a
converging lens.
[0136] Thus, as shown in FIG. 9A, when the first protrusion is
omitted from the light diffusion lens according to the first
embodiment, a dark portion is formed. However, as shown in FIG. 9B,
when the first protrusion 400 is applied to the light diffusion
lens 1 according to the first embodiment, it can be confirmed that
a dark portion is removed such that light uniformity is
improved.
[0137] In this case, a five surface emission light-emitting diode
(LED) may be used as the light source 10. Accordingly, the first
protrusion 400 is disposed in the same radial direction to
correspond to a side light-emitting surface 12 such that the light
uniformity may be improved.
[0138] FIG. 10 is a diagram illustrating a light source for
emitting light to an incidence surface of the light diffusion lens
according to the first embodiment.
[0139] Referring to FIG. 10, the light source 10 emitting light
toward the incidence surface 200 may include a top light-emitting
surface 11 and four side light-emitting surfaces 12. Thus, the
light source 10 may implement five surface emission. In this case,
a bottom surface of the light source 10 may be disposed to be in
contact with a top surface of a substrate 20. Here, an example in
which the five surface emission LED is used as the light source 10
has been described, but the present disclosure is not necessarily
limited thereto.
[0140] Light emitted from the top light-emitting surface 11 of the
light source 10 may be emitted in the optical axis direction, and
light emitted from the side light-emitting surface 12 may be
emitted in the radial direction of the light diffusion lens 1.
Further, an optical axis apex 11a may be formed at a center of the
top light-emitting surface 11. In this case, the optical axis apex
11a may be disposed on a line of the optical axis C.
[0141] Further, the first protrusion 400 of the light diffusion
lens 1 may be disposed in the same radial direction as the side
light-emitting surface 12 to correspond to the side light-emitting
surface 12.
[0142] Meanwhile, a yellow fluorescent material may be applied to
the light source 10.
Second Embodiment
[0143] FIG. 11 is a perspective view illustrating a light diffusion
lens according to a second embodiment, FIG. 12 is a bottom view
illustrating the light diffusion lens according to the second
embodiment, FIG. 13 is a plan view illustrating the light diffusion
lens according to the second embodiment, FIG. 14 is a side view
illustrating the light diffusion lens according to the second
embodiment, FIG. 15 is a cross-sectional view illustrating the
light diffusion lens according to the second embodiment, FIG. 16 is
an enlarged view illustrating area B of FIG. 15, and FIG. 17 is a
diagram illustrating an arrangement relationship between a light
source and the light diffusion lens according to the second
embodiment. Here, FIG. 15 is a cross-sectional view taken along
line A2-A2 of FIG. 11.
[0144] In describing a light diffusion lens 1a according to the
second embodiment, the same components as those of the light
diffusion lens 1 according to the first embodiment are denoted by
the same reference numerals, and thus detailed descriptions thereof
will be omitted herein.
[0145] Comparing the light diffusion lens 1a according to the
second embodiment with the light diffusion lens 1 according to the
first embodiment, the light diffusion lens 1a according to the
second embodiment is different from the light diffusion lens 1 in
that the first protrusions 400 are omitted and second dimples 500
are included.
[0146] Referring to FIGS. 11 to 17, the light diffusion lens 1a
according to the second embodiment may include a bottom surface
100, an incidence surface 200 into which light is incident, an exit
surface 300 from which the light incident through the incidence
surface 200 is emitted, and second dimples 500 concavely formed on
the exit surface 300. Here, the exit surface 300 may include a top
surface 310 and a side surface 320.
[0147] Therefore, the light diffusion lens 1a may diffuse light
emitted from a light source 10 using the aspherical-shaped
incidence surface 200, the exit surface 300, and the second dimples
500 formed on the exit surface 300.
[0148] In embodiments, in the light diffusion lens 1a, since an
optical path of the light emitted from the light source 10 is
changed due to shapes of the incidence surface 200 and the exit
surface 300 and the second dimples 500, the incidence surface 200
which is formed in the aspherical shape, the shape of the exit
surface 300, and arrangements, shapes, and sizes of the second
dimples 500 act as largest factors of light distribution according
to the change of the optical path of the light.
[0149] The second dimple 500 may be concavely formed on the top
surface 310 of the exit surface 300 toward an optical axis C.
Accordingly, the second dimple 500 may be called a first concave
portion or a first groove.
[0150] Referring to FIG. 17, since some of the lights emitted from
the light source 10 may be emitted at a predetermined divergence
angle .theta. based on the optical axis C, the second dimple 500 is
disposed within the divergence angle .theta. so that the light is
refracted to be emitted. Accordingly, the light diffusion lens 1a
may secure light diffusivity and light uniformity by changing the
optical path of some of the lights, which have directivity in a
specific direction, through the second dimple 500. In this case,
the divergence angle .theta. may be 50 degrees or less based on the
optical axis C. Specifically, a center C3 at which a long axis 520
and a short axis 530 of the second dimple 500 meet may be disposed
within 34 to 40 degrees based on the optical axis C. Preferably,
the center C3 of the second dimple 500 may be disposed at an angle
of 37 degrees based on the optical axis C.
[0151] Referring to FIG. 15, the second dimple 500 may include a
second curved surface 510 which is formed of a curved surface in a
vertical cross section. Thus, the second curved surface 510 may be
concavely formed on the exit surface 300 toward the optical axis C.
In this case, a cross section of the second dimple 500 may be
formed in an elliptical shape including a long axis and a short
axis.
[0152] Referring to FIG. 15, two second dimples 500 may be
symmetrically disposed based on the optical axis C in the vertical
cross section. Accordingly, the light diffusion lens 1a may improve
light uniformity in the radial direction. Here, in consideration of
the light emitted from the light source 10, two or more or three or
more second dimples 500 may be disposed. Additionally, in
consideration of light uniformity in the radial direction, two or
more even numbers of second dimples 500 may be disposed to face
each other based on the optical axis C.
[0153] Referring to FIGS. 11 and 13, an edge at which the second
dimple 500 and the exit surface 300 meet may be formed in an
elliptical shape. Here, the edge at which the second dimple 500 and
the exit surface 300 meet may be called a second edge.
[0154] Accordingly, as shown in FIG. 13, the edge may be formed in
an elliptical shape including the long axis 520 and the short axis
530.
[0155] Referring to FIG. 16, the edge at which the second dimple
500 and the exit surface 300 meet may include one point P3 at a
lower end and one point P4 at an upper end based on the optical
axis direction. Here, the one point P3 at the lower end may be
called a third point, and the one point P4 at the upper end may be
called a fourth point.
[0156] Referring to FIG. 16, in embodiments, the second dimple 500
is disposed within a predetermined available range based on the
radial direction. Here, the available range may indicate a range
between a distance R5 from the optical axis C to the one point P3
at the lower end of the edge in the radial direction and a distance
R6 from the optical axis C to the one point P4 at the upper end of
the edge in the radial direction.
[0157] Therefore, when the second dimple 500 is disposed outside
the available range, a dark portion and a bright portion are
generated in an image due to external refraction of the light
diffusion lens 1a such that light uniformity may be degraded.
[0158] Consequently, the light diffusion lens 1a may secure the
light uniformity by locating the second dimple 500 within the
available range.
[0159] As shown in FIG. 15, the distance R5 from the optical axis C
to the one point P3 at the lower end of the edge may be formed to
be greater than the distance R6 from the optical axis C to the one
point P4 at the upper end of the edge. Further, the distance R6
from the optical axis C to the one point P4 at the upper end of the
edge may be formed to be greater than the first radius R1 which is
the maximum radius.
[0160] Therefore, the light diffusion lens 1a may define the
distance R5 from the optical axis C to the one point P3 at the
lower end of the edge and the distance R6 from the optical axis C
to the one point P4 at the upper end of the edge based on the first
radius R1, thereby presenting an arrangement position of the second
dimple 500.
[0161] Here, the first radius R1 may be 4.4 to 4.5 times a
difference R5-R6 between the distance R5 from the optical axis C to
the one point P3 at the lower end of the edge and the distance R6
from the optical axis C to the one point P4 at the upper end of the
edge. Specifically, the first radius R1 may be 4.47 times the
difference R5-R6 between the distance R5 from the optical axis C to
the one point P3 at the lower end of the edge and the distance R6
from the optical axis C to the one point P4 at the upper end of the
edge.
[0162] Further, a size of the second dimple 500 may be presented
according to a ratio between the long axis 520 and the short axis
530 of the edge. In this case, a length L1 of the long axis 520 is
greater than a length L2 of the short axis 530. Consequently, the
light diffusion lens 1a may increase a diffusion amount of light in
a long axis direction of the second dimple 500.
[0163] Here, the length L1 of the long axis 520 may be 5.5 to 6.5
times the length L2 of the short axis 530. Specifically, the length
L1 of the long axis 520 may be six times the length L2 of the short
axis 530.
[0164] Further, a radius R2 of the exit surface 300 may be 3.5
times the length L1 of the long axis 520.
[0165] FIG. 18 is a diagram illustrating an optical path due to a
second dimple of the light diffusion lens according to the second
embodiment, and FIG. 19 shows photographs illustrating before and
after application of the second dimple. Here, FIG. 19A is a diagram
illustrating light formed by a light diffusion lens in which a
second dimple is omitted from the light diffusion lens according to
the second embodiment, and FIG. 19B is a diagram illustrating light
formed by the light diffusion lens, to which the second dimple is
applied, according to the second embodiment.
[0166] Referring to FIG. 18, lights incident into the second dimple
500 may be refracted by the second dimple 500 to improve light
uniformity of the light diffusion lens 1a. For example, the lights
incident into the second dimple 500 may diverge by the second
dimple 500 to be emitted to the outside. For example, the second
dimple 500 may serve as a diverging lens.
[0167] Thus, as shown in FIG. 19A, when the second dimple is
omitted from the light diffusion lens according to the second
embodiment, a dark portion is formed. However, as shown in FIG.
19B, when the second dimple 500 is applied to the light diffusion
lens 1a according to the second embodiment, it can be confirmed
that a dark portion and a bright portion are improved such that
light uniformity is improved.
[0168] In this case, a five surface emission LED may be used as the
light source 10. Accordingly, the second dimple 500 is disposed in
the same radial direction to correspond to a side light-emitting
surface 12 such that the light uniformity of the light diffusion
lens 1a may be improved.
Third Embodiment
[0169] FIG. 20 is a perspective view illustrating a light diffusion
lens according to a third embodiment, FIG. 21 is a bottom view
illustrating the light diffusion lens according to the third
embodiment, FIG. 22 is a plan view illustrating the light diffusion
lens according to the third embodiment, FIG. 23 is a side view
illustrating the light diffusion lens according to the third
embodiment, FIG. 24 is a cross-sectional view illustrating the
light diffusion lens according to the third embodiment, FIG. 25 is
an enlarged view illustrating area D of FIG. 24, and FIG. 26 is a
diagram illustrating an arrangement relationship between a light
source and the light diffusion lens according to the third
embodiment. Here, FIG. 24 is a cross-sectional view taken along
line A3-A3 of FIG. 20.
[0170] In describing a light diffusion lens 1b according to the
third embodiment, the same components as those of the light
diffusion lens 1 according to the first embodiment and the light
diffusion lens 1a according to the second embodiment are denoted by
the same reference numerals, and thus detailed descriptions thereof
will be omitted herein.
[0171] Comparing the light diffusion lens 1b according to the third
embodiment with the light diffusion lens 1 according to the first
embodiment, the light diffusion lens 1b according to the third
embodiment is different from the light diffusion lens 1 in that
second dimples 500 are further included.
[0172] Referring to FIGS. 20 to 26, the light diffusion lens 1b
according to the third embodiment may include a bottom surface 100,
an incidence surface 200 into which light is incident, an exit
surface 300 from which the light incident through the incidence
surface 200 is emitted, first protrusions 400 convexly formed on
the incidence surface 200, and second dimples 500 concavely formed
on the exit surface 300. Here, the exit surface 300 may include a
top surface 310 and a side surface 320.
[0173] Therefore, the light diffusion lens 1b may diffuse light
emitted from a light source 10 using the aspherical-shaped
incidence surface 200, the exit surface 300, the first protrusions
400 formed on the incidence surface 200, and the second dimples 500
formed on the exit surface 300.
[0174] In embodiments, in the light diffusion lens 1b, since an
optical path of the light emitted from the light source 10 is
changed due to shapes of the incidence surface 200 and the exit
surface 300, the first protrusions 400, and the second dimples 500,
the incidence surface 200 which is formed in the aspherical shape,
the shape of the exit surface 300, and arrangements, shapes, and
sizes of the second dimples 500 act as largest factors of light
distribution according to the change of the optical path of the
light. In this case, the second dimple 500 may be formed to
correspond to light refracted due to the first protrusion 400.
[0175] The second dimple 500 may be concavely formed on the top
surface 310 of the exit surface 300 toward an optical axis C.
Accordingly, the second dimple 500 may be called a concave
portion.
[0176] Referring to FIG. 26, since some of the lights emitted from
the light source 10 may be emitted at a predetermined divergence
angle .theta. based on the optical axis C, the first protrusion 400
and the second dimple 500 are disposed within the divergence angle
.theta. so that the light is refracted to be emitted. Accordingly,
the light diffusion lens 1b may secure light diffusivity and light
uniformity by changing the optical path of some of the lights,
which have directivity in a specific direction, through the first
protrusion 400 and the second dimple 500. In this case, the
divergence angle .theta. may be 50 degrees or less based on the
optical axis C.
[0177] In this case, a divergence angle applied to arrange the
second dimple 500 based on the optical axis C may be smaller than a
divergence angle for application of the first protrusion 400. In
one embodiment, as shown in FIG. 26, the second dimple 500 may be
disposed close to the optical axis C based on the divergence angle
for application of the first protrusion 400.
[0178] Referring to FIG. 24, two first protrusions 400 and two
second dimples 500 may be symmetrically disposed based on the
optical axis C in a vertical cross section. Accordingly, the light
diffusion lens 1b may improve light uniformity in the radial
direction. Here, in consideration of the light emitted from the
light source 10, two or more first protrusions 400 and two or more
second dimples 500 may be disposed. Additionally, in consideration
of optical uniformity in the radial direction, two or more even
numbers of first protrusions 400 and two or more even numbers of
second dimples 500 may be disposed to face each other based on the
optical axis C.
[0179] In this case, as shown in FIGS. 20 and 24, the first
protrusion 400 and the second dimple 500 may be disposed in the
same radial direction.
[0180] Meanwhile, an edge at which the first protrusion 400 and the
incidence surface 200 meet may be formed in a circular shape having
a predetermined diameter D1. Further, an edge at which the second
dimple 500 and the exit surface 300 meet may be formed in an
elliptical shape including a long axis 520 and a short axis 530. In
this case, the diameter D1 of the edge at which the first
protrusion 400 and the incidence surface 200 meet may be smaller
than a length L1 of the long axis 520 of the edge at which the
second dimple 500 and the exit surface 300 meet. In this case, the
diameter D1 of the edge at which the first protrusion 400 and the
incidence surface 200 meet may be greater than a length L2 of the
short axis 530 of the edge at which the second dimple 500 and the
exit surface 300 meet.
[0181] FIG. 27 is a diagram illustrating an optical path due to a
second dimple of the light diffusion lens according to the second
embodiment.
[0182] Referring to FIG. 27, lights incident into the first
protrusion 400 may be collected by the first protrusion 400 and
incident into the second dimple 500. Further, the lights incident
into the second dimple 500 may be diffused by the second dimple 500
and emitted to the outside.
[0183] Consequently, the light diffusion lens 1b may further
improve light uniformity by applying the second dimple 500 to an
area of a minute dark portion or a minute bright portion which is
not resolved through the application of the first protrusion
400.
[0184] Meanwhile, a five surface emission LED may be used as the
light source 10. Accordingly, a plurality of the first protrusions
400 and a plurality of the second dimples 500 are disposed in the
same radial direction to correspond to a side light-emitting
surface 12 such that the light uniformity of the light diffusion
lens 1b may be improved.
Fourth Embodiment
[0185] FIG. 28 is a perspective view illustrating a light diffusion
lens according to a fourth embodiment, FIG. 29 is a bottom view
illustrating the light diffusion lens according to the fourth
embodiment, FIG. 30 is a plan view illustrating the light diffusion
lens according to the fourth embodiment, FIG. 31 is a front view
illustrating the light diffusion lens according to the fourth
embodiment, FIG. 32 is a side view illustrating the light diffusion
lens according to the fourth embodiment, FIG. 33 is a
cross-sectional view in a long axis direction based on an exit
surface of the light diffusion lens according to the fourth
embodiment, FIG. 34 is a cross-sectional view in a short axis
direction based on the exit surface of the light diffusion lens
according to the fourth embodiment, and FIG. 35 is an enlarged view
illustrating area E of FIG. 33. Here, FIG. 33 is a cross-sectional
view taken along line A4-A4 of FIG. 28, and FIG. 34 is a
cross-sectional view taken along line A5-A5 of FIG. 28. In FIG. 28,
an x direction indicates a long axis direction based on an exit
surface, a y direction indicates a short axis direction based on
the exit surface, and a z direction indicates an axial direction or
an optical axis direction.
[0186] Meanwhile, an optical axis C may be a center of light
emitted from a light source 10 and may coincide with a center of a
light diffusion lens 1c.
[0187] Comparing the light diffusion lens 1c according to the
fourth embodiment with the light diffusion lens 1 according to the
first embodiment, the light diffusion lens 1c according to the
fourth embodiment is different from the light diffusion lens 1 in
that each of a bottom surface 100a, an incidence hole 210a, an exit
surface 300a, and third protrusions 600 is formed to have a long
axis and a short axis.
[0188] Referring to FIGS. 28 to 33, the light diffusion lens 1c
according to the fourth embodiment may include the bottom surface
100a, an incidence surface 200a concavely formed inward the bottom
surface 100a to form the incidence hole 210a, the exit surface 300a
from which light incident through the incidence surface 200a is
emitted, and the third protrusions 600 convexly formed on the
incidence surface 200a. Here, the exit surface 300a may be formed
to have a first long axis 330 with a predetermined first long axis
length Dx1 and a first short axis 340 with a predetermined first
short axis length Dy1. Thus, the incidence surface 200a may also be
formed to have the first long axis length Dx1 and the first short
axis length Dy1. Further, the exit surface 300a may include a top
surface 310a and a side surface 320a.
[0189] Therefore, the light diffusion lens 1c may diffuse the light
emitted from the light source 10 using the aspherical-shaped
incidence surface 200a, the exit surface 300a, and the third
protrusions 600 formed on the incidence surface 200a.
[0190] In embodiments, in the light diffusion lens 1c, since an
optical path of the light emitted from the light source 10 is
changed due to shapes of the incidence surface 200a and the exit
surface 300a and the third protrusions 600, the shapes and
arrangement of the incidence surface 200a, which is formed in the
aspherical shape, and the exit surface 300a, and arrangements,
shapes, and sizes of the third protrusions 600 act as largest
factors of light distribution according to the change of the
optical path of the light.
[0191] Referring to FIG. 29, the incidence hole 210a may be
disposed at a center of the bottom surface 100a. Further, since the
bottom surface 100a is disposed below the exit surface 300a, the
bottom surface 100a may be formed to have the first long axis
length Dx1 and the first short axis length Dy1. Accordingly, the
bottom surface 100a may be formed in an elliptical shape.
[0192] Further, the bottom surface 100a may be formed in a
downwardly convex shape or a flat surface shape.
[0193] The downwardly convex-shaped bottom surface 100a may be a
curved surface having a curvature that is greater than that of a
central portion of the top surface 310a.
[0194] An example of the bottom surface 100a includes a bottom
surface formed of a curved surface having a downwardly convex
shape, but the present disclosure is not necessarily limited
thereto. For example, in the bottom surface 100a, a flat surface
may be formed from an edge to a predetermined length in a center
direction, and a lower convex surface may be formed from a position
at which the flat surface ends to a center side. In embodiments,
the bottom surface 100a may have a shape of which curvature is zero
from the edge to a predetermined length in the center direction and
increases and then decreases again to the center of the bottom
surface 100a from the predetermined length.
[0195] When compared with a bottom surface comprised of only the
flat surface, the bottom surface 100a having the lower convex
surface may totally reflect more light, which is emitted to the
lower side, toward the upper side among lights emitted from the
light source 10.
[0196] Here, in order to preferentially totally reflect the light
due to the lower convex surface, the flat surface may be disposed
outside the lower convex surface.
[0197] Further, the bottom surface 100a of a flat surface shape may
be formed to be inclined from an end portion of a lower side of the
side surface 320a toward the optical axis C. For example, the
bottom surface 100a of a flat surface shape may be a flat surface
which is formed to be inclined with respect to an imaginary
horizontal surface at a predetermined angle based on the end
portion of the lower side of the side surface 320a. Accordingly,
the bottom surface 100a may totally reflect more light, which is
emitted to the lower side, toward the upper side among lights
emitted from the light source 10.
[0198] The incidence surface 200a is a surface portion through
which the light emitted from the light source 10 located in the
incidence hole 210a is incident into the light diffusion lens
1c.
[0199] As shown in FIGS. 28, 33, and 34, the aspherical-shaped
incidence surface 200a may be formed to be concave inward the
bottom surface 100a from the center thereof. Accordingly, the
incidence hole 210a may be formed at the center of the bottom
surface 100a.
[0200] A vertical cross section of the incidence surface 200a may
be formed in a semi-elliptical shape, a semi-rugby ball shape, or a
parabolic shape. Accordingly, the incidence surface 200a may be
formed of an aspherical surface. In this case, the incidence
surface 200a may be formed to have a predetermined height H1 from
the bottom surface 100a based on the optical axis direction.
[0201] Referring to FIGS. 28 and 29, since the incidence surface
200a extends upward from the incidence hole 210a, a horizontal
cross section of the incidence surface 200a may have an elliptical
shape. In this case, since the vertical cross section of the
incidence surface 200a is formed in a semi-elliptical shape, a
semi-rugby ball shape, or a parabolic shape, the horizontal cross
section of the incidence surface 200a may be decreased toward the
upper side.
[0202] The incidence hole 210a may include a second long axis 211
formed with a second long axis length Dy2 and a second short axis
212 formed with a second short axis length Dx2. Here, when the exit
surface 300a is viewed in the optical axis direction, the second
short axis 212 of the incidence hole 210a may be disposed to
overlap the first long axis 330 of the exit surface 300a. In this
case, the second short axis length Dx2 of the second short axis 212
is smaller than the first long axis length Dx1 of the first long
axis 330.
[0203] Further, a center C4 of the incidence hole 210a may be
disposed on the optical axis C, and the light source 10 may be
disposed at a center of the incidence hole 210a. Accordingly, an
air layer may be disposed between the light source 10 and the
incidence surface 200a. Thus, light emitted from the light source
10 to the air layer may be refracted at the incidence surface 200a
of the light diffusion lens 1c having a different refractive
index.
[0204] The exit surface 300a may be a surface of the light
diffusion lens 1c from which the light incident through the
incidence surface 200a is emitted and may be formed to be
rotationally symmetrical based on the optical axis C. Thus, as
shown in FIG. 30, when viewed in the optical axis direction, the
exit surface 300a may be formed to have the first long axis 330
with the predetermined first long axis length Dx1 and the first
short axis 340 with the predetermined first short axis length Dy1.
For example, the exit surface 300a may be formed in an elliptical
shape.
[0205] Further, a height H2 of the exit surface 300a is greater
than the height H1 of the incidence surface 200a based on the
optical axis direction.
[0206] Referring to FIGS. 31 and 32, the exit surface 300a may
include the convex-shaped top surface 310a and the side surface
320a disposed between the top surface 310a and the bottom surface
100a. In this case, the side surface 320a may be disposed parallel
to the optical axis C. Further, some of lights incident into the
light diffusion lens 1c through the incidence surface 200a is
refracted through the top surface 310a to be emitted to the
outside.
[0207] The top surface 310a may be convexly formed in a
non-hemispherical shape or a rotationally symmetrical shape. For
example, the top surface 310a may be convexly formed in the optical
axis direction (the Z direction).
[0208] In this case, the top surface 310a may be symmetrically
formed based on an imaginary vertical flat surface passing through
the optical axis C. For example, the top surface 310a may implement
a symmetrical optical path with respect to the first long axis 330
or the first short axis 340 based on the optical axis C.
[0209] The top surface 310a may be formed in a convex shape of
which curvature is gradually increased from a central portion of an
uppermost end of the top surface 310a toward an edge portion
thereof. Alternatively, the central portion of the uppermost end of
the top surface 310a may be flatter than the edge portion
thereof.
[0210] Meanwhile, the light diffusion lens 1c may implement
asymmetric light distribution while improving light diffusivity and
image quality using the side surface 320a which forms a free curve
so as to generate a height difference on the upper side of the exit
surface 300a.
[0211] As shown in FIG. 28, since the upper side of the side
surface 320a is formed in a curved shape, the side surface 320a may
include a pair of first side portions 321, each having a first
height H3, and a pair of second side portions 322, each having a
second height H4. Here, the pair of first side portions 321 and the
pair of second side portions 322 are respectively disposed to face
each other based on the optical axis C. In this case, the first
height H3 is formed to be higher than the second height H4 based on
the bottom surface 100a or an edge of a lower side of the side
surface 320a. Thus, the first height H3 may be a maximum height of
the side surface 320a, and the second height H4 may be a minimum
height of the side surface 320a.
[0212] Referring to FIGS. 30, 33, and 34, the first side portion
321 may be disposed in the short axis direction of the incidence
hole 210a, and the second side portion 322 may be disposed in the
long axis direction of the incidence hole 210a. Alternatively, the
first side portion 321 may be disposed in the long axis direction
of the exit surface 300a, and the second side portion 322 may be
disposed in the short axis direction of the exit surface 300a.
[0213] At this time, in order to prevent formation of moire to
improve light uniformity of the light diffusion lens 1c, a ratio Hr
between the first height H1 of the first side portion 321 and the
second height H2 of the second side portion 322 may be designed in
consideration of a ratio of the second short axis 212 to the second
long axis 211 of the incidence hole 210a.
[0214] Meanwhile, an area in which the top surface 310a and the
side surface 320a meet may be formed in a curved shape. Here, the
curved shape may be formed to have a predetermined curvature. As
shown in FIG. 28, the upper side of the side surface 320a may be
formed in a curved shape in which the height of the side surface
320a is decreased from the first side portion 321 toward the second
side portion 322.
[0215] The third protrusion 600 may be convexly formed toward the
optical axis C. Accordingly, the third protrusion 600 may be called
a second protruding portion or a second protrusion.
[0216] A plurality of third protrusions 600 may be formed on the
incidence surface 200a, and the sum of the plurality of third
protrusions 600 may be 30% or less of an entire area of the
incidence surface 200a.
[0217] In embodiments, the plurality of third protrusions 600 are
formed to have an area of 30% or less of the entire area of the
incidence surface 200a. When the third protrusions 600 have an area
exceeding 30% of the entire area of the incidence surface 200a, the
third protrusions 600 affect overall image quality of the light
diffusion lens 1c. For example, since paths of reflected light and
returned light are changed when the entire area of the plurality of
third protrusions 600 increases, when the plurality of third
protrusions 600 are applied, the sum of the entire area of the
plurality of third protrusions 600 are less than or equal to 30% of
the entire area of the incidence surface 200a.
[0218] FIG. 36 is a diagram illustrating an arrangement
relationship between a light source and the light diffusion lens
according to the fourth embodiment.
[0219] Referring to FIG. 36, since some of the lights emitted from
the light source 10 may be emitted at a predetermined divergence
angle .theta. based on the optical axis C, the third protrusion 600
is disposed within the divergence angle .theta. so that the light
is refracted to the top surface 310a of the exit surface 300a and
then emitted. Accordingly, the light diffusion lens 1c may secure
light diffusivity and light uniformity by changing the optical path
of some of the lights, which have directivity in a specific
direction, through the third protrusion 600. In this case, the
divergence angle .theta. may be 50 degrees or less based on the
optical axis C. In one embodiment, the third protrusion 600 is
disposed within 50 degrees based on the optical axis C.
[0220] Referring to FIGS. 33 and 35, the third protrusion 600 may
be formed of a third curved surface 610 which is formed of a curved
surface in a vertical cross section. Thus, the third curved surface
610 may be convexly formed on the incidence surface 200a toward the
optical axis C.
[0221] Referring to FIG. 33, two third protrusions 600 may be
symmetrically disposed based on the optical axis C in the vertical
cross section. Accordingly, the light diffusion lens 1c may improve
light uniformity in the long axis direction of the exit surface
300a. Here, in consideration of the light emitted from the light
source 10, two or more or three or more third protrusions 600 may
be disposed. Additionally, in consideration of light uniformity in
the long axis direction of the exit surface 300a, two third
protrusions 600 may be symmetrically disposed based on the optical
axis C.
[0222] Meanwhile, a cross section of the third protrusion 600 may
be formed in an elliptical shape to protrude from the incidence
surface 200a. Accordingly, the third protrusion 600 may include a
third long axis 620 with a predetermined third long axis length Dy3
and a third short axis 630 with a predetermined third short axis
length Dx3. Here, when the exit surface 300a is viewed, the third
short axis 630 of the third protrusion 600 may be disposed to
overlap the first long axis 330 of the exit surface 300a. In this
case, the second short axis length Dx2 of the second short axis 212
is greater than the third short axis length Dx3 of the third short
axis 630. Further, a center C5 of the third protrusion 600, at
which the third long axis 620 and the third short axis 630 meet,
may be disposed in the long axis direction of the exit surface
300a.
[0223] Referring to FIG. 28, an edge at which the third protrusion
600 and the incidence surface 200a meet may be formed in an
elliptical shape. Here, the edge at which the third protrusion 600
and the incidence surface 200a meet may be called a third edge. In
this case, a cross-sectional area of the third protrusion 600 may
decrease toward the optical axis C. Thus, since the third
protrusion 600 includes a maximum cross-sectional area at the edge,
the third long axis length Dy3 of the third long axis 620 and the
third short axis length Dx3 of the third short axis 630 become
maximum at the edge.
[0224] The edge may include one point P5 at a lower end and one
point P6 at an upper end based on the optical axis direction. Here,
the one point P5 at the lower end may be called a fifth point, and
the one point P6 at the upper end may be called a sixth point.
[0225] Referring to FIGS. 33 and 35, in embodiments, the third
protrusion 600 is disposed within a predetermined available range
based on the long axis direction of the exit surface 300a. Here,
the available range may indicate a range between a distance R7 from
the optical axis C to the one point P5 at the lower end of the edge
in the radial direction and a distance R8 from the optical axis C
to the one point P6 at the upper end of the edge in the radial
direction. In one embodiment, the available range may be a factor
which indicates how far the third protrusion 600 is away from the
optical axis C in the long axis direction of the exit surface
300a.
[0226] Therefore, when the third protrusion 600 is disposed outside
the available range, a dark portion and a bright portion are
generated in an image due to internal reflection of the light
diffusion lens 1c such that light uniformity may be degraded.
[0227] Consequently, the light diffusion lens 1c may secure the
light uniformity by locating the third protrusion 600 within the
available range.
[0228] As shown in FIG. 35, the distance R7 from the optical axis C
to the one point P5 at the lower end of the edge may be formed to
be greater than the distance R8 from the optical axis C to the one
point P6 at the upper end of the edge. Further, the distance R7
from the optical axis C to the one point P5 at the lower end of the
edge may be formed to be smaller than half of the second short axis
length Dx2 of the incidence hole 210a.
[0229] Therefore, the light diffusion lens 1c may define the
distance R7 from the optical axis C to the one point P5 at the
lower end of the edge and the distance R8 from the optical axis C
to the one point P6 at the upper end of the edge based on the half
of the second short axis length Dx2 of the incidence hole 210a,
thereby presenting an arrangement position of the third protrusion
600.
[0230] Here, the half of the second short axis length Dx2 of the
incidence hole 210a may be 9.9 to 10.0 times a difference R7-R8
between the distance R7 from the optical axis
[0231] C to the one point P5 at the lower end of the edge and the
distance R8 from the optical axis C to the one point P6 at the
upper end of the edge. Specifically, the half of the second short
axis length Dx2 of the incidence hole 210a may be 9.95 times the
difference R7-R8 between the distance R7 from the optical axis C to
the one point P5 at the lower end of the edge and the distance R8
from the optical axis C to the one point P6 at the upper end of the
edge.
[0232] Meanwhile, the one point P6 at the upper end of the edge may
be disposed above an imaginary line L passing through a center C2
of the height H1 of the incidence surface 200a in a horizontal
direction based on the optical axis direction. In this case, the
line L may be disposed above the side surface 320a.
[0233] FIG. 37 shows photographs illustrating before and after
application of a third protrusion. Here, FIG. 37A is a diagram
illustrating light formed by a light diffusion lens in which a
third protrusion is omitted from the light diffusion lens according
to the fourth embodiment, and FIG. 37B is a diagram illustrating
light formed by the light diffusion lens, to which the third
protrusion is applied, according to the fourth embodiment.
[0234] Lights incident into the third protrusion 600 may be
refracted by the third protrusion 600 to improve light uniformity
of the light diffusion lens 1c. For example, the lights incident
into the third protrusion 600 may be collected by the third
protrusion 600 and refracted to the top surface 310. For example,
the third protrusion 600 may serve as a converging lens.
[0235] Thus, as shown in FIG. 37A, when the third protrusion is
omitted from the light diffusion lens according to the fourth
embodiment, a dark portion is formed. However, as shown in FIG.
37B, when the third protrusion 600 is applied to the light
diffusion lens 1c according to the fourth embodiment, it can be
confirmed that the dark portion is removed or minimized such that
light uniformity is improved.
[0236] In this case, a five surface emission LED may be used as the
light source 10. Accordingly, the third protrusion 600 is disposed
in the same radial direction to correspond to a side light-emitting
surface 12 such that the light uniformity may be improved.
Fifth Embodiment
[0237] FIG. 38 is a perspective view illustrating a light diffusion
lens according to a fifth embodiment, FIG. 39 is a bottom view
illustrating the light diffusion lens according to the fifth
embodiment, FIG. 40 is a plan view illustrating the light diffusion
lens according to the fifth embodiment, FIG. 41 is a front view
illustrating the light diffusion lens according to the fifth
embodiment, FIG. 42 is a side view illustrating the light diffusion
lens according to the fifth embodiment, FIG. 43 is a
cross-sectional view in a long axis direction based on an exit
surface of the light diffusion lens according to the fifth
embodiment, FIG. 44 is a cross-sectional view in a short axis
direction based on the exit surface of the light diffusion lens
according to the fifth embodiment, FIG. 45 is an enlarged view
illustrating area F of FIG. 43, and FIG. 46 is a diagram
illustrating an arrangement relationship between a light source and
the light diffusion lens according to the fifth embodiment. Here,
FIG. 43 is a cross-sectional view taken along line A6-A6 of FIG.
38, and FIG. 44 is a cross-sectional view taken along line A7-A7 of
FIG. 38.
[0238] In describing a light diffusion lens 1d according to the
fifth embodiment, the same components as those of the light
diffusion lens 1c according to the fourth embodiment are denoted by
the same reference numerals, and thus detailed descriptions thereof
will be omitted herein.
[0239] Comparing the light diffusion lens 1d according to the fifth
embodiment with the light diffusion lens 1c according to the fourth
embodiment, the light diffusion lens 1d according to the fifth
embodiment is different from the light diffusion lens 1c in that
the third protrusions 600 are omitted and a plurality of fourth
dimples 700 are included.
[0240] Referring to FIGS. 38 to 45, the light diffusion lens 1d
according to the fifth embodiment may include a bottom surface
100a, an incidence surface 200a concavely formed inward the bottom
surface 100a to form an incidence hole 210a, an exit surface 300a
from which light incident through the incidence surface 200a is
emitted, and the fourth dimples 700 concavely formed on the exit
surface 300a. Here, the exit surface 300a may include a top surface
310a and a side surface 320a.
[0241] Therefore, the light diffusion lens 1d may diffuse light
emitted from a light source 10 using the aspherical-shaped
incidence surface 200a, the exit surface 300a, and the fourth
dimples 700 formed on the exit surface 300a.
[0242] In embodiments, in the light diffusion lens 1d, since an
optical path of the light emitted from the light source 10 is
changed due to shapes of the incidence surface 200a and the exit
surface 300a and the fourth dimples 700, the shapes of the
incidence surface 200a, which is formed in the aspherical shape,
and the exit surface 300a, and arrangements, shapes, and sizes of
the fourth dimples 700 act as largest factors of light distribution
according to the change of the optical path of the light.
[0243] A plurality of fourth dimples 700 may be concavely formed on
the top surface 310a of the exit surface 300a toward an optical
axis C. Accordingly, each of the plurality of fourth dimples 700
may be called a second concave portion or a second groove.
[0244] Referring to FIG. 45, each of the plurality of fourth
dimples 700 may be formed of a curved surface in a vertical cross
section. For example, each of the plurality of fourth dimples 700
may be formed to be concave toward the optical axis C on the exit
surface 300a. In this case, a cross section of the fourth dimple
700 may be formed in an elliptical shape including a long axis and
a short axis.
[0245] Referring to FIG. 40, the plurality of fourth dimples 700
may include a fourth-first dimple 710 formed at a predetermined
radius R9 from the optical axis C, a fourth-second dimple 720
formed at a predetermined radius R10 from the optical axis C, and
two or more fourth-third dimples 730 disposed at a predetermined
radius R11 based on the optical axis C. Here, the fourth-first
dimple 710 and the fourth-second dimple 720 may be disposed to be
spaced apart from each other in the same radial direction of a
first long axis 330 of the exit surface 300a. Further, the radius
R11 of the fourth-third dimple 730 is smaller than the radius R9 of
the fourth-first dimple 710 and is greater than the radius R10 of
the fourth-second dimple 720.
[0246] The fourth-first dimple 710 may include a fourth-first long
axis 711 with a predetermined fourth-first long axis length Dy4-1
and a fourth-first short axis 712 with a predetermined fourth-first
short axis length Dx4-1. Here, the fourth-first long axis length
Dy4-1 may be called a long axis length of the fourth-first dimple
710, and the fourth-first short axis length Dx4-1 may be called a
short axis length of the fourth-first dimple 710. In this case, the
fourth-first long axis length Dy4-1 is greater than the
fourth-first short axis length Dx4-1.
[0247] Further, a center C6 of the fourth-first dimple 710 may be
disposed at an intersection at which the fourth-first long axis 711
and the fourth-first short axis 712 meet. Accordingly, the radius
R9 of the fourth-first dimple 710 may be a distance from the
optical axis C to the center C6 of the fourth-first dimple 710.
[0248] Further, when the exit surface 300a is viewed in the optical
axis direction, the fourth-first short axis 712 of the fourth-first
dimple 710 may be disposed to overlap the first long axis 330 of
the exit surface 300a.
[0249] The fourth-second dimple 720 may include a fourth-second
long axis 721 with a predetermined fourth-second long axis length
Dy4-2 and a fourth-second short axis 722 with a predetermined
fourth-second short axis length Dx4-2. Here, the fourth-second long
axis length Dy4-2 may be called a long axis length of the
fourth-second dimple 720, and the fourth-second short axis length
Dx4-2 may be called a short axis length of the fourth-second dimple
720. In this case, the fourth-second long axis length Dy4-2 is
greater than the fourth-second short axis length Dx4-2.
[0250] Further, a center C7 of the fourth-second dimple 720 may be
disposed at an intersection at which the fourth-second long axis
721 and the fourth-second short axis 722 meet. Accordingly, the
radius R10 of the fourth-second dimple 720 may be a distance from
the optical axis C to the center C7 of the fourth-second dimple
720.
[0251] Further, when the exit surface 300a is viewed in the optical
axis direction, the fourth-second short axis 722 of the
fourth-second dimple 720 may be disposed to overlap the first long
axis 330 of the exit surface 300a.
[0252] The fourth-third dimple 730 may include a fourth-third long
axis 731 with a predetermined fourth-third long axis length Dy4-3
and a fourth-third short axis 732 with a predetermined fourth-third
short axis length Dx4-3. Here, the fourth-third long axis length
Dy4-3 may be called a long axis length of the fourth-third dimple
730, and the fourth-third short axis length Dx4-3 may be called a
short axis length of the fourth-third dimple 730. In this case, the
fourth-third long axis length Dy4-3 is greater than the
fourth-third short axis length Dx4-3.
[0253] Further, a center C8 of the fourth-third dimple 730 may be
disposed at an intersection at which the fourth-third long axis 731
and the fourth-third short axis 732 meet. Accordingly, the radius
R11 of the fourth-third dimple 730 may be a distance from the
optical axis C to the center C8 of the fourth-third dimple 730.
[0254] Further, when the exit surface 300a is viewed in the optical
axis direction, the fourth-third short axis 732 of the fourth-third
dimple 730 is not disposed to overlap the first long axis 330 of
the exit surface 300a.
[0255] Here, the fourth-third long axis length Dy4-3 of the
fourth-third dimple 730 may be smaller than the fourth-first long
axis length Dy4-1 of the fourth-first dimple 710 and greater than
the fourth-second long axis length Dy4-2 of the fourth-second
dimple 720.
[0256] Referring to FIG. 40, the radius R9 to the center C6 of the
fourth-first dimple 710 and the radius R10 to the center C7 of the
fourth-second dimple 720 are greater than the radius R11 to the
center C8 of the fourth-third dimple 730 based on the optical axis
C.
[0257] Referring to FIG. 40, the center C6 of the fourth-first
dimple 710 and the centers C8 of the two fourth-third dimples 730
may be formed in a triangular shape including an imaginary first
area. Further, the center C7 of the fourth-second dimple 720 and
the centers C8 of the two fourth-third dimples 730 may be formed in
a triangular shape including an imaginary second area. In this
case, the imaginary first area is greater than the imaginary second
area.
[0258] Meanwhile, the fourth-first dimple 710, the fourth-second
dimple 720, and the two fourth-third dimples 730 may form one
group. Further, as shown in FIG. 40, the light diffusion lens 1d
may include two groups facing each other based on the optical axis
C, and the two groups may be symmetrically disposed based on the
optical axis C.
[0259] Accordingly, in the light diffusion lens 1d, the plurality
of fourth dimples 700 may be formed in at least two groups which
are symmetrical based on the optical axis C. Accordingly, the light
diffusion lens 1d may improve light uniformity in the long axis
direction of the exit surface 300a. Here, in consideration of the
light emitted from the light source 10, two or more or three or
more groups of the plurality of fourth dimples 700 may be disposed.
Additionally, in consideration of optical uniformity, two or more
even numbers of groups of the plurality of fourth dimples 700 may
be disposed to face each other based on the optical axis C.
[0260] Referring to FIG. 46, since some of the lights emitted from
the light source 10 may be emitted at a predetermined divergence
angle .theta. based on the optical axis C, the plurality of fourth
dimples 700 are disposed within the divergence angle .theta. so
that the light is refracted to be emitted. Accordingly, the light
diffusion lens 1 d may secure light diffusivity and light
uniformity by changing the optical path of some of the lights,
which have directivity in a specific direction, through the fourth
dimple 700. In this case, the divergence angle .theta. may be 50
degrees or less based on the optical axis C. Specifically, since
the fourth-first dimple 710 of the fourth dimple 700 is disposed at
an outermost side based on the optical axis C, the center C6 of the
fourth-first dimple 710 may be disposed at an angle ranging from 34
degrees to 40 degrees based on the optical axis C. Preferably, the
center C6 of the fourth-first dimple 710 of the fourth dimple 700
may be disposed at an angle of 37 degrees based on the optical axis
C.
[0261] Referring to FIGS. 38 and 40, edges at which the plurality
of fourth dimples 700 and the exit surface 300a meet may be formed
in an elliptical shape. Here, the edge at which the fourth dimple
700 and the exit surface 300a meet may be called a third edge.
[0262] Referring to FIGS. 43 and 45, the edge at which the fourth
dimple 700 and the exit surface 300a meet may include one point at
a lower end and one point at an upper end based on the optical axis
direction. Here, the one point at the lower end of the fourth
dimple 700 may be the center C6 of the fourth-first dimple 710, and
the one point at the upper end of the fourth dimple 700 may be the
center C7 of the fourth-second dimple 720.
[0263] Referring to FIG. 45, in embodiments, the fourth dimple 700
is disposed within a predetermined available range based on the
long axis direction of the exit surface 300a. Here, the available
range may indicate a range between a radius R9 from the optical
axis C to the center C6 of the fourth-first dimple 710 in the long
axis direction and a radius R10 from the optical axis C to the
center C7 of the fourth-second dimple 720 in the long axis
direction.
[0264] Therefore, when the fourth dimple 700 is disposed outside
the available range, a dark portion and a bright portion are
generated in an image due to external refraction of the light
diffusion lens 1d such that light uniformity may be degraded.
[0265] Consequently, the light diffusion lens 1d may secure the
light uniformity by locating the fourth dimple 700 within the
available range.
[0266] As shown in FIG. 45, the radius R9 from the optical axis C
to may be formed to be greater than the radius R10 therefrom.
Further, the radius R10 may be formed to be greater than half of a
second short axis length Dx2 of the incidence hole 210a.
[0267] FIG. 47 shows photographs illustrating before and after
application of a fourth dimple. Here, FIG. 47A is a diagram
illustrating light formed by a light diffusion lens in which a
fourth dimple is omitted from the light diffusion lens according to
the fifth embodiment, and FIG. 47B is a diagram illustrating light
formed by the light diffusion lens, to which the fourth dimple is
applied, according to the fifth embodiment.
[0268] Lights incident into the fourth dimple 700 may be refracted
by the fourth dimple 700 to improve light uniformity of the light
diffusion lens 1d. For example, the lights incident into the fourth
dimple 700 may diverge by the fourth dimple 700 to be diffused to
the outside. For example, the fourth dimple 700 may serve as a
diverging lens.
[0269] Thus, as shown in FIG. 47A, when the fourth dimple is
omitted from the light diffusion lens according to the fifth
embodiment, a bright portion is formed. However, as shown in FIG.
47B, when the fourth dimple 700 is applied to the light diffusion
lens 1d according to the fifth embodiment, it can be confirmed that
the bright portion is improved such that light uniformity is
improved.
[0270] In this case, a five surface emission LED may be used as the
light source 10.
[0271] Accordingly, the fourth dimple 700 is disposed in the same
radial direction to correspond to a side light-emitting surface 12
such that the light uniformity of the light diffusion lens 1d may
be improved.
Sixth Embodiment
[0272] FIG. 48 is a perspective view illustrating a light diffusion
lens according to a sixth embodiment, FIG. 49 is a bottom view
illustrating the light diffusion lens according to the sixth
embodiment, FIG. 50 is a plan view illustrating the light diffusion
lens according to the sixth embodiment, FIG. 51 is a front view
illustrating the light diffusion lens according to the sixth
embodiment, FIG. 52 is a side view illustrating the light diffusion
lens according to the sixth embodiment, FIG. 53 is a
cross-sectional view in a long axis direction based on an exit
surface of the light diffusion lens according to the sixth
embodiment, FIG. 54 is a cross-sectional view in a short axis
direction based on the exit surface of the light diffusion lens
according to the sixth embodiment, FIG. 55 is an enlarged view
illustrating area G of FIG. 53, and FIG. 56 is a diagram
illustrating an arrangement relationship between a light source and
the light diffusion lens according to the sixth embodiment. Here,
FIG. 53 is a cross-sectional view taken along line A8-A8 of FIG.
48, and FIG. 54 is a cross-sectional view taken along line A9-A9 of
FIG. 48.
[0273] In describing a light diffusion lens 1e according to the
sixth embodiment, the same components as those of the light
diffusion lens 1c according to the fourth embodiment and the light
diffusion lens 1d according to the fifth embodiment are denoted by
the same reference numerals, and thus detailed descriptions thereof
will be omitted herein.
[0274] Comparing the light diffusion lens 1e according to the sixth
embodiment with the light diffusion lens 1c according to the fourth
embodiment, the light diffusion lens 1e according to the sixth
embodiment is different from the light diffusion lens 1c in that a
plurality of fourth dimples 700 are further included.
[0275] Referring to FIGS. 48 to 55, the light diffusion lens 1e
according to the sixth embodiment may include a bottom surface
100a, an incidence surface 200a concavely formed inward the bottom
surface 100a to form an incidence hole 210a, an exit surface 300a
from which light incident through the incidence surface 200a is
emitted, third protrusions 600 convexly formed on the incidence
surface 200a, and the fourth dimples 700 concavely formed on the
exit surface 300a. Here, the exit surface 300a may include a top
surface 310a and a side surface 320a.
[0276] Therefore, the light diffusion lens 1e may diffuse light
emitted from a light source 10 using the aspherical-shaped
incidence surface 200a, the exit surface 300a, the third
protrusions 600 formed on the incidence surface 200a, and the
fourth dimples 700 formed on the exit surface 300a.
[0277] In embodiments, in the light diffusion lens 1e, since an
optical path of the light emitted from the light source 10 is
changed due to shapes of the incidence surface 200a and the exit
surface 300a, the third protrusions 600, and the fourth dimples
700, the shapes of the incidence surface 200a, which is formed in
the aspherical shape, and the exit surface 300a, and arrangements,
shapes, and sizes of the fourth dimples 700 act as largest factors
of light distribution according to the change of the optical path
of the light. In this case, the fourth dimple 700 may be formed to
correspond to light which is refracted due to the third protrusion
600.
[0278] The third protrusion 600 may be convexly formed on the
incidence surface 200a toward the optical axis C, and the fourth
dimple 700 may be concavely formed on the top surface 310a of the
exit surface 300a toward the optical axis C.
[0279] Referring to FIG. 56, since some of the lights emitted from
the light source 10 may be emitted at a predetermined divergence
angle .theta. based on the optical axis C, the third protrusion 600
and the fourth dimple 700 are disposed within the divergence angle
.theta. so that the light is refracted to be emitted. Accordingly,
the light diffusion lens 1e may secure light diffusivity and light
uniformity by changing the optical path of some of the lights,
which have directivity in a specific direction, through the third
protrusion 600 and the fourth dimple 700. In this case, the
divergence angle .theta. may be 50 degrees or less based on the
optical axis C.
[0280] In this case, a divergence angle applied to arrange the
fourth dimple 700 based on the optical axis C may be smaller than a
divergence angle for application of the third protrusion 600. In
one embodiments, as shown in FIG. 56, the fourth dimple 700 may be
disposed close to the optical axis C based on the divergence angle
for application of the third protrusion 600.
[0281] Referring to FIG. 53, the third protrusions 600 and the
fourth dimples 700 may be respectively symmetrically disposed based
on the optical axis C in a vertical cross section. Accordingly, the
light diffusion lens 1e may improve light uniformity in a long axis
direction of the exit surface 300a. Here, in consideration of the
light emitted from the light source 10, two or more or three or
more third protrusions 600 and two or more or three or more fourth
dimples 700 may be disposed, respectively. Additionally, in
consideration of light uniformity in the long axis direction of the
exit surface 300a, groups of two third protrusions 600 and two
fourth dimples 700 may be respectively disposed to face each other
based on the optical axis C.
[0282] Here, the exit surface 300a may be formed to have a first
long axis 330 with a predetermined first long axis length Dx1 and a
first short axis 340 with a predetermined first short axis length
Dy1. The third protrusion 600 may be disposed in the same direction
as the first long axis 330. Accordingly, a third short axis 630 of
the third protrusion 600 may be disposed to overlap the first long
axis 330 of the exit surface 300a.
[0283] Further, a plurality of fourth dimples 700 may include a
fourth-first dimple 710, a fourth-second dimple 720, and two
fourth-third dimples 730. A fourth-first short axis 712 of the
fourth-first dimple 710 and a fourth-second short axis 722 of the
fourth-second dimple 720 may be disposed to overlap the first long
axis 330 of the exit surface 300a.
[0284] Thus, when the exit surface 300a is viewed in the optical
axis direction, the third short axis 630, the fourth-first short
axis 712 of the fourth-first dimple 710, and the fourth-second
short axis 722 of the fourth-second dimple 720 may be disposed to
overlap the first long axis 330 of the exit surface 300a.
[0285] Meanwhile, a third long axis length Dy3 of a third long axis
620 of the third protrusion 600 may be greater than a fourth-first
long axis length Dy4-1 of a fourth-first long axis 711 of the
fourth-first dimple 710.
[0286] Further, lights incident into the third protrusion 600 may
be collected by the third protrusion 600 and incident into the
fourth dimple 700. Further, the lights incident into the fourth
dimple 700 may be diffused by the fourth dimple 700 and emitted to
the outside.
[0287] Consequently, the light diffusion lens 1e may further
improve light uniformity by applying the fourth dimple 700 to an
area of a minute dark portion or a minute bright portion which is
not resolved through the application of the third protrusion
600.
[0288] Meanwhile, a five surface emission LED may be used as the
light source 10. Accordingly, a plurality of the third protrusions
600 and the plurality of the fourth dimples 700 are disposed in the
same direction to correspond to a side light-emitting surface 12
such that the light uniformity of the light diffusion lens 1e may
be improved.
[0289] As described above, in accordance with the present
disclosure, there is an effect in that light diffusivity and light
uniformity can be secured by changing an optical path of a part of
light having directivity in a specific direction using dimples
formed on an incidence surface or an exit surface.
[0290] Further, in accordance with the present disclosure, there is
an effect in that light uniformity can be improved by removing or
minimizing a dark portion due to light distribution using a dimple
formed on the incidence surface and can be improved by removing or
minimizing the dark portion or a bright portion using a dimple
formed on the exit surface.
[0291] As discussed in the foregoing, although all the elements
forming the embodiments of the present disclosure are combined into
one or operated as one element, the present disclosure is not
limited thereto. That is, all the elements may be selectively
combined or operated if within an object scope of the present
disclosure. Furthermore, it will be understood that the terms
"includes" and/or "including", "forming" and/or "formed" when used
in this specification, specify the presence of stated features,
regions, integers, steps, operations, elements, and/or components,
but do not preclude the presence or addition of one or more other
features, regions, integers, steps, operations, elements,
components, and/or groups thereof.
* * * * *