KR20170077578A - Total Internal Reflection LED Lens and Design Method Thereof - Google Patents

Total Internal Reflection LED Lens and Design Method Thereof Download PDF

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KR20170077578A
KR20170077578A KR1020150187594A KR20150187594A KR20170077578A KR 20170077578 A KR20170077578 A KR 20170077578A KR 1020150187594 A KR1020150187594 A KR 1020150187594A KR 20150187594 A KR20150187594 A KR 20150187594A KR 20170077578 A KR20170077578 A KR 20170077578A
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incident
peripheral
total reflection
central
light
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KR101849771B1 (en
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이승걸
양재석
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인하대학교 산학협력단
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G02B3/0006—Arrays
    • G02B3/0037—Arrays characterized by the distribution or form of lenses
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21K—NON-ELECTRIC LIGHT SOURCES USING LUMINESCENCE; LIGHT SOURCES USING ELECTROCHEMILUMINESCENCE; LIGHT SOURCES USING CHARGES OF COMBUSTIBLE MATERIAL; LIGHT SOURCES USING SEMICONDUCTOR DEVICES AS LIGHT-GENERATING ELEMENTS; LIGHT SOURCES NOT OTHERWISE PROVIDED FOR
    • F21K9/00—Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
    • F21K9/60—Optical arrangements integrated in the light source, e.g. for improving the colour rendering index or the light extraction
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V5/00—Refractors for light sources
    • F21V5/04—Refractors for light sources of lens shape
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2101/00—Point-like light sources
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G02B2003/0093—Simple or compound lenses characterised by the shape

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Abstract

The present invention is characterized in that it includes a central refracting portion and a peripheral total reflecting portion and is axially symmetric with respect to a rotation axis, and both a surface on which a light beam is incident and a surface on which light is emitted are all of a free- The present invention relates to a TIR (Total Internal Reflection) LED lens and a method of designing the same.

Description

TIR LED Lens and Design Method Thereof [0001]

The present invention relates to a TIR (Total Internal Reflection) LED lens and a method of designing the same. More specifically, the present invention relates to a TIR (Total Internal Reflection) LED lens, The present invention relates to a TIR LED lens and a method of designing the TIR LED lens to allow incident light to reach a target plane.

Compared to traditional light sources such as incandescent or fluorescent light, LED (Light Emitting Diode) is a safe light source with high efficiency, long life and eco-friendly advantages. Due to these advantages, LEDs are widely used in various indoor and outdoor lighting, display, and display devices. However, since the luminous flux emitted from the LED has a lambertian emission distribution, secondary optics for controlling the emitted light flux of the LED to form a required illuminance distribution, Is required. Such a secondary optical system can be realized by a reflective optical system, a refractive optical system, or a hybrid optical system combining the two, but a refractive optical system is preferred for miniaturization of the product. LED lens.

For cost reduction, the LED lens for illumination is designed to include one or more freeform surfaces, and the differential equation method is widely used as a design method for LED lenses. In the differential equation method, assuming that the shape of one side of the lens is known, the differential equation related to the ray progression is solved, and the shape of the remaining side is designed as the upper side of the free form. It first determines where on the target surface the ray emitted from the LED should reach the target plane according to the illumination model selected to form the desired illumination distribution on the target plane to be illuminated. Next, the surface slope of the arrival point is determined so that the light ray incident on the free-form surface reaches the designated position on the target surface. Although it is easy to determine the free form topology if it can derive the related linear differential equations, the luminous flux efficiency is influenced by the plane which is not set as the top of the free form, since only one side is assumed to be the free form top surface.

In order to overcome the limitation of the conventional differential equation method which assumes one freeform surface, lens design methods including two free form surfaces have been proposed. Among them, Mikhail A. Moiseev et al. Proposed a method of designing both sides of free surface by introducing condition for minimizing fresnel loss. The condition that the reflection loss is minimized when the incident ray has the same deflection angle on the incident surface (or incidence surface) of the lens and the exit surface is called a condition for minimizing the fresnel loss. The LED lens designed by this method can obtain a luminous flux efficiency higher than that of a lens having one free-form surface even when the beam spread angle is less than 100 °.

However, when the illumination angle of the LED lens is 40 DEG or less, it is pointed out that it is impossible to improve the luminous flux efficiency even when the Fresnel loss minimization condition is applied. Often in an LED lens, light rays emitted vertically from the LED emitting surface reach the central area of the target surface through the lens center area, and light rays emitted at a large angle reach the edge of the target surface through the lens peripheral area. Therefore, in order to realize a narrow illumination angle, the light rays incident on the peripheral region of the lens must be deflected at a large angle, so that the fresnel loss occurring in the peripheral region of the lens can not be reduced.

Patent Literature 10-1305728, "Free-form Lens Having Superimposing Effect of Distribution of Light Distribution to Improve Fabrication Tolerance of LED Lighting Apparatus", Mar. Patent No. 10-1439746 "Method and system for implementing a three-dimensional free-form lens for high-efficiency uniform illumination of a rectangular area", 2014. 09. 12.

M.A. Moiseev, S.V. Kravchenko, L.L. Doskolovich, N.L. Kazanskiy, Design of LED optics with two aspherical surfaces and the highest efficiency, Proc. of SPIE 8550 (2012) 1-6.

The present invention is characterized in that it includes a central refracting portion and a peripheral total reflecting portion and is axially symmetric with respect to a rotation axis, and both the surface on which the light beam is incident and the surface on which the light is emitted are both of a free- And a method of designing the TIR LED lens.

In order to solve the above-described problems, the present invention adopts an LED lens structure including a total reflection surface so that the LED lens has a high luminous flux efficiency even when the illumination angle is 40 degrees or less, A TIR LED lens having an incident surface and a light emitting surface formed of a free-form surface, and a method of designing the same.

The central refraction portion of the TIR LED lens includes an incident surface and a central exit surface, and these two surfaces can be designed as a free-form surface in a manner applied to a conventional LED lens. However, since the total reflection part of the TIR LED lens includes a total reflection surface in addition to the incidence side surface and the peripheral emission surface, a relation relating to three surfaces must be newly established for the design. The present invention derives a relational expression for solving the problem, and since the derived relational expressions do not form a perfect linear differential equation, an artificial condition is added so that the incident side, the peripheral exit surface, As well as the design of the system.

More specifically, the present invention relates to a liquid crystal display device comprising: a central refracting portion including an incident surface and a central exit surface from which light rays incident on the incident surface are emitted; And a total reflection surface provided on both sides of the central refracting portion, the incidence surface being bent and connected to the incidence surface, the total reflection surface being totally reflected by the light incident on the incidence side surface, A peripheral total reflecting portion including a peripheral emitting surface through which the totally reflected light is emitted; Wherein the incident surface, the incident surface, the central exit surface, and the peripheral exit surface are formed in a free-form surface, wherein the incident surface and the light incident on the incident surface are emitted And a TIR (Total Internal Reflection) LED lens that reaches a target plane located in front of the surface.

In this case, the total reflection surface may not be formed as a free-form surface.

Further, according to the present invention, there is provided a method of designing a TIR LED lens, comprising the steps of: (a) setting an origin of a three-dimensional coordinate system as an LED light source; setting a Z axis as a rotation axis; An emitting angle which is an angle formed by the light ray from the LED light source to the Z axis in a state in which an emitting point which is an intersection between the central emitting plane and the Z axis is arbitrarily set,

Figure pat00001
Which is a boundary emission angle at which light rays can be incident on the incident surface
Figure pat00002
Forming a central refraction portion in such a manner that the shape points of the incident surface and the central exit surface are sequentially determined while increasing the thickness of the central refraction portion; And (b)
Figure pat00003
To
Figure pat00004
The light ray incident on the incidence side is totally emitted from the total reflection surface and emitted to the peripheral emission surface to reach the target surface,
Figure pat00005
The total reflection surface on the incidence side, the total reflection on the total reflection surface, and the reflection surface on the peripheral exit surface are sequentially determined by determining the shape points of the incident side, the total reflection surface, And a differential equation derived from a convergent illumination model and a minimization condition of Fresnel loss and differential equations obtained from arbitrary conditions, Forming a peripheral total reflecting portion in such a manner that the shape points of the incident side, the total reflection surface, and the peripheral emission surface are sequentially determined; And a TIR LED lens design method characterized by comprising the steps of:

At this time, the optional condition of the step (b) may include a progress angle defined by an angle formed by the ray totally reflected by the total reflection surface and incident on the peripheral exit surface,

Figure pat00006
Is defined as [Equation 1] below,
Figure pat00007
Wow
Figure pat00008
Intersection coordinates between the total reflection plane and the peripheral emission plane and a constant
Figure pat00009
Is set in advance. In this case, the method of designing a TIR LED lens according to the present invention may further comprise the step of: (c) after the step (b), the step of forming the central exit surface of the central refraction part formed in step (a) When the end points of the peripheral emission surface of the total reflection part do not coincide with each other, the step (b) is performed by using the intersection coordinates of the total reflection surface and the peripheral emission surface,
Figure pat00010
And repeating the steps one or more times.

[Formula 1]

Figure pat00011

(

Figure pat00012
And
Figure pat00013
Respectively,
Figure pat00014
The traveling angle of the incoming ray when it is incident on the peripheral exit surface and the traveling angle when it is emitted)

Meanwhile, in the step (b) of the TIR LED lens designing method according to the present invention, the distance from the LED light source to the incident point is R, and the angle formed by the ray incident on the incident side in the counterclockwise direction

Figure pat00015
, A distance between the incidence side surface and the total reflection surface is l ab, and a distance from the total reflection surface to the peripheral emission surface is l bc , refraction at the incidence side, total reflection at the incidence side, The three differential equations derived respectively from the refraction in the plane are as shown in the following Equations 2 to 4 and are derived from the convergent illumination model and the differential equation derived from the condition of minimizing the fresnel loss Can be characterized by the following equation (5).

[Formula 2]

Figure pat00016

(n is an internal refractive index)

[Formula 3]

Figure pat00017

Figure pat00018

(

Figure pat00019
))

[Formula 4]

Figure pat00020

Figure pat00021

(

Figure pat00022

[Formula 5]

Figure pat00023

Figure pat00024

Figure pat00025

Figure pat00026

(

Figure pat00027
,

Figure pat00028
)

The present invention has the following effects.

1. It is possible to realize a TIR LED lens in which both a surface on which a light beam is incident and a surface on which a light beam is emitted are both of a free-form surface.

2. It is possible to realize a TIR LED lens having high light flux efficiency even when the illumination angle is 40 ° or less.

1 is a schematic cross-sectional view showing a structure of a TIR LED lens according to an embodiment of the present invention and a path of a light beam.
2 is a flowchart corresponding to the TIR LED lens design method according to the present invention.
[Fig. 3] is a schematic diagram showing problems that may occur in the coupling process between the central reflex part and the peripheral reflex part designed in [Fig. 2].
4 is a table of initial values used in the design for verification of the present invention.
5 is a result of summarizing the shape and luminous flux efficiency of a TIR LED lens designed according to FIG. 4 and a conventional LED lens.
FIG. 6 is a diagram of illuminance distribution charts formed on a target surface of a TIR LED lens designed according to FIG. 4 and a conventional LED lens.

Hereinafter, the TIR LED lens and the design method thereof according to the present invention will be described in detail.

1. TIR LED Lens

FIG. 1 is a schematic cross-sectional view showing a structure of a TIR LED lens according to an embodiment of the present invention and a path of a light beam.

The TIR lens shown in the XZ Cartesian coordinate system is divided into a central refraction part and a peripheral TIR part, and has rotational symmetry about the Z axis. The internal refractive index is n. The central refracting portion is composed of an inner surface including a point P 1a and a central outer surface including a point P 1c . The peripheral total reflection portion has a side surface including a point P 2a A TIR surface including a point P 2b , a peripheral outer surface including a point P 2c , and a bottom surface connecting the incidence side surface and the total reflection surface. The bottom surface does not have any effect on the progress of the light beam.

The central exit surface of the central refracting portion and the peripheral exit surface of the peripheral total reflecting portion intersect each other at the intersection C OO at the intersection C IS between the incident surface of the central refracting portion and the incident surface of the peripheral total reflecting portion. The peripheral exit surface and the total reflection surface intersect at an intersection C OT in the peripheral total reflection portion, and both end points of the bottom surface are referred to as C SB and C BT , respectively.

In FIG. 1, the origin is referred to as a light source S, and the distance from S to the incident surface or the incident point of the light on the incident side is defined as R, and the emission angle of the light emitted from S is defined as:

Figure pat00029
Is defined with reference to the Z axis. At this time, the emission angle of the ray incident on the intersection C IS is split angle,
Figure pat00030
, And if the emission angle is
Figure pat00031
The corresponding ray is incident on the peripheral total reflecting portion. The rays passing through the central refracting portion to reach a uniform target illuminance distribution on the target surface reach the entire target plane according to a divergent illumination model, It is assumed that the rays reach the entire target surface according to a convergent illumination model.

The ray 1 is emitted from S as a representative ray passing through the central refraction portion and is incident on a point P 1a on the incident surface. The light refracted at this point is incident on the point P 1c on the central exit plane, and the distance between the two points P 1a and P 1c is called l ac . The ray refracted at the point P 1c finally reaches the point P 1T on the target surface and the X axis distance from the target surface center axis to the point P 1T is r. At this time, the propagation angles of the rays refracted at the incident surface and the central exit surface are respectively

Figure pat00032
,
Figure pat00033
And is defined as the angle between the Z axis and the ray. The traveling angle rotated in the clockwise direction with respect to the Z axis is defined as having a positive value. Since the rays passing through the central refraction follow the divergence illumination model,
Figure pat00034
Regardless of the progress angle
Figure pat00035
Wow
Figure pat00036
Is always positive.

On the other hand, the ray 2 is emitted from the S as a representative ray passing through the peripheral total reflecting portion and is incident on the point P 2a on the incident side. This ray finally reaches the point P 2T on the target surface via the point P 2b on the total reflection surface and the point P 2c on the peripheral exit surface. The distance between two points P 2a and P 2b and the distance between two points P 2b and P 2c are called l ab and l bc , respectively. A traveling angle of a ray of light refracted from the incident side surface, a traveling angle of a ray of light incident on the peripheral emitting surface, and a traveling angle of a ray of light refracted by the peripheral emitting surface,

Figure pat00037
,
Figure pat00038
,
Figure pat00039
. Angle
Figure pat00040
Wow
Figure pat00041
Is defined with respect to the Z axis, but the angle
Figure pat00042
Defines the angle counterclockwise to have a positive value with the exception of the X axis. Since the rays passing through the surrounding total arc must follow a convergent illumination model,
Figure pat00043
A slightly larger light beam must reach the edge of the target surface and a light ray with a maximum emission angle
Figure pat00044
Must reach the center of the target surface. Therefore, at the peripheral total reflecting portion,
Figure pat00045
Angle according to
Figure pat00046
Wow
Figure pat00047
Can be changed. Ray ② angle
Figure pat00048
Wow
Figure pat00049
Is a ray having a positive value, and the ray 3
Figure pat00050
Wow
Figure pat00051
Is another ray of light traveling through the peripheral totality having a negative value.

The central refracting portion includes R, which is a distance from the light source S to an incident point,

Figure pat00052
, And the length l ac , and the peripheral total internal reflection part determines R,
Figure pat00053
Wow
Figure pat00054
, And the lengths l ab and l bc . These are all functions of the emission angle j, and the relationship of the functions related to the central refraction portion among them is already proposed by the prior art.

The TIR LED lens according to the present invention includes a central refracting portion including an incident surface and a central exit surface from which light incident on the incident surface is emitted, as shown in FIG. 1; And a total reflection surface provided on both sides of the central refracting portion, the incidence surface being bent and connected to the incidence surface, the total reflection surface being totally reflected by the light incident on the incidence side surface, The incident surface, the incident surface, the central exit surface, and the peripheral exit surface are formed in a free-form surface, and the peripheral reflection surface includes a peripheral exit surface through which the totally-reflected light is emitted. And allows the light incident on the incident surface and the incident side to reach a target plane located in front of the exit surface.

In this case, the total reflection surface may not be formed as a free-form surface.

2. TIR LED lens design method

The method of designing a TIR LED lens according to the present invention is a method of designing a TIR LED lens as described above, the method comprising the steps of: (a) setting an origin of a three-dimensional coordinate system as an LED light source; setting a Z axis as a rotation axis; An emission angle, which is an angle formed by the light ray from the LED light source to the Z axis, in a state in which an incidence point that is an intersection with the Z axis and an emission point that is an intersection of the center emission plane and the Z axis are arbitrarily set,

Figure pat00055
Which is a boundary emission angle at which light rays can be incident on the incident surface
Figure pat00056
Forming a central refraction portion in such a manner that the shape points of the incident surface and the central exit surface are sequentially determined while increasing the thickness of the central refraction portion; And (b)
Figure pat00057
To
Figure pat00058
The light ray incident on the incidence side is totally emitted from the total reflection surface and emitted to the peripheral emission surface to reach the target surface,
Figure pat00059
The total reflection surface on the incidence side, the total reflection on the total reflection surface, and the reflection surface on the peripheral exit surface are sequentially determined by determining the shape points of the incident side, the total reflection surface, And a differential equation derived from a convergent illumination model and a minimization condition of Fresnel loss and differential equations obtained from arbitrary conditions, And forming a peripheral total reflecting surface by sequentially determining shape points of the incident side, the total reflection surface, and the peripheral emission surface.

A flowchart corresponding to the TIR LED lens design method according to the present invention is shown in FIG.

The step (a) corresponds to the design of the central refraction part of FIG. 2, and is a step of designing a central refraction part of the TIR LED lens to maximize a luminous flux efficiency while forming a uniform illumination distribution . In the step (a), the origin of the three-dimensional coordinate system is assumed to be an LED light source, the Z axis is set as a rotation axis, and the incident point (Z in ), which is an intersection between the incident surface and the Z axis, of intersection of the exit point (Z out) from the arbitrarily set state, the light emitted from the LED light source, the angle Z axis and the angle

Figure pat00060
Which is a boundary emission angle at which light rays can be incident on the incident surface
Figure pat00061
The central refraction portion is designed in such a manner that the shape points of the incident surface and the central exit surface are sequentially determined. To minimize the numerical error, we can use the Runge-Kutta method to solve the solution of the linear differential equation.

The step (b) is a step corresponding to the design of the surrounding overall quadrilateral of FIG. 2, and sequentially determining the shape points constituting the surrounding total quadrilateral while increasing the emission angle j from j split to j max . Wherein the step (b)

Figure pat00062
To
Figure pat00063
The light ray incident on the incidence side is totally emitted from the total reflection surface and emitted to the peripheral emission surface to reach the target surface,
Figure pat00064
The total reflection surface on the incidence side, the total reflection on the total reflection surface, and the reflection surface on the peripheral exit surface are sequentially determined by determining the shape points of the incident side, the total reflection surface, And a differential equation derived from a convergent illumination model and a minimization condition of Fresnel loss and differential equations obtained from arbitrary conditions, And the shape points of the incidence side, the total reflection plane and the peripheral emission plane are sequentially determined.

At this time, the optional condition of the step (b) may include a progress angle defined by an angle formed by the ray totally reflected by the total reflection surface and incident on the peripheral exit surface,

Figure pat00065
Is defined as [Equation 1] below,
Figure pat00066
Wow
Figure pat00067
Intersection coordinates between the total reflection plane and the peripheral emission plane and a constant
Figure pat00068
Is set in advance.

[Formula 1]

Figure pat00069

(

Figure pat00070
And
Figure pat00071
Respectively,
Figure pat00072
The traveling angle of the incoming ray when it is incident on the peripheral exit surface and the traveling angle when it is emitted)

More specifically, in the step (b), the distance from the LED light source to the incident point is R, and the angle formed by the ray incident on the incident side in the counterclockwise direction with respect to the X axis is

Figure pat00073
, A distance between the incidence side surface and the total reflection surface is l ab, and a distance from the total reflection surface to the peripheral emission surface is l bc , refraction at the incidence side, total reflection at the incidence side, (5) derived from the convergence illumination model and the Fresnel loss minimization condition derived from the following equations (2) to (4) derived from the refraction of the plane And the shape points of the incident side, the total reflection plane, and the peripheral emission plane are sequentially determined by using solutions of differential equations.

[Formula 2]

Figure pat00074

(n is an internal refractive index)

[Formula 3]

Figure pat00075

Figure pat00076

(

Figure pat00077
))

[Formula 4]

Figure pat00078

Figure pat00079

(

Figure pat00080

[Formula 5]

Figure pat00081

Figure pat00082

Figure pat00083

Figure pat00084

(

Figure pat00085
,

Figure pat00086
)

The method of designing a TIR LED lens according to the present invention may further include the step of: (c) after the step (b), the step of forming an edge of the exit surface of the central refraction part formed in step (a) When the end points of the exit surface do not coincide with each other, the step (b) is performed by using the intersection coordinates of the total reflection surface and the peripheral exit surface,

Figure pat00087
And repeating the steps one or more times.

If the two end points of the central refracting portion designed in the step (a) can be used as the shape starting points of the peripheral total reflecting portion designed in the step (b), one TIR LED lens in which the two parts are perfectly combined can be formed Due to the structural nature of the TIR LED lens, this is not possible. The step (c) is performed to solve such a problem.

Referring to FIG. 1, in order for the two end points of the central refracting portion and the starting point of the surrounding total reflecting portion to be connected, a light ray having an emission angle j split enters the point C IS on the side surface, And must pass through point C OO . However, if there is a ray not passing through the total reflection surface, the purpose of introducing the total reflection surface, which lowers the deflection angle at the incident surface (or the incident surface) and the central exit surface (or the peripheral exit surface) I can not. Therefore, in the step (b) of the present invention, as shown in FIG. 2, the incidence side of the peripheral total reflecting portion starts from the point C IS to the downward direction, the exit surface starts from the point C OT , The slope starts at point C OT and sequentially determines the shape points downward. Therefore, the coordinate points C OT and to design the peripheral across the phloem

Figure pat00088
The value must be preset,
Figure pat00089
Wow
Figure pat00090
Is determined by the point C OT coordinate.

Point C OT coordinate and

Figure pat00091
If the value is not properly set, the central refraction portion and the peripheral total reflection portion may not be integrally combined as shown in FIG. In FIG. 3, a point C OO_C and a point C OO_P respectively denote an end point forming an emitting surface of the central refracting portion and an emitting end forming an emitting surface of the surrounding total reflecting portion. (A) and (b) of FIG. 3 are diagrams illustrating a case in which two exit surfaces of the peripheral total reflecting portion and the central reflecting portion intersect with each other or the progress of some rays transmitted through the central refracting portion or the peripheral total reflecting portion is disturbed to be. This is a problem that occurs when the point C OT is set too close to the point C OO . Meanwhile
Figure pat00092
If the value is set too large, the light ray incident on the total reflection surface will not satisfy the total reflection condition,
Figure pat00093
If the value is set to be too small, a problem that the total reflection surface intersects with the incident side as shown in (c) of FIG. 3 may occur. (D) of FIG. 3 is a case in which the two exit surfaces of the central refracting portion and the peripheral total reflecting portion are not connected to each other correctly. However, if they do not correspond to (a) and (b) Simply by connecting them in a straight line. However, if the size of the light source can not be ignored, some rays can be incident on the straight line, and these rays travel to an undesired position on the target surface, which causes problems such as deterioration of luminous flux efficiency and deterioration of illuminance uniformity Can be generated. Thus point through the step (c) the coordinates C OT and if the exit surface of the central refraction exit surface portion and the peripheral half phloem does not,
Figure pat00094
So that the exit surface of the central refracting portion and the exit surface of the surrounding total reflecting portion are connected as far as possible.

Hereinafter, specific examples of the TIR LED lens manufactured according to the TIR LED lens design method, illuminance distribution, luminous flux efficiency, and the like will be described. The illuminance distribution and luminous flux efficiency of the designed lens were evaluated using the LightToolsTM program.

For the verification through the concrete example, the LED is treated as a point light source (S), and the half angle of the LED is assumed to be 60 °, and the lens is assumed to be composed of PMMA material having a refractive index of 1.493. It is also assumed that the target surface is a circular region whose center lies on the Z axis and is located at f = 1000 mm from S. The LightTools program was used to calculate the illuminance distribution and luminous flux efficiency on the target surface, where more than 500,000 rays were used.

In order to show the advantage of the TIR LED lens design method according to the present invention in designing a TIR LED lens having a narrow illumination angle, the TIR LED lens is used for three cases where the maximum radius rmax of the target surface is 50 mm, 100 mm, Respectively. Since the illumination angle can be defined as [Equation 6], the illumination angles are 5.7 °, 11.4 °, and 22.6 °, respectively.

[Formula 6]

Figure pat00095

The initial values used in the design are as shown in Fig. 4, and D x and D z mean the X and Z components of the vector D (= C OT - C OO ). The split angle, which separates the central reflex and the peripheral reflex,

Figure pat00096
Was set at 60 °.

The result of summarizing the shape of the designed TIR LED lens and the luminous flux efficiency is shown in Fig. 5, and Fig. 6 shows the illuminance distribution chart formed on the target surface. 5, it can be seen that the luminous flux efficiency of the TIR LED lens designed according to the present invention is at least 5% higher than that of the conventional LED lens having both sides of the free-form surface, and as the illumination angle becomes narrower, It can be seen that it is larger. 6, the roughness uniformity is similar when comparing the conventional LED lens and the TIR LED lens designed according to the present invention, but the boundary of the illumination region is more pronounced in the case of the TIR LED lens designed according to the present invention Able to know.

The present invention has been described in detail above with reference to specific examples. However, the present invention is not limited to the above embodiments, and can be modified or modified without departing from the gist of the present invention. It is therefore intended that the appended claims cover such modifications and variations.

none

Claims (6)

A central refracting portion including an incidence surface and a central emergence surface from which light rays incident on the incidence surface are emitted; And
A total reflection surface which is provided on both sides of the central refraction portion and is connected to the incidence surface so as to be bent, a total reflection surface which totally reflects the light incident on the incidence side surface, and a total reflection surface which is connected to the total reflection surface, A peripheral total reflecting portion including a peripheral emitting surface through which the emitted light is emitted; Lt; / RTI >
Axis symmetry with respect to the rotation axis,
Wherein the incident surface, the incident surface, the central exit surface, and the peripheral exit surface are formed as free-form surfaces,
And a total internal reflection (TIR) LED lens that allows the light incident on the incident surface and the incident surface to reach a target plane positioned in front of the exit surface.
The method of claim 1,
Wherein the total reflection surface is not a free-form surface.
10. A method of designing a TIR LED lens according to claim 1 or 2,
(a) assuming that the origin of the three-dimensional coordinate system is an LED light source, setting a Z axis as a rotation axis, and arbitrarily setting an exit point that is an intersection between the incident surface and the Z axis and an intersection between the center exit surface and the Z axis In the set state, the emission angle which is the angle formed by the light ray from the LED light source to the Z axis
Figure pat00097
Which is a boundary emission angle at which light rays can be incident on the incident surface
Figure pat00098
Forming a central refraction portion in such a manner that the shape points of the incident surface and the central exit surface are sequentially determined while increasing the thickness of the central refraction portion; And
(b)
Figure pat00099
To
Figure pat00100
The light ray incident on the incidence side is totally emitted from the total reflection surface and emitted to the peripheral emission surface to reach the target surface,
Figure pat00101
And the shape of the incident side, the total reflection surface and the peripheral emission surface are sequentially determined while forming the peripheral total reflection portion,
Derived from three differential equations, a convergent illumination model and a fresnel loss minimization condition, which are respectively derived from refraction at the incident side, total reflection at the total reflection plane, and refraction at the peripheral exit surface, Forming a peripheral total reflecting portion by sequentially determining shape points of the incidence side surface, the total reflection surface, and the peripheral emission surface using a solution obtained by obtaining a differential equation obtained from a differential equation and any condition; Wherein the TIR LED lens design method comprises the steps of:
4. The method of claim 3,
The optional condition of step (b)
Wherein a total angle of incidence of the light reflected by the total reflection surface on the peripheral exit surface
Figure pat00102
Is defined as [Equation 1] below,
[Formula 1]
Figure pat00103

(
Figure pat00104
And
Figure pat00105
Respectively,
Figure pat00106
The traveling angle of the incoming ray when it is incident on the peripheral exit surface and the traveling angle when it is emitted)
remind
Figure pat00107
Wow
Figure pat00108
Intersection coordinates between the total reflection plane and the peripheral emission plane and a constant
Figure pat00109
Wherein the TIR LED lens design method comprises the steps of:
5. The method of claim 4,
After the step (b)
(c) if the end point of the central exit surface of the central refracting portion formed in the step (a) does not match with the end point of the peripheral exit surface of the peripheral total reflecting portion formed in the step (b) The intersection coordinates and the constant between the oblique plane and the above-
Figure pat00110
And repeating the step of repeating at least one time.
4. The method of claim 3,
The step (b)
A distance from the LED light source to an incident point is R, and an angle formed by the ray incident on the incident side in a counterclockwise direction with respect to the X axis is
Figure pat00111
, A distance between the incidence side surface and the total reflection surface is denoted by l ab, and a distance from the total reflection surface to the peripheral emission surface is defined as l bc ,
The three differential equations respectively derived from the refraction at the incidence side, the total reflection at the total reflection plane and the refraction at the peripheral emission plane are as shown in the following Equation 2 to Equation 4, and convergent illumination model and a Fresnel loss minimization condition is expressed by Equation (5) below. < EMI ID = 6.0 >
[Formula 2]
Figure pat00112

(n is an internal refractive index)
[Formula 3]
Figure pat00113

Figure pat00114

(
Figure pat00115
))
[Formula 4]
Figure pat00116

Figure pat00117

(
Figure pat00118
)
[Formula 5]
Figure pat00119

Figure pat00120

Figure pat00121

Figure pat00122

(
Figure pat00123
,
Figure pat00124
)
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