KR20170085793A - Illumination apparatus and optical lens for diffusing light - Google Patents

Abstract

An illumination device and an optical lens for diffusing light are disclosed.
The optical lens includes a first surface on which light emitted from a light source is incident and a second surface on which light is emitted, and the first surface has a first inflection point on the optical axis and a second inflection point on an area off the optical axis And the second surface includes a second inflection point on the optical axis and a fourth inflection point provided in an area off the optical axis to improve the light distribution characteristic of the light.

Description

[0001] DESCRIPTION [0002] Illumination apparatus and optical lens for light diffusion [0003]

Embodiments of the present invention relate to an illumination device and an optical lens for diffusing illumination light.

An illumination device is an electric device used to brighten a space. Various light sources such as an incandescent lamp, a discharge lamp, a fluorescent lamp, and a light emitting diode (LED) are used as a light source mainly used for illumination. A resistive light source such as an incandescent bulb has a disadvantage in that it has a low efficiency and generates a lot of heat. In the case of a discharge lamp, it is expensive and has a disadvantage of a high voltage. In the case of fluorescent lamps, there are environmental problems caused by the use of mercury.

Recently, a light emitting diode (LED) having many advantages in terms of efficiency, color diversity, and design autonomy has been widely used as a light source in order to overcome the disadvantages of such light sources.

A light emitting diode is a semiconductor device that emits light when a voltage is applied in a forward direction, has a long life, low power consumption, and has electrical, optical, and physical characteristics suitable for mass production. Therefore, the light emitting diode is widely seen as an illumination means for replacing an incandescent lamp or a fluorescent lamp. However, the light emitting diodes have a limit in that the light distribution is relatively more distributed in the central portion than in the peripheral portion, so that the illumination is not uniform. By improving the light distribution characteristics of such light emitting diodes, various optical means have been developed in order to make light emitting diodes more suitable for use in illumination devices.

An exemplary embodiment provides an optical lens that can improve the light diffusion characteristics of an illuminating light source.

An exemplary embodiment provides an illumination device using an optical lens to improve light diffusion characteristics.

The optical lens according to the exemplary embodiment,

A first surface on which light emitted from a light source is incident;

And a second surface on which light is emitted,

Wherein the first surface includes a first inflection point on an optical axis and a second inflection point on an area off the optical axis, the second surface includes a second inflection point on the optical axis and a fourth inflection point provided in an area off the optical axis ,

Wherein the first surface and the second surface include a plurality of sections, and the boundary between the plurality of sections is a node, the first surface and the second surface satisfy the following expressions respectively.

<Expression>

Wherein, Z is a new geugap of the first surface and the second surface, h is the vertical distance away from the optical axis, H _{i -1} is a (i-1) located on the second node, H _i is the position of the i-th node, Z _{i -1} is the new value at H _{i -1} , Z _i is the new value at Hi, S _i is the slope at H _i , S _{i -1} is the slope at H _{i -1} , Mi Is the slope at Hi, and M _{i -1} is the curvature at H _{i -1} .

The optical lens can satisfy the following expression.

<Expression>

　　　　　　　　　　　　　　　　　　　　　　　　　　

Here, H ₂ is the vertical distance from the optical axis to the fourth inflection point on the second plane, and H ₁ is the vertical distance from the optical axis to the second inflection point on the first plane.

The first surface may be convex in the central region including the optical axis, and may have a concave shape toward the peripheral portion.

The second surface may be concave in the central region including the optical axis, and may have a convex shape toward the peripheral portion.

The first to fourth inflection points may include a point where the first-order differential value of Z is zero.

The first surface and the second surface may be rotationally symmetrical about an optical axis, respectively.

The optical lens may be a cylindrical lens.

The illumination device according to the exemplary embodiment includes:

Light source; And

And an optical lens including a first surface on which light emitted from the light source is incident and a second surface on which light is emitted,

Wherein the first surface includes a first inflection point on an optical axis and a second inflection point on an area off the optical axis, the second surface includes a second inflection point on the optical axis and a fourth inflection point provided in an area off the optical axis ,

Wherein the first surface and the second surface include a plurality of sections, and the boundary between the plurality of sections is a node, the first surface and the second surface satisfy the following expressions respectively.

<Expression>

Wherein, Z is a new geugap of the first surface and the second surface, h is the vertical distance away from the optical axis, H _{i -1} is a (i-1) located on the second node, H _i is the position of the i-th node, Z _{i -1} is the new value at H _{i -1} , Z _i is the new value at Hi, S _i is the slope at H _i , S _{i -1} is the slope at H _{i -1} , Mi Is the slope at Hi, and M _{i -1} is the curvature at H _{i -1} .

And a diffuser plate may be further provided to be spaced apart from the second surface of the optical lens.

The optical lens according to the exemplary embodiment can improve the light diffusion characteristics of the illumination light source. The optical lens according to the exemplary embodiment improves the light distribution characteristics of the central portion and the peripheral portion of the illumination light source, thereby improving the performance of the illumination light source. For example, the optical lens according to the exemplary embodiment can improve the light distribution characteristic of the light illuminated from the light emitting diode.

The illumination device according to the exemplary embodiment diffuses the light irradiated from the light source at a wide angle as much as possible and can have a uniform light distribution over a wide range.

1 schematically shows a lighting device according to an exemplary embodiment.
2 is a graph showing light distribution characteristics of a lambuster cyan light source.
Fig. 3 shows an example of an optical lens according to the first comparative example.
FIG. 4 shows a light distribution graph by the optical lens shown in FIG.
5 shows another example of the optical lens according to the second comparative example.
Fig. 6 shows a light distribution graph by the optical lens shown in Fig. 5. Fig.
Figure 7 illustrates an optical lens according to an exemplary embodiment of the present invention.
FIG. 8 shows a light distribution graph by the optical lens shown in FIG.
9 shows an optical lens according to the first numerical embodiment of the present invention.
Fig. 10 shows a light distribution graph by the optical lens shown in Fig. 9. Fig.
11 shows an optical lens according to a second numerical example of the present invention.
Fig. 12 shows a light distribution graph by the optical lens shown in Fig.
13 shows an optical lens according to a third numerical example of the present invention.
Fig. 14 shows a light distribution graph by the optical lens shown in Fig. 13. Fig.
15 shows an optical lens according to an exemplary embodiment of the present invention.
Fig. 16 shows a light distribution graph by the optical lens shown in Fig. 15. Fig.
Fig. 17 shows an example in which the diffuser plate is further provided in the illumination apparatus shown in Fig.

Hereinafter, an illumination device and an optical lens according to an exemplary embodiment will be described in detail with reference to the accompanying drawings. It should be understood, however, that this invention is not intended to be limited to the particular embodiments described herein but includes various modifications, equivalents, and / or alternatives of the embodiments of this document . In connection with the description of the drawings, like reference numerals may be used for similar components.

In the following drawings, like reference numerals refer to like elements, and the size of each element in the drawings may be exaggerated for clarity and convenience of explanation. The terms first, second, etc. may be used to describe various elements, but the elements should not be limited by terms. Terms are used only for the purpose of distinguishing one component from another.

The singular expressions include plural expressions unless the context clearly dictates otherwise. Also, when an element is referred to as "comprising ", it means that it can include other elements as well, without departing from the other elements unless specifically stated otherwise.

Figure 1 shows a lighting device according to an exemplary embodiment. Referring to FIG. 1, the illumination device may include a light source 10 and an optical lens 20 for diffusing the light emitted from the light source 10. The light source 10 may include, for example, a light emitting diode. The light emitting diode is, for example, a Lambertian light source having a bright central portion and a relatively dark peripheral portion. Fig. 2 shows the distribution of the light distribution of the Lambertian light source. Referring to FIG. 2, the lambuster cyan light source can be illuminated in a narrow range because the light diffusion angle is small. Therefore, a light source having a Lambertian light distribution needs an optical lens for diffusing light so as to make the distribution of the light in the central part and the peripheral part of the light source as wide as possible. A lens having such a function may be referred to as a secondary lens, for example.

The optical lens 20 may be formed of, for example, glass or plastic. The optical lens 20 may include a first surface 21 on which light is incident from the light source 10 and a second surface 22 on which light is emitted. The first side may be referred to as the incidence side. The second surface may also be referred to as the exit surface. The first side 21 may have at least one inflection point. The second side 22 may have at least one inflection point. The radius of curvature can indicate, for example, a value indicating the degree of curvature at each point on the curved surface or the curve. For example, the radius of curvature may have a (+) sign if it convexes on the basis of the point at which light is formed, and a (-) sign if it is concave. The inflection point may indicate, for example, a point where the sign of the radius of curvature changes from (+) to (-) or changes from (-) to (+).

Alternatively, the inflection point may indicate, for example, a point where the shape of the lens changes from convex to concave or from concave to convex. Therefore, the inflection point may be a point at which the first-order differential value of the equation representing the curvature of the lens surface or the lens cross-section becomes zero. This will be described in more detail later.

The first surface 21 may have, for example, a first inflection point IP1 and a second inflection point IP2. For example, the first inflection point IP1 may be provided on the optical axis or on the central axis OA (hereinafter referred to as the optical axis). The second inflection point IP2 is provided in an area deviated from the optical axis, and there may be infinitely many inflection points along the optical axis or along the optical axis. However, in this specification, Is based on the inflection point. The optical lens 20 may be, for example, a circular lens or a cylindrical lens. The cylindrical lens may represent, for example, a lens in the form of a bar. For example, when the optical lens 20 is a circular lens, there may be infinite number of inflection points along the optical axis, but the inflection point at the longitudinal section cut to include the optical axis of the optical lens is referred to. Alternatively, if the optical lens 20 is a cylindrical lens, it may have at least one inflection point in the longitudinal section cut to include the optical axis or the central axis (see Fig. 14).

The second inflection point IP2 may be an inflection point located closest to the optical axis OA in an area not including the optical axis OA, for example. The first surface 21 may have, for example, a rotationally symmetrical shape about the optical axis OA. In this case, the first surface 21 may have a second inflection point IP2 at the same radial position from the optical axis OA. When the optical lens 20 is a cylindrical lens, it may be vertically symmetrical or symmetrical.

The first surface 21 has a convex shape in the center area including the optical axis OA and may have a concave shape from the center area toward the peripheral part.

The first surface 21 may further include an inflection point at the peripheral portion from the second inflection point IP2. For example, the first surface 21 may have a concave shape around the second inflection point IP2 and a convex shape toward the peripheral portion.

The second surface 22 may have, for example, a third inflection point IP3 and a fourth inflection point IP4. For example, the third inflection point IP3 may be provided on the optical axis OA. The fourth inflection point IP4 may be provided in an area outside the optical axis OA. The fourth inflection point IP4 may be an inflection point located closest to the optical axis OA in an area not including the optical axis OA, for example. The second surface 22 may have a rotationally symmetrical shape about the optical axis OA, for example. In this case, the second surface 22 may have a fourth inflection point IP4 at the same radial position from the optical axis OA.

The second surface 22 may have a concave shape in the central area including, for example, the optical axis OA, and may have a convex shape from the central area toward the peripheral part.

The first surface 21 and the second surface 22 may have a rotationally symmetric shape about the optical axis OA. For example, the first surface 21 and the second surface 22 may each have an optical axis and may have a spline curve shape in a longitudinal section cut parallel to the optical axis. The spline curve shows a smooth curve passing through a predetermined plurality of points, for example, and a curve can be defined by using a separate polynomial for each section between adjacent two points. For example, when the first surface 21 and the second surface 22 include a plurality of sections, and the boundary of each section is a node, the first surface 21 and the second surface 22 are next Can be satisfied.

<식 1>

<Formula 1>

Here, Z is the sag value of the first surface 21 and the second surface 22, h is the vertical distance away from the optical axis OA, H _{i -1} is the distance from the (i-1) position, H _i is the i-th position of the node, Z _{i -1} H _i is the new geugap at _-1, Zi is new geugap, S _i in the Hi is at H _i slope (slope), S _{i -1} is The slope at H _{i -1} , Mi is the slope at Hi, and M _{i -1} is the curvature at H _{i -1} .

The position of the node represents the distance from the optical axis of each section to the boundary point when the spline curve is divided into a plurality of sections, and the slope represents the slope of the tangent at each node.

In Equation 1, H _i and S _i are given values, and considering the rotational symmetry of the optical lens, S ₀ becomes 0, M ₀ becomes the curvature at the center of the optical axis, and the remaining values can be defined by the following equation.

　　　　　 <식 2>

<Formula 2>

If the first surface 21 and the second surface 22 have curves defined by Equations 1 and 2 and know the slope S _i of the tangent line at the i-th node, the inflection point at which the first-order differential value of Equation 1 becomes zero M _i can be obtained, and the sag value Z _i at each node can be obtained as shown in equation (2).

When the first surface and the second surface include curves defined by Equations 1 and 2 and the first and second surfaces each include at least one inflection point, The characteristics can be improved.

On the other hand, it is difficult to obtain a point where the first-order differential value becomes zero in a general aspheric sag value as in the following expression. Assuming that the direction of the optical axis is the x-axis and the direction perpendicular to the optical axis direction is the y-axis, the aspheric surface value can be expressed by the following equation with the traveling direction of the ray being positive.

　　　　　　　　　　<식 3>

<Formula 3>

Here, x represents the distance from the vertex of the lens to the optical axis direction, i.e., the new value, y represents the distance in the direction perpendicular to the optical axis, k represents the conic constant, A ₄ , A ₆ , A ₈ , A _{10 ...} denote aspherical surface coefficients, and c denotes an inverse number (1 / R) of the radius of curvature at the apex of the lens.

It is difficult to determine the position where the first-order differential value determining the position of the curvature apex (or inflection point) and the curvature, that is, the second-order differential value of which the refractive power of the ray is determined becomes zero.

However, since the spline curve defined by equation (1) defines the curved surface as the slope of the initial curved surface, it is easy to obtain the inflection point where the first derivative value becomes 0 on the lens surface. It is possible to improve the light distribution characteristic of the light passing through the optical lens by adjusting the position where the first-order differential value of the expression representing the lens surface becomes zero. As described above, in the case of the illumination optical system, it is necessary to change the sag value only in a specific portion of the curved surface unlike the imaging optical system, and it is preferable to use a spline curved surface instead of the aspherical surface 3 having conical coefficients and higher order aspherical surface coefficients .

The optical lens according to the exemplary embodiment can satisfy the following expression.

　　　　　<식 4>　　　　　　　　　　　　　　　　　　　　　

<Formula 4>

Here, h ₂ is the vertical distance from the optical axis OX to the fourth inflection point IP 4 on the second surface 22, h ₁ is the distance from the optical axis OX to the second inflection point IP ₂ on the first surface 22, Represents the vertical distance. Equation (4) defines the position of the inflection point where the first-order differential value of the spline curve on the lens surface becomes zero. Where h ₁ is the distance from the optical axis to the point at which the first order differential value becomes 0 with respect to the incident surface located on the light source side and h ₂ is the distance from the optical axis to the point where the first order differential value becomes 0 with respect to the exit surface. (h ₂ -h ₁ ) satisfies the expression (4), the light distribution characteristic can be improved. (h ₂ -h ₁ ) is smaller than the lower limit value of the expression (4), the light distribution characteristic can be deteriorated. When (h ₂ -h ₁ ) is larger than the upper limit value of the expression The light distribution uniformity becomes worse even if the light distribution angle is increased, so that an additional lens may be required.

Hereinafter, the light distribution characteristic change according to the shape including the inflection point of the optical lens will be described in more detail.

3 shows an optical lens 100 according to a first comparative example. The optical lens 100 has, for example, a planar incident surface 101, a fifth inflection point IP5 and a sixth inflection point IP6, And an exit surface 102 including an exit surface 102. The fifth inflection point IP5 is an inflection point existing on the optical axis OA and the sixth inflection point IP6 may indicate an inflection point closest to the optical axis OA in an area not including the optical axis. The exit surface 102 has a concave shape in the center area including the optical axis OA and may have a convex shape toward the periphery of the lens. The concave shape to the convex shape at the sixth inflection point IP6 can be changed.

4 is a graph showing light distribution characteristics of the optical lens 100 according to the first comparative example shown in FIG. A is a case where the light source is, for example, a 3 mm diameter LED light source, and B is a 5 mm diameter LED light source. For example, the size of the LED light source can be appropriately selected within the range of 3 to 5 mm, and the light distribution characteristics are shown for a 3 mm light source and a 5 mm light source.

5 is a sectional view of the optical lens 200 according to the second comparative example. The optical lens 200 includes an incident surface 201 and an exit surface 202. The incident surface 201 may include a seventh inflection point IP7 on the optical axis OA and an eighth inflection point IP8 in an area not including the optical axis OA. The exit surface 202 may include a ninth inflection point IP9 on the optical axis and a tenth inflection point IP10 in an area not including the optical axis OA. The first vertical distance H1 from the optical axis OA to the eighth inflexion point IP8 is approximately 1.596 mm and the second vertical distance H2 from the optical axis OA to the tenth inflection point IP10 is approximately 2.056 mm. In this case, (h ₂ -h ₁ ) is 0.46.

6 shows the light distribution characteristics of the optical lens 200 according to the second comparative example shown in FIG. A is a case where the light source is, for example, a 3 mm diameter LED light source, and B is a 5 mm diameter LED light source.

4 and 6, it is shown that the light distribution characteristic is relatively improved when the inflection point is located on two sides of the lens, compared with the case where the inflection point is on one side of the lens.

7 shows an example where the first vertical distance h1 is approximately 1.596 mm and the second vertical distance h2 is approximately 3.212 mm, for example. In the case of the optical lens shown in Fig. 7, (h ₂ -h ₁ ) is 1.616. 8 is a graph showing a light distribution characteristic by the optical lens shown in Fig. The light distribution characteristics shown in FIG. 8 are relatively improved as compared with the light distribution characteristics in the cases shown in FIGS. As described above, in the optical lens according to the exemplary embodiment, the first surface (incident surface) and the second surface (outgoing surface) each have at least one inflection point, and the first surface has a vertical from the inflection point closest to the optical axis to the optical axis The light distribution characteristic can be adjusted by adjusting the distance h ₁ and the vertical distance h ₂ from the inflection point closest to the optical axis on the second surface to the optical axis.

Based on the above description, it can be seen that the light distribution angle increases as the value of (h ₂ -h ₁ ) increases. However, as the value of (h ₂ -h ₁ ) increases, the diameter of the lens increases and the size of the lens increases. Even if the angle of the light distribution increases, the light distribution uniformity becomes worse. Therefore, the upper limit value of (h ₂ -h ₁ ) can be defined in consideration of the effective diameter of the lens. (h ₂ -h ₁ ) may be less than 3, for example. (h ₂ -h ₁ ) may be less than 2.5, for example.

As described above, the light from the light source can be diffused at a desired angle by using the optical lens according to the exemplary embodiment. For example, the optical lens according to the exemplary embodiment can be used to diffuse light emitted from an LED with a light distribution angle (diffusion angle) of 100 degrees or more. The light distribution angle can be adjusted by appropriately adjusting the point at which the first-order differential value of the equation representing the lens surface of the optical lens becomes zero.

The following is a numerical example of an optical lens according to an embodiment of the present invention.

Hereinafter, Height (Hi) represents the height (position of the node) from the optical axis in each section i when the lens surface is divided into a plurality of predetermined sections, Slope (Si) represents the slope in each section i Curvature (Mi) represents curvature as a second derivative value in each interval i, and sag (Zi) represents a sag value in each interval i.

&Lt; First Numerical Embodiment >

9 shows an optical lens according to the first numerical example in which the first vertical distance h ₁ is approximately 1.716 mm and the second vertical distance h ₂ is approximately 3.285 mm, Respectively. In the case of the optical lens shown in Fig. 9, (h ₂ -h ₁ ) is 1.569.

The first surface (incident surface) The second surface (emitting surface) Height (Hi) Slope (Si) Curvature
(Mi) sag (Zi) Height (Hi) Slope (Si) Curvature
(Mi) sag (Zi) 0 0 2.183406 0 0 0 0.197824 0 0.1 0.21718 2.148632 0.010888 0.2 0.039404 0.19542 0.003948 0.2 0.42744 2.045324 0.043205 0.4 0.077848 0.188221 0.015698 0.3 0.624059 1.876499 0.095921 0.6 0.114376 0.17627 0.03496 0.4 0.800719 1.647105 0.167351 0.8 0.148044 0.159638 0.061257 0.5 0.951685 1.363899 0.255207 One 0.177926 0.138427 0.093925 0.6 1.071983 1.035286 0.356665 1.2 0.203118 0.11277 0.132115 0.7 1.157555 0.671107 0.468445 1.4 0.222748 0.082831 0.174801 0.8 1.205386 0.28239 0.586916 1.6 0.235978 0.048812 0.220787 0.9 1.213612 -0.118932 0.708201 1.8 0.242016 0.010949 0.268713 One 1.181596 -0.520336 0.828296 2 0.24012 -0.030478 0.317065 1.1 1.109968 -0.909058 0.943198 2.2 0.229609 -0.07515 0.364187 1.2 1.00063 -1.272448 1.049031 2.4 0.209869 -0.122698 0.408293 1.3 0.856728 -1.598354 1.142171 2.6 0.180366 -0.172703 0.447483 1.4 0.682586 -1.875499 1.219367 2.8 0.140655 -0.224693 0.479758 1.5 0.48359 -2.093869 1.277858 3 0.090392 -0.278134 0.503041 1.6 0.266052 -2.245083 1.315467 3.2 0.029344 -0.332427 0.515196 1.7 0.037027 -2.322743 1.330685 3.4 -0.042592 -0.386907 0.514053 1.8 -0.195905 -2.322761 1.322741 3.6 -0.125381 -0.440828 0.497435 1.9 -0.424884 -2.24364 1.291636 3.8 -0.218831 -0.493365 0.463189 2 -0.642036 -2.086705 1.238159 4 -0.322575 -0.543606 0.409216 2.1 -0.839771 -1.856273 1.163877 4.2 -0.436053 -0.590539 0.33351 2.2 -1.011084 -1.559736 1.071087 4.4 -0.558496 -0.633055 0.234197 2.3 -1.149861 -1.207571 0.962746 4.6 -0.688899 -0.669931 0.10958 2.4 -1.251189 -0.813227 0.842365 4.8 -0.826003 -0.699827 -0.04181 2.5 -1.311638 -0.392906 0.713873 5 -0.968268 -0.721278 -0.221166 2.6 -1.329522 0.034797 0.581458 5.2 -1.113845 -0.732682 -0.429339 2.7 -1.305113 0.449407 0.44938 5.4 -1.260555 -0.732293 -0.66678 2.8 -1.240799 0.829246 0.321768 5.6 -1.40585 -0.718212 -0.933467 2.9 -1.141158 1.152296 0.202401 5.8 -1.546789 -0.688375 -1.228831 3 -1.012944 1.397276 0.094491 6 -1.680001 -0.640547 -1.551669

FIG. 10 shows a graph of light distribution characteristics by the optical lens shown in FIG. The light distribution characteristics are improved relative to the light distribution characteristics of the case shown in FIGS. 5 and 6.

&Lt; Second Numerical Embodiment >

That Figure 11 illustrates an optical lens according to the second numerical example, for instance, first a vertical distance (h ₁₎ is approximately 1.5mm, the second vertical distance (h ₂₎ is an example of approximately 3.6mm Respectively. In the case of the optical lens shown in Fig. 11, (h ₂ -h ₁ ) is 2.1.

The first surface (incident surface) The second surface (emitting surface) Height (Hi) Slope (Si) curvature (Mi) sag (Zi) Height (Hi) Slope (Si) curvature (Mi) sag (Zi) 0 0 2.497703 0 0 0 0.18053 0 0.1 0.248034 2.445686 0.012445 0.3 0.053748 0.176421 0.008093 0.2 0.485731 2.291618 0.049262 0.6 0.105035 0.164137 0.032003 0.3 0.703148 2.041388 0.108914 0.9 0.151426 0.143816 0.070624 0.4 0.89112 1.704603 0.188909 1.2 0.190543 0.11569 0.12213 0.5 1.041614 1.294283 0.285888 1.5 0.220092 0.080092 0.183993 0.6 1.148056 0.826445 0.395761 1.8 0.237895 0.037463 0.253011 0.7 1.2056 0.31957 0.513867 2.1 0.241923 -0.011637 0.325352 0.8 1.211346 -0.20601 0.635152 2.4 0.230335 -0.066517 0.396602 0.9 1.16449 -0.728821 0.75438 2.7 0.201517 -0.126343 0.461829 One 1.066402 -1.227015 0.86634 3 0.154134 -0.190115 0.515655 1.1 0.920622 -1.679194 0.966068 3.3 0.087171 -0.256657 0.55235 1.2 0.73277 -2.065255 1.04906 3.6 0 -0.324586 0.565935 1.3 0.510376 -2.367259 1.111469 3.9 -0.10756 -0.392296 0.550309 1.4 0.262622 -2.570263 1.150288 4.2 -0.235171 -0.457931 0.499392 1.5 0 -2.663126 1.163497 4.5 -0.381898 -0.519353 0.407293 1.6 -0.266105 -2.639235 1.150172 4.8 -0.546118 -0.574117 0.268501 1.7 -0.5239 -2.497128 1.110553 5.1 -0.725425 -0.619437 0.07811 1.8 -0.761723 -2.240975 1.046058 5.4 -0.916521 -0.652149 -0.167936 1.9 -0.968624 -1.880898 0.959241 5.7 -1.115097 -0.668676 -0.472554 2 -1.13497 -1.433063 0.853688 6 -1.315707 -0.664993 -0.837202 2.1 -1.253041 -0.919531 0.733859 6.3 -1.511622 -0.636577 -1.261514 2.2 -1.317598 -0.367803 0.604867 6.6 -1.694676 -0.578372 -1.742894 2.3 -1.326396 0.189964 0.472202 6.9 -1.855104 -0.484738 -2.276063 2.4 -1.280589 0.718145 0.341412 7.2 -1.981351 -0.349405 -2.852545 2.5 -1.185003 1.179263 0.217747 2.6 -1.048216 1.536103 0.105788 2.7 -0.882408 1.754372 0.009075 2.8 -0.702909 1.805961 -0.070234 2.9 -0.527388 1.672869 -0.131638 3 -0.374621 1.351857 -0.176471

Fig. 12 shows a graph of the light distribution characteristic by the optical lens shown in Fig. The light distribution characteristics are improved relative to the light distribution characteristics of the case shown in FIGS. 5 and 6.

&Lt; Third Numerical Embodiment >

Fig. 13 shows an example where, for example, the first vertical distance h ₁ is approximately 1.5 mm and the second vertical distance h ₂ is approximately 2.1 mm. In the case of the optical lens shown in Fig. 13, (h ₂ -h ₁ ) is 0.6.

The first surface (incident surface) The second surface (emitting surface) Height (Hi) Slope (Si) Curvature
(Mi) sag (Zi) Height (Hi) Slope (Si) Curvature
(Mi) sag (Zi) 0 0 2.497703 0 0 0 0.30948 0 0.1 0.248034 2.445686 0.012445 0.15 0.046163 0.304303 0.003472 0.2 0.485731 2.291618 0.049262 0.3 0.090775 0.288813 0.013771 0.3 0.703148 2.041388 0.108914 0.45 0.132298 0.263137 0.03055 0.4 0.89112 1.704603 0.188909 0.6 0.169217 0.227487 0.05323 0.5 1.041614 1.294283 0.285888 0.75 0.20006 0.182168 0.081011 0.6 1.148056 0.826445 0.395761 0.9 0.223404 0.127579 0.112873 0.7 1.2056 0.31957 0.513867 1.05 0.237895 0.064223 0.14759 0.8 1.211346 -0.20601 0.635152 1.2 0.242263 -0.007287 0.183736 0.9 1.16449 -0.728821 0.75438 1.35 0.235338 -0.086217 0.219704 One 1.066402 -1.227015 0.86634 1.5 0.21607 -0.171699 0.25372 1.1 0.920622 -1.679194 0.966068 1.65 0.183551 -0.262723 0.283862 1.2 0.73277 -2.065255 1.04906 1.8 0.137034 -0.358116 0.308085 1.3 0.510376 -2.367259 1.111469 1.95 0.075964 -0.456533 0.324244 1.4 0.262622 -2.570263 1.150288 2.1 0 -0.556433 0.330129 1.5 0 -2.663126 1.163497 2.25 -0.090952 -0.656064 0.323494 1.6 -0.266105 -2.639235 1.150172 2.4 -0.196707 -0.753444 0.302102 1.7 -0.5239 -2.497128 1.110553 2.55 -0.316761 -0.846333 0.263767 1.8 -0.761723 -2.240975 1.046058 2.7 -0.450257 -0.932217 0.206401 1.9 -0.968624 -1.880898 0.959241 2.85 -0.595936 -1.008275 0.128079 2 -1.13497 -1.433063 0.853688 3 -0.752092 -1.071361 0.027096 2.1 -1.253041 -0.919531 0.733859 3.15 -0.916521 -1.117969 -0.097963 2.2 -1.317598 -0.367803 0.604867 3.3 -1.086465 -1.144206 -0.248137 2.3 -1.326396 0.189964 0.472202 3.45 -1.25855 -1.145763 -0.42401 2.4 -1.280589 0.718145 0.341412 3.6 -1.428722 -1.117877 -0.625608 2.5 -1.185003 1.179263 0.217747 3.75 -1.592179 -1.055305 -0.852292 2.6 -1.048216 1.536103 0.105788 3.9 -1.743292 -0.952279 -1.102646 2.7 -0.882408 1.754372 0.009075 4.05 -1.875525 -0.802478 -1.374338 2.8 -0.702909 1.805961 -0.070234 4.2 -1.981351 -0.59898 -1.663985 2.9 -0.527388 1.672869 -0.131638 4.35 -2.052158 -0.334231 -1.966994 3 -0.374621 1.351857 -0.176471 4.5 -2.078148 0.000003 -2.277393

FIG. 14 shows a graph of a light distribution characteristic by the optical lens shown in FIG. The light distribution angle characteristics are improved relative to the light distribution characteristics of the case shown in FIGS. 5 and 6.

15 shows an example in which the optical lens 320 is a cylindrical lens. In Fig. 15, the longitudinal axis (A-A cross section) including the optical axis or the central axis OA can satisfy equations 1, 2, and 4. For example, the A-A cross section of the optical lens 320 shown in Fig. 15 may include the data shown in Table 1. FIG. 16 shows a graph of a light distribution characteristic by the optical lens 320 shown in FIG.

Meanwhile, FIG. 17 shows an example in which the diffuser plate 30 is further provided in the illumination apparatus shown in FIG. The diffuser plate 30 may be disposed apart from the second surface 22 of the optical lens 20. The diffusing plate 30 can further diffuse the light primarily diffused by the optical lens 20 in the second order. Thereby, it is possible to diffuse light having a narrow light distribution angle irradiated from the light source 10, for example, an LED, to supply even illumination light in a wide range.

Although the illumination device and the optical lens according to the embodiment of the present invention have been described with reference to the embodiments shown in the drawings for the sake of understanding, it is to be understood that those skilled in the art will appreciate various modifications And other equivalent embodiments are possible. Accordingly, the true scope of the present invention should be determined by the appended claims.

10: light source, 20: optical lens
30: diffusion plate, OA: optical axis
IP1, IP2, IP3, IP4, IP5, IP6, IP7, IP8, IP9, IP10: Inflection point

Claims (12)

A first surface on which light emitted from a light source is incident;
And a second surface on which light is emitted,
Wherein the first surface includes a first inflection point on an optical axis and a second inflection point on an area off the optical axis, the second surface includes a second inflection point on the optical axis and a fourth inflection point provided in an area off the optical axis ,
Wherein the first surface and the second surface include a plurality of sections and the boundary of the plurality of sections is a node, the first surface and the second surface satisfy the following expression.
<Expression>

Wherein, Z is a new geugap of the first surface and the second surface, h is the vertical distance away from the optical axis, H _{i -1} is a (i-1) located on the second node, H _i is the position of the i-th node, Z _{i -1} is the new value at H _{i -1} , Z _i is the new value at Hi, S _i is the slope at H _i , S _{i -1} is the slope at H _{i -1} , Mi Is the slope at Hi, and M _{i -1} is the curvature at H _{i -1} . The method according to claim 1,
An optical lens satisfying the following expression.
<Expression>

Here, h ₂ is the vertical distance from the optical axis to the fourth inflection point on the second plane, and h ₁ is the vertical distance from the optical axis to the second inflection point on the first plane. 3. The method according to claim 1 or 2,
Wherein the first surface is convex in a central region including an optical axis and has a concave shape toward a peripheral portion. 3. The method according to claim 1 or 2,
Wherein the second surface is concave in a central region including an optical axis and convex in a peripheral portion. 3. The method according to claim 1 or 2,
Wherein the first to fourth inflection points include points where the first-order differential value of Z is zero. 3. The method according to claim 1 or 2,
Wherein the first surface and the second surface are rotationally symmetrical about an optical axis, respectively. 3. The method according to claim 1 or 2,
Wherein the optical lens is a cylindrical lens. Light source; And
And an optical lens including a first surface on which light emitted from the light source is incident and a second surface on which light is emitted,
Wherein the first surface includes a first inflection point on an optical axis and a second inflection point on an area off the optical axis, the second surface includes a second inflection point on the optical axis and a fourth inflection point provided in an area off the optical axis ,
Wherein the first surface and the second surface include a plurality of sections and the boundary of the plurality of sections is a node, the first surface and the second surface satisfy the following equations respectively.
<Expression>

Wherein, Z is a new geugap of the first surface and the second surface, h is the vertical distance away from the optical axis, H _{i -1} is a (i-1) located on the second node, H _i is the position of the i-th node, Z _{i -1} is the new value at H _{i -1} , Z _i is the new value at Hi, S _i is the slope at H _i , S _{i -1} is the slope at H _{i -1} , Mi Is the slope at Hi, and M _{i -1} is the curvature at H _{i -1} . 9. The method of claim 8,
A lighting device satisfying the following formula.
<Expression>

Here, h ₂ is the vertical distance from the optical axis to the fourth inflection point on the second plane, and h ₁ is the vertical distance from the optical axis to the second inflection point on the first plane. 10. The method according to claim 8 or 9,
Wherein the first surface is convex in a central region including an optical axis, and has a concave shape toward a peripheral portion. 10. The method according to claim 8 or 9,
Wherein the second surface is concave in a central region including an optical axis, and convex in shape toward a peripheral portion. 10. The method according to claim 8 or 9,
And a diffusion plate is further disposed apart from the second surface of the optical lens.

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