WO2012031867A1

WO2012031867A1 - A method for fabricating a lens and a lens

Info

Publication number: WO2012031867A1
Application number: PCT/EP2011/064179
Authority: WO
Inventors: Yabin Luo; Yubao He; Tengzhi Qin; Haiping Yuan
Original assignee: Osram GmbH
Current assignee: Osram GmbH
Priority date: 2010-09-10
Filing date: 2011-08-17
Publication date: 2012-03-15
Anticipated expiration: 2013-03-10
Also published as: CN102401318A

Abstract

The present invention relates to a method for fabricating a flat plate lens, including the following steps: providing a base body; processing an upper part of the base body to form upper central portion (1) having a continuous curve shape and a plurality of upper circumferential sawtooth portions (2) directly adjacent to the upper central portion, each having one of a plurality of arc-section or quasi-arc section profile; processing a bottom part of the base body to form a plurality of bottom central sawtooth portions each having one of a plurality of other arc-section or quasi-arc section profiles and a bottom circumferential straight portion (3) directly adjacent to the bottom central sawtooth portions (4). In addition, the present invention relates to a flat plate lens. The lens according to the present invention has special curves and small volume. By the curves, the thickness of the lens can be decreased, the optical efficiency can be improved, and the costs are reduced. Good optical performance and high efficiency can be obtained by the application of such lens.

Description

A Method for Fabricating a Lens and a Lens Technical Field

The present invention relates to a method for fabricating a lens and to the corresponding lens.

Background of the Invention

In the current luminaire, LED secondary lens is a lens popularly used. It is quite adaptable to high or low power LED or similar light source. The oval lens is usually used for the streetlight or the application requiring the oval light distribution. In order to obtain the oval light distribution for streetlight, one existing solution is to use the reflector. The disadvantage of such solution is the low light distribution performance and low system efficiency. Another solution to obtain the oval light distribution is to use the plastic or glass lens which has continuous smooth curve, but also has the disadvantages such as low efficiency, high cost and large volume.

Summary of the Invention

The object of the present invention is to provide a method for fabricating a novel lens and corresponding lens so as to meet the requirement to the circular or oval light distribution. The present invention accomplishes the above object by the specific profile configuration of the lens and overcomes the defects such as low efficiency, high cost and large volume of the lens with continuous smooth curve in the prior art.

The method for fabricating the lens according to the present invention includes the following steps: a) providing a base body; b) processing an upper part of the base body to form upper central portion having a continuous curve shape and a plurality of upper circumferential sawtooth portions directly adjacent to the upper central portion, each having one of a plurality of arc-section or quasi-arc section profile; and c) processing a bottom part of the base body to form a plurality of bottom central sawtooth portions each having one of a plurality of other arc-section or quasi-arc section profiles and a bottom circumferential straight portion directly adjacent to the bottom central sawtooth portions.

The inventive concept of the present invention lies in: a plurality of upper circumferential sawtooth portions, each having one of a plurality of arc-section or quasi-arc section profile, adjacent to an upper central portion having a continuous curve shape are constructed, so that a plurality of arc-section or quasi-arc section profile of the upper circumferential sawtooth portions are capable to achieve the functional effect of corresponding continuous curved profiles of the smooth curve of a lens generating circular or oval light distribution in the prior art, that is, the smooth curve extending from the upper central portion to the peripheral part in the prior art can be replaced with the combination of the upper central portion having a continuous curve shape and a plurality of arc-section or quasi-arc section profiles of the upper circumferential sawtooth portions. Correspondingly, at the bottom of the lens, the replacement of the continuous curved profile of the bottom in the prior art with further arc-section or quasi-arc section profiles of bottom central sawtooth portions is realized by a plurality of bottom central sawtooth portions, each having one of a plurality of other arc-section or quasi-arc section profiles, directly adjacent to a bottom circumferential straight portion. According to the present invention, the problem in the prior art that both upper part and bottom part are designed as continuous curved, which causes a low efficiency, is avoided, while the circular or oval light distribution in the prior art is also achievable. In the present invention, the effect that the corresponding continuous curved profile can achieve in the prior art is realized by means of the arc-section or quasi-arc section profiles of the sawtooth portions, while the disadvantage of low efficiency caused by the continuous curved profile is banished, and the problem of larger value of lens thickness caused by the continuous curved profile is solved, so that it is possible to reduce the thickness and volume of the lens.

Preferably, prior to the step b), a part of the continuous curved profile of the lens forming a certain particular light distribution pattern is replaced by a plurality of arc-sections formed by dividing the continuous curved profile. In other words, a plurality of arc-sections of the a plurality of upper circumferential sawtooth portions can be combined to form the curve of a certain particular light distribution pattern. For instance, a plurality of other arc-sections or quasi-arc sections of the plurality of bottom central sawtooth portions are combined to form the curve of a certain particular light distribution pattern. One preferred solution according to the present invention further comprises the following steps prior to the fabricating step b):

obtaining profile parameters of the flat plate lens by measuring a first lens forming an oval or circular light distribution pattern, wherein, the first lens has a cross-section formed by an upper curve, a bottom curve, an symmetry axis and a bottom straight edge;

in step b), including

b1 ) determining a first horizontal reference line starting from an intersection point between the symmetry axis and the upper curve of the first lens, the first horizontal reference line intersecting with the upper curve of the first lens forming a upper intersection point,

b2) fabricating the upper central portion of the flat plate lens and the plurality of the upper circumferential sawtooth portions directly adjacent to the upper central portion on the first horizontal reference line , wherein, the upper central portion has a profile the same as that of the upper curve before the upper intersection point, and each of the plurality of the upper circumferential sawtooth portions has one of a plurality of arc-section or quasi-arc section profile formed by dividing the upper curve after the upper intersection point.

Preferably,in step c), including

c1 )determining a second horizontal reference line below the first horizontal reference line with a predetermined distance between the first and second horizontal reference lines, a bottom intersection point (P) between the bottom curve and the bottom straight edge forming a projection point by projecting on the second horizontal reference line,

c2)fabricating the plurality of bottom central sawtooth portions and the bottom circumferential straight portion directly adjacent to the plurality of bottom central sawtooth portions on the second horizontal reference line, wherein, each of the plurality of bottom central sawtooth portions has one of a plurality of arc-section or quasi-arc section profile by dividing the bottom curve before the projection point, and the bottom circumferential straight portion has a profile the same as that of the bottom straight edge after the projection point.

The inventive concept of the above preferred solution starts from an existing circular or oval lens, to move a plurality of continuous curved arcs of the lens onto one reference surface of the lens surface to form the sawtooth portions by means of approximately translational movement while keeping the main configuration of the lens unchanged, so as to reduce the thickness of the lens, and further to reduce the volume of the lens, and to accomplish the effect of circular or oval light distribution. In other words, Preferably, the profile of the upper curve of the first lens can be defined by the following equation: y = 0.0004χ^Λ6 - 0.0096χ^Λ5 + 0.0725χ^Λ4 - 0.2733χ^Λ3 + 0.4174χ^Λ2 + 0.0244χ + 2.5397, wherein, χ is abscissa value on a cross section, and y is ardinate value on the cross section. The profile of the first len can be precisely obtianed by said equation. Preferably according to the present invention, the profile of the bottom curve of the first lens is circular arc or approximately circular arc. The profiles of the upper curve and bottom curve above can render quite uniform light distribution.

Preferably, the predetermined distance between the first refrence line and the second reference line is 0.05mm-5mm. This distance is also the thickness of the fabricated and moulded lens. This thickness especially embodies the advantage of the thin lens according to the present invention.

Preferably, the number of the upper circumferential sawtooth portions and the bottom central sawtooth portions is designed to 10-100, respectively. The lens fabricated by such solution not only produces high optical efficientcy but also is easy to be processed.

Advantageously, the first lens is provided to be an oval lens, and a height from the long axis to the short axis of one same upper circumferential sawtooth portion is linearly varied. A flat plate lens is provided according to the present inveniton. The flat plate lens is fabricated by the method according to the present invention. Therefore, the flat plate lens has the advantageous shape and specially preferred characteristics of the lens obtained by the fabircating method of the present invention. Unnecessary details will not be given herein.

The lens according to the present invention has special curve and small volume, by which the thickness of the lens can be reduced, the optical efficiency is improved, and the fabricating costs are reduced. Good optical performance and high efficiency can be obtained by application of such lens.

Description of the Drawings Embodiments of the present invention are illustrated with reference to the drawings. In the drawings:

Figure 1 is a solid view of the lens according to the present invention, in which the upper surface is shown;

Figure 2 is a solid view of the lens according to the present invention, in which the bottom face is shown;

Figure 3 is a sectional view of the lens in the X-Z plane according to the present invention;

Figure 4 is a sectional view of the lens in the Y-Z plane according to the present invention; Figure 5 shows an embodiment of the LED luminous body of the lens according to the present invention;

Figures 6a and 6b show the oval lens in the prior art and light distribution curve diagram thereof;

Figure 7 shows one step of the fabricating method according to the present invention with a cross sectional view of the first lens;

Figure 8 shows another step of the fabricating method according to the present invention with a cross sectional view of the first lens; Figure 9 shows a comparison diagram between the first lens and the lens obtained on the basis of the first lens according to the present invention;

Figure 10 is a light distribution scheme of the lens according to the present invention;

Figure 11 shows an embodiment of the LED luminous body with one lens according to the present invention; and

Figures 12 and 13 show the optical paths of the lens according to the present invention, respectively. Detailed Description of Embodiments

Figure 1 is a solid view of the lens according to the present invention, in which the curve profile of the upper surface of the lens can be particularly seen. The curve profile of the upper surface of the lens according to the present invention raises to the peak from the center and then gradually descends to form the curve-shaped upper central portion 1 . The upper central portion 1 with a curve shape is directly adjacent to a plurality of sawtooth regions with arc-section or quasi-arc section profile. The sawtooth portions form the upper circumferential sawtooth portions 2. The lens in this embodiment has an oval shape, also can be of a circular shape. Figure 2 is a solid view of the lens according to the present invention, in which the bottom face is shown. The bottom face of the lens in Figure 2 comprises the bottom circumferential straight portion 3 and a plurality of bottom central sawtooth portions 4 adjacent thereto. The bottom central sawtooth portions 4 are similar to the upper circumferential sawtooth portions 2, and each has the arc-section or quasi-arc section profile, while the arc and bent line may have different radians or gradients. The number of the bottom central sawtooth portions 4 preferably is 10-100.

Of course, Figures 1 and 2 show the oval lenses that, of course, also can be circular lenses. Figure 3 is a sectional view of the oval lens in the X-Z plane according to the present invention. In the figure it is clearly shown that the left and right sides of the oval lens are symmetrical to each other. The upper surface curve of the lens smoothly extends to the peak from the center 5 and then gradually descends to form the upper central portion 1 with a continuous curve shape. A plurality of upper circumferential sawtooth portions 2 are adjacent to the upper central portion 1. The upper circumferential sawtooth portions 2 formed at that position have the lowest height. A plurality of bottom central sawtooth portions 4 and the bottom circumferential straight portion 3 directly adjacent to the bottom central sawtooth portions 4 are on the bottom face of the lens.

Figure 4 is a sectional view of the oval lens in the Y-Z plane according to the present invention. Compared with Figure 3, Figure 4 shoes the first portion of the upper circumferential sawtooth portions 2 with the highest height, while the profiles of the other portions of the lens are not changed with respect to Figure 3.

Preferably, the height of one upper circumferential sawtooth portion from the long axis (in Y-Z direction) to the short axis (in X-Z direction) is linearly varied. Figure 5 shows an embodiment of the LED luminous body of the flat plate oval lens according to the present invention. In this embodiment, the flat plate oval lens according to the present invention is horizontally placed over the LED luminous body to form second optics distribution so as to obtain the oval light distribution. Figures 6a and 6b show the oval lens in the prior art and light distribution curve diagram thereof. The oval lens can provide the oval light distribution pattern. It can be seen from the light distribution cuve diagram in Figure 6a that the light distribution curve presents a batwing shape. The lens (referred to as "the first lens" below) used in the prior art as shown in Figure 6 uses the continuous smooth curve with a big thickness and a surface profile raising to the peak from the center and then gradually descending. The central portion of the bottom profile is a concave curve, and the bottom circumferential portion is straight. Figure 7 shows one step of the fabricating method according to the present invention with a cross sectional view of the first lens. The profile parameters of the flat plate lens according to the present invention by measuring the first lens 6 forming an oval pattern (or circular pattern) light distribution pattern, wherein, the first lens 6 has a profile formed by upper curves 12, 13, a bottom curve 10, an symmetry axis 9 and a bottom straight edge 11 on a cross section. The profile of the upper curve preferably is defined by the following equation: y = 0.0004χ^Λ6 - 0.0096χ^Λ5 + 0.0725χ^Λ4 - 0.2733χ^Λ3 + 0.4174χ^Λ2 + 0.0244χ + 2.5397. The profile of the bottom curve is preferably circular arc or approximately circular arc. In the figure, the first horizontal reference line 7 shown by the dot-and-dash line is parallel to the second horizontal reference line 8 below. The second horizontal reference line 8 is starting from the upper intersection point 5 between the symmetry axis 9 and the upper curves 12 and 13, with a predetermined distance from the first horizontal reference line 7. The intersection point between the first horizontal reference line 7 and the surface of the first lens 6 is A. Herein, the predetermined distance is preferably 0.05mm-5mm. The bottom intersection point between the bottom curve 10 and teh the bottom straight edge 11 is shown by the mark P. The portion of the upper curve after A is divided into six arcs by five points.

Figure 8 shows another step of the fabricating method according to the present invention with a cross sectional view of the first lens. The upper central portion 1 of the flat plate lens and each of the plurality of the upper circumferential sawtooth portions 2 directly adjacent to the upper central portion are processed on the first horizontal reference line 7 of the first lens 6, wherein, the upper central portion 1 has a profile the same as that of the upper curve 13 before the upper intersection point A, and each of the plurality of the upper circumferential sawtooth portions 2 has an arc-section or quasi-arc section profile divided by the upper curve 12 after the upper intersection point A. It should be indicated that arcs are preferred. And of course, the bent lines approximate to the arc also may be used.

Figure 9 shows a comparison diagram between the first lens and the oval lens according to the present invention, showing another step of the fabricating method according to the present invention. The bottom intersection point P between the bottom curve 10 and the bottom straight edge 8 forms a projection point on the second horizontal reference line 8. A plurality of bottom central sawtooth portions 4 and the bottom circumferential straight portion 3 directly adjacent to the plurality of bottom central sawtooth portions 4 are processed on the second horizontal reference line 8, wherein, each of the plurality of bottom central sawtooth portions 4 has an arc-section or quasi-arc section profile by dividing the bottom curve 10 before the projection point, and the bottom circumferential straight portion 3 has a profile the same as that of the bottom straight edge 11 after the projection point. By such fabricating method, the lens with the special curves according to the present invention is finally formed on the basis of the first lens.

From the comparison between the upper and bottom lenses in the figures it can be seen that the lens profile processed by the method according to the present invention extracts the curve characteristics in the present application he first lens, replaces the expression with the continuous curve with a plurality of upper circumferential sawtooth portions dispersed on the first horizontal reference line 7, therefore it is capable of realizing the light distribution function of the first lens but also accomplishing the objective of reducing the lens thickness, volume and costs. Figure 10 is a light distribution scheme of the lens according to the present invention. The light distribution pattern of the lens obtained by the fabricating method of the present invention is clearly shown as an oval pattern with good uniformity.

Figure 11 shows an embodiment with one lens according to the present invention. The flat plate lens according to the present invention can be used in the LED module, for instance, as shown in Figure 11 . In the figure, the lens and the LED are enveloped to render the illuminating apparatus with good light distribution performance and high system efficiency. Figures 12 and 13 show the optical paths of the lens according to the present invention, respectively. From the figure it can be seen that good light distribution performance can be obtained by the present invention. Reference signs

1 upper central portion

2 upper circumferential sawtooth portion

3 bottom circumferential straight portion 4 bottom central sawtooth portion

5 center of the first lens

6 first lens

7 first horizontal reference line

8 second horizontal reference line 9 optical axis

10 bottom curve

11 bottom straight edge

12 upper curve

A upper intersection point

P bottom intersection point

Claims

Claims:

1 . A method for fabricating a flat plate lens, characterized by including the following steps:

a) providing a base body;

b) processing an upper part of the base body to form upper central portion (1 ) having a continuous curve shape and a plurality of upper circumferential sawtooth portions (2 ) directly adjacent to the upper central portion, each having one of a plurality of arc-section or quasi-arc section profile; and

c) processing a bottom part of the base body to form a plurality of bottom central sawtooth portions each having one of a plurality of other arc-section or quasi-arc section profiles and a bottom circumferential straight portion (3) directly adjacent to the bottom central sawtooth portions (4).

2. The fabricating method according to Claim 1 , characterized by, prior to step b), including

obtaining profile parameters of the flat plate lens by measuring a first lens (6) forming an oval or circular light distribution pattern, wherein, the first lens has a cross-section formed by an upper curve(12), a bottom curve(10), an symmetry axis (9) and a bottom straight edge (11 );

in step b), including

b1 ) determining a first horizontal reference line (7) starting from an intersection point between the symmetry axis( 9 )and the upper curve (12) of the first lens, the first horizontal reference line (7) intersecting with the upper curve (12) of the first lens(6) forming a upper intersection point (A),

b2) fabricating the upper central portion (1 ) of the flat plate lens and the plurality of the upper circumferential sawtooth portions (2) directly adjacent to the upper central portion on the first horizontal reference line (7), wherein, the upper central portion (1 ) has a profile the same as that of the upper curve (12) before the upper intersection point(A), and each of the plurality of the upper circumferential sawtooth portions (2) has one of a plurality of arc-section or quasi-arc section profile formed by dividing the upper curve(12) after the upper intersection point(A).

3. The fabricating method according to Claim 2, characterized by,

in step c), including

c1 )determining a second horizontal reference line (8) below the first horizontal reference line (7) with a predetermined distance between the first (7) and second (8) horizontal reference lines, a bottom intersection point (P) between the bottom curve ( 10 )and the bottom straight edge ( 11 )forming a projection point by projecting on the second horizontal reference line ( 8 ) , c2 fabricating the plurality of bottom central sawtooth portions (4) and the bottom circumferential straight portion (3) directly adjacent to the plurality of bottom central sawtooth portions (4) on the second horizontal reference line ( 8 ) , wherein, each of the plurality of bottom central sawtooth portions has one of a plurality of arc-section or quasi-arc section profile by dividing the bottom curve (10) before the projection point (P), and the bottom circumferential straight portion (3) has a profile the same as that of the bottom straight edge after the projection point(P).

4. The fabricating method according to Claim 3, characterized in that, the profile of the upper curve ( 12 ) of the first lens can be defined by the following equation: y = 0.0004χ^Λ6 - 0.0096χ^Λ5 + 0.0725χ^Λ4 -

0.2733χ^Λ3 + 0.4174χ^Λ2 + 0.0244χ + 2.5397, wherein, χ is abscissa value and y is ordinate value on the cross section.

5. The procesing method according to Claim 2 or 3, characterized in that the profile of the bottom curve ( 10 ) of the first lens is circular arc or approximately circular arc.

6. The procesing method according to Claim 2 or 3, characterized in that the predetermined distance is 0.05mm-5mm.

7. The procesing method according to Claim 2 or 3, characterized in that the number of the upper circumferential sawtooth portions (2) and the bottom central sawtooth portions(4) is 10-100, respectively. The procesing method according to Claim 2 or 3, characterized in that the first lens ( 6 )is an oval lens and a height of a same upper circumferential sawtooth portion from long axis to short axis is linearly varied.

The procesing method according to Claim 2 or 3, characterized in that the first lens is a circular lens.

A flat plate lens, comprising an upper part and a bottom part, the upper part comprising an upper central portion (1 ) with an upper continuous curve shape and a plurality of upper circumferential sawtooth portions(2) directly adjacent to this upper central portion(1 ), each having one of a plurality of arc-section or quasi-arc section profile, the bottom part comprising a plurality of bottom central sawtooth portions (4) each having one of a plurality of other arc-section or quasi-arc section profiles and a bottom circumferential straight portion (3) directly adjacent to the bottom central sawtooth portions (4).

The lens according to Claim 10, characterized by obtaining profile parameters of the flat plate lens by measuring a first lens (6) forming an oval or circular light distribution pattern, wherein, the first lens has a cross-section formed by an upper curve(12), a bottom curve(10), an symmetry axis (9) and a bottom straight edge (11 ); the first lens (6) having a first horizontal reference line (7), starting from an intersection point between the symmetry axis ( 9 )and the upper curve

(12) of the first lens and intersecting with the upper curve (12) of the first lens(6) forming a upper intersection point (A), the upper central portion (1 ) has a profile the same as that of the upper curve (12) before the upper intersection point(A) on the first horizontal reference line (7) and each of the plurality of the upper circumferential sawtooth portions (2) has one of a plurality of arc-section or quasi-arc section profile formed by dividing the upper curve(12) after the upper intersection point(A).

12. The lens according to Claim 11 , characterized in that the first lens (6) have a second horizontal reference line (8) below the first horizontal reference line (7) with a predetermined distance between the first (7) and second (8) horizontal reference lines, on which a projection point of a bottom intersection point( P )between the bottom curve ( 10 ) and the bottom straight edge ( 11 ) is projected; each of the plurality of bottom central sawtooth portions on second horizontal reference lines (8) has one of a plurality of arc-section or quasi-arc section profile by dividing the bottom curve (10) before the projection point (P), and the bottom circumferential straight portion (3) has a profile the same as that of the bottom straight edge after the projection point(P).

13. The lens according to Claim 12, characterized in that the profile of the upper curve of the first lens can be defined by the following equation: y = 0.0004χ^Λ6 - 0.0096χ^Λ5 + 0.0725χ^Λ4 - 0.2733χ^Λ3 + 0.4174χ^Λ2 +

0.0244x + 2.5397,wherein, x is abscissa value and y is ordinate value on the cross section.

14. The lens according to Claim 11 or 12, characterized in that the profile of the bottom curve ( 10 ) of the first lens is circular arc or approximately circular arc.

15. The lens according to Claim 11 or 12, characterized in that the predetermined distance is 0.05mm-5mm.

16. The lens according to Claim 11 or 12, characterized in that the number of the upper circumferential sawtooth portions and the bottom central sawtooth portions is 10-100, respectivel.

17. The lens according to Claim 11 or 12, characterized in that the first lens is an oval lens and a height of a same upper circumferential sawtooth portion from long axis to short axis is linearly varied.

18. The lens according to Claim 11 or 12, characterized in that the first lens is a circular lens.