A Lens and an Illuminating Device Equipped with the Lens Technical Field

The present invention relates to a lens and an illuminating device equipped with the lens.

Background Art

At present, the illuminating devices are widely used in vari- ous fields in daily life. For instance, strip illuminating devices are usually installed on edges of furniture, cabinets or other objects to be illuminated. Such illuminating de ^¬ vices are required to provide an elongated light distribu ^¬ tion. Thus, a lens is often used as a lamp cover of the strip illuminating device for offsetting emergent light from a light source to a predetermined angle.

In the prior art there exist two types of such lens: one is TIR (total internal reflection) extrusion lens, and the other is lens with column stripes. As to the TIR extrusion lens, the big angle part emergent light is total internally re ^¬ flected in lens, and the small angle part emergent light is refracted in lens. In this situation, the lens required has a big thickness, resulting in inapplicability of the strip illuminating device having such lens in environments where the thickness or geometrical shape of the illuminating device is strictly restricted. As to the lens with column stripes, it has a shape of convex lens on the whole and has a rela ^¬ tively small thickness compared with the first type of lens, but cannot totally control light of different incident angles according to the optical principle as the column strips thereon are uniformly distributed, and a uniform light dis ^¬ tribution pattern long and thin enough can hardly be obtained with such lens.

Summary of the Invention Therefore, one object of the present invention lies in pro ^¬ viding a lens which has a small thickness and can totally re ^¬ fract and internally reflect light of different incident an ^¬ gles so as to render a uniform elongated light distribution pattern . A lens for a linear light source is provided according to the present invention, wherein the lens comprising an outer surface facing away the light source and an inner surface facing to the light source, wherein the outer surface is a planar emergent surface and the inner surface comprises a first con- vex region and second concave regions, symmetrical with re ^¬ spect to the first convex region, wherein respective second concave region has a microstructure, through which light from the light source is refracted and further reflected to the emergent surface. The lens configured to have a shape with a center first convex region and both second concave re ^¬ gions , which are symmetrical with respect to the first convex region , can reduce the thickness of the lens according to the principle of segmenting a TIR lens. As a linear light source is usually arranged below a lens rightly opposite a central portion of the lens, distances from respective regions of the inner surface of the lens to the light source are different, and angles of incident light obtained on respective regions are not the same. As the inner surface is configured to be a continuous curved surface projecting towards the light source in the middle and both sides being recessed to be away from the surface, and the second concave regions primarily receiv ^¬ ing inclined incident light have the microstructures, the in ^¬ cident light can emerge from the emergent surface after total internally reflected in the lens at a predetermined angle ac- cording to the optical principle. Thereby, an elongated light distribution can be obtained in the precondition of assuring a high optical efficiency.

According to a preferred solution of the present invention, respective microstructure is a continuous sawteeth-like structure, and the sawteeth-like structure comprising a plu ^¬ rality of total internally reflective sawteeth-like units. The surface of the continuous sawteeth-like structure advan ^¬ tageously reflects and refracts the incident light of differ ^¬ ent incident angles. According to a preferred solution of the present invention, respective total internally reflective sawteeth-like unit comprises a first sawteeth edge and a second sawteeth edge in cross section that define an angle with vertex facing to the light source, the first sawteeth edge form a light incident surface facing to the light source and form a light refrac ^¬ tion surface facing away the light source, and the second sawteeth edge form a total internally reflective surface fac ^¬ ing to the light refraction surface. Light from the light source firstly strikes the incident surface of the first saw- teeth edge, and then it is refracted and strikes the total internally reflective surface of the second sawteeth edge from the light refraction surface, and thus, the total inter ^¬ nal reflection is accomplished in the lens.

According to a preferred solution of the present invention, two first angles formed between a line connecting one vertex with the light source and lines respectively connecting two vertexes adjacent to said vertex with the light source are equal. This configuration is beneficial for obtaining uniform elongated light distribution.

According to a preferred solution of the present invention, wherein the number of the total internally reflective saw ^¬ teeth-like units is equal to a ratio of a light incident range of the light incident to the second concave regions to the first angle. The more the sawteeth-like units are, the more uniform the light distribution is. According to a preferred solution of the present invention, an angle between respective first sawteeth edge and an opti ^¬ cal axis of the light source is 2°-5°. Particularly prefera ^¬ bly, the angle can be minimally 2°.

According to a preferred solution of the present invention, a first distance from the first convex region to the emergent surface is smaller than a third distance from an edge region of respective second concave region to the emergent surface. Particularly preferably, the third distance is 3mm. As a re ^¬ sult, an arched shape recessed in the middle to be away from a surface where the light source is located is formed to both sides of the first convex region, wherein edge regions at both sides of the lens are substantially in the same horizon ^¬ tal plane as the light source.

According to another preferred solution of the present inven- tion, the first sawteeth edge and the second sawteeth edge of sawteeth-like units increased as a second distance from re ^¬ spective second concave region to the emergent surface de ^¬ crease. This means that the length of respective the first and the second sawteeth edge in respective second concave re- gion are gradually reduced from a vault of the arch shape to both ends of the arch shape adjacent to the first convex re ^¬ gion and respective edge region.

According to another preferred solution of the present invention, the lens is made from PC or PMMA. Material of the lens, especially optical properties thereof, is associated with the shape and length of the sawteeth-like unit.

Preferably, the lens is an extrusion lens stretched along a direction parallel to an extending direction of the linear light source. In addition, the present invention further relates to an illuminating device comprising a plurality of linearly arranged light sources , wherein the illuminating device is equipped with the lens.

Preferably, the linearly arranged light source is a linear LED array. An optical axis of the LED array is perpendicular faced a center of the first convex region.

It shall be understood that both the above general descrip ^¬ tion and the following detailed description are for illustrative and explanative purposes in order to provide further de- scription of the claimed present invention.

Brief Description of the Drawings

The accompanying drawings constitute a part of the present Description and are used to provide further understanding of the present invention. Such accompanying drawings illustrate the embodiments of the present invention and are used to de ^¬ scribe the principles of the present invention together with the Description. In the accompanying drawings the same com- ponents are represented by the same reference numbers. As shown in the drawings :

Fig. 1 is a sectional view of a lens according to the present invention ; Fig. 2 is a detailed view of a second concave region 2 of the lens in Fig. 1 ;

Fig. 3 is a 3D view of a lens according to the present invention;

Fig. 4 is a optical pathway diagram of a lens according to the present invention; and

Fig. 5 is a light distribution diagram of a lens according to the present invention.

Detailed Description of the Embodiments

Fig. 1 is a sectional view of a lens according to the present invention, wherein the lens is used for a linear light source L extending inwardly and perpendicularly to the paper surface. The lens according to the present invention comprises a planar outer surface as an emergent surface F and an inner surface facing the light source L. In order to get a uniform elongated light spot in the precondition of assuring a high optical efficiency, a central region of the inner surface of the lens is configured to be a first convex region 1 towards the light source L, second concave regions 2 being symmetri ^¬ cal and recessed away from the light source L are configured to both sides of the first convex region 1, and edge regions 3 of the second concave regions 2, i.e., at least part of edge regions 3 parallel to an extending direction of the ^

light source L, is substantially in the same horizontal plane as the light source L, as a result, a radiation range of the light source L can be generally covered. Thereby, second concave regions 2 each having an arch shape recessed in the middle to be away from the light source L. More advanta ^¬ geously, respective second concave region 2 that mainly re ^¬ ceives light from the light source L has a microstructure, i.e., a continuous sawteeth-like structure consisting of a plurality of total internally reflective sawteeth-like units T.

Respective sawteeth-like unit T is defined by a first saw ^¬ teeth edge SI and a second sawteeth edge S2 to have an acute- angulate structure with a vertex P and facing the light source L, wherein the first sawteeth edge SI has an incident surface al facing the light source L and a light refraction surface a2 back to the light source L, and the second saw ^¬ teeth edge S2 has a total internally reflective surface a3 opposite to the light refraction surface a2. The sawteeth- like units T have different shapes, and a length of respec ^¬ tive sawteeth-like unit T and inclined angles of the sawteeth edges SI and S2 can be flexibly designed according to the light distribution required, thus an internal reflection angle of light in the lens is changed, and further an tilted angle between light emitted from the emergent surface F and the emergent surface F is adjusted to allow light from the light source L to pass through the lens to be offset to a predetermined direction.

In conjunction with the detailed view of Fig. 2, it can be seen that in one segment of the second concave region 2, an angle formed by lines connecting two adjacent vertexes P with the light source L is a first angle a, and an angle between the first sawteeth edge SI and an optical axis of the light source L is a second angle β. The shape of respective saw ^¬ teeth-like unit T and a trend of a curve of the continuous sawteeth-like structure can be changed by adjusting the first angle a and the second angle β, which also directly deter- mines the pattern of the light distribution. The second an ^¬ gle β may be 2°-5°, and the first angle a may be artificially set. Fig. 2 shows an enlarged view of the second angle β of 5° for showing the sawteeth-like unit T clearly. As second angles β corresponding respective sawteeth-like units T is the same, the first sawteeth edges SI of respective sawteeth- like units T are parallel to each other. A length of the first sawteeth edge SI of respective sawteeth-like unit T is determined, for instance, as follow: two beams of light hav ^¬ ing the first angle a from the light source L rightly can pass through two adjacent vertexes P. Light passing through the vertex P of a first sawteeth-like unit Tl passes through the first sawteeth edge SI of a second sawteeth-like unit T2 to strike the total internally reflective surface a3 of the second sawteeth edge S2 and forms a reflection point P' thereon. The reflection point P' is also an end point of the first sawteeth edge SI of a third sawteeth-like unit T3.

Consequently, a length of a first sawteeth edge SI of the third sawteeth-like unit T3 is determined by the vertex P and the end point P' . Besides, it can be seen upon comparison with Fig. 1 that first angles a formed by each two lines con ^¬ necting two adjacent vertexes P with the light source L are the same. The number of the sawteeth-like units T is equal to a ratio of a light incident range of the light source cor ^¬ responding to the second concave regions 2 to the first angle a. For example, when the first angle a is 10° and the second concave regions 2 cover a range of 0°-80°, there are eight sawteeth-like units T in respective second concave region 2.

The lens according to the present invention may be configured according to the geometrical relation above depending upon application environments.

Fig. 3 is a 3D view of the lens according to the present invention. As can be seen from Fig. 3, the lens according to the present invention is an extrusion lens stretched along a direction parallel to an extending direction of the light source L extends. The lens may be made from PC or PMMA.

Fig. 4 and Fig. 5 are optical pathway diagram and light dis ^¬ tribution diagram of a lens according to the present inven- tion, respectively. As can be seen from Fig. 4, light from the light source L exits uniformly through the lens; and it can be seen from Fig. 5 that a uniform elongated light dis ^¬ tribution pattern can be obtained on a target plane, for instance, at a distance of 0.5m from the light source L. The above is merely preferred embodiments of the present in ^¬ vention but not to limit the present invention. For the per ^¬ son skilled in the art, the present invention may have vari ^¬ ous alterations and changes. Any alterations, equivalent sub ^¬ stitutions, improvements, within the spirit and principle of the present invention, should be covered in the protection scope of the present invention.

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List of reference signs

1 first convex region

2 second concave region

3 edge region al incident surface a2 light refraction surface a3 total internally reflective surface dl first distance d2 second distance d3 third distance

F emergent surface

L light source

P vertex

P' reflection point/end point of first sawteeth edge SI

51 first sawteeth edge

52 second sawteeth edge T sawteeth-like unit Tl first sawteeth-like unit

T2 second sawteeth-like unit

T3 third sawteeth-like unit first angle second angle