Lens plate

Abstract

The present invention is a lens plate 10 for an LED device 100, comprising a plurality of lens elements 12a-12e and flexible connections 24a-24d between two lens elements of the plurality of lens elements, the flexible connections 24a-24d being spaced apart by a distance P between the two lens elements. 11 and a flexible connection part so that at least one of the angles can be adjusted, wherein the two lens elements and the flexible connection part are made of the same material.

Description

[Technical field]

[0001] The present invention relates to a lens plate for an LED (Light Emitting Diode) device. The present invention also relates to an LED device comprising such a lens plate, to the use of such a lens plate, and to a method for manufacturing such a lens plate. [Background technology]

[0002] In various LED devices, a lens plate with multiple lens elements may be used to cover an LED substrate (i.e., a substrate or carrier with light-emitting diodes attached to the substrate or carrier) to affect the light distribution of the light-emitting diodes. However, even if the light distribution (shape of the lenses in the lens plate) is to be kept the same, every change in the LED pitch (distance between LEDs) on the LED substrate requires investment in new manufacturing tools. For example, if the LED pitch is changed by 0.05 mm in a 2-foot LED device with 48 light-emitting diodes, the position of the last light-emitting diode will change by 0.05 x 47 = 2.35 mm, which is very significant from an optical point of view.

[0003] US2012189800 discloses an element array in which pitch errors between elements in the element array are reliably absorbed in a step of stacking a plurality of element arrays so that each group of elements arranged in the stacking direction can be aligned with high accuracy. The element array has a plurality of lenses arranged one-dimensionally or two-dimensionally, and a flexible support formed of a material more elastic than a material forming the lenses. The lenses are bonded to each other via the support. The lenses and the support are integrally formed by double molding. Summary of the Invention [Problem to be solved by the invention]

[0004] It is an object of the present invention to overcome or at least mitigate the above mentioned problems and to provide an improved lens plate. [Means for solving the problem]

[0005] According to a first aspect of the present invention, this and other objects are achieved by a lens plate for an LED device, said lens plate having a plurality of lens elements and a flexible connection between two consecutive lens elements of a further plurality of said plurality of lens elements, such that at least one of the distance and the angle between each of said two lens elements can be adjusted, each of said two lens elements and said flexible connection being made of the same material.

[0006] The present invention is based on the realization that the flexible connections between lens elements allow one type of lens plate to fit LED substrates with different LED pitches and / or even different shapes by stretching (or possibly squeezing) these connections. Thus, the lens plate is universally applicable, which saves costs in manufacturing many different types of LED devices / substrates. Furthermore, since the lens elements and the flexible connections of the lens plate are made of the same material, the structure of an adjustable lens plate can be simplified and easy to manufacture.

[0007] For example, the flexible connection may be molded together with the two lens elements, for example by injection molding.

[0008] The flexibility of the flexible connection may be achieved by at least one of the shape, size and position of the flexible connection, rather than by selecting a different (e.g., more elastic) material for the flexible connection compared to the lens element.

[0009] The flexible connection may comprise two (parallel) spring members.

[0010] The flexible connection may for example comprise two V-shaped members. V-shaped members are advantageous in that they can be stretched or crushed. Also, the V-shaped members do not need to overlap, which allows for easy molding. The V-shaped members are preferably in a plane that is perpendicular to the optical axis of the lens elements, since in that case the V-shaped members may not cover the lenses of the lens elements or the light beams emitted from the lenses. The V-shaped members also require less material.

[0011] Other shapes of the flexible connection are possible, for example W-shaped, U-shaped or Π-shaped. Other orientations / positions of the flexible connection are also possible, such as standing in a plane parallel to the optical axis of the lens elements.

[0012] Furthermore, the two lens elements may each have a base portion, the two base portions at least partially defining two triangular or isosceles trapezoidal spaces pointing towards each other between the two base portions, each of the two triangular or isosceles trapezoidal spaces accommodating one of the two V-shaped (or W-shaped) members of the flexible connection. The advantage of this is that a relatively short minimum distance between the (two) lens elements can be realized despite the flexible connection between them. To obtain the two triangular or isosceles trapezoidal spaces, the base portion may be, for example, hexagonal or octagonal.

[0013] There may be a gap between the two lens elements when no force is applied to the flexible connection. In this way, the pitch of the lens elements may be made larger or smaller, so that the lens plate can fit a wide variety of LED substrates. The gap may be, for example, between a side of the aforementioned hexagonal or octagonal base of one of the two lens elements and an opposite side of the hexagonal or octagonal base of the other lens element. In another embodiment, there is (substantially) no gap between the two lens elements when no force is applied to the flexible connection.

[0014] In one embodiment, each lens element of the plurality of lens elements includes two protrusions adapted to engage with a corresponding notch in an LED substrate of the LED device for positioning the lens plate on the LED substrate. Such positioning solves the problem of the effect of thermal elongation on the light distribution, since the position of the lens element relative to the light emitting diode of the LED substrate is stable. In another embodiment, each lens element includes two notches adapted to engage with a corresponding protrusion in the LED substrate. A combination of these two embodiments is also possible. Additional elements, such as a frame, may also be used for positioning.

[0015] The lens elements may be arranged in a linear array, which may be a rectilinear array, or in another embodiment, the linear array is curved in a plane perpendicular to the optical axis of the lens elements.

[0016] According to a second aspect of the present invention, there is provided an LED device comprising a substrate comprising a plurality of LED light sources and a lens plate according to the first aspect, wherein the pitch of the plurality of lens elements of the lens plate matches the pitch of the plurality of LED light sources of the substrate.

[0017] Each lens element of the plurality of lens elements may include two protrusions that engage with corresponding notches in the substrate for positioning the lens plate on the substrate.

[0018] A third aspect of the invention relates to the use of a lens plate according to the first aspect with any one of at least two LED substrates with different LED pitches and / or different shapes.

[0019] According to a fourth aspect of the present invention there is provided a method for manufacturing an LED device comprising the steps of: providing a lens plate according to the first aspect; providing a substrate comprising a plurality of LED light sources; if necessary stretching and / or compressing the flexible connections by applying a force such that the pitch of the plurality of lens elements of the lens plate matches the pitch of the plurality of LED light sources of the substrate; and arranging the lens plate on the substrate.

[0020] It is to be noted that the invention relates to all possible combinations of the features recited in the claims. [Brief description of the drawings]

[0021] These and other aspects of the invention will now be described in more detail with reference to the accompanying drawings, in which embodiments of the invention are shown. [Figure 1] 2 is a top view of a lens plate according to an embodiment of the present invention, when no force is applied to the flexible connections of the lens plate; FIG. [Diagram 2] FIG. 2 is a side view of the lens plate of FIG. [Figure 3a] 2 is a top view of a lens plate according to an embodiment of the present invention, when no force is applied to the flexible connections of the lens plate; FIG. [Figure 3b]FIG. 3b is a top view of the lens plate of FIG. 3a, with the flexible connections of the lens plate stretched. [Figure 3c] FIG. 3b is an exploded perspective view of an LED device including the lens plate of FIG. 3a disposed on an LED substrate. [Figure 3d] FIG. 3c is an exploded perspective view of an LED device including the lens plate of FIG. 3b disposed on another LED substrate. [Figure 4a] 1 shows an alternative flexible connection. [Figure 4b] 1 shows an alternative flexible connection. [Figure 4c] 1 shows an alternative flexible connection. [Figure 4d] 1 shows an alternative flexible connection. [Diagram 5] FIG. 2 is a top view of the lens plate of FIG. 1 in a curved configuration. [Figure 6] 2 is a flowchart of a method according to an embodiment of the present invention.

[0022] Like numbers refer to like elements throughout. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The present invention will now be described in more detail below with reference to the accompanying drawings, in which presently preferred embodiments of the invention are shown. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are presented for the purposes of completeness and completeness, and will fully convey the scope of the invention to those skilled in the art.

[0024] 1 and 2 (and 3a) show a lens plate 10 according to an embodiment of the present invention.

[0025] The lens plate 10 comprises a number of lens elements 12a-12e. The lens elements 12a-12e may be (substantially) rigid. The lens elements 12a-12e are here arranged in a linear array. Each lens element 12a-12e comprises a lens portion 14 and a base portion 16. The lens portion 14 may be, for example, dome-shaped, but other shapes are also possible. Each lens portion 14 has an optical axis 18. In the case of non-imaging lens portions, the optical axis 18 may be interpreted as a line coinciding with the axis of the associated light-emitting diode (see, for example, the LED light source 104 described below), i.e. the light-emitting diode for which the lens portion is designed. The base portion 16 is here octagonal in a plane 20 perpendicular to the optical axis 18. Each two adjacent base portions 16, for example the base portions of lens elements 12a and 12b, may at least partially define two triangular or isosceles trapezoidal spaces 22a and 22b between the two base portions 16 pointing towards each other.

[0026] The lens plate 10 further includes flexible connections 24a-24d between each two consecutive lens elements 12a-12e, such as flexible connection 24a between lens elements 12a and 12b, flexible connection 24b between lens elements 12b and 12c, etc. The number of lens elements in the lens plate 10 may be N, and the number of flexible connections in the lens plate 10 may be N-1, where N is an integer, such as in the range of 2 to 200. An exemplary lens plate of about 2 feet may have, for example, 48 lens elements and 47 flexible connections. Another exemplary lens plate of about 1 foot may have, for example, 24 lens elements and 23 flexible connections. Each flexible connection 24a-24d allows adjustment of at least one of the distance and angle between the two lens elements 12a-12e, as will be further described below.

[0027] The lens elements 12a-12e and the flexible connections 24a-24d are made of the same material. That is, the lens plate 10 can be made of one material. The lens elements 12a-12e and the flexible connections 24a-24d can be made of an inelastic material. The lens elements 12a-12e and the flexible connections 24a-24d can be made of, for example, PC (polycarbonate) (which is an inelastic material). In another example, the lens elements 12a-12e and the flexible connections 24a-24d can be made of silicone. The flexible connections 24a-24d can be molded together with the lens elements 12a-12e, for example. Thus, the lens elements 12a-12e and the flexible connections 24a-24d of the lens plate 10 can be made in one piece. Furthermore, the lens elements 12a-12e and the flexible connections 24a-24d can be made in one manufacturing process, such as liquid silicone (LSR) injection or injection molding.

[0028] Each flexible connection 24a-d may have two V-shaped members 26a and 26b. The V-shaped members 26a and 26b lie in the plane 20. The V-shaped members 26a and 26b point (generally) towards each other. As can be seen especially in the enlarged portion of FIG. 1, one end 28a of each V-shaped member 26a, 26b is connected to one lens element 12a and the other end 28b of each V-shaped member 26a, 26b is connected to an adjacent lens element 12b. Specifically, the V-shaped members 26a, 26b may be accommodated in the aforementioned triangular or isosceles trapezoidal spaces 22a, 22b, with the ends 28a connected to the side surfaces 30a of the base 16 of the lens element 12a, which side surfaces 30a partially define the space 22a, and the ends 28b connected to the side surfaces 30b of the base 16 of the lens element 12b, which side surfaces 30b also partially define the space 22a. Exemplary dimensions (in mm) of the V-shaped members are shown in FIG.

[0029] In Fig. 4a to 4d, various alternative flexible connections are shown. In Fig. 4a, the flexible connection has a V-shaped member 26' that stands in a plane perpendicular to the plane 20. In Fig. 4b, the flexible connection has a V-shaped member 26'' that is in the plane 20 but points away from the opposite flexible connection member. Compared to Fig. 1, the V-shaped member 26'' can be made longer and therefore more flexible. In Fig. 4c, the flexible connection has a W-shaped member 26''' that can be in the plane 20. In Fig. 4d, the flexible connection has a Π-shaped member 26'''' ("three-sided rectangle") that can be in the plane 20 but points away from the opposite flexible connection member.

[0030] Returning to Fig. 1, when no force is applied to the flexible connections 24a-24d, a gap 32 may exist between each two consecutive lens elements, such as lens elements 12a and 12b. Specifically, the gap 32 may exist between a side 34a of the octagonal base 16 of one lens element 12a and an opposing (here parallel) side 34b of the octagonal base 16 of an adjacent lens element 12b. In particular, the side 34a is between a side 30a that partially defines the space 22a and a corresponding side 30'a that partially defines the space 22b.

[0031] As mentioned above, each flexible connection 24a-24d allows the distance between its two lens elements 12a-12e to be adjusted. Specifically, as shown in FIG. 3b, by stretching the flexible connection 24a-24d (by applying an external force F), the distance between the lens elements 12a-12e can be increased. That is, the pitch of the lens elements 12a-12e can be increased by, for example, P 11 =12mm to P 12 = 14mm, up to, for example, 40% larger. Note that the distance (pitch) between the lens elements is adjusted in plane 20, here along the linear direction of the linear array discussed above.

[0032] The lens plate 10 in the state shown in FIG. 3a is, as shown in FIG. 11 Pitch P is equal to 21 3b, the lens plate 10 may be disposed on a substrate 102 having a plurality of LED light sources 104 with a P 12 Equal to, a different (larger) LED pitch P 22 10, the lens plate 10 and the substrate 102' with the LED light sources 104' may form part of the LED device 100'. Thus, the lens plate 10 may be disposed on another substrate 102' with a different LED pitch P 21 and P 22 1, making the lens plate 10 universally applicable.

[0033] The substrate 102 (102') may be a printed circuit board. The substrate 102 (102') may be rectangular. The LED light sources 104 (104') may be attached to a surface of the substrate 102 (102'). The LED light sources 104 (104') may be arranged in a linear array. The number of the LED light sources 104 (104') may be N. The LED device 100 (100') may be a luminaire or form part of a luminaire.

[0034] Furthermore, each lens element 12a-12e of the lens plate 10 may include two protrusions 36a and 36b adapted to engage with corresponding notches 106a and 106b (106'a and 106'b) in the substrate 102 (102') for positioning the lens plate 10 on the substrate 102 (102'). Specifically, one protrusion 36a may be located on a lateral side 38a of the octagonal base 16, and the other protrusion 36b may be located on the opposite lateral side 38b. The corresponding notches 106a and 106b (106'a and 106'b) may be located on longitudinal edges 108a and 108b (108'a and 108'b) of the substrate 102 (102'). Such positioning solves the problem of thermal expansion affecting light distribution since the position of the lens element 16 relative to the LED light source 104 (104') on the substrate 102 (102') is stable.

[0035] Turning to FIG. 5, the lens plate 10 may also be arranged on a curved substrate 102″. Here, the linear array of lens elements 16 is curved (in the plane 20). This may be achieved by applying an external force such that only the V-shaped members 26b (or most of the V-shaped members 26b) on one side of the lens plate 10 are stretched, while the V-shaped members 26a on the other side of the lens plate 10 are (slightly) crushed, as shown in FIG. 5, the angle between every two consecutive lens elements is adjusted (compared to FIG. 1), as can be seen by the non-aligned dashed lines.

[0036] FIG. 6 is a flow chart of a method for manufacturing an LED device 100' according to an embodiment of the present invention.

[0037] The method comprises, at S1, providing a lens plate 10, for example as shown in Figures 1 and 3a.

[0038] In S2, substrates 102, 102' each having a plurality of LED light sources 104(104') are supplied.

[0039] The method, in S3, (optionally) stretches and / or compresses flexible connection parts 24a to 24d by applying a force F such that the pitch P of a plurality of lens elements 12a to 12e of a lens plate matches the pitch P of the plurality of LED light sources 104'. Here, step S3 need not be performed when the lens plate 10 is arranged on the substrate 102 as shown in FIGS. 1 and 3a, but it should be noted that it is actually performed when the lens plate 10 is arranged on the substrate 102'. 12 matches the pitch P of the plurality of LED light sources 104' 22 and / or compresses flexible connection parts 24a to 24d by applying a force F such that the pitch P of a plurality of lens elements 12a to 12e of a lens plate matches the pitch P of the plurality of LED light sources 104'. Here, step S3 need not be performed when the lens plate 10 is arranged on the substrate 102 as shown in FIGS. 1 and 3a, but it should be noted that it is actually performed when the lens plate 10 is arranged on the substrate 102'.

[0040] In S4, the lens plate 10 is arranged on the substrate 102(102'), for example, using the aforementioned protrusions / notches.

[0041] Those skilled in the art will understand that the present invention is by no means limited to the above preferred embodiments. On the contrary, many modifications and changes are possible within the scope of the appended claims. For example, in the embodiments shown in FIGS. 1, 2, and 3a, the gap 32 is relatively small, but if the gap is wider when no force is applied to the flexible connection part, the flexible connection part may (also) be compressed, making it possible to reduce the pitch of the lens elements.

[0042] Furthermore, those skilled in the art can understand and achieve variations to the disclosed embodiments from the study of the drawings, the description, and the appended claims in the implementation of the invention described in the claims. In the claims, the word "comprising" does not exclude other elements or steps, and the singular form does not exclude the plural. Merely the fact that certain specific means are recited in mutually different dependent claims does not indicate that these means cannot be used advantageously in combination.

Claims

1. 1. A lens plate for an LED device, the lens plate comprising: a plurality of lens elements, each having an optical axis, the lens elements being disposed in a plane perpendicular to the optical axis; and flexible connections between two consecutive lens elements of a further plurality of the lens elements, such that at least one of the distance and the angle between each of the two lens elements can be adjusted in the plane; each of the two lens elements and the flexible connection are made of the same material; A lens plate, the flexible connection being molded together with the two lens elements.

2. 2. The lens plate of claim 1, wherein the flexibility of the flexible connections is achieved by at least one of the shape, size, and location of the flexible connections.

3. 3. The lens plate of claim 1, wherein the flexible connection comprises two V-shaped members.

4. 4. The lens plate of claim 3, wherein the two lens elements each have a base portion, the two base portions at least partially define two triangular or isosceles trapezoidal spaces between the two base portions pointing toward each other, and each of the two triangular or isosceles trapezoidal spaces accommodates one of the two V-shaped members of the flexible connection portion.

5. 3. A lens plate according to claim 1 or 2, wherein a gap exists between the two lens elements when no force is applied to the flexible connection.

6. 3. The lens plate of claim 1 or 2, wherein each lens element of the plurality of lens elements includes two protrusions adapted to engage with a corresponding notch in an LED substrate of the LED device for positioning the lens plate on the LED substrate.

7. 3. The lens plate of claim 1, wherein the lens elements are arranged in a linear array.

8. The lens plate of claim 7 , wherein the linear array is curved in a plane perpendicular to the optical axis of the plurality of lens elements.

9. A substrate having a plurality of LED light sources; 9. An LED device comprising: a lens plate according to claim 1, wherein a pitch of the lens elements of the lens plate matches a pitch of the LED light sources of the substrate.

10. 10. The LED device of claim 9, wherein each lens element of the plurality of lens elements includes two protrusions that engage with a corresponding notch in the substrate for positioning the lens plate on the substrate.

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