Lens plates and lighting equipment with lens plates

Abstract

The lens plate has an array of convex lenses, each convex lens having a top portion forming a light input surface for facing a light source, and a base forming a light exit surface. Each convex lens has a height H and a diameter D at the base, where H / D > 0.85. The lens plate has, for example, a height in the range of 1.5 mm to 5 mm from the base to the top portion of the convex lens.

Description

Technical Field

[0001] The present invention relates to a lens plate as part of an illuminator, for example, a lens plate used to shape light output from an array of LEDs. Background Technology

[0002] It is desirable for some types of illuminators to produce uniform illumination, that is, a relatively constant light intensity above a region in the (horizontal) plane below the illuminator.

[0003] This requires the light output intensity to have a function of the emission angle, such that light from a large emission angle has a large light intensity (because it must travel further to the illuminated plane). An example of the desired light output intensity distribution is the so-called bat wing intensity distribution.

[0004] It is known to use lenses or lens plates to convert the output light intensity distribution from a light source (such as the Lambertian light intensity distribution of an LED light source) into a desired batwing intensity distribution.

[0005] Currently, concave and convex lenses have been used to generate large beam angles for this type of uniform illumination.

[0006] exist Figure 1 The image shows a typical concave and convex lens and its ray tracing diagram.

[0007] Figure 1 An LED source 10 with a lens 20 above its light output surface is shown. The lens 20 has a concave light-entry surface 22 and a convex light-exit surface 24. This type of lens is typically used where there is a one-to-one correspondence between the LED chip and the lens, or where an assembly of LED chips may be present below the lens. Without this correspondence between the lens and the LED, it is difficult to achieve the desired optical performance.

[0008] Figure 2 An alternative design for the lens plate 30 is shown, which is formed as an array of convex spherical microlenses 32. Due to the small size of the microlenses, this type of lens design can tolerate different alignments between the lens plate and the light source. It also achieves better color uniformity, but the output beam angle is not significantly different from the native light source.

[0009] Figure 2 The light traces for three LED light sources 10 are shown. It can be seen that the desired wide beam output is not achieved, and the output beam width matches the input beam width. The focal point FP1 of the microlens is on the side of the lens plate opposite the LED light source, at approximately the same distance from the lens surface as the LED light source.

[0010] There is still a need for a lens structure that is suitable for various types of LED light sources, is insensitive to the relative position of the light source and the lens structure, and achieves the desired wide beam output, such as the intensity distribution of a batwing. Summary of the Invention

[0011] This invention is defined by the claims.

[0012] According to an example of one aspect of the present invention, a lens plate is provided, the lens plate comprising:

[0013] An array of convex lenses, each convex lens having a top portion forming a light input surface for facing a light source, and having a substrate forming a light exit surface, wherein the substrate is positioned on or defines a common substrate for the array.

[0014] Each convex lens has a height H and a diameter D at the base, where H / D > 0.85. The lens plate, for example, has a height ranging from 1.5 mm to 5 mm from the base to the top portion of the convex lens. Preferably, the height H of the convex lens is in the range of 1 mm to 4 mm.

[0015] Due to the height-to-diameter ratio, the convex lenses of this lens plate have a tall and narrow bullet shape. Therefore, the convex lenses are aspherical and have very short focal lengths. For a lens plate with spherical lenses (i.e., with H / D = 0.5), the output beam angle is not significantly different from the light source beam (paraxial rays remain paraxial). A bullet-shaped lens with H / D > 0.85 causes the focal point to be located inside the lens body, which means that the divergence of paraxial rays is very pronounced. Off-axis rays also remain off-axis, resulting in batwing light output intensity that can be obtained from the Lambertian output of the LED light source.

[0016] Lens plates make the light output characteristics insensitive to the position of the lens plate above the light source (e.g., an LED array). The same lens structure can also be used for different light source designs.

[0017] Preferably, each convex lens has a focal point between its top portion and the substrate. The top portion of each lens thus focuses to a focal point with a very short focal length, such that the focal point is within the lens body. This provides a large convergence angle and therefore provides divergence after the focal point, meaning that off-axis rays are emitted from the substrate at large angles.

[0018] The lens plate may also include microstructures formed in the central region of each top portion.

[0019] The array of convex lenses and microstructures each further disperses the light emitted from the light source. The central microstructure on the convex top portion of each lens diffuses small-angle light rays from the light source.

[0020] Preferably, each microstructure is diffuse or scattering. This provides the desired dispersion of small-angle light from the light source.

[0021] Each microstructure may include:

[0022] An array of microlenses; or

[0023] relief pattern; or

[0024] Device for embedding particles.

[0025] Therefore, there are various possible designs for microstructures.

[0026] Preferably, the base of each convex lens and the common substrate are flat. Therefore, in this case, the optical function is entirely defined by the top side facing the light source, and the lens plate is simple to manufacture, with no alignment requirements between the top and bottom surfaces.

[0027] For example, the top portion of each convex lens forms a protrusion that is rotationally symmetrical about the optical axis.

[0028] Preferably, the lenses in the array of convex lenses completely occupy the effective area of ​​the lens plate. By filling the effective area of ​​the lens plate, all the light to be processed passes through the lenses. The effective area is the region of the lens plate designed for beam shaping of the light output from the light source.

[0029] For example, the lens has a pitch ranging from 0.5 mm to 5 mm. This provides a small lens pitch, which helps to make the light output insensitive to the alignment between the lens plate and the light source.

[0030] Preferably, the bases of the convex lenses are merged together. The merged lens bases allow the effective area of ​​the lens plate to be completely covered as described above, and achieve a small-pitch array in the top portion.

[0031] Each convex lens may have a cross-sectional profile, which includes:

[0032] Elliptical line;

[0033] Bézier curve;

[0034] Parabola; or

[0035] Polynomial aspherical curves.

[0036] Preferably, the lens plate includes a molded component.

[0037] The present invention also provides a lighting device, the lighting device comprising:

[0038] LED arrays; and

[0039] The lens plate is defined above, wherein the light output surface of each LED in the LED array faces the top portion of the convex lens of the lens plate.

[0040] For example, an LED array has a pitch between 0.5 mm and 3 mm between the LEDs.

[0041] The distance between the light output surface of the LED and the top portion of the convex lens along the optical axis is, for example, in the range of 3mm to 7mm. This spacing allows for compliance with thermal conditions.

[0042] When the lens plate includes microstructures formed in the central region of each top portion (as described above), the microstructures can extend over a region along the optical axis of the associated convex lens, the angle between the point on the plane of the LED output surface that the region subtends is in the range of 10 to 15 degrees.

[0043] When the incident angle is greater than half of that angle (e.g., 12 degrees), the angle of departure of the light will increase dramatically. Incident light from an adjacent LED will strike the side of the convex lens furthest from the microstructure (again, where the incident angle is greater than half of that angle), and this will result in a departure angle of, for example, 60 to 80 degrees.

[0044] The lighting equipment can meet the following requirements:

[0045] Less than 15% of the light from the LED array is emitted at an angle ranging from 0 to 30 degrees;

[0046] More than 70% of the light from the LED array is emitted at an angle ranging from 30 to 70 degrees; and

[0047] 5% to 20% of the light from the LED is emitted at an angle ranging from 70 to 90 degrees.

[0048] Therefore, the light output distribution is shaped like a bat's wing, with the maximum light intensity ranging from 30 to 60 degrees.

[0049] These and other aspects of the invention will become apparent and elucidated with reference to the embodiments described below. Attached Figure Description

[0050] To better understand the invention, and to more clearly illustrate how the invention can be practiced, reference will now be made to the accompanying drawings by way of example only, wherein:

[0051] Figure 1 A typical concave-convex lens and ray tracing diagram are shown;

[0052] Figure 2An alternative design for a lens plate is shown, which is formed as an array of convex spherical microlenses;

[0053] Figure 3 A lens plate according to an example of the present invention is shown;

[0054] Figure 4 It shows the relationship with Figure 3 The same lens plate, but showing light rays passing through other parts of the convex lens;

[0055] Figure 5 The optical performance of a convex lens design without microstructures for small-angle incident beams is shown.

[0056] Figure 6 The optical performance of a convex lens design without microstructures for large-angle incident beams is shown.

[0057] Figure 7 This demonstrates how input light with an even larger angle of incidence from the light source to the lens plate can be converted again into output light with a larger beam angle;

[0058] Figure 8 Used to explain possible designs for convex lenses;

[0059] Figure 9 An example of an LED array consisting of concentric rings of LEDs is shown;

[0060] Figure 10 An example of a convex lens array comprising a square grid of lenses is shown;

[0061] Figure 11 A perspective view of the top surface of the lens plate is shown; and

[0062] Figure 12 The simulation of the performance of a lens plate provided on an array of medium-power LEDs is shown as an intensity polar plot. Detailed Implementation

[0063] The invention will be described with reference to the accompanying drawings.

[0064] It should be understood that while the detailed description and specific examples indicate exemplary embodiments of the apparatus, system, and method, they are intended for illustrative purposes only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, system, and method of the present invention will become better understood from the following description, the appended claims, and the accompanying drawings. It should be understood that the drawings are merely schematic and not drawn to scale. It should also be understood that the same reference numerals are used throughout the drawings to indicate the same or similar parts.

[0065] The present invention provides a lens plate having an array of convex lenses, each convex lens having a top portion forming a light input surface for facing a light source, and a base forming a light output surface. Each convex lens has a height H and a diameter D at the base, wherein H / D > 0.85.

[0066] Figure 3 A lens plate 40 according to an example of the present invention is shown. The lens plate includes an array 42 of convex lenses 44. Each convex lens 44 has a top portion 44a forming a light input surface facing a light source, and a substrate 44b forming a light output surface. The substrate is flat and is mounted on or integrally formed with a common flat substrate 48. The light source is an array of LEDs 10, and the light output surface of each LED in the LED array faces the top portion 44a of the convex lens of the lens plate.

[0067] Therefore, the convex lenses have a beam-shaping surface only on one side (the side facing the light source 10), making them easy to manufacture, for example, by injection molding. The convex lenses have aspherical surfaces. In particular, the curvature of the top portion 44a corresponds to a shape having a height H and a diameter D at the base, where H / D > 0.85.

[0068] like Figure 3 As shown, and discussed in more detail below, convex lenses can be joined together at their bases. In this case, the diameter D will be defined by extrapolation of the remaining convex lens surface area. Alternatively, the convex lenses can be separated from each other (spaced apart or tangentially in contact), in which case the diameter is the actual diameter at the base. When individual lenses are separated, they preferably have a spacing of less than 0.1 mm to minimize the size of the flat gap between the lenses.

[0069] Extrapolation will involve a smooth extension of the remaining convex lens surface region (i.e., the top portion 44a of the lens). Curve extrapolation methods for deriving the approximate overall shape of the convex lens from the top portion 44a are well known. Based on this extrapolation, the diameter D can be defined.

[0070] Extrapolation takes into account the type of lens shape. For example, the cross-sectional curve of a convex lens might include:

[0071] Elliptical line;

[0072] Bézier curve;

[0073] Parabola; or

[0074] Polynomial aspherical curves.

[0075] For these lens shapes, the generatrix is ​​a parabola, a Bézier curve, an arc, a hyperbola, or a combination thereof.

[0076] When the bases of the lenses are joined together, the convex lenses in the array of convex lenses completely occupy the effective area of ​​the lens plate. Specifically, the bases of the lenses are joined together to define a solid plate without gaps. This avoids the gaps between lenses that would otherwise act as flat plates. Furthermore, the joined bases mean there are no vertical cylindrical sidewalls of the lenses, and these vertical sidewalls are not what is expected for the desired light deflection. The convex lenses, for example, form a square grid. The top portion of each convex lens forms a projection that is rotationally symmetrical about the optical axis of the lens, and this projection extends from the joined bases toward the light source.

[0077] The lens can instead be formed as a hexagonal grid.

[0078] Due to the ratio of height to diameter, a convex lens is both tall and narrow. Consequently, a convex lens has a very short focal length, specifically, where the focal point is located inside the lens body. This means that paraxial rays diverge very significantly, such as... Figure 3 The light rays in the image are shown.

[0079] By keeping the off-axis light rays off-axis, it is possible to obtain batwing output intensity from the Lambertian output of the LED light source.

[0080] Figure 3 Optional additional design features of microstructure 46 are shown, which is formed in the central region of each top portion 44a. Each microstructure 46 is diffuse or scattering. Any suitable structure can be used, such as an array of microlenses, an embossed pattern, or a device for embedding particles.

[0081] Both the convex lens design and the microstructure enhance the diffusion of light emitted from the light source. The microstructure diffuses small-angle light rays from the light source 10, while other portions of the convex surface of the lens control large-angle light rays to achieve the desired target wide angle. This structure thus enhances large-angle light rays from the light source 10 and attenuates small-angle light rays from the center of the light source 10.

[0082] The total height of the entire lens plate (H and the thickness of the substrate 48) is, for example, in the range of 1.5 mm to 5 mm, such as approximately 3 mm. Preferably, the height H of the convex lens is in the range of 1 mm to 4 mm. The vertical distance d between the LED light source 10 and the top of the convex lens 44 is, for example, in the range of 3 mm to 7 mm, such as approximately 5 mm. This is beneficial for meeting the thermal conditions of the lens.

[0083] Figure 3This schematic illustrates that the LED pitch does not need to be the same as the convex lens pitch. In practice, the lens plate can be used with different light source devices (with different LED pitches), and the relative alignment between the lens plate and the light source is not important.

[0084] Figure 3 The diagram illustrates light rays passing through a region of microstructure. It shows how light rays are focused within the body of a convex lens (regardless of the presence of microstructure), causing the light to exit the lens at a wide beam angle. Therefore, small-angle rays are refracted to form large-angle rays.

[0085] Figure 4 The same lens plate is shown, but light rays passing through other parts of the convex lens are illustrated. This applies to light from a light source that already has a large ray angle (relative to the normal, optical axis). These large-angle rays are also refracted to form an even larger beam angle.

[0086] Therefore, this structure achieves a wide beam angle light distribution suitable for uniform illumination.

[0087] Figures 5 to 7 The optical performance of a convex lens design without microstructures is shown.

[0088] Figure 5 The diagram illustrates how input light from a light source (with three different incident beam angles, but centered on the optical axis) is converted into output light with a larger beam angle in each case in the same manner as described above.

[0089] Figure 5 The design of the convex lens is shown such that the focal point FP2 is within the lens body, meaning the distance between the focal point FP2 and the lens surface along the optical axis is less than the lens height. Therefore, the focal point is within the lens plate. The lens focal point is defined based on the incident parallel beam of light, but the relatively large spacing to the display panel means that light from each LED 10 (considered a point light source) will also be focused at the focal point within the lens body. This is consistent with... Figure 2 This contrasts with conventional lens designs, where the focal point FP1 is below the lens plate and outside the lens body. As described above, the lens design of this invention provides significant divergence of paraxial rays. Light converges before the focal point and then diverges after it. The short focal length provided by the convex lens of this invention results in greater deflection of paraxial rays.

[0090] Figure 6 This demonstrates how input light with a large incident angle from the light source to the lens plate can be converted again into output light with a larger beam angle in the same manner as described above.

[0091] Figure 7This illustrates how input light with an even larger angle of incidence from the light source to the lens plate can be converted again into output light with a larger beam angle, and this can then lead to some total internal reflection from the bottom surface of the substrate, as shown.

[0092] Figure 8 This is used to explain the possible designs of the convex lens and to illustrate more clearly the dimensions D, H, and d discussed above.

[0093] Furthermore, the optical axis of the light emitted from the light output surface 10a of the light source 10 is shown.

[0094] The microstructure extends over the region that, with respect to the optical axis, is half the angle (θ) of the plane opening from the output surface 10a of the LED10, which is between 10 and 15 degrees.

[0095] When the incident light is at an angle greater than half of that angle (e.g., 12 degrees), the angle of the light rays exiting from the base of the lens will increase dramatically, for example, causing the angle between the exiting light rays and the optical axis to be in the range of 60 to 80 degrees.

[0096] For illumination with a Lambertian intensity distribution of an LED array, the resulting optical properties, for example, result in:

[0097] Less than 15% of the light from the LED array is emitted at an angle ranging from 0 to 30 degrees;

[0098] More than 70% of the light from the LED array is emitted at an angle ranging from 30 to 70 degrees; and

[0099] 5% to 20% of the light from the LED is emitted at an angle ranging from 70 to 90 degrees.

[0100] Figure 9 An example of an LED array comprising concentric rings of LEDs 10 is shown. For example, the spacing between the LEDs is approximately 1 mm in both the width and height directions to provide thermal separation.

[0101] Figure 10 An example of an array of convex lenses, including a square grid of lenses 40, is shown. Therefore, the lens array of the lens plate does not need to be designed to match the design of the LED array, and the same lens plate can be used with different light sources.

[0102] The pitch of the LED array and the lens plate does not need to be matched, and the alignment between them is not important.

[0103] For example, the lenses in an array of convex lenses have a pitch in the range of 0.5 mm to 5 mm and a base diameter D in the range of 0.5 mm to 5 mm. For example, an LED array has a pitch in the range of 0.5 mm to 3 mm.

[0104] Therefore, lens plates are suitable for a wide range of possible LED configurations. Many convex lenses exist due to their small pitch and the way they merge at their base to fill the effective area.

[0105] Figure 11 A perspective view of the top surface of the lens plate 40 is shown. It shows a square grid structure with microstructures 46 on the top portion of the convex lens.

[0106] Figure 12 A simulation of the performance of a lens plate provided on top of an array of medium-power LEDs is shown, along with an intensity polar plot. It illustrates the desired batwing intensity distribution that can be achieved.

[0107] The microstructure is optional. In the example above, it is provided on the top surface of each convex lens. However, alternatively, the microstructure can be present on a common substrate, or it can be present on both surfaces.

[0108] By studying the accompanying drawings, the disclosure, and the appended claims, those skilled in the art can understand and implement variations of the disclosed embodiments when practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality.

[0109] The simple fact that certain measures are recorded in mutually different dependent claims does not indicate that a combination of these measures cannot be used advantageously.

[0110] If the term “suitable” is used in the claims or specification, it should be noted that the term “suitable” is intended to be equivalent to the term “configured as”.

[0111] Any reference numerals in the claims should not be construed as limiting the scope.

Claims

1. A lighting device, comprising: An array of LEDs (10); as well as Lens plate, including: An array (42) of convex lenses (44), each convex lens (44) having a top portion (44a) forming a light input surface for facing a light source, and having a substrate (44b) forming a light output surface, wherein the substrate is positioned on or defines a common substrate (48) of the array. Each convex lens has a diameter D at the base and a height H from the base to its top portion, wherein H / D > 0.85; wherein the height H is in the range of 1 mm to 4 mm, and each convex lens has a cross-sectional curve, the cross-sectional curve including an ellipse, a Bézier curve, a parabola, or a polynomial aspherical curve; Wherein, when the convex lenses are separated from each other, the diameter D is the actual diameter at the base, and when the convex lenses are joined together at their bases, the diameter D is defined by extrapolation of the surface area of ​​the remaining convex lenses; The light output surface (10a) of each LED (10) in the LED array faces the top portion (44a) of the convex lens of the lens plate. in: The array of LEDs has a pitch between the LEDs (10) in the range of 0.5 mm to 3 mm; and / or the distance (d) along the optical axis (12) between the light output surface (10a) of the LED (10) and the top portion of the convex lens is in the range of 3 mm to 7 mm.

2. The lighting device of claim 1, wherein each convex lens has a focal point between the top portion and the substrate.

3. The lighting device according to claim 1 or 2, wherein the lens plate has a thickness in the range of 1.5 mm to 5 mm, wherein the thickness of the lens plate includes the height H of the convex lens and the thickness of the substrate (48).

4. The lighting device according to claim 1 or 2 further includes a microstructure (46) formed in the central region of each top portion (44a).

5. The lighting device according to claim 4, wherein each microstructure is diffuse or scattering.

6. The lighting device according to claim 5, wherein each microstructure comprises: An array of microlenses; or Relief pattern; or Device for embedding particles.

7. The lighting device according to claim 1 or 2, wherein the substrate of each convex lens and the common substrate are flat.

8. The lighting device according to claim 1 or 2, wherein the top portion of each convex lens forms a protrusion that is rotationally symmetrical about the optical axis.

9. The lighting device according to claim 1 or 2, wherein the lenses in the array of convex lenses completely occupy the effective area of ​​the lens plate, and the lenses have a pitch in the range of 0.5 mm to 5 mm; wherein the effective area is the area of ​​the lens plate intended for beam shaping of light output from the light source.

10. The lighting device according to claim 1 or 2, wherein the base (44b) of the convex lens is joined together.

11. The lighting device according to claim 1 or 2, wherein the lens plate includes a microstructure (46) formed at a central region of each top portion (44a), wherein the microstructure (46) extends over the region along the optical axis (12) of the associated convex lens (44), and half of the angle (θ) at which the region faces a point on the plane of the output surface (10a) of the LED (30) is in the range of 10 to 15 degrees.

12. The lighting device according to claim 1 or 2, wherein: Less than 15% of the light from the array of said LEDs is emitted at an angle ranging from 0 to 30 degrees; More than 70% of the light from the array of LEDs is emitted at an angle in the range of 30 to 70 degrees; and 5% to 20% of the light from the LED is emitted at an angle in the range of 70 to 90 degrees.

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