Lens and lighting device

Abstract

To provide a lens capable of evenly emitting light in a lateral direction orthogonal to a front direction without causing light leakage in the front direction, based on the shape or the like of an incident surface and an emission surface for light emitted from a light source.SOLUTION: A cylindrical lens 10 is arranged on a light-emitting surface 3a side of a light-emitting device 2. A lower part of the lens 10 is provided with: a cavity part 16 covering the light-emitting surface 3a and having a lateral incident surface 17 and an upper incident surface 18; and an uneven surface part 14a formed on an outer surface of the lower part of the lens 10 corresponding to the lateral incident surface 17. An upper part of the lens 10 is provided with a recess part 19 with an inverted conical inclination surface 19a corresponding to the upper incident surface 18 of the cavity part 16, and a vertical flat surface portion 15a formed on an outer surface of the upper part of the lens 10.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a lens and a lighting device that deflect and emit the light emitted from an LED light source in a lateral direction.

Background Art

[0002] An LED light source has a characteristic that its light emission distribution has directivity and emits strong light in the front direction. Conventionally, as a lighting device that emits light laterally using an LED light source, there is known one that covers the LED light source with a lens and deflects it in a lateral direction orthogonal to the front direction by utilizing the reflection of the lens.

[0003] Patent Document 1 discloses a lighting device including a lens that refracts the light emitted from a light source in a lateral direction. This lighting device includes a light source and a lens disposed so as to cover this light source. The lens is formed by a lower lens portion having an outer peripheral surface processed in a saw blade shape and an upper lens portion having a reflection surface in a bellows shape on the upper part of the lower lens portion, and has a structure that refracts the light emitted upward from the light source by the outer peripheral surface of the lower lens portion and the reflection surface of the upper lens portion and emits it in a lateral direction.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the lighting device described in the above Patent Document 1, the light emitted from the light source at a predetermined angle is set to be refracted or reflected laterally directly by the saw blade surface or the reflecting surface. However, the interior of the lens from the light source to the saw blade-shaped outer peripheral surface and the upper reflecting surface, as well as the shape and size of the saw blade, are not considered. For this reason, it is actually difficult to emit the light laterally at an ideal angle as shown in the figure for all emission directions. Further, since the outer shapes of the saw blade-shaped outer peripheral surface and the upper reflecting surface are different, there is a possibility that variations in the emission intensity may occur.

[0006] Therefore, an object of the present invention is to provide a lens and a lighting device that can evenly emit light in a lateral direction orthogonal to the front direction without causing light leakage in the front direction based on the shape of the incident surface and the emission surface of the light emitted from the light source.

Means for Solving the Problems

[0007] The present invention is a cylindrical lens disposed on the light emitting surface side of a light source, a cavity portion that covers the light emitting surface of the light source and has a side incident surface and an upper incident surface, and an uneven surface portion formed on the lower outer peripheral surface of the lens corresponding to the side incident surface are provided at the lower part of the lens, a concave portion having an inverted conical inclined surface corresponding to the upper incident surface of the cavity portion, and a vertical flat surface portion formed on the upper outer peripheral surface of the lens are provided at the upper part of the lens.

Effects of the Invention

[0008] According to the present invention, among the light emitted from the light source, the light incident on the side incident surface can be refracted laterally by the uneven surface portion formed on the outer peripheral surface of the lower part of the lens by the cavity portion provided in the lower part of the lens. Further, the light incident on the side incident surface of the cavity portion can be reflected by the conical inclined surface of the upper part of the lens and emitted laterally from the vertical flat surface portion. As a result, the side can be uniformly irradiated without light leakage above the cylindrical lens, and further, the size can be made more compact.

Brief Description of the Drawings

[0009]

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Mode for Carrying Out the Invention

[0010] Hereinafter, the lens and the lighting device of the present invention will be described based on each embodiment with reference to the drawings. The drawings are schematic representations, and the actual dimensions and dimensional ratios thereof do not necessarily match the dimensions and dimensional ratios shown in the drawings. Also, for convenience in this specification, the directions such as up and down, left and right are represented based on the orientation of the light-emitting unit shown in FIG. 2, and the upward direction is taken as the front direction of light emission. Furthermore, redundant descriptions will be omitted as appropriate, and the same members may be denoted by the same reference numerals.

[0011] FIGS. 1 and 2 show the external shape and the cross-sectional structure of the light-emitting unit 1 using the lens 10 of the first embodiment of the present invention. The light-emitting unit 1 includes a columnar lens 10 and a light-emitting device 2 on which the lens 10 is placed. As shown in FIG. 2, the light-emitting device 2 is a COB (Chip On Board) type LED (Light Emitting Diode) light-emitting device in which a light-emitting portion 3 is arranged at the center of the upper surface of a substrate 4, and the lens 10 is arranged so as to surround the light-emitting portion 3. The light-emitting portion 3 of the light-emitting device 2 is also referred to as a light source.

[0012] The lens 10 is formed of a transparent resin and is composed of a lower lens 11 and an upper lens 12 provided on the upper side of the lower lens 11. The lower lens 11 has a lower outer peripheral surface 14 on the outer periphery, and the upper lens 12 has an upper outer peripheral surface 15 on the outer periphery. An uneven surface portion 14a is formed on the lower outer peripheral surface 14. The uneven surface portion 14a is a cylindrical surface with a sawtooth cross-section in which a plurality of convex portions 13 having an annular upper surface 13a and a lower surface 13b are formed concentrically along the height direction. Between one convex portion 13 and another convex portion 13 adjacent to the upper side of the one convex portion 13, the lower surface 13b of the other convex portion 13 and the upper surface 13a of the one convex portion 13 are in contact with each other at a valley portion 20, and in the one convex portion 13, the upper surface 13a and the lower surface 13b are in contact with each other at a peak portion 21. The upper outer peripheral surface 15 has a flat surface portion 15a and a gradient surface portion 15b provided below the flat surface portion 15a. The flat surface portion 15a is a cylindrical surface perpendicular to the upper surface of the substrate 4 and having a flat cross-section, and the gradient surface portion 15b is a cylindrical surface that slopes downward and inward from the lowermost end of the flat surface portion 15a. The refractive index of the transparent resin forming the lens 10 is preferably 1.3 or more and 1.6 or less. Further, the inside of the lower lens 11 is a frustum-shaped cavity portion 16 having a flat upper surface. The side and upper sides of this cavity portion 16 are a side incident surface 17 and an upper incident surface 18 on which light emitted from the light emitting surface 3a of the light emitting portion 3 at a predetermined emission angle is incident, respectively. The light incident on the side incident surface 17 is refracted by the convex portion 13 at a height corresponding to the incident angle and is emitted in a horizontal direction toward the outside of the uneven surface portion 14a. The height of the upper end of the uneven surface portion 14a is at least equal to or higher than the height of the upper incident surface 18 of the lower lens 11. The height of the lower end of the uneven surface portion 14a is preferably lower than the height of the upper end of the light emitting portion 3. The convex portions 13 are continuously formed from the upper end to the lower end of the uneven surface portion 14a. Further, a non-uneven surface portion where no convex portion 13 is formed may be formed below the lower end of the uneven surface portion 14a of the lower outer peripheral surface 14. Note that the uneven surface portion 14a is not limited to a sawtooth shape, and may be, for example, a wavy shape or a Fresnel lens surface.

[0013] The upper lens 12 has a concave portion 19 with an internally inverted conical inclination. The light incident on the upper incident surface 18 of the cavity 16 is reflected at a predetermined lower position along the flat inclined surface 19a of the concave portion 19 and is emitted laterally from the flat surface portion 15a. Also, the lowermost end of the gradient surface portion 15b of the upper lens 12 is connected to the upper surface 13a of the convex portion 13 at the uppermost end of the lower lens 11.

[0014] The upper surface of the light emitting portion 3 is a light emitting surface 3a. The light emitted around the optical axis Oa of this light emitting surface 3a is evenly irradiated into the cavity 16. The lower lens 11 and the upper lens 12 are formed in a rotationally symmetric shape around the optical axis Oa, and the light emitted to the side of the lens 10 is evenly emitted in a 360° plane direction around the optical axis Oa.

[0015] The lateral incident surface 17 of the cavity 16 of the lower lens 11 has a taper with a taper angle (the taper angle) α such that it is slightly inclined inward upward. The taper angle α is preferably ideally 0°. However, when molding the lower lens 11 including the cavity 16 using a mold, a taper required for mold release is necessary. The uneven surface portion 14a composed of a plurality of convex portions 13 is formed using a mold in which a plurality of saw blade patterns are formed, similarly to the cavity 16.

[0016] Figure 3 schematically shows the traveling direction of light in the light-emitting unit 1. In the following description, the direction of the light indicated by the arrow line shows a cross-section of the lens 10, and it is the same for any cross-section of the entire circumference of the lens 10. Also, the light emission angles shown below are exemplary values, and in practice, some errors are taken into account. Among the light emitted from the light-emitting portion 3, the light incident on the side incident surface 17 is within the first emission angle range (30° to 90°) with respect to the optical axis Oa. To deflect all the light in this range laterally, it is necessary to set the refraction of the light near 30° to be the largest and the refraction of the light near 90° to be the smallest. For this reason, the convex portions 13 are formed such that the cross-sectional shape of a saw blade gradually increases upward from the lower end of the concavo-convex surface portion 14a of the lower lens 11. As a result, among the plurality of convex portions 13, the uppermost convex portion 13H is the largest and has an acute angle, while the lowermost convex portion 13L is the smallest and has an obtuse angle.

[0017] The diameter of the concavo-convex surface portion 14a is uniform in the height direction, and the diameter is defined by the distance to the tip of the peak portion 21 of each convex portion 13. For this reason, the depth to the tip of the valley portion 20 of the convex portion 13 gradually increases from the bottom surface side toward the upper surface side. Also, the diameter of the flat surface portion 15a of the upper lens 12 is the same as the diameter of the concavo-convex surface portion 14a.

[0018] As shown in Fig. 4(a), when the flat surface portion 15a of the upper lens 12 is inclined inward downward with respect to the shape indicated by the virtual line C, the inclination angle of the inclined surface 19a of the concave portion 19 becomes smaller. For this reason, as shown by the arrow line B, there may be a case where light leaks in the front direction by refracting upward at the inclined surface 19a. Also, as shown in Fig. 4(b), when the flat surface portion 15a is inclined outward downward with respect to the shape indicated by the virtual line C, the inclination angle of the inclined surface 19a of the concave portion 19 becomes larger. For this reason, if designed so that light does not leak in the front direction, a part of the flat surface portion 15a will protrude outward from the concavo-convex surface portion 14a. For this reason, in order to prevent light leakage in the front direction, emit light evenly in the lateral direction, and further achieve compactness, as shown in Figs. 2 and 3, the flat surface portion 15a preferably extends along the vertical direction.

[0019] A representative emission direction of the light emitted from the light-emitting unit 3 will be described with reference to FIG. 3. The light emitted within the first emission angle range θA (30° to 90°) with respect to the optical axis Oa enters the side incident surface 17, is refracted by the plurality of convex portions 13, and is emitted in the lateral direction (horizontal direction) indicated by the arrow A. On the other hand, the light emitted within the second emission angle range θB (0° to 30°) with respect to the optical axis Oa enters the upper incident surface 18 of the cavity portion 16, is reflected at a predetermined lower position along the inclined surface 19a of the concave portion 19 of the upper lens 12, and then is emitted in the lateral direction indicated by the arrow B from the flat surface portion 15a. FIG. 5 shows the light distribution characteristics of the lens 10. It is shown that although there is light emission on the upper surface side near the optical axis Oa, all other light emissions are directed in the lateral direction (horizontal direction).

[0020] It is preferable that the lowest end position P2 of the inclined surface 19a of the concave portion 19 of the upper lens 12 is located above the lowest end position P1 of the flat surface portion 15a of the upper lens 12. As shown in FIG. 6, when the lowest end position P2 of the concave portion 19 of the upper lens 12 reaches below the lowest end position P1 of the flat surface portion 15a of the upper lens 12, the light incident on the lower lens 11 from the upper incident surface 18 of the cavity portion 16 of the lower lens 11 passes through the upper lens 12 and is reflected laterally by the inclined surface 19a. Then, since the laterally reflected light hits the gradient surface portion 15b of the upper lens 12 or the uppermost convex portion 13H of the lower lens 11, as shown by the arrow B, it may be irregularly emitted, refracted, or totally reflected upward or downward. To avoid such problems, as shown in FIGS. 2 and 3, it is desirable that the concave portion 19 of the upper lens 12 is formed such that the lowest end position P2 of the inclined surface 19a is located at the same level as or above the lowest end position P1 of the flat surface portion 15a. For this reason, a planar flat surface portion 19b may be formed at the lowest end position P2 of the inclined surface 19a.

[0021] Next, a first design example of the lower lens 11 will be described with reference to FIG. 7. FIG. 7 is a cross-sectional view of the lens of the first embodiment with a part of the upper lens 12 omitted, and shows a case where a part of the light emitted from the center O of the light emitting surface 3a is incident on the upper end portion 17a of the lateral incident surface 17 with an inclination angle α. The upper surface 13Ha of the convex portion 13H at the uppermost end of the concavo-convex portion 14a is set horizontally. The light incident on the upper end portion 17a is refracted, directed toward the upper surface 13Ha, and incident on the upper surface 13Ha at the critical angle, so that it is refracted at the upper surface 13Ha and designed to be emitted laterally (horizontally) from the lens 10. The arrow line L1 shows the optical path of a part of the light emitted from the center O of the light emitting surface 3a and emitted laterally (horizontally) from the lens 10 according to this design example. At this time, assuming that the height of the optical path L1 of the light emitted starting from the light emitting surface 3a is T1, the condition for the height T of the concavo-convex portion 14a is that T = T1 is satisfied.

[0022] If the upper surface 13Ha of the convex portion 13H at the uppermost end of the concavo-convex portion 14a is inclined upward from the inside to the outside of the lens 10, light may leak in the front direction. In order to reduce light leakage in the front direction, it is preferable that the upper surface 13Ha of the convex portion 13H at the uppermost end of the concavo-convex portion 14a is horizontal or inclined downward from the inside to the outside of the lens 10. In order to make the upper surface 13Ha horizontal or inclined downward from the inside to the outside of the lens 10, the condition for the height T of the concavo-convex portion 14a when starting from the light emitting surface 3a is that T ≦ T1 is satisfied.

[0023] Next, a second design example of the lower lens 11 will be described with reference to FIG. 8. FIG. 8 is a cross-sectional view showing the second design example of the lens. As shown in FIG. 8, assuming that the distance from the optical axis Oa when the light emitted from the center O of the light emitting surface 3a and incident from the end portion 18a of the upper incident surface 18 of the cavity portion 16 is emitted laterally from the upper end 19c of the concave portion 19 of the upper lens 12 is r, the maximum radius R in the plan view of the lower lens 11 is set to R ≧ r.

[0024] If the height of the uneven face portion 14a is set low as shown in FIG. 9(a), the upper incident surface 18 of the cavity portion 16 becomes wider than the side incident surface 17, so that more light is incident on the upper incident surface 18. As a result, as indicated by the arrow B, when the light refracted upward by the inclined surface 19a of the upper lens 12 is not effectively emitted laterally, or when it does not reach the inclined surface 19a and is reflected inward by the flat face portion 15a and is not effectively emitted laterally. On the other hand, if the height of the uneven face portion 14a is set high as shown in FIG. 9(b), the side incident surface 17 of the cavity portion 16 becomes wider than the upper incident surface 18, so that more light is incident on the side incident surface 17. As a result, as indicated by the arrow B, after the light emitted from the light emitting portion 3 is incident on the side incident surface 17 of the cavity portion 16, it may not be refracted laterally even when it reaches the uneven face portion 14a. Note that the height of the uneven face portion 14a of the lower lens 11 is preferably 1.7 times or more and 2.4 times or less the height of the upper outer peripheral surface 15 of the upper lens 12.

[0025] Further, in the uneven face portion 14a, the valley portion 20 corresponding to the peak portion 21 of the convex portion 13 becomes deeper as it goes upward, but it is necessary to make the diameter of the uneven face portion 14a uniform in the height direction while ensuring a certain thickness from the cavity portion 13. In order to satisfy such conditions, the taper angle α is preferably 15° or less with respect to the vertical direction.

[0026] FIG. 10 shows a second light emitting unit 1a including a lens 10a of the second embodiment. The lens 10a is composed of a second lower lens 11a having a second cavity portion 26 obtained by deforming a part of the cavity portion 16 of the lower lens 11 of the first embodiment, and an upper lens 12 common to the first embodiment. The cavity portion 26 of the present embodiment has a downward protruding portion 24 with a V-shaped cross section whose upper surface protrudes downward in a conical shape, and the inclined surface of the downward inclined protruding portion 24 serves as an upper incident surface 28 for refracting light toward the upper lens 12. Note that the lower outer peripheral surface 14 is common to the lower lens 11 of the first embodiment, and the refraction action of light on the side incident surface 17 is also common, so detailed description thereof is omitted here.

[0027] As shown in FIG. 10, when the upper surface of the cavity 26 is flat as indicated by the broken line, the light emitted from the outer peripheral portion of the light emitting surface 3a of the light emitting unit 3 across the cavity 26 may be reflected inward and deviate from the inclined surface 19a of the upper lens 12 and leak in the front direction as indicated by the arrow B1. On the other hand, in the present embodiment, the light emitted from the outer peripheral portion of the light emitting surface 3a of the light emitting unit 3 can be refracted at the upper end of the inclined surface 19a and then emitted toward the flat surface portion 15a as indicated by the arrow B2. As a result, the light incident on the upper incident surface 28 of the lower lens 11a can be reflected on the lower side along the inclined surface 19a of the upper lens 12, making it easier to emit the light laterally.

[0028] FIG. 11 shows a third light emitting unit 1b including a lens 10b of the third embodiment. The lens 10b is composed of a third lower lens 11b having a third cavity 36 obtained by deforming a part of the cavity 16 of the lower lens 11 of the first embodiment, and an upper lens 12 common to the first embodiment. The cavity 36 of the present embodiment has a protruding portion 34 with a W-shaped cross-section that protrudes downward in a curved shape along the rotation direction centered on the central portion of the upper surface, and the curved bottom surface of the protruding portion 34 serves as an upper incident surface 38 for refracting light toward the upper lens 12. Since the lower outer peripheral surface 14 is common to the lower lens 11 of the first embodiment and the refraction action of light on the side incident surface 17 is also common, detailed description is omitted here.

[0029] As shown in FIG. 11, when the upper surface of the cavity 36 is flat as indicated by the broken line, the light emitted from the outer peripheral portion of the light emitting surface 3a of the light emitting unit 3 in the direction of the optical axis Oa may travel straight upward in the front direction as it is from the central portion of the concave portion 19 of the upper lens 12 as indicated by the arrow B1. On the other hand, in the present embodiment, the light emitted from the outer peripheral portion of the light emitting surface 3a of the light emitting unit 3 in the direction of the optical axis Oa can be refracted at the upper incident surface 38 and then emitted toward the inclined surface 19a of the upper lens 12 as indicated by the arrow B2. As a result, the light incident on the upper incident surface 38 of the lower lens 11b can be reflected on the lower side along the inclined surface 19a of the upper lens 12, making it easier to emit the light laterally.

[0030] FIG. 12 shows a configuration example of a lighting device 40 in which the light-emitting unit 1 of the first embodiment and the reflector 41 are combined. The reflector 41 includes a circular bottom plate portion 42 on which the light-emitting unit 1 is placed, and a side plate portion 43 that inclines so as to surround the outer peripheral edge of the bottom plate portion 42 at an angle of about 45°. By combining such a reflector 41, the light radiated laterally in a radial direction from the light-emitting unit 1 can be made to be emitted in the front direction by the side plate portion 43 of the reflector 41. As a result, as shown in FIG. 13, it is possible to obtain a narrow directivity characteristic in one direction while being thin.

[0031] FIG. 14 shows a light-emitting unit 50 in which a light-shielding plate 51 made of a circular non-transparent member that covers the entire concave portion 19 is disposed on the upper surface of the upper lens 12. By disposing the light-shielding plate 51, it is possible to completely shield the light leaking from the entire concave portion 19 of the upper lens 12.

[0032] FIG. 15 shows a light-emitting unit 60 in which a light-shielding member 61 made of a non-transparent member is disposed only on the flat portion 19b which is the bottom of the concave portion 19 of the upper lens 12. In this way, by disposing the light-shielding member 61 only on the flat portion 19b which is the bottom of the concave portion 19, it is possible to effectively shield or reflect the light leaking in the front direction particularly along the optical axis Oa.

Explanation of Reference Numerals

[0033] Oa Optical axis 1, 1a, 1b, 50, 60 Light-emitting unit 2 Light-emitting device 3 Light-emitting portion 3a Light-emitting surface 4 Substrate 10 Lens 10a Lens 10b Lens 11 Lower lens 11a Lower lens 11b Lower lens 12 Upper lens 13 Convex part 13H Convex part 13Ha Upper surface 13L Convex part 13a Upper surface 13b Lower surface 14 Lower outer peripheral surface 14a Concavo-convex surface part 15 Upper outer peripheral surface 15a Flat surface part 15b Gradient surface part 16 Hollow part 17 Lateral incident surface 17a Upper end part 18 Upper incident surface 18a End part 19 Concave part 19a Inclined surface 19b Flat surface part 19c Upper end 20 Valley part 21 Ridge part 24 Protruding part 26 Hollow part 28 Upper incident surface 34 Protruding part 36 Hollow part 38 Upper incident surface 40 Lighting device 41 Reflector 42 Bottom plate part 43 Side plate part 51 Light-shielding plate 61 Light-shielding member

Claims

1. A cylindrical lens disposed on the light emitting surface side of a light source, wherein a cavity portion that covers the light emitting surface of the light source and has a side incident surface and an upper incident surface, and an uneven portion formed on the lower outer peripheral surface of the lens corresponding to the side incident surface are provided below the lens, and a concave portion having an inverted conical inclined surface corresponding to the upper incident surface of the cavity portion and a vertical flat surface portion formed on the upper outer peripheral surface of the lens are provided above the lens.

2. The lens according to claim 1, wherein the uneven portion is continuously formed from the upper end portion of the light emitting surface to at least the same height position as the height of the cavity portion.

3. The lens according to claim 2, wherein the uneven portion has a saw blade-shaped cross-sectional shape, and the saw blade-shaped cross-sectional shape gradually increases upward from the lower end portion of the lower outer peripheral surface of the lens.

4. The lens according to claim 1, wherein the cavity portion is formed in a frustum of a cone shape, and the inclination angle of the side incident surface is 15 degrees or less with respect to the vertical direction.

5. The lens according to claim 1, wherein the cavity portion is formed in a frustum of a cone shape and the upper surface is formed flat.

6. The lens according to claim 1, wherein the cavity portion is formed in a frustum of a cone shape and the upper surface is formed in a V-shaped cross section.

7. The lens according to claim 1, wherein the cavity portion is formed in a frustum of a cone shape and the upper surface is formed in a W-shaped cross section.

8. The lens according to claim 1, wherein the lowermost end position of the inclined surface of the concave portion is located above the lowermost end position of the flat surface portion.

9. The lens according to claim 8, wherein a planar bottom portion is formed at the lowermost end position of the inclined surface.

10. The lens according to claim 1, wherein the outer diameters of the uneven portion and the flat surface portion coincide with each other.

11. The lens according to claim 1, wherein the upper part of the concave portion is shielded by a circular light shielding plate.

12. The lens according to claim 1, wherein the bottom of the concave portion is shielded by a light shielding member.

13. An illumination device comprising the lens according to any one of claims 1 to 12 and a reflector disposed so as to surround the periphery of the lens.

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