Optical element, light source device and luminaire

Abstract

To increase luminous intensity at the center of emission light of an optical element.SOLUTION: A lens 1 irradiating one side in a first direction with light from a light source 2 comprises a recess 3 opened at an end on the other side in the first direction, and a side face 4. The recess 3 comprises: a refraction internal surface 7 extending from the opening to the one side in the first direction and formed to surround the light source 2; and a transmission refractive surface 6 including an outer periphery connected to an end of the refraction internal surface 7 on the one side in the first direction, and formed in a position facing the light source 2. The side face 4 is arranged to surround the refraction internal surface 7. When a first angle is defined as an angle formed between the first direction and a direction from the center of ends of the refraction internal surface 7 on the other end side to a contact point P1 of the transmission refractive surface 6 and the refraction internal surface 7, and a second angle is defined as an angle formed between the first direction and a direction in which a tangent line of the refraction internal surface 7 extends at the contact point P1, the second angle is smaller than the first angle.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an optical element, a light source device, and an illumination device. [Background technology]

[0002] BACKGROUND ART In recent years, the miniaturization of light sources such as LEDs (Light Emitting Diodes) has led to the miniaturization of lighting devices. Optical elements used in lighting devices having such light sources have been proposed.

[0003] For example, Patent Document 1 discloses an illumination lens (optical element) that suppresses changes in illuminance distribution that accompany changes in the position of a light source. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-99409 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, some conventional lighting devices, like the lighting lens of Patent Document 1, have a recess corresponding to the incident surface formed so as to surround the light source.

[0006] In the lighting device of Fig. 3, the recess is composed of a convex transmissive-refractive surface formed to face the light source, and a refractive inner wall surface that extends upward from the opening of the recess and has an upper end connected to the outer periphery of the transmissive-refractive surface. This refractive inner wall surface is formed so that the width at its bottom end is smaller than the width at its top end in a side cross section of the lens.

[0007] In the configuration shown in Figure 3, to increase the luminous intensity of the central portion of the emitted light from the lighting device, it is necessary to increase the distance between the transmissive-refractive surface and the light source. If the width of the lower end of the refractive inner wall surface is smaller than the width of the upper end of the refractive inner wall surface, as shown in Figure 3, light incident on the lower portion of the side surface is reflected by the upper portion of the refractive inner wall surface, resulting in stray light. Furthermore, since the incident angle of the light with respect to the upper portion of the refractive inner wall surface becomes large, the incident light that is incident on the upper portion of the refractive inner wall surface is Fresnel reflected, resulting in stray light. As a result, the luminous intensity of the central portion of the emitted light may be reduced.

[0008] Therefore, an object of the present disclosure is to provide an optical element, a light source device, and an illumination device that are capable of increasing the luminous intensity of the central portion of emitted light. [Means for solving the problem]

[0009] In order to achieve the above object, an optical element according to one embodiment of the present disclosure is an optical element that irradiates light from a light source to one side in a first direction, and comprises a recess having an opening at an end on the other side in the first direction, and a side surface, wherein the recess extends from the opening to the one side and comprises a refractive inner wall surface formed to surround the light source, and a transparent refractive surface whose outer periphery is connected to the end on the one side of the refractive inner wall surface and is formed in a position facing the light source, and the side surface is arranged to surround the refractive inner wall surface, and when the optical element is viewed from the side, the angle between the first direction and the direction from the center of the ends on the other side of the refractive inner wall surface toward the tangent point of the transparent refractive surface and the refractive inner wall surface is defined as a first angle, and the angle between the first direction and the direction in which a tangent line at the tangent point of the refractive inner wall surface extends is defined as a second angle, and the second angle is smaller than the first angle. [Effects of the Invention]

[0010] According to the present disclosure, the luminous intensity of the central portion of the light emitted from the optical element can be increased. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view of a lighting device according to an embodiment. [Figure 2] FIG. 1 is a perspective view of a lens according to an embodiment. [Figure 3] FIG. 10 is a cross-sectional view of a lighting device according to a comparative example. [Figure 4] 10A and 10B are diagrams showing simulation results of the illumination device according to the example and the illumination device according to the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its applications, or its uses. In the following description, the same parts will be designated by the same reference numerals, and detailed description will be omitted as appropriate.

[0013] (First embodiment) (Overall configuration of lighting equipment) FIG. 1 is a cross-sectional view of an illumination device according to a first embodiment, FIG. 2(a) is a perspective view of the lens according to the first embodiment as viewed from below, and FIG. 2(b) is a perspective view of the optical lens according to the first embodiment as viewed from above. For convenience, the up-down direction in FIG. 1 may be simply referred to as the up-down direction (corresponding to the first direction), and the left-right direction in FIG. 1 may be simply referred to as the left-right direction (corresponding to the second direction). In addition, in each of the figures described below, light rays emitted from the light source 2 are shown by dashed lines. In addition, in FIG. 1, the upper side of the figure corresponds to one side in the first direction, and the lower side of the figure corresponds to the other side in the first direction.

[0014] As shown in FIG. 1, the illumination device according to the first embodiment includes a lens 1 (optical element) and a light source 2. When actually arranging the illumination device, the illumination device may be arranged so that the up-down direction in FIG. 1 coincides with the actual up-down direction, or may not coincide with the actual up-down direction. For example, in the actual arrangement, the illumination device may be arranged so that the illumination surface of the lens 1 faces upward, downward, sideways, or diagonally. Furthermore, although the light source 2 is arranged below the lens 1 in FIG. 1, the light source 2 may also be arranged diagonally below the lens 1 in the drawing.

[0015] Lens 1 is made of, for example, a transparent resin such as acrylic or glass, and is formed in an axially rotationally symmetrical shape with the light emission center of light source 2 as its axis. Lens 1 collects light emitted from light source 2 and emits it upward (to one side in the first direction). Light source 2 is a small light source made of, for example, an LED. In this embodiment, light source 2 is arranged so that the optical axis direction is along the first direction.

[0016] The lens 1 has a recess 3, a side surface 4, and an exit surface 5. The recess 3 corresponds to the entrance surface of the lens 1.

[0017] The recess 3 is formed below the lens 1 so as to surround the light source 2. The recess 3 corresponds to the incident surface of the lens 1. Specifically, the recess 3 includes a transmissive refractive surface 6 and a refractive inner wall surface 7.

[0018] The transmissive-refractive surface 6 is a convex curved surface formed on the inner surface of the lens 1 so as to face the light source 2. The transmissive-refractive surface 6 refracts the light incident from the light source 2 and transmits it upward.

[0019] The refractive inner wall surface 7 is a curved surface formed on the inner surface of the lens 1, extending upward (to one side in the first direction) from the opening of the recess 3 (the other end in the first direction) and surrounding the outer periphery of the light source 2. The upper end (the end on one side in the first direction) of the refractive inner wall surface 7 is connected to the outer periphery of the transmissive-refractive surface 6. The refractive inner wall surface 7 is formed so that its cross section is convex inward. The refractive inner wall surface 7 refracts light incident from the light source 2 and transmits it to the left or right.

[0020] The side surface 4 is a surface formed on the side surface of the lens 1. For example, the side surface 4 is a conical surface or an elliptical curved surface. Specifically, the side surface 4 is formed so that its cross section extends in the upper left direction or the upper right direction. The side surface 4 is also arranged so as to surround the refractive inner wall surface 7. The side surface 4 totally reflects the light refracted by the refractive inner wall surface 7 in the upward direction.

[0021] The exit surface 5 is a flat surface formed on the upper surface of the lens 1. The exit surface 5 emits light incident from the transmissive / refractive surface 6 and the side surface 4 upward.

[0022] As shown in FIG. 1, in the side cross section of the lens 1, the refractive inner wall surface 7 is formed so that the bottom width S2 is smaller than the top width S1. The bottom width S2 is the opening width in the left-right direction of the recess 3, i.e., the distance between the bottom ends of both left and right side surfaces of the refractive inner wall surface 7 in the side cross section of the lens 1 (the ends on the other side in the first direction). The top width S1 is the distance between the left and right contact points of the transmitting-refractive surface 6 and the refractive inner wall surface 7 in the side cross section of the lens 1, i.e., the distance between the top ends of both left and right side surfaces of the refractive inner wall surface 7 in the side cross section of the lens 1 (the ends on one side in the first direction). Therefore, the refractive inner wall surface 7 can be inclined in the same direction as the side surface 4. As a result, light incident on the refractive inner wall surface 7 from the light source 2 can be refracted in the left-right direction, thereby reducing the length of the side surface 4 in the up-down direction. Furthermore, by making the refractive inner wall surface 7 convex inward, the light refracted by the refractive inner wall surface 7 is condensed, and the thickness of the lens 1 can be reduced.

[0023] Here, as shown in Figure 1, in a side cross section of the lens 1, when the angle between the optical axis direction (vertical direction) of the light source 2 and the direction from the center of the lower ends of the refractive inner wall surfaces 6 (the center of the light source 2) toward the tangent point P1 of the transparent refractive surface 6 and the refractive inner wall surface 7 is θ1, and the angle between the optical axis direction of the light source 2 and the direction in which the tangent line at the tangent point P1 of the refractive inner wall surface 7 extends is θ2, angle θ2 is smaller than angle θ1.

[0024] FIG. 3 is a cross-sectional view of a lighting device according to a comparative example. The lighting device of FIG. 3 has a configuration similar to that of FIG. 1, except that the lower end width S2 of the refraction inner wall surface 7 is smaller than the upper end width S1 of the refraction inner wall surface 7. With this configuration, the angle θ2 is approximately the same as the angle θ1. Therefore, as shown in FIG. 3, light L1' incident on the lower part of the side surface 4 is reflected by the upper part of the refraction inner wall surface 7 (near the contact point P1), resulting in stray light. Furthermore, light L2' incident on the upper part of the refraction inner wall surface 7 has a larger incident angle with respect to the refraction inner wall surface 7, and is Fresnel-reflected by the refraction inner wall surface 7, resulting in stray light. As a result, there is a limit to increasing the luminous intensity of the central part of the emitted light from the lighting device.

[0025] 1, the angle θ2 is smaller than the angle θ1. Therefore, the light L1 incident on the lower part of the side surface 4 is not reflected by the upper part of the refraction inner wall surface 7 (near the contact point P1). Furthermore, the incident angle of the light L2 incident on the upper part of the refraction inner wall surface 7 with respect to the refraction inner wall surface 7 is small, so Fresnel reflection of the light from the refraction inner wall surface 7 is suppressed, the light L2 is incident on the side surface 4, and is emitted from the emission surface 5. This makes it possible to increase the luminous intensity of the central part of the emitted light from the lighting device.

[0026] The above effect is more easily achieved when the angle θ2 is smaller than the angle θ1, so it is preferable that the angle θ2 is an angle equal to or smaller than 0.6 times the angle θ1.

[0027] 1 , the distance between the center of the light source 2 and the transmissive-refractive surface 6 in the up-down direction is a, the vertical distance between the light source 2 and the tangent point P in the up-down direction is b, the vertical distance between the light source 2 and the upper end of the side surface 4 in the up-down direction is c, the horizontal distance between the lower ends of the refracting inner wall surfaces 7 in the left-right direction is d, the horizontal distance between the tangent points P in the left-right direction is e, the horizontal distance between the upper ends of the side surfaces 4 in the left-right direction is f, and the size of the light source 2 in the left-right direction (the size of the light-emitting surface of the light source 2 in the left-right direction) is h. In this embodiment, when h is 1, it is preferable that the distance a is 1.3 to 2.1, the vertical distance b is 2.3 to 3.5, the vertical distance c is 4 to 5, the horizontal distance d is 3 to 4, the horizontal distance e is 3 to 5, and the horizontal distance f is 2 to 3 times the vertical distance c.

[0028] In particular, it is preferable that the distance a is close to the vertical distance c. This makes it possible to reduce the size of the lens 1 in the vertical direction, thereby reducing the size of the lighting device.

[0029] Furthermore, the distance a and the vertical distance c are preferably large. In particular, when h is 1, it is preferable that the distance a is 1.3 to 2.1, the vertical distance b is 2.3 to 3.5, and the vertical distance c is 4 to 5. This allows the distance between the center of the light source 2 and the transmissive refractive surface 6 to be large, which increases the focal length of the convex lens having the transmissive refractive surface 6, thereby increasing the luminous intensity of the central part of the emitted light from the lighting device.

[0030] Furthermore, it is preferable that the horizontal distance f is two to three times the distance c. This allows the light reflected by the side surface 4 to be emitted from the emission surface 5 without any loss, thereby increasing the central luminous intensity of the lighting device.

[0031] (Simulation results) FIG. 4 is a diagram showing simulation results of the illumination device according to the example and the illumination device according to the comparative example.

[0032] 4, the angle θ1 is 35.8° and the angle θ2 is 1.5° in the lighting device according to Example 1, the angle θ1 is 33.8° and the angle θ2 is 16.76° in the lighting device according to Example 2, and the angle θ1 is 35.4° and the angle θ2 is 35.4° in the lighting device according to the comparative example. That is, the angle θ2 in the lighting devices according to Examples 1 and 2 is smaller than 0.6 times the angle θ1.

[0033] Also, in Figure 4, when h is 1, the lighting device of Example 1 has a distance a of 1.33, a vertical distance b of 2.35, a vertical distance c of 4.575, a horizontal distance d of 3.66, a horizontal distance e of 3.65, and a horizontal distance f of 11.5, the lighting device of Example 2 has a distance a of 2.085, a vertical distance b of 3.325, a vertical distance c of 4.575, a horizontal distance d of 3.66, a horizontal distance e of 4.7, and a horizontal distance f of 11.5, and the lighting device of the comparative example has a distance a of 2.08, a vertical distance b of 3.9, a vertical distance c of 4.4, a horizontal distance d of 3.75, a horizontal distance e of 5.55, and a horizontal distance f of 11.5.

[0034] As shown in Fig. 4, the luminous intensity (peak luminous intensity) at the center of the emitted light is higher in the lighting devices according to Examples 1 and 2 than in the lighting device according to the comparative example. From this result, it can be said that the luminous intensity at the center of the emitted light from the lighting device can be increased by making the angle θ2 smaller than the angle θ2. In particular, the lens size of the lighting device according to Example 2 can be reduced more than that of the lighting device according to the comparative example. [Industrial Applicability]

[0035] The optical element of the present disclosure is useful because, when used in an illumination device, it can increase the luminous intensity of the central part of the emitted light from the illumination device. [Explanation of symbols]

[0036] 1. Lens (optical element) 2 light source 3 recess 4 Sides 5. Exit surface 6 Transmissive and refractive surfaces 7 Refraction inner wall surface S1 Top width S2 Bottom width

Claims

1. An optical element that irradiates light from a light source to one side in a first direction, a recess having an opening at an end on the other side in the first direction; and a side surface. The recessed portion is a refractive inner wall surface extending from the opening to the one side and formed to surround the light source; a transmissive refractive surface whose outer periphery is connected to the one end of the refractive inner wall surface and which is formed at a position facing the light source, the side surface is disposed so as to surround the refraction inner wall surface, When the optical element is viewed from the side, the angle between the first direction and the direction from the center of the ends on the other end side of the refractive inner wall surface toward the tangent point of the transparent refractive surface and the refractive inner wall surface is defined as a first angle, and the angle between the first direction and the direction in which the tangent line at the tangent point of the refractive inner wall surface extends is defined as a second angle, and the second angle is smaller than the first angle.

2. The optical element according to claim 1 , wherein the second angle is equal to or smaller than 0.6 times the first angle.

3. 2. The optical element according to claim 1, wherein a first distance, which is the distance between the light source and the transmissive refractive surface in the first direction, is equal to or greater than 1 / 3 of a second distance, which is the distance between the light emitting surface of the light source and the end of one of the side surfaces in the first direction.

4. The optical element according to claim 1, wherein a first distance, which is a distance between the light source and the transmissive refractive surface in the first direction, is 1.3 to 2.1 times the length of the light emitting surface of the light source in a second direction perpendicular to the first direction when the optical element is viewed from the side.

5. The optical element of claim 1, wherein a second distance, which is the distance between the light-emitting surface of the light source in the first direction and the end of one of the side surfaces, is 4 to 5 times the length of the light-emitting surface of the light source in a second direction perpendicular to the first direction when the optical element is viewed from the side.

6. The optical element of claim 1, wherein a third distance, which is the distance between the ends of the side surfaces on one side in a second direction perpendicular to the first direction when the optical element is viewed from the side, is 2 to 3 times the second distance, which is the distance between the light-emitting surface of the light source and the ends of the side surfaces on one side in the first direction.

7. The optical element according to claim 1; a light source device comprising the light source.

8. An illumination device comprising the light source device according to claim 7.

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