Light guide body and vehicle interior lighting device

Abstract

To provide a light guide body which can emit light directed in a specific direction from a desired range in a longitudinal direction and can be suitably used for notification illumination and to provide a vehicle interior lighting device incorporating the light guide body.SOLUTION: In a light guide body 1, a V-groove-shaped lens cut 12 is provided on a side face of a rod-shaped light guide main body 10. One or both of two faces forming a V-groove shape of the lens cut 12 are curved inclined surfaces, in which a contour of a cross section perpendicular to a longitudinal direction of the lens cut 12 is curved toward an inside of the light guide main body 10. When assuming that the contour is not curved, an inclination angle θ of a straight line 122 is greater than 0° and less than 90°.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a light guide and an interior lighting device for vehicles.

Background Art

[0002] Conventionally, a lighting device used for the interior of a vehicle, which includes a rod-shaped light guide, is known (see Patent Document 1). In the lighting device described in Patent Document 1, a light-emitting element is arranged facing one end surface of the rod-shaped light guide, and light is introduced into the light guide from the one end surface to cause the light guide to emit light.

[0003] Further, in the lighting device described in Patent Document 1, the light emitted from the light-emitting element is condensed by a condensing portion formed on the end surface on the input side of the light guide and is guided into the light guide. Then, the light is diffusely reflected by the textured portion on the side surface of the light guide and is emitted to the outside.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, a lighting device called notification illumination, which is used in a vehicle interior and has a function of attracting the attention of passengers by light, has been attracting attention. In this notification illumination, for example, by irradiating light directed in a specific direction, such as the direction facing the driver's seat, from a wide range in the length direction of the light guide, it becomes easier for passengers to recognize even in a bright environment such as during the day.

[0006] A lighting device that does not include a mechanism for irradiating light directed in a specific direction from a wide range in the length direction of the light guide, including the lighting device described in Patent Document 1, is not suitable for use as notification illumination.

[0007] An object of the present invention is to provide a light guide that can irradiate light directed in a specific direction from a desired range in the longitudinal direction and can be suitably used for notification illumination, and a vehicle interior lighting device including the light guide.

Means for Solving the Problems

[0008] One aspect of the present invention provides the following light guide and vehicle interior lighting device in order to achieve the above object.

[0009] [1] On the side surface of a rod-shaped light guide body, a V-groove-shaped lens cut is provided for reflecting light propagating along the longitudinal direction inside the light guide body and emitting it to the outside of the light guide body. One or both of the two surfaces constituting the V-groove shape of the lens cut are curved inclined surfaces. The curved inclined surface has a contour in a cross section perpendicular to the longitudinal direction of the lens cut that curves toward the inside of the light guide body, and the inclination angle θ with respect to a straight line when the contour is not curved, based on the longitudinal direction of the light guide body, is greater than 0° and less than 90°. A light guide. [2] The light guide according to [1] above, wherein both of the two surfaces constituting the V-groove shape of the lens cut are the curved inclined surfaces. [3] The light guide according to [1] or [2] above, wherein an end portion of the light guide body located on the side of the curved inclined surface among the end portions in the longitudinal direction has a TIR lens structure. [4] A vehicle interior lighting device including the light guide according to [1] or [2] above, a light emitting device that allows light to enter the inside of the light guide body from an end portion of the light guide body located on the side of the curved inclined surface among the end portions in the longitudinal direction, and a light directing means that directs the light emitted from the light emitting device in the longitudinal direction of the light guide body. [5] The vehicle interior lighting device according to [4] above, wherein the light guide is installed on an instrument panel in a vehicle interior, and the inclination angle θ is 20° or more and 60° or less.

Effects of the Invention

[0010] According to the present invention, there can be provided a light guide that can irradiate light directed in a specific direction from a desired range in the longitudinal direction, and that can also be suitably used for notification illumination, and a vehicle interior lighting device including the light guide.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

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Figure 8

Figure 9

Best Mode for Carrying Out the Invention

[0012] Figs. 1(a), (b), and (c) are a perspective view, a side view, and a bottom view of the light guide 1 according to an embodiment of the present invention.

[0013] On the side surface of the rod-shaped light guide body 10 of the light guide 1, there is provided a V-groove-shaped lens cut 12 for reflecting the light propagating along the length direction of the light guide body 10 inside the light guide body 10 and emitting it to the outside of the light guide body. Typically, as shown in Figs. 1(a) and (c), a plurality of lens cuts 12 are provided side by side along the length direction of the light guide body 10.

[0014] Since the lens cut 12 reflects the light traveling along the length direction of the light guide body 10, the length direction of the lens cut 12 (the direction of the linear V-groove pattern) is substantially perpendicular to the length direction of the light guide body 10.

[0015] The light guide body 10 is made of a transparent resin such as an acrylic resin, for example. The light guide body 10 has, for example, a cylindrical shape as shown in Figs. 1(a), (b), and (c), and has a plane 11 extending in the length direction of the light guide body 10 in a part thereof. In this case, the lens cut 12 is provided on the plane 11. Further, the light guide body 10 may have other shapes such as a polygonal prism shape. When the light guide body 10 has a polygonal prism shape, the lens cut 12 is provided on one of the plurality of planes constituting the side surface of the polygonal prism.

[0016] Fig. 2(a) is a cross-sectional view of the light guide 1 parallel to the length direction of the light guide body 10 and perpendicular to the plane 11. Fig. 2(b) is an enlarged view of the periphery of the lens cut 12 of the cross section of Fig. 2(a). The length direction of the lens cut 12 is perpendicular to the cross sections of Figs. 2(a) and (b).

[0017] In the lens cut 12 shown in FIG. 2(b), one surface 121 of the two surfaces constituting the V-groove shape is a curved inclined surface. Here, the curved inclined surface means that in a cross-section perpendicular to the length direction of the lens cut 12 as shown in FIG. 2(b), the contour curves with a radius of curvature R toward the inside of the light guide body 10, and the inclination angle θ of the straight line 122 when the contour is not curved is greater than 0° and less than 90°. Here, the inclination angle θ is the inclination angle of the straight line 122 with respect to the length direction of the light guide body 10.

[0018] And the above radius of curvature R preferably satisfies the condition that it is Y / sin2θ or more when the depth of the lens cut 12 is Y. By satisfying this condition, when the light guide body 10 is formed by injection molding, it can be easily extracted from the mold.

[0019] FIGS. 3(a) and (b) are conceptual diagrams for showing the relationship between the radius of curvature R of the contour in a cross-section perpendicular to the length direction of the lens cut 12 of the surface 121 which is a curved inclined surface and the way the reflected light spreads.

[0020] As shown in FIG. 3(a), when the surface 121 is not curved, the bundle of light traveling parallel to the length direction of the light guide body 10 hardly spreads after being reflected by the surface 121. On the other hand, as shown in FIG. 3(b), when the surface 121 is curved, the bundle of light traveling parallel to the length direction of the light guide body 10 spreads according to the magnitude of the radius of curvature R after being reflected by the surface 121.

[0021] As can be understood from this, when the radius of curvature R increases and the surface 121 approaches a plane, the spread of the reflected light becomes smaller, and conversely, when the radius of curvature R decreases, the spread of the reflected light becomes larger. That is, by adjusting the radius of curvature R, the magnitude of the spread of the light reflected by the surface 121 can be controlled.

[0022] Further, by adjusting the above inclination angle θ, the emission direction of the light reflected by the surface 121 from the light guide body 10 can be controlled. Therefore, by adjusting the inclination angle θ and the radius of curvature R, for example, according to the installation position of the light guide 1 in the vehicle interior, light can be irradiated in a desired range in a desired direction such as the direction facing the driver's seat. That is, the light guide 1 can be suitably used as a light guide for notification illumination.

[0023] For example, when the light guide 1 is installed on the instrument panel in the vehicle interior and a notification is made toward the driver's seat, it is preferable to set the inclination angle θ of the lens cut 12 to 20° or more and 60° or less, and set the radius of curvature R and the depth Y of the lens cut 12 according to the desired irradiation range.

[0024] Note that the above inclination angle θ is preferably set to an angle such that light traveling parallel to the length direction of the light guide body 10 is totally reflected on a plane (a plane in which the contour in the cross section of FIG. 2(b) is a straight line 122) when the curved inclined surface 121 is not curved.

[0025] That is, when the incident angle of the light traveling parallel to the length direction of the light guide body 10 on the plane when the surface 121 is not curved is such that the refractive index of air is N1 and the refractive index of the light guide body 10 is N2, sin -1 (N1 / N2), it is preferable that the inclination angle θ is set to be larger than the critical angle represented by.

[0026] Further, when the light traveling parallel to the length direction of the light guide body 10 is totally reflected on the plane when the surface 121 is not curved but does not totally reflect in a part of the curved surface 121, it is more preferable to adjust the inclination angle θ so that all of it is totally reflected. That is, it is more preferable that the light traveling parallel to the length direction of the light guide body 10 is totally reflected on the entire curved inclined surface 121.

[0027] When considering the variation in the direction of light traveling inside the light guide body 10, not only the light traveling parallel to the length direction of the light guide body 10 but also the light traveling in the direction most deviated from the length direction of the light guide body 10 (for example, the light traveling in a direction inclined by 15° from the length direction of the light guide body 10) are preferably set with the inclination angle θ so that they are totally reflected on the plane when the surface 121 is not curved. More preferably, the light traveling parallel to the length direction of the light guide body 10 and the light traveling in the direction most deviated from the length direction of the light guide body 10 are totally reflected on the entire curved inclined surface 121.

[0028] In the light guide 1, light enters the inside from the end 13 located on the side of the surface 121 which is the curved inclined surface of the lens cut 12 among the ends in the length direction of the light guide body 10, is reflected by the surface 121, and is taken out to the outside from the region opposite to the region where the lens cut 12 is provided on the side surface of the light guide body 10.

[0029] FIG. 4(a) is a cross-sectional view of the light guide body 10 around the end 13 when the end 13 of the light guide body 10 has a TIR (Total Internal Reflection) lens structure. FIG. 4(b) is a schematic diagram showing the trajectory of the light entering the light guide body 10 from the end 13 shown in FIG. 4(a). The cross-sections shown in FIGS. 4(a) and 4(b) are cross-sections parallel to the length direction of the light guide body 10.

[0030] As shown in FIG. 4(b), the light entering the light guide body 10 from the end 13 is directed in the length direction of the light guide body 10 by the TIR structure of the end 13. The TIR lens structure is provided at the end 13 located on the side of the surface 121 which is the curved inclined surface among the ends in the length direction of the light guide body 10.

[0031] FIGS. 5(a) and 5(b) are a perspective view and a cross-sectional view of the vehicle interior lighting device 2 including the light guide 1. The cross-section shown in FIG. 5(b) is a cross-section parallel to the length direction of the light guide body 10 of the light guide 1 and perpendicular to the plane 11.

[0032] The vehicle interior lighting device 2 includes a light guide 1, a light emitting device 20 that allows light to enter the interior of the light guide body 10 from an end 13 located on the side of a surface 121 that is a curved inclined surface of a lens cut 12 at an end in the length direction of the light guide body 10, and a light directing means that directs the light emitted from the light emitting device 20 in the length direction of the light guide body 10.

[0033] In the vehicle interior lighting device 2 shown in FIGS. 5(a) and 5(b), the end 13 having a TIR structure of the light guide body 10 functions as the above-described light directing means.

[0034] The light emitting device 20 includes a light source 21 such as an LED element mounted on a substrate 22, and a housing 23 composed of components 231 and 232 that houses these.

[0035] In the example shown in FIGS. 5(a) and 5(b), the end 13 of the light guide body 10 is fitted into the opening of the housing 23, and the light guide 1 and the light emitting device 20 are fixed in a state where the light source 21 and the end 13 face each other.

[0036] The light emitted from the light source 21 enters the interior of the light guide body 10 from the end 13. At this time, the TIR structure of the end 13 directs the light in the length direction of the light guide body 10. The light traveling in the length direction of the light guide body 10 inside the light guide body 10 is reflected by the surface 121 which is the curved inclined surface of the lens cut 12, and is taken out to the outside from a region on the opposite side of the region where the lens cut 12 is provided on the side surface of the light guide body 10.

[0037] FIGS. 6(a) and 6(b) are conceptual diagrams showing the configuration of a modified example of the light directing means included in the vehicle interior lighting device 2.

[0038] In the example shown in FIG. 6(a), a convex lens 31 is used as the light directing means, and the end 13 of the light guide body 10 has a flat end face. In the example shown in FIG. 6(b), a reflector 32 and a convex shape provided on the end face of the end 13 of the light guide body 10 are used as the light directing means. Thus, a component separate from the light guide body 10 may be used as the light directing means.

[0039] FIG. 7(a) is a cross-sectional view of a light guide 1 (hereinafter referred to as light guide 1w) having a configuration that takes in light from both ends in the longitudinal direction. FIG. 7(b) is an enlarged view of the periphery of the lens cut 12 in the cross-section of FIG. 7(a). The cross-sections shown in FIGS. 7(a) and 7(b) are cross-sections parallel to the longitudinal direction of the light guide body 10 and perpendicular to the plane 11.

[0040] As shown in FIG. 7(b), in the light guide 1w, both the surface 121a and the surface 121b, which are two surfaces constituting the V-groove shape of the lens cut 12, are curved inclined surfaces. Here, among both ends in the longitudinal direction of the light guide body 10, the end located on the side of the surface 121a of the lens cut 12 is referred to as end 13a, and the end located on the side of the surface 121b of the lens cut 12 is referred to as end 13b.

[0041] FIG. 8 is a conceptual diagram showing how the light entering the light guide body 10 from the end 13a and the end 13a is reflected by the surfaces 121a and 121b, which are curved inclined surfaces.

[0042] The light that enters the inside of the light guide body 10 from the end 13a and propagates in the longitudinal direction of the light guide body 10 is reflected by the surface 121a, which is the curved inclined surface of the lens cut 12, and taken out to the outside of the light guide body 10. Also, the light that enters the inside of the light guide body 10 from the end 13b and propagates in the longitudinal direction of the light guide body 10 is reflected by the surface 121b, which is the curved inclined surface of the lens cut 12, and taken out to the outside of the light guide body 10.

[0043] By making both the surface 121a and the surface 121b, which are two surfaces constituting the V-groove shape of the lens cut 12, into curved inclined surfaces and introducing light from the ends 13a and 13b on both sides in the longitudinal direction of the light guide body 10, it is possible to reduce the degree to which the brightness of the light emitted from the light guide 1w changes depending on the position where this light is viewed.

[0044] In addition, by complementing the gaps in the emission range of the reflected light by the surfaces 121a of the plurality of lens cuts 12 with the emission range of the reflected light by the surface 121b, and complementing the gaps in the emission range of the reflected light by the surfaces 121b of the plurality of lens cuts 12 with the emission range of the reflected light by the surface 121a, the uniformity of the brightness of the light extracted from the light guide 1w can be improved.

[0045] The radius of curvature R of the contour in a cross-section perpendicular to the length direction of the lens cut 12 of the surface 121a and the surface 121b may be different, and the inclination angle θ1 of the surface 121a and the inclination angle θ2 of the surface 121b may also be different. In this case, the emission directions and the spreading ranges of the reflected light by the surface 121a and the reflected light by the surface 121b can be controlled independently. Note that one of the surface 121a and the surface 121b may be an inclined surface that is not a curved inclined surface and is not curved (the inclination angle θ is greater than 0° and less than 90°).

[0046] In the example shown in FIG. 7(a), TIR structures as light directing means are provided at the end portions 13a and 13b which are both end portions in the length direction of the light guide body 10.

[0047] FIGS. 9(a) and (b) are a perspective view and a cross-sectional view of a vehicle interior lighting device 2w including the light guide 1w. The cross-section shown in FIG. 9(b) is a cross-section parallel to the length direction of the light guide body 10 of the light guide 1w and perpendicular to the plane 11.

[0048] The vehicle interior lighting device 2w includes a light guide 1w, a light emitting device 20a and a light emitting device 20b that respectively allow light to enter the inside of the light guide body 10 from the end portions 13a and 13b of the light guide body 10, and a light directing means that directs the light emitted from the light emitting device 20a and the light emitting device 20b in the length direction of the light guide body 10, respectively.

[0049] In the vehicle interior lighting device 2w shown in FIGS. 9(a) and (b), the end portions 13a and 13b having the TIR structure of the light guide body 10 function as the above-described light directing means.

[0050] The light-emitting device 20a and the light-emitting device 20b each include a light source 21 such as an LED element mounted on a substrate 22, and a housing 23 composed of components 231 and 232 that houses these components.

[0051] In the examples shown in FIGS. 9(a) and 9(b), the end portion 13a of the light guide body 10 is fitted into the opening of the housing 23 of the light-emitting device 20a, and the light guide 1w and the light-emitting device 20a are fixed in a state where the light source 21 and the end portion 13a face each other. Similarly, the end portion 13b of the light guide body 10 is fitted into the opening of the housing 23 of the light-emitting device 20b, and the light guide 1w and the light-emitting device 20b are fixed in a state where the light source 21 and the end portion 13b face each other.

[0052] The light emitted from the light sources 21 of the light-emitting device 20a and the light-emitting device 20b enters the inside of the light guide body 10 from the end portions 13a and 13b, respectively. At this time, the light is directed in the length direction of the light guide body 10 by the TIR structure of the end portions 13a and 13b. The light traveling in the length direction of the light guide body 10 inside the light guide body 10 is reflected by the surfaces 121a and 121b of the lens cut 12, and is taken out to the outside from the region opposite to the region where the lens cut 12 is provided on the side surface of the light guide body 10.

[0053] The light guide 1, the light guide 1w, and the vehicle interior lighting device 2 and the vehicle interior lighting device 2w using these can be attached to, for example, a door panel or an instrument panel in a vehicle interior and used as components for notification illumination.

[0054] (Effect of the embodiment) According to the light guides 1 and 1w according to the above-described embodiment of the present invention, light directed in a specific direction can be irradiated from a desired range in the length direction by using the curved inclined surface of the lens cut 12. Therefore, the light guides 1 and 1w, and the vehicle interior lighting devices 2 and 2w provided with these can be suitably used for notification illumination and the like.

[0055] Note that the uses of the light guides 1 and 1w and the vehicle interior lighting devices 2 and 2w are not limited to notification illumination.

[0056] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the invention. Also, the components of the above embodiments can be arbitrarily combined without departing from the gist of the invention.

[0057] Also, the above embodiments do not limit the invention according to the claims. It should also be noted that not all combinations of the features described in the embodiments are necessarily essential means for solving the problems of the invention.

Explanation of Reference Numerals

[0058] 1, 1w Light guide 10 Light guide body 12 Lens cut 121, 121a, 121b Surfaces 13, 13a, 13b Ends 2, 2w Interior lighting device for vehicle 20, 20a, 20b Light emitting device 21 Light source

Claims

1. On the side surface of a rod-shaped light guide body, a V-groove-shaped lens cut is provided for reflecting light propagating along the length direction inside the light guide body and emitting it outside the light guide body. One or both of the two surfaces constituting the V-groove shape of the lens cut are curved inclined surfaces. In a cross-section perpendicular to the length direction of the lens cut, the contour of the curved inclined surface curves toward the inside of the light guide body, and the inclination angle θ of the straight line when the contour is not curved, with respect to the length direction of the light guide body, is greater than 0° and less than 90°. Light guide body.

2. Both of the two surfaces constituting the V-groove shape of the lens cut are the curved inclined surfaces. The light guide body according to Claim 1.

3. The end portion located on the side of the curved inclined surface among the end portions in the length direction of the light guide body has a TIR lens structure. The light guide body according to Claim 1 or 2.

4. The light guide body according to Claim 1 or 2, a light-emitting device that allows light to enter the inside of the light guide body from the end portion located on the side of the curved inclined surface among the end portions in the length direction of the light guide body, and a light directing means that directs the light emitted from the light-emitting device in the length direction of the light guide body. A vehicle interior lighting device comprising: A vehicle interior lighting device.

5. The light guide body is installed on an instrument panel in a vehicle interior, and the inclination angle θ is 20° or more and 60° or less. The vehicle interior lighting device according to Claim 4.

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