Light guide structure of side turn signal lamps

Abstract

When the light guide structure has a bent portion in the direction of the optical axis, light leakage during the light guide process is suppressed, enabling efficient light guidance. [Solution] The light guide structure has a light guide section 38 that is incorporated into the turn lamp 20 and guides light from the light source 36 from the incident surface 40 and radiates it toward the external environment from the radiating surface 22. The light guide section 38 has a bent section 54 that bends the optical axis 48 of the light guide section 38 in a rounded shape. The outer circumferential surface of the bent section 54 has an arc-shaped surface 56 formed at least on the outer side of the bent shape of the bent section 54, with a convex arc shape in cross-section perpendicular to the optical axis 48 and extending in the direction of the optical axis 48, and a strip-shaped surface 60 formed at the outermost circumferential position of the bent shape of the bent section 54 within the plane of the arc-shaped surface 56, with a flat cross-section perpendicular to the optical axis 48 and extending in the direction of the optical axis 48.

Description

[Technical Field]

[0001] The present invention relates to a light guide structure for a side turn signal lamp mounted on a vehicle, and is configured to suppress light leakage during light guiding and enable efficient light guiding when the light guide structure has a bent portion in the optical axis direction. [Background Art]

[0002] Some side turn signal lamps for vehicles incorporate a light guide structure. This light guide structure is configured such that light from a light source in the side turn signal lamp enters through a predetermined incident surface, is guided, and is emitted toward the external environment from a predetermined emission surface. As a conventional light guide structure, structures having a bent portion in the optical axis direction are described in the following Patent Documents 1 to 3. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2015-229386 [Patent Document 2] Japanese Patent No. 6003177 [Patent Document 3] Japanese Unexamined Patent Publication No. 2021-097013 [Patent Document 4] U.S. Patent No. 8475018 Specification [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] A light guide structure having a bent portion in the optical axis direction has a large amount of light leakage during light guiding, and accordingly, the amount of light emitted from a predetermined emission surface decreases, causing a problem that light guiding efficiency (the ratio of light incident from the incident surface reaching the emission surface) decreases. As a result, in order to secure a predetermined amount of light for the light emitted from the predetermined emission surface, it is necessary to increase the number of light sources such as LEDs or use a high-output light source, which causes problems of cost and heat generation. Additionally, the problem of heat generation has been an obstacle to the miniaturization of side turn signal lamps.

[0005] This invention solves the problems of the prior art and provides a light guide structure for a side turn signal lamp that suppresses light leakage during light guidance and enables efficient light guidance when the light guide structure has a bent portion in the direction of the optical axis. [Means for solving the problem]

[0006] The light guide structure of this invention is a light guide structure incorporated into a side turn signal lamp, which has a light guide section that guides light from the light source of the side turn signal lamp from a predetermined incident surface and radiates it toward the external environment from a predetermined radiating surface. The light guide section has a bent section that curves and bends the optical axis of the light guide section, and the outer circumferential surface of the bent section has an arc-shaped surface formed at least on the outer side of the bent shape of the bent section, with a convex arc shape (circular arc, elliptical arc, etc.) in the cross-sectional shape perpendicular to the optical axis and extending in the direction of the optical axis, and a strip-shaped surface formed at the outermost periphery of the bent shape of the bent section within the plane of the arc-shaped surface, with a flat cross-sectional shape perpendicular to the optical axis and extending in the direction of the optical axis. With this, by having a strip-shaped surface at least on the outer side of the bent shape of the bent section, light leakage during light guidance can be suppressed (i.e., the light-gathering efficiency of the light guide section can be improved) and the light-guiding efficiency can be improved. Therefore, compared to a system without a strip-shaped surface, it becomes possible to reduce the number of light sources or use light sources with relatively low output, thereby resolving issues of cost and heat generation.

[0007] In the light guide structure of this invention, the width of the strip-shaped surface in a cross-section perpendicular to the optical axis can be, for example, 1 / 2 or less of the width of the arc-shaped surface or the width of the light guide portion in the same cross-section. That is, if the width of the strip-shaped surface is too wide, there will be a lot of light leakage, so it is desirable that the width of the strip-shaped surface be 1 / 2 or less (more preferably 1 / 3 or less, and even more preferably 1 / 4 or less) of the width of the light guide portion.

[0008] In the light guide structure of this invention, the light guide portion has a reflective surface at an intermediate position in the optical axis direction of the bent portion, on the outer side of the bent shape of the bent portion, with the outer surface of the bent portion cut flat, and the strip-shaped surface is formed on either side of the reflective surface, closer to the light source and closer to the radiating surface, respectively. According to this, by forming the reflective surface at an intermediate position in the optical axis direction of the bent portion, light from the light source can be efficiently reflected in the direction of the radiating surface. In this case, by forming the strip-shaped surface on either side of the reflective surface, closer to the light source and closer to the radiating surface, light leakage during light guidance can be suppressed and light guidance efficiency can be improved.

[0009] In the light guide structure of this invention, the bent portion can be designed to bend the optical axis of the light guide at an angle such that the incident surface faces the front or oblique front of the side turn signal lamp. This allows the circuit board on which the light source is mounted to be positioned nearly parallel to the front of the side turn signal lamp, thus allowing the side turn signal lamp to be made thinner compared to cases where there is no bend or the bend angle is shallow and the circuit board is positioned nearly perpendicular to the front of the side turn signal lamp. Therefore, when the side turn signal lamp is housed in a side mirror or the like, it is easy to design an arrangement that prevents the side turn signal lamp from interfering with other equipment. In this case, the bent portion can be designed to bend the optical axis at a right angle, for example. This allows the circuit board on which the light source is mounted to be positioned almost parallel to the front of the side turn signal lamp, thus allowing the side turn signal lamp to be made particularly thin.

[0010] In the light guide structure of this invention, the bent portion can be positioned so that it is not visible from the external environment when the side turn signal lamp is mounted on a vehicle. This makes it possible to prevent the bent portion from being visible from the external environment when the side turn signal lamp is mounted on a vehicle.

[0011] In the light guide structure of this invention, the cross-sectional shape of the light guide portion perpendicular to the optical axis can be circular at the incident surface, gradually becoming flatter as it moves away from the incident surface, and changing to a flattened rectangle at the radiating surface. With this, since the incident surface of the light guide portion is circular, light from a light source having a circular light-emitting surface with a uniform light distribution can be efficiently incident from the incident surface. Furthermore, by gradually changing the incident circular cross-sectional light to a flattened cross-section and changing the cross-section to a flattened rectangle at the radiating surface, the light from the light source can be efficiently guided to the radiating surface and emitted from the radiating surface.

[0012] In the light guide structure of this invention, the light guide portion can be integrally configured with a lamp cover that covers the lamp housing on which the circuit board on which the light source is mounted is located in the side turn signal lamp, forming a lamp chamber between the lamp housing and the light guide portion, and shielding the lamp chamber from the external environment. As a result, since the light guide portion is integrally configured with the lamp cover, the number of parts can be reduced compared to when the light guide portion and the lamp cover are configured as separate parts. [Brief explanation of the drawing]

[0013] [Figure 1] Figures 4(A-F) show exploded perspective views illustrating an embodiment of a side turn signal lamp (hereinafter abbreviated as "turn lamp") to which this invention is applied, with the turn lamp shown in Figure 4(A-F) disassembled into its components. [Figure 2A] Figure 4(A~F) is a perspective view showing a physical side mirror (door mirror using a physical mirror) for the right side of a vehicle with the turn signal installed (shown with the lower cover of the visor removed), viewed from the front, oblique side (the side closer to the vehicle body). [Figure 2B] Figure 2A is a perspective view of the side mirror from the rear, obliquely to the side (the side furthest from the vehicle body) (shown with the lower cover of the visor removed, similar to Figure 2A). [Figure 3A] Figure 2B is a partially enlarged view (shown with the lower visor cover attached) and a further enlarged view of the area enclosed by the dashed line in the same enlarged view. [Figure 3B]It is a partial cross-sectional view taken along arrow A in FIGS. 2B and 3A (shown with the lower visor cover attached) and an enlarged view of the portion enclosed by a broken line in the cross-sectional view of the same portion (together showing the optical path of light emitted from the light source). [Figure 3C] It is an enlarged cross-sectional view taken along arrow B in FIGS. 2B and 3A (shown with the lower visor cover attached and the upper visor cover removed). [Figure 4A] It is a front view showing the assembled state of the turn signal lamp of FIG. 1. [Figure 4B] It is a rear view of the turn signal lamp of FIG. 4A. [Figure 4C] It is a top plan view of the turn signal lamp of FIG. 4A. [Figure 4D] It is a bottom view of the turn signal lamp of FIG. 4A. [Figure 4E] It is a left side view of the turn signal lamp of FIG. 4A. [Figure 4F] It is a right side view of the turn signal lamp of FIG. 4A. [Figure 5A] It is a front view of the lamp cover (outer lens) of FIG. 1. [Figure 5B] It is a cross-sectional view taken at the position of arrow A in FIG. 5A (same as the position of arrow A in FIGS. 2B and 3A). [Figure 5C] It is a cross-sectional view taken at the position of arrow B in FIG. 5A (same as the position of arrow B in FIGS. 2B and 3A). [Figure 5D] It is a cross-sectional view taken at the position of arrow C in FIG. 5B and an enlarged view of the portion enclosed by a broken line in said cross-sectional view. [Figure 5E] It is a cross-sectional view taken at the position of arrow D in FIG. 5B. [Figure 6A] It is a simulation diagram showing ray tracing of light emitted from a light source for the turn signal lamp of FIGS. 4(A to F), which is obtained when the turn signal lamp is viewed from diagonally upper front. [Figure 6B] It is a simulation diagram showing the ray tracing obtained by the simulation of FIG. 6A, as viewed from the diagonally right front side of the turn signal lamp. [Figure 7A]As a comparative example to Figure 6(A,B), the simulation diagram shows the ray tracing of light emitted from the light source for a turn lamp in which the strip-shaped surface of the light guide section has been removed (the strip-shaped surface has also been replaced with an arc-shaped surface), and the turn lamp is viewed from the front and slightly above (the same direction as Figure 6A). [Figure 7B] Figure 7A is a simulation diagram showing the ray tracing obtained from the simulation, viewed from the front, slightly to the right (same direction as Figure 6B) of the turn signal. [Figure 8A] As a comparative example to Figure 6(A,B), the following simulation diagram shows the ray tracing of light emitted from the light source for a turn signal in which the cross-sectional shape of the outer surface of the bent portion (the cross-sectional shape perpendicular to the optical axis at the outer side of the bent portion) has been changed from an arc shape to a square shape, as seen from the front diagonally above (the same direction as Figure 6A). [Figure 8B] Figure 8A is a simulation diagram showing the ray tracing obtained from the simulation, viewed from the front, slightly to the right (same direction as Figure 6B) of the turn signal. [Figure 9A] Figure 4(A-F) shows a magnified view of the turn signal ramp, specifically the area enclosed by the dashed line E in Figure 3B, schematically illustrating the path of light that deviates from the optical axis of the light guide near the incident surface. [Figure 9B] As a comparative example to Figure 9A, the path of light that deviates from the optical axis of the light guide near the incident surface is schematically shown when the mortar-shaped inclined surface of the structure in Figure 9A is removed and replaced with a flat surface. [Modes for carrying out the invention]

[0014] Embodiments of this invention will now be described. Here, we will describe the case in which this invention is applied to a turn signal mounted on a vehicle door mirror (a side mirror using a physical mirror). Figure 2(A,B) shows a vehicle right-side door mirror 10 equipped with a turn signal to which this invention is applied. Figure 2A shows the view from the front side (rear side of the vehicle) of the door mirror 10, and Figure 2B shows the view from the rear side (front side of the vehicle), both with the lower cover 18 (Figure 3(A~C)) removed from the door mirror 10. The door mirror 10 comprises a mirror plate 12, a mirror housing 14, an upper cover 16, a lower cover 18 (Figure 3(A~C)), and a turn signal 20. The mirror plate 12 is positioned in the front opening 12a of the mirror housing 14. The turn signal 20 is attached to the back side of the mirror housing 14. The upper cover 16 is attached to the mirror housing 14 so as to cover the upper part of the back side of the mirror housing 14 above the turn signal 20. The lower cover 18 (Figure 3(A~C)) is attached to the mirror housing 14 so as to cover the lower side of the mirror housing 14. The lower cover 18 has an opening 18a (Figure 3(A~C)) that exposes the radiating surface 22 of the turn lamp 20 (the front surface of the radiating portion 44 of the light guide portion 38, described later) to the external environment (atmospheric space). The opening 18a is formed in a structure where the end furthest from the vehicle body is open (see Figure 3A). The radiating surface 22 radiates turn signal light from its forward-facing surface 22a toward the front and front sides of the vehicle, and from its tip surface 22b furthest from the vehicle body (the tip surface of the radiating portion 44 of the light guide portion 38, described later) toward the rear and rear sides of the vehicle.

[0015] The turn signal lamp 20 will now be described. Figure 1 shows the turn signal lamp 20 disassembled into its components. The turn signal lamp 20 comprises a lamp housing 24, a circuit board 26, and a lamp cover 28 (outer lens). With the circuit board 26 housed in the circuit board arrangement space 30 of the lamp housing 24, the lamp cover 28 is placed over the lamp housing 24, and the two are joined at their periphery using ultrasonic welding, adhesive, etc., to assemble the turn signal lamp 20. In the assembled state of the turn signal lamp 20, a lamp chamber 32 (Figure 3B) is formed between the lamp housing 24 and the lamp cover 28. The lamp chamber 32 is shielded from the external environment except for a connector insertion opening 34 for connecting a connector (not shown) to the terminals 27 on the back of the circuit board 26. The circuit board 26 is housed in the lamp chamber 32 without any rattle.

[0016] The lamp housing 24 is made from a single molded piece of black resin (such as ABS). One LED 36 (light source) and other circuit elements are mounted on the front surface of the circuit board 26 (printed circuit board). The light-emitting surface 36a of the LED 36 faces in a direction perpendicular to the board surface of the circuit board 26. The front shape of the light-emitting surface 36a is circular, which allows light to be emitted with a uniform distribution.

[0017] The lamp cover 28 is made of a single molded product made of transparent resin (PMMA, etc.). A light guide section 38 is integrally formed in the lamp cover 28. The light guide section 38 has an incident surface 40 that faces the light-emitting surface 36a of the LED 36 and directs the light emitted from the light-emitting surface 36a into the light guide section 38, a relay section 42 that guides the light incident from the incident surface 40 and passes it to the radiating section 44, and a radiating section 44 that guides the light passed from the relay section 42 and radiates it toward the external environment from the forward surface 22a and tip surface 22b of the radiating surface 22. The incident surface 40 is formed in the shape of a circle with a diameter slightly larger than the light-emitting surface 36a of the LED 36 (see the enlarged view at the bottom of Figure 3B). The relay section 42 has a bent section 54 that curves and bends the optical axis 48 of the light guide section 38. A strip-shaped surface 60 is formed within the plane of the arc-shaped surface 56 of the bent section 54. The strip-shaped surface 60 is formed to improve the light-gathering efficiency of the light guide section 38 by suppressing light leakage from the light guide section 38. In addition, the lamp cover 28 has a plate-shaped portion 50 formed at a position facing the circuit board 26 housed in the circuit board arrangement space 30 of the lamp housing 24. On the front surface 50a of the plate-shaped portion 50, a mortar-shaped inclined surface 51 is formed adjacent to the outer circumferential surface of the light guide section 38 as a light leakage prevention structure, and is inclined concavely toward the outer circumferential surface.

[0018] Figures 4(A-F) show the assembled turn signal lamp 20 from Figure 1. Figure 4A is a front view, Figure 4B is a rear view, Figure 4C is a top view, Figure 4D is a bottom view, Figure 4E is a left side view, and Figure 4F is a right side view. In Figure 4A, the outer peripheral end surface 28a (outer peripheral wall surface) of the lamp cover 28 is surrounded and facing the inner peripheral surface 24ab of the outer peripheral wall 24a of the lamp housing 24, except for the tip surface 22b of the light guide portion 38. Light that leaves the light guide portion 38, passes through the plate surface of the lamp cover 28 and is emitted from the outer peripheral end surface 28a is absorbed by the black outer peripheral wall 24a (light-shielding wall) of the lamp housing 24 or by an adhesive (light-shielding wall) not shown that fills the gap between the outer peripheral end surface 28a and the outer peripheral wall 24a.

[0019] The detailed structure of the lamp cover 28 will be explained. Figures 5(A~E) show the structure of the lamp cover 28. Figure 5A is a front view, Figure 5B is a cross-sectional view taken at the position indicated by arrow A in Figure 5A, Figure 5C is a cross-sectional view taken at the position indicated by arrow B in Figure 5A, Figure 5D is a cross-sectional view taken at the position indicated by arrow C in Figure 5B and an enlarged view of the area enclosed by the dashed line in the same cross-sectional view, and Figure 5E is a cross-sectional view taken at the position indicated by arrow D in Figure 5B. The lamp cover 28 is joined to the lamp housing 24 around the entire circumference of its outer edge as seen in Figure 5A. The lamp cover 28 has a light guide portion 38, a plate-like portion 50, etc., integrally formed. The lamp cover 28 is constructed to have a nearly constant plate thickness, except for the light guide portion 38. The light guide portion 38 is constructed as a structure in which an uneven portion is formed on a part of the plate surface having this constant plate thickness.

[0020] As seen in Figure 5B, the light guide section 38 is composed of an incident surface 40, a relay section 42, and a radiating section 44 arranged continuously along the optical axis 48. The relay section 42 is composed of a straight section 52, a bent section 54, and a connecting section 55 arranged continuously along the optical axis 48 from the incident surface 40 side. The straight section 52 extends perpendicular to the incident surface 40. Here, the incident surface 40 is parallel to the plate surface of the plate-like section 50 and is flush with the back surface 50b of the plate-like section 50. The cross-sectional shape of the straight section 52 in the direction perpendicular to the optical axis 48 is circular.

[0021] The bent portion 54 is formed seamlessly from the straight portion 52 without any steps. The bent portion 54 bends the optical axis 48 at roughly a right angle with a rounded shape. The outer surface of the outer circumference (outer side) of the curved shape of the bent portion 54 is formed as an arc-shaped surface 56 with a convex cross-sectional shape perpendicular to the optical axis 48 (see Figures 5D and 5E, which show the cross-section at the positions indicated by arrows C and D in Figure 5B). The arc-shaped surface 56 is formed along the entire length of the bent portion 54 in the direction of the optical axis 48. The cross-sectional shape of the arc-shaped surface 56 perpendicular to the optical axis 48 is the same circular arc as the straight portion 52 at the point where it connects to the straight portion 52, and gradually becomes a flattened ellipse as it moves away from the straight portion 52 (see Figures 5D and 5E).

[0022] A reflective surface 58 is formed at an intermediate position in the direction of the optical axis 48 of the arc-shaped surface 56, with a shape obtained by cutting the arc-shaped surface 56 flat (elliptical when viewed from the front, see Figure 4F). The reflective surface 58 is provided to efficiently guide the light emitted from the LED 36 in the direction of the front of the light-emitting surface 36a towards the radiating part 44 by reflecting (total internal reflection) the light towards the radiating part 44.

[0023] Within the plane of the arc-shaped surface 56 (within the region of the arc-shaped surface 56), a strip-shaped surface 60 is formed at the outermost position of the curve of the bent shape of the bent portion 54 (see Figures 4F, 5A, etc.). The strip-shaped surface 60 has a flat cross-sectional shape perpendicular to the optical axis 48 (see Figures 5D, 5E). The strip-shaped surface 60 is formed in the direction of the optical axis 48, extending from the straight portion 52 to the entire length of the bent portion 54, with the reflective surface 58 in between (see Figures 4F, 5A, 5B). By forming the strip-shaped surface 60, as will be described later, light leakage from the light guide portion 38 can be suppressed (i.e., the light-gathering efficiency of the light guide portion 38 can be improved) compared to when the strip-shaped surface 60 is not formed (when the position of the strip-shaped surface 60 is also the arc-shaped surface 50), thereby improving the light-guiding efficiency. The width of the strip-shaped surface 60 in a cross-section perpendicular to the optical axis 48 is preferably 1 / 2 or less (more preferably 1 / 3 or less, even more preferably 1 / 4 or less), and 1 / 20 or more (more preferably 1 / 10 or more), of the width of the arc-shaped surface 56 in the same cross-section (here, equal to the diameter of the light guide portion 38). In other words, if the width of the strip-shaped surface 60 is too wide, there will be a lot of light leakage. Also, if the width of the strip-shaped surface 60 is too narrow, the effect of the strip-shaped surface 60 will be reduced. In the design of this embodiment, as shown in Figure 5D, the width of the arc-shaped surface 56 (diameter of the light guide portion 38) is set to 4 mm. In this case, it is preferable to set the width of the strip-shaped surface 60 to 0.2 mm to 2 mm. In the example in Figure 5D, the width of the strip-shaped surface 60 is set to 0.4 mm.

[0024] The outer surface of the inner circumference (inward curve) of the bent shape of the bent portion 54 is formed as a flat surface 62 with a cross-sectional shape perpendicular to the optical axis 48 (see Figures 5D and 5E). The flat surface 62 is formed so that there is no step when it connects to the straight portion 52, and the cross-sectional shape perpendicular to the optical axis 48 gradually changes from the arcuate surface of the straight portion 52 to the flat surface 62.

[0025] The connecting portion 55 is the part formed between the bent portion 54 and the radiating portion 44. As shown in the enlarged view of Figure 3B, the connecting portion 55 is configured as a recess into which a projection 18ab formed on the back side of the edge of the opening 18a of the lower cover 18 fits and is held. By holding the projection 18ab in the connecting portion 55, the radiating portion 44 (radiating surface 22) of the turn ramp 20 is positioned in the correct position relative to the opening 18a.

[0026] The radiating portion 44 has a flattened rectangular cross-sectional shape perpendicular to the optical axis 48 (see Figure 5C). The frontal shape of the radiating portion 44 is elongated in the left-right direction (see Figures 5A, 3A, etc.). The planar shape of the radiating portion 44 is gently curved, following the curvature of the opening 18a (Figure 3A) where the radiating surface 22 is exposed (see Figure 5B). As shown in Figure 5B, the back surface 38a of the light guide portion 38 is formed without any large steps from the incident surface 40 through the relay portion 42 (straight portion 52, bent portion 54, connecting portion 55) to the radiating portion 44. However, on the back surface 38a at the location of the radiating portion 44, fine peaks and valleys (a structure in which protrusions and recesses extending in a direction perpendicular to the plane of the paper in Figure 5B are alternately arranged in a direction along the optical axis 48) are formed by lens cuts 44a (also called prism cuts) across the entire back surface of the radiating portion 44. Light guided to the radiating section 44 is reflected by the lens cut 44a and radiated from the radiating surface 22 toward the external environment, causing the radiating surface 22 to appear luminous and visible from the external environment. No lens cuts are formed on the back surface 38a at the location of the relay section 42 (straight section 52, bent section 54, connecting section 55). Light that reaches the tip of the radiating section 44 is radiated toward the external environment from the tip surface 22b.

[0027] As described above, the cross-sectional shape of the light guide section 38 perpendicular to the optical axis 48 is circular at the incident surface 40, gradually becoming flatter as it moves away from the incident surface 40, and becoming a flattened rectangle at the position of the radiating section 44 where the radiating surface 22 is located. This allows the light emitted from the circular light-emitting surface 36a of the LED 36 to be efficiently incident from the incident surface 40, and the incident circular cross-sectional light is bent at a right angle in a gentle curve at the bending section 54, gradually changing to a flattened cross-section, so that the cross-section at the radiating surface becomes a flattened rectangle. This allows the light from the LED 36 to be efficiently guided to the radiating section 44 and emitted from the radiating surface 22. The optical path when the light 37 emitted from the LED 36 is radiated from the radiating surface 22 is schematically shown in the enlarged view of Figure 3B.

[0028] With the turn signal lamp 20 configured as described above, the light guide portion 38 has a bent portion 54, so the incident surface 40 can be positioned facing the front of the turn signal lamp 20, as shown in Figure 3B. As a result, the circuit board 26 can be positioned parallel to the front of the turn signal lamp 20, so the thickness of the turn signal lamp in the front-to-back direction can be made thinner compared to a structure in which there is no bent portion in the light guide portion and the incident surface is positioned perpendicular to the front of the turn signal lamp (the circuit board is also positioned perpendicular to the front of the turn signal lamp; for example, the structure described in Patent Document 4). Therefore, the turn signal lamp 20 can be easily assembled to the door mirror 10 without interfering with other equipment (mirror actuator, other lights, cameras, etc.) that are assembled to the door mirror 10. Furthermore, as shown in Figure 3B, when the turn lamp 20 is assembled to the door mirror 10, the bent portion 54, the incident surface 40, the inclined surface 51, etc. are hidden behind the cover (lower cover 18 or upper cover 16) and positioned so that they are not visible from the external environment. Therefore, the bent portion 54, the incident surface 40, the inclined surface 51, etc. do not detract from the aesthetic design of the turn lamp 20.

[0029] Here, we will explain the effect of the strip-shaped surface 60 formed within the plane of the arc-shaped surface 56 of the light guide section 38. Figure 6(A,B) is a simulation diagram showing the ray tracing of light emitted from the LED 36 for the turn lamp 20. Figure 6A shows the turn lamp 20 viewed from the front at an oblique angle above, and Figure 6B shows the turn lamp 20 viewed from the front at an oblique angle to the right. The light emitted from the LED 36 is guided by the light guide section 38 and radiated into the external environment from the forward-facing surface 22a and the tip surface 22b of the radiating surface 22.

[0030] Figure 7(A,B) is a simulation diagram showing the ray tracing of light emitted from an LED 36 in a turn lamp 20 in which the strip-shaped surface 60 of the light guide portion 38 has been eliminated (the area where the strip-shaped surface 60 was replaced with an arc-shaped surface 56), as a comparative example. Figures 7A and 7B are viewed from the same direction as Figures 6A and 6B, respectively. Comparing Figures 6A and 7A, it can be seen that in Figure 7A, the amount of light guided to the tip surface 22b of the radiating surface 22 of the light guide portion 38 is less than in Figure 6A. The reason why the amount of light guided to the tip surface 22b is less in Figure 7A is not clear, but comparing Figures 6(A,B) and 7(A,B), it can be seen that in Figure 7(A,B), the light rays converge and cross at a single point in the area enclosed by the dashed line P of the bent portion 54, which may be causing more light to leak out from the light guide portion 38. In other words, in Figure 6(A,B), the strip-shaped surface 60 (Figure 4A, etc.) suppresses the concentration of light rays at the bent portion 54, which may reduce the amount of light leaking from the light guide portion 38.

[0031] Figure 8(A,B) is a simulation diagram showing the ray tracing of light emitted from an LED 36 for a turn lamp 20 in which the cross-sectional shape of the outer surface of the bent portion 54 of the light guide portion 38 of the turn lamp 20 (the cross-sectional shape perpendicular to the optical axis at the outer surface (outer side) of the curve of the bent shape) has been changed from an arc shape to a square shape, as a comparative example. Figures 8A and 8B are viewed from the same direction as Figures 6A and 6B, respectively. Comparing Figures 6A and 8A, it can be seen that in Figure 8A the amount of light guided to the tip surface 22b of the radiating surface 22 of the light guide portion 38 is significantly less than in Figure 6A.

[0032] Thus, by configuring the strip-shaped surface 22 within the plane of the arc-shaped surface 56 of the light guide section 38, light leakage during light guidance by the light guide section 38 is suppressed (i.e., the light-gathering efficiency of the light guide section is improved), and the light-guiding efficiency is improved. Therefore, it becomes possible to reduce the number of LEDs 36 or to use LEDs with relatively low output, thereby resolving issues of cost and heat generation.

[0033] The inclined surface 51 (Figures 1, 3B, 4A, and 5A) formed on the plate-shaped portion 50 of the lamp cover 28 as a light leakage prevention structure will now be described. On the front surface 50a of the plate-shaped portion 50, a mortar-shaped inclined surface 51 is formed adjacent to the outer surface of the light guide portion 38 and surrounding the light guide portion 38, inclining concavely toward the outer surface of the light guide portion 38. The shape of the inclined surface 51 as seen from the front of the lamp cover 28 is circular (see Figures 4A and 5A). The inclined surface 51 constitutes a light leakage prevention structure and is formed to prevent light that has deviated from the light guide portion 38 near the incident surface 40 from penetrating (transmitting) through the plate-shaped portion 50 and leaking to the outside of the turn lamp 20 by totally reflecting the light that has deviated from the light guide portion 38 and guiding it into the plate surface of the plate-shaped portion 50. The inclination angle of the inclined surface 51 with respect to the front surface 50a of the plate-shaped portion 50 is set to an angle at which all or part of the light irradiated directly onto the inclined surface 51 from the LED 36 is totally reflected by the inclined surface 51.

[0034] The operation of preventing light leakage by the inclined surface 51 will be explained. Figure 9A is an enlarged view of the turn lamp 20, showing the area enclosed by the dashed line E in Figure 3B, schematically illustrating the path of light 37a that deviates from the optical axis 48 of the light guide 38 near the incident surface 40. The light 37a that deviates from the optical axis 48 is totally reflected by the inclined surface 51, passes through the plate surface of the plate-shaped part 50, reaches the outer peripheral end surface 28a of the plate-shaped part 50, and is absorbed (shielded) by the inner peripheral surface 24ab of the outer peripheral wall 24a of the black lamp housing 24 facing the outer peripheral end surface 28a (or an adhesive (not shown) filled in the gap between the outer peripheral end surface 28a and the inner peripheral surface 24ab). Therefore, it is possible to suppress light 37a that deviates from the optical axis 48 from penetrating the plate-shaped part 50 and leaking to the outside of the turn lamp 20.

[0035] Figure 9B schematically shows, as a comparative example, the path of light 37a that deviates from the optical axis 48 of the light guide section 38 near the incident surface 40 when the mortar-shaped inclined surface 51 is removed from the structure of Figure 9A and replaced with a flat surface. Since there is no inclined surface, the light 37a that deviates from the optical axis 48 penetrates (is transmitted through) the plate-shaped section 50 and leaks to the outside of the turn lamp 20. The light that leaks to the outside of the turn lamp 20 may be reflected inside the door mirror 10 and leak into the external environment, making it visible. Therefore, in this case, it is necessary to take measures such as placing a light-shielding sheet on top of the plate-shaped section 50 to block the light that penetrates the plate-shaped section 50.

[0036] In the above embodiment, the strip-shaped surface 60 is formed along the entire length of the straight section 52 and the bent section 54, excluding the reflective section 44, in the direction of the optical axis. However, it may also be formed only in a portion of the entire length of the straight section 52 and the bent section 54, or only in a portion of the entire length of the bent section 54, in the direction of the optical axis.

[0037] In the above embodiment, the bending angle of the bent portion 54 was set to a right angle so that the incident surface 40 of the light guide portion 38 faces the front of the turn lamp 20. However, the bending angle of the bent portion 54 can also be set so that the incident surface 40 faces diagonally in front of the turn lamp 20. Furthermore, in the above embodiment, the bent portion 54 was bent with a curved shape, but the bent portion can also be bent with a curved shape.

[0038] In the above embodiment, the arc-shaped surface 56 of the bent portion 54 was positioned only on the outer side of the curve of the bent shape of the bent portion 54. However, the arc-shaped surface 56 can also be formed around the entire circumference of the bent portion 54 in the circumferential direction (around the optical axis 48). Such a structure can be realized, for example, by separating (floating from) a portion of the bent portion 54 in the direction of the optical axis 48 from the plate surface of the lamp cover 28. In this case, the arc-shaped surface 56 can be formed around the entire circumference of the bent portion 54 in the circumferential direction at the point where the bent portion 54 is separated from the plate surface of the lamp cover 28.

[0039] In the above embodiment, the case in which this invention is applied to a turn signal lamp equipped with one LED was described, but this invention can also be applied to turn signal lamps equipped with two or more light sources, or to turn signal lamps equipped with light sources other than LEDs.

[0040] In the above embodiment, the case in which a turn signal lamp equipped with the light guide structure of this invention is mounted on a physical side mirror for a vehicle was described. However, the turn signal lamp equipped with the light guide structure of this invention can also be mounted on an electronic side mirror (a side mirror using a camera). Furthermore, this invention can also be applied to turn signals mounted on parts of the vehicle other than side mirrors.

[0041] Although the above embodiment described a case in which the light guide structure is integrated with the lamp cover, this invention can also be applied to cases in which the light guide structure is configured separately from the lamp cover (for example, the structures described in Patent Documents 1 to 3). [Explanation of Symbols]

[0042] 10...Door mirror, 12...Mirror plate, 12a...Front opening of mirror housing, 14...Mirror housing, 16...Upper cover, 18...Lower cover, 18a...Opening of lower cover, 18ab...Protrusion formed on the back side of the edge of the opening of lower cover, 20...Side turn signal lamp (turn lamp), 22...Radiating surface of side turn signal lamp, 22a...Forward-facing surface of radiating surface, 22b...End face of radiating surface on the side furthest from the vehicle body, 24...Lamp housing, 24a...Outer periphery wall (light-shielding wall) of lamp housing, 24ab...Inner periphery surface of outer periphery wall of lamp housing, 26...Circuit board, 27...Terminals on the back of the circuit board, 28...Lamp cover (outer -Lens), 28a...Outer edge surface of lamp cover (outer wall surface), 30...Circuit board placement space, 32...Lamp chamber, 34...Connector socket, 36...LED (light source), 36a...Light-emitting surface of LED, 37...Light emitted from LED, 37a...Light deviating from the optical axis of the light guide, 38...Light guide, 38a...Back surface of the light guide, 40...Incident surface, 42...Intermediate section, 44...Radiating section, 44a...Lens cut on the back surface of the radiating section, 48...Optical axis of the light guide (optical axis of the light guide structure), 50...Plate-shaped section, 50a...Front surface of the plate-shaped section, 50b...Back surface of the plate-shaped section, 51...Inclined surface, 52...Straight section, 54...Bent section, 55...Connection section, 56...Arch-shaped surface, 58...Reflective surface, 60...Strip-shaped surface, 62...Flat surface

Claims

1. In a light guide structure incorporated into a side turn signal lamp, which has a light guide section that guides light from the light source of the side turn signal lamp from a predetermined incident surface and radiates it toward the external environment from a predetermined radiating surface, The light guide portion has a bent portion that curves and bends the optical axis of the light guide portion. The outer circumferential surface of the bent portion is An arc-shaped surface formed at least on the outer side of the bent shape of the bent portion, having a convex arc shape in cross-section perpendicular to the optical axis and extending in the direction of the optical axis, Within the plane of the arc-shaped surface, there is a band-shaped surface formed at the outermost periphery of the bent shape of the bent portion, with a flat cross-sectional shape perpendicular to the optical axis and extending in the direction of the optical axis. Light guiding structure.

2. The light guide structure according to claim 1, wherein the width of the strip-shaped surface in a cross section perpendicular to the optical axis is 1 / 2 or less of the width of the arc-shaped surface or the width of the light guide portion in the same cross section.

3. The light guide portion has a reflective surface at a position midway along the optical axis of the bent portion, on the outer side of the bent shape of the bent portion, with the outer surface of the bent portion cut flat. The aforementioned strip-shaped surfaces are formed on either side of the reflective surface, at positions closer to the light source and closer to the radiating surface, respectively. The light guide structure according to claim 1.

4. The light guide structure according to claim 1, wherein the bent portion bends the optical axis of the light guide portion at an angle such that the incident surface faces the front or oblique front of the side turn signal lamp.

5. The light guide structure according to claim 4, wherein the bending portion bends the optical axis at a right angle.

6. The light guide structure according to claim 1, wherein the bent portion is positioned so as not to be visible from the external environment when the side turn signal lamp is mounted on the vehicle.

7. The light guide structure according to claim 1, wherein the cross-sectional shape of the light guide portion perpendicular to the optical axis is circular at the position of the incident surface, gradually becomes flatter as it moves away from the incident surface, and changes to a flattened rectangle at the position of the radiating surface.

8. The light guide portion is integrally configured with a lamp cover that covers the lamp housing on which the circuit board on which the light source is mounted is arranged in the side turn signal lamp, forming a light chamber between the lamp housing and the lamp housing, and shielding the light chamber from the external environment, as described in claim 1.

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