Light leakage prevention structure for the light guide structure of the side turn signal lamp

Abstract

This prevents light that deviates from the optical axis of the light guide structure near the incident surface of the light guide structure from leaking outside the turn lamp. [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 into the incident surface 40 and radiates it outwards from the radiating surface 22 towards the external environment. The light leakage prevention structure has a plate-shaped section 50 that is connected to one end of the light guide section 38 where the incident surface 40 is located and is integrally formed with the light guide section 38 so as to extend in a plane direction parallel or non-parallel to the incident surface 40. The plate-shaped section 50 has an inclined surface 51 on its front surface 50a adjacent to the outer circumferential surface of the light guide section 38, which is concave inclined toward the outer circumferential surface of the light guide section 38.

Description

[Technical Field]

[0001] The present invention relates to a light leakage prevention structure for a light guide structure of a side turn signal lamp mounted on a vehicle, which suppresses leakage of light deviating from a predetermined optical axis of the light guide structure to the outside of the side turn signal lamp near an incident surface of the light guide structure. [Background Art]

[0002] Some side turn signal lamps for vehicles incorporate a light guide structure. This light guide structure is configured to allow light from a light source in the side turn signal lamp to enter through a predetermined incident surface, guide the light, and emit the light toward the external environment from a predetermined emission surface. Conventional light guide structures include those described in, for example, the following Patent Documents 1 to 3. [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-229386 [Patent Document 2] Japanese Patent No. 6003177 [Patent Document 3] Japanese Patent Application Laid-Open No. 2021-097013 [Patent Document 4] U.S. Pat. No. 8,475,018 Specification [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] In conventional light guide structures, there has been a problem that light deviating from the predetermined optical axis of the light guide structure near the incident surface leaks out of the side turn signal lamp from locations other than the emission surface, and becomes visible to the external environment. Therefore, in order to solve this problem, it has been necessary to block light deviating from the optical axis of the light guide structure by, for example, arranging a light shielding sheet near the incident surface of the light guide structure.

[0005] This invention solves the problems of the prior art and provides a light leakage prevention structure for a side turn signal lamp's light guide structure that suppresses light that deviates from a predetermined optical axis of the light guide structure from leaking to the outside of the side turn signal lamp from locations other than the radiating surface. [Means for solving the problem]

[0006] The light leakage prevention structure for a light guide structure of this invention is a light leakage prevention structure for a light guide structure that is incorporated into a side turn signal lamp and 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, wherein the light leakage prevention structure has a plate-like section that is connected to one end of the light guide section where the incident surface is located and extends in a plane direction parallel or non-parallel to the incident surface and is integrally configured with the light guide section, and the plate-like section has an inclined surface on its front surface adjacent to the outer circumferential surface of the light guide section that is concavely inclined toward the outer circumferential surface of the light guide section. With this, at least a portion of the light that deviates from the optical axis of the light guide section near the incident surface of the light guide section is totally reflected by the inclined surface of the plate-like section and travels through the plate-like section, so that the light that deviates from the optical axis can be prevented from leaking to the outside of the side turn signal lamp.

[0007] In the light leakage prevention structure of the light guide structure of this invention, the incident surface may be circular, and the inclined surface may be formed in a mortar shape that surrounds the incident surface. With this, at least a portion of the light that deviates from the optical axis of the light guide portion in each radial direction around the incident surface near the incident surface is totally reflected by the mortar-shaped inclined surface that surrounds the incident surface and travels through the plate-like portion, thereby suppressing the leakage of light deviating from the optical axis to the outside of the side turn signal lamp.

[0008] The light leakage prevention structure of the light guide structure of this invention may have a light-shielding wall positioned facing the outer peripheral end surface of the plate-shaped portion. With this, light that deviates from the optical axis of the light guide near the incident surface of the light guide, undergoes total internal reflection at the inclined surface of the plate-shaped portion, and travels through the plate-shaped portion is shielded by the light-shielding wall when it exits from the outer peripheral end surface of the plate-shaped portion, thereby more reliably suppressing the leakage of such light to the outside of the side turn signal lamp.

[0009] In the light leakage prevention structure of the light guide structure of this invention, the light guide portion may have a bent portion that curves and bends the optical axis of the light guide portion so that the incident surface faces the front or oblique front of the side turn signal lamp. As a result, the circuit board on which the light source is mounted can be positioned in a position nearly parallel to the front of the side turn signal lamp, so the thickness of the side turn signal lamp can be made thinner compared to when there is no bent portion or the bend angle is shallow and the circuit board is positioned in a position 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 and other equipment from interfering with each other. Furthermore, since the incident surface is positioned to face the front or oblique front of the side turn signal lamp, light that deviates from the optical axis of the light guide near the incident surface of the light guide will attempt to move in the front or oblique front direction of the side turn signal lamp. However, at least a portion of the light that deviates from the optical axis of the light guide is totally reflected by the inclined surface and travels through the plate-like part, thus suppressing it from moving in the front or oblique front direction of the side turn signal lamp, and thus preventing the light from leaking outside the side turn signal lamp.

[0010] In the light leakage prevention structure of the light guide structure of this invention, the incident surface and the inclined surface can be positioned so that they are not visible from the external environment when the side turn signal lamp is mounted on a vehicle. As a result, since the incident surface and the inclined surface are positioned so that they are not visible from the external environment when the side turn signal lamp is mounted on a vehicle, it is possible to further suppress the visibility of light that deviates from the optical axis of the light guide near the incident surface of the light guide from the external environment.

[0011] In the light leakage prevention structure of the light guide structure of this invention, the plate-shaped portion is fitted over 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 plate-shaped portion, and forming a part of the lamp cover that shields the lamp chamber from the external environment. The plate-shaped portion can be positioned so that when the lamp cover is fitted over the lamp housing, it faces the circuit board and its incident surface faces the light source. As a result, since the light guide portion is integrated 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.

[0012] In the light leakage prevention structure of the light guide structure of this invention, when the lamp cover is fitted over the lamp housing, the outer peripheral end surface of the plate-shaped portion can be positioned facing the inner peripheral surface of the outer peripheral wall of the lamp housing. With this arrangement, light that deviates from the optical axis of the light guide near the incident surface of the light guide, undergoes total internal reflection on the inclined surface of the plate-shaped portion, and travels through the plate-shaped portion is shielded by the outer peripheral wall of the lamp housing (or the adhesive filled between the outer peripheral end surface of the plate-shaped portion and the outer peripheral wall of the lamp housing) when emitted from the outer peripheral end surface of the plate-shaped portion, thereby suppressing light leakage to the outside of the side turn signal lamp. [Brief explanation of the drawing]

[0013] [Figure 1]It is a view showing an embodiment of a side turn signal lamp (hereinafter abbreviated as "turn lamp") to which the present invention is applied, and is an exploded perspective view showing the turn lamp of Figs. 4(A to F) exploded into constituent components. [Figure 2A] It is a perspective view showing a physical side mirror for the right side of a vehicle (a door mirror using a physical mirror) assembled with the turn lamp of Figs. 4(A to F) (shown with the lower cover of the visor removed), as viewed from the front side oblique lateral side (the side close to the vehicle body). [Figure 2B] It is a perspective view of the side mirror of Fig. 2A as viewed from the rear side oblique lateral side (the side far from the vehicle body) (shown with the lower cover of the visor removed similarly to Fig. 2A). [Figure 3A] It is a partially enlarged view of Fig. 2B (shown with the lower cover of the visor attached) and an enlarged view of a portion enclosed by a broken line in the enlarged view of the same portion. [Figure 3B] It is a partial cross-sectional view at the position viewed from arrow A in Figs. 2B and 3A (shown with the lower cover of the visor attached) and an enlarged view of a portion enclosed by a broken line in the cross-sectional view of the same portion (also showing the optical path of light emitted from the light source). [Figure 3C] It is an enlarged cross-sectional view at the position viewed from arrow B in Figs. 2B and 3A (shown with the lower cover of the visor attached and the upper cover removed). [Figure 4A] It is a front view showing the turn lamp of Fig. 1 in an assembled state. [Figure 4B] It is a rear view of the turn lamp of Fig. 4A. [Figure 4C] It is a plan view of the turn lamp of Fig. 4A. [Figure 4D] It is a bottom view of the turn lamp of Fig. 4A. [Figure 4E] It is a left side view of the turn lamp of Fig. 4A. [Figure 4F] It is a right side view of the turn 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 at the position viewed from arrow A in Fig. 5A (the same as the position viewed from arrow A in Figs. 2B and 3A). [Figure 5C]It is a cross-sectional view taken at the arrow B position in FIG. 5A (same as the arrow B position in FIG. 2B and FIG. 3A). [Figure 5D] It is a cross-sectional view taken at the arrow C position in FIG. 5B and an enlarged view of a portion enclosed by a broken line in the cross-sectional view. [Figure 5E] It is a cross-sectional view taken at the arrow D position in FIG. 5B. [Figure 6A] It is a simulation diagram showing ray tracing of light emitted from a light source for the turn lamp of FIGS. 4(A to F), which shows the turn lamp viewed from an obliquely upper front direction. [Figure 6B] It is a simulation diagram showing the ray tracing obtained by the simulation in FIG. 6A, viewed from an obliquely right front side of the turn lamp. [Figure 7A] As a comparative example for FIGS. 6(A, B), this is a simulation diagram showing ray tracing of light emitted from a light source for a turn lamp obtained by removing the strip-shaped surface of the light guide portion from the turn lamp of FIGS. 4(A to F) (the portion of the strip-shaped surface is also formed as an arc-shaped surface), which shows the turn lamp viewed from an obliquely upper front direction (the same direction as FIG. 6A). [Figure 7B] It is a simulation diagram showing the ray tracing obtained by the simulation in FIG. 7A, viewed from an obliquely right front side (the same direction as FIG. 6B) of the turn lamp. [Figure 8A] As a comparative example for FIGS. 6(A, B), this is a simulation diagram showing ray tracing of light emitted from a light source for a turn lamp obtained by changing the cross-sectional shape of the outer peripheral surface of the bent portion (the cross-sectional shape in the direction orthogonal to the optical axis at the position on the outer side of the bent shape) from an arc shape to a square shape in the turn lamp of FIGS. 4(A to F), which shows the turn lamp viewed from an obliquely upper front direction (the same direction as FIG. 6A). [Figure 8B] It is a simulation diagram showing the ray tracing obtained by the simulation in FIG. 8A, viewed from an obliquely right front side (the same direction as FIG. 6B) of the turn lamp. [Figure 9A] It is an enlarged view showing a portion enclosed by broken line E in FIG. 3B for the turn lamp of FIGS. 4(A to F), and schematically shows the propagation path of light deviated from the optical axis of the light guide portion 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 incident surface 40 of the light guide portion 38 was arranged to be approximately flush with the back surface of the plate-shaped portion 50. However, this invention can also be applied to light guide structures in which the incident surface 40 is not flush with the back surface of the plate-shaped portion 50 (for example, the incident surface 40 is arranged to protrude into the lamp chamber 32).

[0037] In the above embodiment, the incident surface 40 of the light guide portion 38 was arranged parallel to the plate surface of the plate-shaped portion 50. However, this invention can also be applied to a structure in which the incident surface 40 is arranged not parallel to the plate surface of the plate-shaped portion 50.

[0038] In the above embodiment, the case in which the light guide is integrated with the lamp cover was described, but this invention can also be applied when the light guide is configured separately from the lamp cover. In that case, the plate-shaped part can be configured separately from the lamp cover, such as a plate-shaped member connected to one end of the light guide.

[0039] In the above embodiment, the case in which the present invention is applied to a turn signal lamp equipped with a light guide portion having a bent portion was described, but the present invention can also be applied to a turn signal lamp equipped with a light guide portion that does not have a bent portion.

[0040] 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.

[0041] In the above embodiment, the case in which a turn signal lamp equipped with the light leakage prevention 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 leakage prevention 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. [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 leakage prevention structure for a light guide structure that is incorporated into a side turn signal lamp and 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 leakage prevention structure has a plate-like portion that is integrally formed with the light guide portion and is connected to one end of the light guide portion where the incident surface is located, and extends in a plane direction parallel or non-parallel to the incident surface. The plate-like portion has an inclined surface on its front surface adjacent to the outer surface of the light guide portion, which slopes concavely toward the outer surface of the light guide portion. Light guide structure with light leakage prevention mechanism.

2. The light leakage prevention structure for a light guide structure according to claim 1, wherein the incident surface is circular and the inclined surface is formed in a mortar shape surrounding the incident surface.

3. A light leakage prevention structure for a light guide structure according to claim 1, having a light-shielding wall positioned facing the outer peripheral end surface of the plate-like portion.

4. The light guide structure according to claim 1, wherein the light guide portion has a bent portion that curves and bends the optical axis of the light guide portion so 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 incident surface and the inclined surface are positioned so as not to be visible from the external environment when the side turn signal lamp is mounted on the vehicle.

6. The plate-shaped portion is fitted over 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 lamp housing, and forming part of the lamp cover that shields the lamp chamber from the external environment. The plate-shaped portion is positioned so that it faces the circuit board and its incident surface faces the light source when the lamp cover is fitted over the lamp housing. A light leakage prevention structure for the light guide structure according to claim 1.

7. The light leakage prevention structure for a light guide structure according to claim 6, wherein the outer peripheral end surface of the plate-shaped portion is positioned facing the inner peripheral surface of the outer peripheral wall of the lamp housing when the lamp cover is fitted over the lamp housing.

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