Primary lens for vehicle headlight

Abstract

A primary lens (1) for a vehicle headlight outputs light emitted from a light source (30) forward and comprises: a first lens section (10) that has a bullet shape convex forward, and has a front face serving as a refractive surface (13); and a pair of second lens sections (20) that are provided at two opposite places on the outer circumferential surface (12) of the first lens section (10). Each of the second lens sections (20) is formed as a part including the outer circumferential surface of a parabolic shape that is convex backward and has the inside hollowed. The refractive surface (13) of the first lens section (10) causes light emitted from the light source (30) at a first emission angle (Φ1) to be outputted forward, and the outer lateral surface (22) of each of the second lens sections (20) causes a portion of light emitted from the light source (30) at a second emission angle (Φ2) larger than the first emission angle (Φ1) to be totally reflected forward.

Description

Primary lens for vehicle headlights

[0001] The present disclosure relates to a primary lens for a vehicle headlamp.

[0002] There are known primary optical elements for vehicle headlights. The primary optical element converts light emitted from a light source into parallel light and outputs the parallel light to other optical elements. The primary optical element includes a bullet-shaped primary lens and a TIR (Total Internal Reflection) primary lens.

[0003] As disclosed in Patent Documents 1 and 2, a bullet-shaped primary lens can emit highly parallel light and therefore emit light with high luminous intensity. On the other hand, as disclosed in Patent Documents 3 and 4, a TIR primary lens has a large acceptance angle of incident light.

[0004] Japanese Patent Publication No. 2005-174685 Japanese Patent Publication No. 2009-218211 Japanese Patent Publication No. 2008-288010 Japanese Patent Publication No. 2022-090064

[0005] A bullet-shaped primary lens has a high degree of parallelism of parallel light but a small acceptance angle of incident light, whereas a TIR primary lens has a large acceptance angle of incident light but is unlikely to have a high degree of parallelism of parallel light.

[0006] An object of the present disclosure is to provide a primary lens for a vehicle headlamp that has a large angle of acceptance of incident light and easily emits light with high luminous intensity.

[0007] A primary lens according to one aspect of the present disclosure is a primary lens of a vehicle headlamp that irradiates light emitted from a light source forward, and includes: a first lens portion that is bullet-shaped and convex forward, with its front surface being a refractive surface; and a pair of second lens portions that are provided at two locations facing each other on the outer circumferential surface of the first lens portion, each of the second lens portions being convex backward and comprising a portion that includes a parabolic outer circumferential surface with an interior hollowed out, the refractive surface of the first lens portion causing light emitted from the light source at a first emission angle to be emitted forward, and the rear surface of the second lens portion totally reflecting a portion of the light emitted from the light source at a second emission angle that is greater than the first emission angle toward the front.

[0008] According to the present disclosure, the bullet-shaped first lens portion can convert light emitted at a first emission angle into parallel light, and the second lens portion can convert light from a light source that spreads at an angle greater than the first emission angle into parallel light. In addition, the bullet-shaped first lens portion can emit parallel light with high luminous intensity.

[0009] According to the present disclosure, a primary lens for a vehicle headlamp is provided that has a large angle of acceptance of incident light and easily emits light with high luminous intensity.

[0010] FIG. 1 is a perspective view of a primary lens of a vehicle headlamp according to this embodiment, as seen from the front. FIG. 2 is a perspective view of the primary lens, as seen from the rear. FIG. 3 is a front view of the primary lens. FIG. 4 is a rear view of the primary lens. FIG. 5 is a left side view of the primary lens. FIG. 6 is a right side view of the primary lens. FIG. 7 is a plan view of the primary lens. FIG. 8 is a bottom view of the primary lens. FIG. 9 is a cross-sectional view of the primary lens taken along line IX-IX in FIG. 2. FIG. 10 is a cross-sectional view of the primary lens taken along line X-X in FIG. 2.

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. For the sake of convenience, descriptions of components having the same reference numerals as those already described in the description of the embodiments will be omitted. Furthermore, for the sake of convenience, the dimensions of each component shown in the drawings may differ from the actual dimensions of each component.

[0012] Furthermore, in the description of this embodiment, for convenience of explanation, the terms "left-right direction," "up-down direction," and "front-rear direction" may be referred to as appropriate. These directions are relative directions set for the primary lens 1 of the vehicle headlamp illustrated in FIG. 1 . Here, the "left-right direction" includes the "left direction" and the "right direction," and is also the width direction of the vehicle on which the vehicle headlamp is mounted. The "up-down direction" includes the "upward direction" and the "downward direction." The "front-rear direction" includes the "forward direction" and the "rearward direction." The front-rear direction is a direction perpendicular to the left-right direction and the up-down direction. In this embodiment, the emission direction of the light source 30, which will be described later, is defined as the forward direction. Note that in each drawing, the symbol U indicates the upward direction. The symbol D indicates the downward direction. The symbol F indicates the forward direction. The symbol B indicates the rearward direction. The symbol L indicates the leftward direction. The symbol R indicates the rightward direction. The left-right direction is an example of the horizontal direction.

[0013] A primary lens 1 according to this embodiment will be described with reference to Figures 1 to 9. The primary lens 1 is a primary lens of a vehicle headlamp that irradiates light emitted from a light source 30 (described later) forward. Optical components such as lenses are provided in front of the primary lens 1. The light irradiated from the primary lens 1 passes through the optical components and can form a light distribution pattern in front of a vehicle on which the primary lens 1 and optical members are mounted. The light distribution pattern is, for example, a low-beam light distribution pattern.

[0014] Fig. 1 is a perspective view of a primary lens 1 of a vehicle headlamp according to this embodiment, as seen from the front. Fig. 2 is a perspective view of the primary lens 1, as seen from the rear. Fig. 3 is a front view of the primary lens 1. Fig. 4 is a rear view of the primary lens 1. Fig. 5 is a left side view of the primary lens 1. Fig. 6 is a right side view of the primary lens 1. Fig. 7 is a plan view of the primary lens 1. Fig. 8 is a bottom view of the primary lens 1.

[0015] As shown in FIGS. 1 to 8 , a primary lens 1 of a vehicle headlamp includes a first lens portion 10 and a pair of second lens portions 20 .

[0016] As shown in Figures 1, 5 to 8, etc., the first lens unit 10 has a bullet shape that is convex forward. When viewed from the top-bottom or left-right direction, the central portion of the first lens unit 10 is convex forward. The first lens unit 10 has a first rear surface 11 and an outer peripheral surface 12. The first rear surface 11 may be perpendicular to the front-to-back direction and have a substantially circular flat surface. The outer peripheral surface 12 is a surface that is convex forward from the first rear surface 11. The outer peripheral surface 12 is configured to emit light emitted from the light source 30 at a first emission angle φ1 forward. The way the light travels will be described later. The first rear surface 11 is an example of the rear surface of the first lens unit 10.

[0017] Next, the configuration of the pair of second lens units 20 will be described with reference to FIG. 9 as well. FIG. 9 is a cross-sectional view of the primary lens 1 taken along line IX-IX in FIG. 2. FIG. 9 is a cross-sectional view taken along a plane along the optical axis A1 of the first lens unit 10 and extending in the left-right direction. FIG. 9 also shows cross sections of the first lens unit 10 and the second lens unit 20. FIG. 9 is an example of a cross section taken along the front and left-right directions, passing through the light source installation position.

[0018] 1, 2, 7 to 9, etc., the pair of second lens units 20 are part of a parabolic shape formed by rotating a parabola around the optical axis A1 of the first lens unit 10. The pair of second lens units 20 are rotationally symmetrical with respect to the optical axis A1 as the axis of symmetry, and have a bilaterally symmetrical shape.

[0019] The pair of second lens portions 20 are respectively provided at two locations facing each other on the outer peripheral surface 12 of the first lens portion 10. The pair of second lens portions 20 are part of a parabolic shape that opens forward. Furthermore, the pair of second lens portions 20 are part of a parabolic shape whose interior is hollowed out into a small truncated cone, and are part of a parabolic shape that includes the outer peripheral surface of the parabolic shape. In other words, the pair of second lens portions 20 are shaped as if a region from the apex to a portion of the base of the parabolic shape had been hollowed out, and the other portions had been removed to leave only the radially opposing portions. The hollowed-out region is a conical shape whose front surface is smaller than the rear surface and is smaller than the parabolic shape. The parabolic shape and the cone are convex in opposite directions. The hollowed-out small conical shape is coaxial with the parabolic shape being hollowed out.

[0020] 1 to 9 , each second lens unit 20 has a second front surface 21, an outer surface 22, and an inner surface 23. The second front surface 21 is located in the front and corresponds to the bottom surface of the parabolic shape. The second front surface 21 is a flat surface perpendicular to the front-to-rear direction.

[0021] The outer surface 22 corresponds to the outer peripheral surface of the parabolic shape, and is a curved surface that extends at an inclination radially outward from the rear to the front as shown in Figures 7 to 9. The rear end 221 of the outer surface 22 is located at the rear end of the inner surface 23, and the front end 222 of the outer surface 22 is located at the outer peripheral edge of the second front surface 21. The outer surface 22 is a total reflection surface configured to totally reflect light incident on the inner surface toward the front. The outer surface 22 is an example of the rear surface of the second lens unit 20.

[0022] The inner surface 23 is a curved surface that corresponds to the side peripheral surface portion of the hollowed-out cone. The inner surface 23 is located more inward than the outer surface 22 and extends from the rear to the front. More specifically, the inner surface 23 extends in the front-to-rear direction from the rear end 221 of the outer surface 22 to the first rear surface 11 of the first lens unit 10. The inner surface 23 is slightly inclined radially inward from the rear to the front. The inner surface 23 is configured to refract light emitted from the light source 30 toward the outer surface 22.

[0023] Next, with reference to FIG. 9, the way in which light that spreads in the left-right direction travels as it passes through the primary lens 1 will be described.

[0024] 9 , light is emitted from a light source 30 provided behind the primary lens 1. The light source 30 is, for example, an LED (Light Emitting Diode) element or an LD (Laser Diode) element. The center C of the light emission surface 31 of the light source 30 is located on the optical axis A1 of the first lens unit 10. Here, the center C of the light emission surface 31 will be described as the light source installation position.

[0025] 9 , part of the light emitted from light source 30 and spreading in the left-right direction is incident on first rear surface 11 of first lens unit 10, and the other part of the light is incident on inner surface 23 of second lens unit 20. The travel of each type of light will now be described.

[0026] As shown in Fig. 9 , light L1 emitted from light source 30 at a first emission angle φ1 is incident on first rear surface 11 of first lens unit 10. First emission angle φ1 is an arbitrary emission angle greater than or equal to 0 degrees and less than or equal to a first threshold angle Th1. In the cross section shown in Fig. 9 , first threshold angle Th1 is the angle between optical axis A1, which passes through center C of light source 30 and extends in the front-to-rear direction, and LP1. LP1 is the leftmost portion of the contact area between inner surface 23 and first rear surface 11 of first lens unit 10 (Figs. 4, 7, and 8).

[0027] Light L1 is refracted at first rear surface 11, passes through the inside of first lens unit 10, and reaches refractive surface 13 of first lens unit 10. Light L1 is further refracted by refractive surface 13 and emitted forward. Light L1 emitted from refractive surface 13 is emitted forward as collimated light parallel to optical axis A1 of first lens unit 10.

[0028] Meanwhile, a portion of the light L2 emitted from the light source 30 at a second emission angle φ2 greater than the first emission angle φ1 is incident on the inner surface 23 of the second lens unit 20. The second emission angle φ2 is an arbitrary emission angle greater than the first threshold angle Th1 and equal to or less than the second threshold angle Th2. In the cross section shown in FIG. 9 , the second threshold angle Th2 is the angle range formed by RP2 and the optical axis A1, which passes through the center C of the light source 30 and extends in the front-to-rear direction. RP2 is the rightmost portion of the rear end 221 of the outer surface 22 ( FIGS. 4 , 7 , and 8 ).

[0029] Light L2 is refracted at the inner surface 23, passes through the inside of the second lens unit 20, and reaches the outer surface 22. Light L2 is then totally reflected forward by the outer surface 22. The totally reflected light L2 reaches the second front surface 21 of the second lens unit 20 and is emitted forward from the second front surface 21. Light L2 emitted from the second front surface 21 is emitted forward as collimated light parallel to the optical axis A1 of the first lens unit 10.

[0030] Next, with reference to FIG. 10, the travel of light that spreads in the vertical direction and passes through the primary lens 1 will be described.

[0031] Fig. 10 is a cross-sectional view of the primary lens 1 taken along line X-X in Fig. 2. Fig. 10 is a cross-sectional view taken along a plane along the optical axis A1 of the first lens unit 10 and extending in the vertical direction. Fig. 10 shows only the cross-section of the first lens unit 10, and does not show the cross-section of the second lens unit 20. Fig. 10 is an example of a cross-section taken along the front and vertical directions, passing through the light source installation position.

[0032] 10 , part of the light emitted from light source 30 and spreading in the vertical direction is incident on first rear surface 11 of first lens unit 10, but the other part of the light is not incident on first rear surface 11 of first lens unit 10 or on inner surface 23 of second lens unit 20. The way each type of light travels will now be described.

[0033] As shown in Fig. 10 , light L3 emitted from light source 30 at a third emission angle φ3 is incident on first rear surface 11 of first lens unit 10. Third emission angle φ3 is an arbitrary emission angle greater than or equal to 0 degrees and less than or equal to a third threshold angle Th3. In the cross section shown in Fig. 10 , third threshold angle Th3 is the angle between UP3 and optical axis A1, which passes through center C of light source 30 and extends in the front-to-rear direction. UP3 is the uppermost portion of first rear surface 11 of first lens unit 10 (Figs. 4, 5, and 6).

[0034] Light L3 is refracted at first rear surface 11, passes through the inside of first lens unit 10, and reaches refractive surface 13 of first lens unit 10. Light L3 is further refracted by refractive surface 13 and emitted forward. Light L3 emitted from refractive surface 13 is emitted forward as collimated light parallel to optical axis A1 of first lens unit 10.

[0035] On the other hand, light L4 emitted from light source 30 at an emission angle greater than third threshold angle Th3 does not enter first rear surface 11 of first lens unit 10, and does not enter inner surface 23 of second lens unit 20. Since a pair of second lens units 20 is not provided in the vertical direction, light L4 emitted and spread in the vertical direction does not enter either first lens unit 10 or the pair of second lens units 20.

[0036] As described above, the primary lens 1 of this embodiment converts light L1 emitted from the light source 30 at a first emission angle φ1 into parallel light in the left-right direction by the first lens unit 10, and converts light L2 emitted in a spread manner at a second emission angle φ2 larger than the first emission angle φ1 into parallel light by the second lens unit 20. This makes it possible to increase the angle at which light emitted from the light source 30 can be captured, compared to a case in which the second lens unit 20 is not provided in the left-right direction. Furthermore, the bullet-shaped first lens unit 10 can emit parallel light with high luminous intensity. Therefore, this embodiment makes it possible to provide a primary lens 1 that has a large angle at which incident light can be captured and that can emit light with high luminous intensity.

[0037] The pair of second lens units 20 may be provided at positions facing each other in the left-right direction (FIGS. 3 and 4). Vehicle headlamps are required to emit a flat light distribution pattern that is wide in the left-right direction but narrow in the up-down direction. The primary lens 1 in which the pair of second lens units 20 are provided facing each other in the left-right direction is suitable for irradiating light onto a flat area, and is therefore suitable for vehicle headlamps.

[0038] The inner surface 23 of the second lens unit 20 may refract light L2 from the light source 30 toward the outer surface 22 of the second lens unit 20 ( FIG. 9 ). With this configuration, the second lens unit 20 can efficiently guide light L2 emitted from the light source 30 to the outer surface 22. Since the outer surface 22 can totally reflect a larger amount of light forward, the luminous flux utilization rate can be increased.

[0039] Each of the pair of second lens portions 20 may be a part including the outer periphery of a sector when viewed from the front. As shown in Fig. 3 , the second front surfaces 21 of the pair of second lens portions 20 correspond to the sector shape, and the front ends 222 of the outer surfaces 22 correspond to the outer periphery of the sector. With this configuration, the primary lens 1 is likely to form a flat light distribution pattern, making it suitable for vehicle headlights.

[0040] A rear end 221 of the outer surface 22 of the second lens unit 20 may be located rearward of the first rear surface 11 of the first lens unit 10. With this configuration, the outer surface 22 can reflect a larger amount of the light L2 emitted from the light source 30 at the second emission angle φ2, thereby increasing the luminous flux utilization rate.

[0041] The front end 222 of the outer surface 22 of the second lens unit 20 may be located forward of the first rear surface 11 of the first lens unit 10. In other words, the second front surface 21 of the second lens unit 20 may be located forward of the first rear surface 11 of the first lens unit 10. The outer surface 22 is a reflective surface that extends obliquely outward in the front-to-rear direction, and the larger the outer surface 22, the more light can be reflected forward. By ensuring that the outer surface 22 is wide so that the front end of the outer surface 22 of the second lens unit 20 is located forward of the first rear surface 11 of the first lens unit 10, it is possible to reflect more light forward and form a wide light distribution pattern in the left-right direction.

[0042] The mutually facing inner surfaces 23 of the pair of second lens units 20 extend rearward from the first rear surface 11 of the first lens unit 10. Because the inner surfaces 23 extend rearward beyond the first rear surface 11, it is possible to capture a larger amount of light L2 emitted from the light source 30 at the second emission angle φ2 that is larger than the first emission angle φ1. Therefore, it is possible to increase the capture angle of incident light.

[0043] The first rear surface 11 of the first lens portion 10 is exposed rearward from the gap between the opposing inner surfaces 23 of the pair of second lens portions 20. Because the first rear surface 11 is exposed rearward from the gap between the inner surfaces 23, it becomes easier to capture light L1 emitted from the light source 30 at the first emission angle φ1. This light L1 passes through the first lens portion, allowing the primary lens 1 of this embodiment to emit highly luminous, parallel light.

[0044] A light source accommodating space S is formed by the first rear surface 11 of the first lens unit 10 and the mutually facing inner surfaces 23 of the pair of second lens units 20. The light source accommodating space S is a space that includes the emission surface 31 of the light source 30. In this way, the first rear surface 11 of the first lens unit 10 and the inner surfaces 23 of the second lens units 20 are arranged to surround the emission surface 31 of the light source 30, and therefore the primary lens 1 of this embodiment can efficiently take in light emitted from the light source 30.

[0045] In a cross section taken along the front and left-right direction and passing through the center C (light source installation position) of light source 31, a cross section of first lens unit 10 and a cross section of the pair of second lens units 20 appear ( FIG. 9 ). On the other hand, in a cross section taken along the front and up-down direction and passing through the center C (light source installation position) of light source 30, only a cross section of first lens unit 10 appears, and a cross section of the pair of second lens units 20 does not appear ( FIG. 10 ).

[0046] In this way, since a pair of second lens units 20 is not provided in the vertical direction, the light L4 that is emitted and spreads in the vertical direction is not incident on either the first lens unit 10 or the pair of second lens units 20. With this configuration, it is possible to form a wide light distribution pattern in the horizontal direction without increasing the vertical dimension of the primary lens 1.

[0047] Although the embodiments of the present disclosure have been described above, it goes without saying that the technical scope of the present disclosure should not be interpreted as being limited by the description of the present embodiments. The present embodiments are merely examples, and it will be understood by those skilled in the art that various modifications of the embodiments are possible within the scope of the disclosure described in the claims. The technical scope of the present disclosure should be determined based on the scope of the disclosure described in the claims and its equivalents.

[0048] The primary lens 1 can be mounted on a vehicle headlamp that emits a low-beam light distribution pattern. The central region of the low-beam light distribution pattern can be illuminated with light of relatively high luminous intensity emitted from the first lens portion 10, and regions to the left and right of the central region can be illuminated with light of relatively low luminous intensity emitted from the pair of second lens portions 20, making the primary lens 1 suitable for vehicle headlamp use.

[0049] The configurations described in the following items also constitute part of the present disclosure. Item 1: A primary lens for a vehicle headlamp that irradiates light emitted from a light source forward, comprising: a first lens portion that is bullet-shaped and convex forward, with a front surface being a refractive surface; and a pair of second lens portions provided at two locations facing each other on the outer circumferential surface of the first lens portion, each of the second lens portions being convex backward and formed by a portion that includes an outer circumferential surface that is parabolic and hollowed out internally, the refractive surface of the first lens portion causing light emitted from the light source at a first emission angle to emit forward, and a rear surface of the second lens portion totally reflecting forward a portion of light emitted from the light source at a second emission angle that is larger than the first emission angle. Item 2: The primary lens according to item 1, wherein the pair of second lens portions are provided at positions facing each other in the left-right direction. Item 3: The primary lens according to item 1 or 2, wherein the inner surface of the second lens unit refracts light emitted from the light source at the second emission angle toward the rear surface. Item 4: The primary lens according to any one of items 1 to 3, wherein the second lens unit is a part including an outer periphery of a sector when viewed from the front. Item 5: The primary lens according to any one of items 1 to 4, wherein a rear end of the rear surface of the second lens unit is located rearward of the rear surface of the first lens unit. Item 6: The primary lens according to any one of items 1 to 5, wherein a front end of the rear surface of the second lens unit is located forward of the rear surface of the first lens unit. Item 7: The primary lens according to any one of items 1 to 6, wherein inner surfaces of a pair of second lens units facing each other extend rearward from the rear surface of the first lens unit. Item 8: The primary lens according to any one of items 1 to 7, wherein the rear surface of the first lens unit is exposed rearward from a gap between inner surfaces of the pair of second lens units facing each other. Item 9: The primary lens according to any one of Items 1 to 8, wherein a light source accommodating space is formed by the rear surface of the first lens portion and inner surfaces of the pair of second lens portions facing each other.Item 10: The primary lens according to any one of Items 1k to 19, wherein a cross section of the first lens portion appears in a cross section taken along the front and up-down direction through a light source installation position, and a cross section of the first lens portion and a cross section of the second lens portion appear in a cross section taken along the front and left-right direction through a light source installation position.

[0050] This application claims priority based on Japanese Application No. 2024-012840 filed on January 31, 2024, and incorporates by reference all of the contents of the aforementioned Japanese application.

Claims

1. A primary lens for a vehicle headlamp that irradiates light emitted from a light source forward, comprising: a first lens portion that is bullet-shaped and convex forward, with a refractive surface on its front surface; and a pair of second lens portions provided at two locations facing each other on the outer periphery of the first lens portion, each of the second lens portions being convex backward and comprising a portion of the outer periphery that includes a hollowed-out parabolic shape; the refractive surface of the first lens portion causes light emitted from the light source at a first emission angle to be emitted forward; and the rear surface of the second lens portion totally reflects, forward, a portion of the light emitted from the light source at a second emission angle that is greater than the first emission angle.

2. The primary lens according to claim 1, wherein the pair of second lens portions are provided at positions facing each other in the left-right direction.

3. The primary lens of claim 1, wherein the inner surface of the second lens portion refracts light emitted from the light source at the second emission angle toward the rear surface.

4. The primary lens according to claim 1, wherein the second lens portion is a part including the outer periphery of a sector when viewed from the front.

5. The primary lens of claim 1, wherein a rear end of the rear surface of the second lens portion is located rearward of the rear surface of the first lens portion.

6. The primary lens of claim 1, wherein a front edge of the rear surface of the second lens portion is located forward of a rear surface of the first lens portion.

7. The primary lens according to claim 1, wherein the opposing inner surfaces of the pair of second lens portions extend rearward from the rear surface of the first lens portion.

8. The primary lens according to claim 1, wherein the rear surface of the first lens portion is exposed rearward from a gap between the inner surfaces of the pair of second lens portions facing each other.

9. The primary lens according to claim 1, wherein a light source accommodating space is formed by the rear surface of said first lens portion and the inner surfaces of the pair of said second lens portions facing each other.

10. A primary lens as described in claim 1, wherein a cross section of the first lens portion appears in a cross section taken along the front and vertical directions through the light source installation position, and wherein a cross section of the first lens portion and a cross section of the second lens portion appear in a cross section taken along the front and horizontal directions through the light source installation position.

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