Lamp unit

Abstract

A lamp unit comprises a light guide body that guides light emitted from a first light source and a second light source to a projection lens. The light guide body has: a first optical element that forms light emitted from the first light source into parallel light; a cut-off line formation part that fully reflects some of the light emitted from the first light source to form a cut-off line of a low beam light distribution pattern; a first reflection surface that fully reflects the parallel light formed by the first optical element so that the light passes through the upper side of the cut-off line formation part and heads toward the projection lens; a second optical element that forms light emitted from the second light source into parallel light; and a second reflection surface that fully reflects the parallel light formed by the second optical element so that the light passes through the lower side of the cut-off line formation part and heads toward the projection lens.

Description

Lighting unit

[0001] The present disclosure relates to a lamp unit.

[0002] Patent Document 1 discloses a lamp unit that forms a desired light distribution pattern by controlling incident light to a projection lens using a light guide disposed between a light source and a projection lens. The light guide has a first exit surface for emitting light for a low-beam light distribution pattern and a second exit surface for emitting light for an additional light distribution pattern that is added when forming a high-beam light distribution pattern.

[0003] Japanese Patent Application Publication No. 2022-94635

[0004] However, in recent years, design requirements have led to a demand for vehicle lamps that are small in height and long in width. If the technology disclosed in Patent Document 1 is applied to vehicle lamps of this shape, the diffusion component in the left and right directions of the light distribution pattern tends to be insufficient.

[0005] An object of the present disclosure is to provide a lighting unit that can form a wide light distribution pattern in the left-right direction.

[0006] a first optical element that converts the light emitted from the first light source into parallel light; a cutoff line forming portion that totally reflects a portion of the light emitted from the first light source to form the cutoff line of the low beam distribution pattern; a first reflecting surface that totally reflects the parallel light formed by the first optical element so that the parallel light passes above the cutoff line forming portion and heads toward the projection lens; a second optical element that converts the light emitted from the second light source into parallel light; and a second reflecting surface that totally reflects the parallel light formed by the second optical element so that the parallel light passes below the cutoff line forming portion and heads toward the projection lens.

[0007] According to the present disclosure, it is possible to provide a lighting unit that can form a wide light distribution pattern in the left-right direction.

[0008] Fig. 1 is a vertical cross-sectional view illustrating the configuration of a lamp unit according to a first embodiment. Fig. 2 is a vertical cross-sectional view illustrating the configuration of a lamp unit according to a modified example. Fig. 3 is a vertical cross-sectional view illustrating the configuration of a lamp unit according to a modified example. Fig. 4 is a vertical cross-sectional view illustrating the configuration of a lamp unit according to a second embodiment. Fig. 5 is a vertical cross-sectional view illustrating the configuration of a lamp unit according to a third embodiment.

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. For the sake of convenience, the dimensions of each component shown in the drawings may differ from the actual dimensions of each component. 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. These directions are relative directions set for the lamp unit 1 illustrated in FIG. 1, and the direction of light emitted from the lamp unit 1 is defined as the forward direction.

[0010] First Embodiment Fig. 1 is a vertical cross-sectional view illustrating the configuration of a lamp unit 1 according to a first embodiment. In Fig. 1, some light emitted from a light source is illustrated as light beams L1 to L4.

[0011] The lamp unit 1 is mounted in a vehicle headlamp and configured to form a low beam light distribution pattern and a high beam light distribution pattern including a cut-off line.

[0012] As shown in FIG. 1 , the lighting unit 1 includes a plurality of primary light sources 2 , a plurality of secondary light sources 3 , a projection lens 4 , and a light guide 5 .

[0013] The multiple primary light sources 2 are arranged side by side in the left-right direction (the direction perpendicular to the plane of FIG. 1 ). Only one primary light source 2 is shown in FIG. 1 . The primary light source 2 is mounted on the wiring board 6 with its light-emitting surface facing obliquely upward and forward. The primary light source 2 is, for example, an LED (Light Emitting Diode) element or an LD (Laser Diode) element.

[0014] The primary light source 2 is controlled to be turned on when forming a low beam light distribution pattern and a high beam light distribution pattern. That is, the light emitted from the primary light source 2 is emitted from the lamp unit 1 as light for forming a low beam light distribution pattern and a high beam light distribution pattern.

[0015] The multiple secondary light sources 3 are arranged side by side in the left-right direction (the direction perpendicular to the plane of the paper in FIG. 1 ). Only one secondary light source 3 is shown in FIG. 1 . The secondary light source 3 is located behind the primary light source 2. The secondary light source 3 is mounted on the wiring board 6 with its light-emitting surface facing diagonally upward and forward. The secondary light source 3 is, for example, an LED element or an LD element.

[0016] The secondary light source 3 is controlled to be turned on when forming a high beam light distribution pattern. That is, the light emitted from the secondary light source 3 is emitted from the lamp unit 1 as light for forming a high beam light distribution pattern.

[0017] The projection lens 4 is configured to project forward the light emitted from the first light source 2 and the second light source 3. The projection lens 4 has an optical axis Ax extending in the front-to-rear direction of the lamp unit 1, and is configured to form a light distribution pattern by inverting and projecting an image formed on a rear focal plane thereof.

[0018] The light guide 5 is configured to guide the light emitted from the first light source 2 and the second light source 3 to the projection lens 4. The light guide 5 is formed of a resin such as an acrylic resin, a silicone resin, or a PC (polycarbonate) resin. The light guide 5 is provided above the first light source 2 and the second light source 3. The light guide 5 is provided behind the projection lens 4. Light emitted from the first light source 2 and the second light source 3 enters the light guide 5 from below, and the light guide 5 emits the light forward.

[0019] The light guide 5 has a plurality of first optical elements 51 , a cutoff line forming portion 52 , a first reflecting surface 53 , a plurality of second optical elements 54 , a second reflecting surface 55 , and an exit surface 56 .

[0020] The multiple first optical elements 51 are arranged side by side in the left-right direction (the direction perpendicular to the plane of the paper in Fig. 1 ). Only one first optical element 51 is shown in Fig. 1 . Each first optical element 51 is arranged opposite its corresponding first light source 2. Each first optical element 51 is configured to refract or reflect light emitted from the first light source 2 to form parallel light.

[0021] In this example, the first optical element 51 is a TIR (Total Internal Reflection) lens. Specifically, the first optical element 51 has a first incident surface 511, a second incident surface 512, and a reflecting surface 513. The first incident surface 511 is located opposite the first light source 2. In this example, the first incident surface 511 has a convex shape facing the first light source 2. The second incident surface 512 is located as a vertical wall surrounding the periphery of the first incident surface 511. The reflecting surface 513 is located so as to surround the periphery of the second incident surface 512. Light incident on the first incident surface 511 from the first light source 2 is refracted by the first incident surface 511 and travels toward the first reflecting surface 53 as parallel light. Light incident on the second incident surface 512 from the first light source 2 is reflected by the reflecting surface 513 as parallel light and travels toward the first reflecting surface 53. The parallel light beam traveling from the first incident surface 511 toward the first reflecting surface 53 and the parallel light beam traveling from the reflecting surface 513 toward the first reflecting surface 53 are parallel to each other.

[0022] The cutoff line forming portion 52 is configured to totally reflect a part of the light emitted from the primary light source 2 to form a cutoff line of the low-beam light distribution pattern.

[0023] In this example, the light guide 5 has a notch element 57 formed between the first reflecting surface 53 and the exit surface 56. The notch element 57 extends rearward from near the rear focal point F1 of the projection lens 4. In this example, the notch element 57 is a space (opening) formed as a triangular prism penetrating in the left-right direction. The space inside the notch element 57 is hollow. The cutoff line forming portion 52 is formed in the notch element 57.

[0024] Specifically, the notch element 57 has an upper surface 57U that extends rearward from near the rear focal point F1 of the projection lens 4. The upper surface 57U extends along the optical axis Ax of the projection lens 4. The upper surface 57U is the boundary surface between the cavity (air) of the notch element 57 and other portions (resin), and is formed as a total reflection surface that totally reflects light from the first reflection surface 53 due to the difference in refractive index between air and resin. In other words, the upper surface 57U forms the cutoff line forming portion 52. When viewed from the front, the upper surface 57U is configured to have a substantially Z-shape that corresponds to the cutoff line of the low-beam light distribution pattern, for example.

[0025] The lower surface 57L of the cut element 57 is the boundary surface between the cavity (air) of the cut element 57 and other parts (resin), and due to the difference in refractive index between air and resin, it is formed as a total reflection surface that totally reflects light from the second reflection surface 55.

[0026] The notch element 57 is provided above the first light source 2 and the second light source 3. The notch element 57 is also provided above the first optical element 51. That is, the cutoff line forming portion 52 is located above the first light source 2, the second light source 3, and the first optical element 51. The notch element 57 is provided between the first reflecting surface 53 and the second reflecting surface 55 in the up-down direction.

[0027] The first reflecting surface 53 is provided on the rear surface 5B of the light guide 5 above the notch elements 57. That is, the first reflecting surface 53 is located above the cut-off line forming portion 52. In the cross section shown in FIG. 1 , the first reflecting surface 53 is an inclined surface extending upward and diagonally forward. The inclined surface is not limited to a flat surface, but may be a curved surface. The first reflecting surface 53 extends in the left-right direction along the multiple first optical elements 51. The first reflecting surface 53 is configured to totally reflect the parallel light formed by the first optical elements 51 so that the parallel light passes above the cut-off line forming portion 52 and heads toward the projection lens 4. The first reflecting surface 53 is also configured to totally reflect light from the multiple first light sources 2. The light distribution patterns of the light from the multiple first light sources 2 are irradiated side by side in the left-right direction, forming a light distribution pattern with a wide range of left-right diffusion.

[0028] The second optical element 54 is configured to refract or reflect the light emitted from the second light source 3 to form parallel light. The second optical element 54 is provided below the notch element 57.

[0029] In this example, the second optical element 54 is a TIR lens. Specifically, the second optical element 54 has a first incident surface 541, a second incident surface 542, and a reflecting surface 543. The first incident surface 541 is located opposite the second light source 3. In this example, the first incident surface 541 has a convex shape toward the second light source 3. The second incident surface 542 is located as a vertical wall surrounding the periphery of the first incident surface 541. The reflecting surface 543 is located so as to surround the periphery of the second incident surface 542. Light incident on the first incident surface 541 from the second light source 3 is refracted by the first incident surface 541 and travels toward the second reflecting surface 55 as parallel light. Light incident on the second incident surface 542 from the second light source 3 is reflected by the reflecting surface 543 as parallel light and travels toward the second reflecting surface 55. The parallel light beam traveling from the first incident surface 541 to the second reflecting surface 55 and the parallel light beam traveling from the reflecting surface 543 to the second reflecting surface 55 are parallel to each other.

[0030] The second reflecting surface 55 is provided on the rear surface 5B of the light guide below the cut-off line forming portion 52. In the cross section shown in FIG. 1 , the second reflecting surface 55 is an inclined surface extending upward and diagonally forward. The second reflecting surface 55 extends in the left-right direction along the plurality of second optical elements 54. The second reflecting surface 55 is located behind the first reflecting surface 53. The second reflecting surface 55 is located below the first reflecting surface 53. The second reflecting surface 55 is configured to totally reflect the parallel light formed by the second optical elements 54 so that the parallel light passes below the cut-off line forming portion 52 and heads toward the projection lens 4.

[0031] The exit surface 56 is provided on the front surface of the light guide 5. The exit surface 56 is configured to emit the light totally reflected by the first reflecting surface 53 and the second reflecting surface 55 forward.

[0032] The light guide 5 integrally includes a plurality of first optical elements 51, a cutoff line forming portion 52, a first reflecting surface 53, a plurality of second optical elements 54, and a second reflecting surface 55. In this specification, the expression "integrally includes" means that the light guide 5 is integrally molded. For example, the light guide 5 integrally including the first optical elements 51, the cutoff line forming portion 52, the first reflecting surface 53, the second optical elements 54, and the second reflecting surface 55 is formed by resin molding using a mold.

[0033] In the lamp unit 1 configured as above, when a low beam light distribution pattern is to be formed, the primary light source 2 is turned on and the secondary light source 3 is not turned on.

[0034] When the light beams L1 and L2 emitted from the first light source 2 enter the first optical element 51, they are refracted or reflected by the first optical element 51 and travel toward the first reflecting surface 53 as parallel light beams.

[0035] The first reflecting surface 53 totally reflects the light L1 and L2 from the primary light source 2, which have been collimated by the first optical element 51, diagonally downward and forward toward the rear focal point F1 of the projection lens 4. The light totally reflected by the first reflecting surface 53 travels toward the vicinity of the rear focal point F1 of the projection lens 4. A portion of the light L1 traveling toward the vicinity of the rear focal point F1 of the projection lens 4 passes above the cutout element 57. Meanwhile, a portion of the light L2 totally reflected by the first reflecting surface 53 and traveling toward the vicinity of the rear focal point F1 of the projection lens 4 is totally reflected by the total reflection surface of the cutoff line forming portion 52. Therefore, an image with its lower half cut off is incident on the rear focal plane of the projection lens 4. The projection lens 4 inverts this image upside down and projects a light distribution pattern with its upper half cut off onto the projection screen. In other words, a low-beam light distribution pattern including a cutoff line is formed by the light distribution pattern formed by the light L1 and L2 emitted from the primary light source 2.

[0036] On the other hand, when forming a high beam light distribution pattern, both the primary light source 2 and the secondary light source 3 are turned on.

[0037] When the light beams L3 and L4 emitted from the second light source 3 enter the second optical element 54, they are refracted or reflected by the second optical element 54 and travel as parallel light beams toward the second reflecting surface 55. The second reflecting surface 55 totally reflects the light beams L3 and L4 from the second light source 3, which have been converted into parallel light beams by the second optical element 54, obliquely forward and upward toward the rear focal point F1 of the projection lens 4.

[0038] Since the second light source 3 is located behind the first light source 2 and the second reflecting surface 55 is located behind and below the first reflecting surface 53, the light L3 and L4 from the second light source 3 that is totally reflected by the second reflecting surface 55 intersects with the light L1 and L2 from the first light source 2 at a position after the light L1 and L2 from the first light source 2 have passed through the first optical element 51 and before they are incident on the first reflecting surface 53.

[0039] The light beams L3 and L4 totally reflected by the second reflecting surface 55 travel toward the vicinity of the rear focal point F1 of the projection lens 4. A portion of the light beam L4 traveling toward the vicinity of the rear focal point F1 of the projection lens 4 passes below the notch element 57. On the other hand, a portion of the light beam L3 totally reflected by the second reflecting surface 55 and traveling toward the vicinity of the rear focal point F1 of the projection lens 4 is totally reflected by the lower surface 57L of the notch element 57. Therefore, an image with its upper half cut off is incident on the rear focal plane of the projection lens 4. The projection lens 4 inverts this image upside down and projects a light distribution pattern with its lower half cut off onto the projection screen. A high-beam light distribution pattern is formed by the light distribution pattern formed by the light emitted from the first light source 2 and the light distribution pattern formed by the light emitted from the second light source 3.

[0040] According to the lighting unit 1 of the present disclosure, the light emitted from the first light source 2 is first parallelized by the first optical element 51 and then totally reflected by the first reflecting surface 53, making it easy to control the light distribution and forming a wide low-beam light distribution pattern in the left-right direction.

[0041] In addition, second reflecting surface 55 is provided separately from first reflecting surface 53. For this reason, first reflecting surface 53 and second reflecting surface 55 can be easily designed to match desired light distribution characteristics, such as first reflecting surface 53 reflecting light from first light source 2 so as to be widely diffused in the left-right direction, and second reflecting surface 55 reflecting light from second light source 3 so as to be concentrated near the center in the left-right direction.

[0042] Furthermore, since the light guide 5 has the cutout elements 57, a cutoff line forming portion can be formed by the boundary surface between the cutout elements 57 and other portions.

[0043] Furthermore, when the second light source 3 is located behind the first light source 2, the angle of light reflected by the second reflecting surface 55 and emitted from the emission surface 56 is smaller than when the second light source 3 is located ahead of the first light source 2, and becomes an angle at which the light is more likely to enter the projection lens 4. This makes it possible to suppress a decrease in luminous flux utilization efficiency.

[0044] Furthermore, since the first light source 2 and the second light source 3 are located below the cutoff line forming section 52, the optical path length of the light emitted from each light source can be ensured without increasing the size of the light guide in the front-to-back direction, compared to when the first light source 2 and the second light source 3 are arranged in a linear manner in the front-to-back direction with the cutoff line forming section 52 and the projection lens 4.

[0045] In this embodiment, the notch element 57 has a triangular prism shape penetrating in the left-right direction, but is not limited to this shape. The notch element 57 has a space (opening) of a certain size, but may also be a thin notch such as a slit. For example, the notch element 57 may be a slit cut from the rear surface 5B of the light guide 5. The space inside the notch element 57 may be filled with a material having a lower refractive index than the material of the rest of the light guide. For example, the light guide 5 is formed from a material such that the difference in refractive index between the inside of the notch element 57 and the area around the notch element 57 is 0.03 or more.

[0046] In this embodiment, the light guide 5 integrally includes the first optical element 51, the cutoff line forming portion 52, the first reflecting surface 53, the second optical element 54, and the second reflecting surface 55. However, as shown in Fig. 2, for example, the first optical element 51 and the second optical element 54 may be formed of a material different from that of the other portion 5A of the light guide 5. The first optical element 51, the second optical element 54, and the other portion 5A are each formed separately and then fixed together with, for example, an adhesive or screws. Note that the projection lens 4 is not shown in Fig. 2.

[0047] The first optical element 51 and the second optical element 54 are preferably made of a material having heat resistance superior to that of the material constituting the other portion 5A, for example. This is because the first optical element 51 and the second optical element 54 are disposed near the first light source 2 and the second light source 3, which are heat-generating elements. For example, the first optical element 51 and the second optical element 54 are made of a silicone resin, and the other portion 5A is made of a resin such as an acrylic resin, a silicone resin, or a PC resin.

[0048] Heat resistance can be easily ensured by forming the first optical element 51 and the second optical element 54, which are close to the first light source 2 and the second light source 3, which are heat generating elements, from a material with excellent heat resistance. On the other hand, by forming the other portion 5A from, for example, an inexpensive material (e.g., acrylic resin), an increase in manufacturing costs can be suppressed.

[0049] Alternatively, as illustrated in Fig. 3, in the light guide 5, a portion 5C above the notch element 57 and a portion 5D below the notch element 57 may be made of different materials. The upper portion 5C and the lower portion 5D are formed separately and then fixed together with, for example, an adhesive or screws. Note that the projection lens 4 is not shown in Fig. 3.

[0050] In this example, the upper portion 5C is a portion above the upper surface 57U of the cutting element 57, and the lower portion 5D is a portion below the upper surface 57U. Specifically, the lower surface of the upper portion 5C forms the upper surface 57U of the cutting element 57, and the recess formed in the upper surface of the lower portion 5D forms the side surface 57S and the lower surface 57L of the cutting element 57.

[0051] By forming the upper portion 5C and the lower portion 5D separately and then integrating them in this manner, a notch element can be formed inside the light guide 5 without forming a notch or hole in the light guide 5.

[0052] The upper portion 5C and the lower portion 5D are made of a material having heat resistance superior to that of the material of the upper portion 5C. For example, the portion 5D below the cutting element 57 is made of silicone resin, and the portion 5C above the cutting element 57 is made of resin such as acrylic resin, silicone resin, or PC resin.

[0053] The first light source 2 and the second light source 3, which are the heating elements, are located below the notch elements 57. Therefore, for example, heat resistance can be ensured by forming the portion below the notch elements 57, which is close to the first light source 2 and the second light source 3, from a material with excellent heat resistance (e.g., silicone resin). On the other hand, an increase in manufacturing costs can be suppressed by forming the portion above the notch elements 57 from, for example, an inexpensive material (e.g., acrylic resin).

[0054] Second Embodiment Fig. 4 is a vertical cross-sectional view illustrating the configuration of a lamp unit 10 according to a second embodiment. In Fig. 4, some light emitted from the light source is illustrated as light L11 to L14. In the description of this embodiment, components having the same functions as those in the first embodiment are given the same reference numerals, and for the sake of convenience, detailed description thereof will be omitted.

[0055] 4, the lighting unit 10 includes a plurality of primary light sources 2, a plurality of secondary light sources 3, a projection lens 4, and a light guide 15. The lighting unit 10 according to this embodiment differs from the lighting unit 1 according to the first embodiment in the shape of the light guide 15.

[0056] The light guide 15 has a plurality of first optical elements 51, a cutoff line forming portion 152, a first reflecting surface 53, a plurality of second optical elements 54, a second reflecting surface 55, and an exit surface 56. In this example, the light guide 15 integrally has the plurality of first optical elements 51, the cutoff line forming portion 52, the first reflecting surface 53, the plurality of second optical elements 54, and the second reflecting surface 55.

[0057] The cutoff line forming portion 152 is configured to totally reflect a part of the light emitted from the primary light source 2 to form a cutoff line of the low-beam light distribution pattern.

[0058] In this example, the front portion of the light guide 15 has a lower surface 5L extending rearward from near the rear focal point F1 of the projection lens 4. The lower surface 5L extends along the optical axis Ax of the projection lens 4. The lower surface 5L is the boundary surface between the light guide 15 made of resin and air, and is formed as a total reflection surface that totally reflects light from the first reflection surface 53 that has passed through the interior of the light guide 15 due to the difference in refractive index between air and resin. In other words, the lower surface 5L of the front portion of the light guide 15 forms the cutoff line forming portion 152. The lower surface 5L of the front portion of the light guide 15 is configured to have a substantially Z-shape that corresponds to the cutoff line of the low-beam light distribution pattern when viewed from the front, for example.

[0059] A metal reflective layer is formed on the surface (outer surface) of the lower surface 5L of the front part of the light guide 15. The surface of the lower surface 5L corresponds to the lower surface of the cutoff line forming portion 152 of the present disclosure. Specifically, the metal reflective layer is formed in an area on the surface of the lower surface 5L of the front part of the light guide 15, where light totally reflected by the second reflective surface 55 reaches. As the metal reflective layer, a metal vapor deposition film may be formed, or a metal foil may be attached.

[0060] The metal for the metal vapor deposition film or metal foil may be aluminum or the like. For example, aluminum may be heated and evaporated in a vacuum, and the vapor may be deposited on the surface of the front lower surface 5L of the light guide 15 to form an aluminum vapor deposition film as a metal reflective layer. Alternatively, aluminum foil may be attached instead of the aluminum vapor deposition film.

[0061] In the lamp unit 10 configured as above, when a low beam light distribution pattern is to be formed, the primary light source 2 is turned on and the secondary light source 3 is not turned on.

[0062] When the light beams L11 and L12 emitted from the first light source 2 enter the first optical element 51, they are refracted or reflected by the first optical element 51 and travel toward the first reflecting surface 53 as parallel light beams.

[0063] The first reflecting surface 53 totally reflects the light beams L11 and L12 from the first light source 2, which have been converted into parallel light by the first optical element 51, diagonally downward and forward toward the rear focal point F1 of the projection lens 4. The light beams L11 and L12 totally reflected by the first reflecting surface 53 proceed toward the vicinity of the rear focal point F1 of the projection lens 4. Of the light beams proceeding toward the vicinity of the rear focal point F1 of the projection lens 4, the light beam L11 that attempts to pass above the rear focal point F1 passes above the cutoff line forming portion 152. On the other hand, of the light beams totally reflected by the first reflecting surface 53 and proceeding toward the vicinity of the rear focal point F1 of the projection lens 4, the light beam L12 that attempts to pass below the rear focal point F1 is totally reflected by the total reflecting surface of the cutoff line forming portion 152. Therefore, an image with its lower half cut off is incident on the rear focal plane of the projection lens 4. The projection lens 4 flips this image upside down and projects a light distribution pattern with its upper half cut off onto the projection screen. That is, a low-beam light distribution pattern including a cutoff line is formed by the light distribution pattern formed by the light beams L11 and L12 emitted from the primary light source 2.

[0064] On the other hand, when a high beam light distribution pattern is to be formed, the primary light source 2 and the secondary light source 3 are turned on.

[0065] When the light beams L13 and L14 emitted from the second light source 3 enter the second optical element 54, they are refracted or reflected by the second optical element 54 and travel as parallel light beams toward the second reflecting surface 55. The second reflecting surface 55 totally reflects the light beams L13 and L14 from the second light source 3, which have been converted into parallel light beams by the second optical element 54, obliquely forward and upward toward the rear focal point F1 of the projection lens 4.

[0066] Since the second light source 3 is located behind the first light source 2 and the second reflecting surface 55 is located behind and below the first reflecting surface 53, the light L13 and L14 from the second light source 3 that is totally reflected by the second reflecting surface 55 intersects with the light L11 and L12 from the first light source 2 at a position after the light L11 and L12 from the first light source 2 have passed through the first optical element 51 and before they are incident on the first reflecting surface 53.

[0067] The light beams L13 and L14 totally reflected by the second reflecting surface 55 pass through the light guide 15 and proceed toward the vicinity of the rear focal point F1 of the projection lens 4. Of the light beams proceeding toward the vicinity of the rear focal point F1 of the projection lens 4, light beam L14 that attempts to pass below the rear focal point F1 passes below the cutoff line forming portion 152. On the other hand, of the light beams totally reflected by the second reflecting surface 55 and proceeding toward the vicinity of the rear focal point F1 of the projection lens 4, light beam L13 that attempts to pass above the rear focal point F1 is totally reflected by the lower surface of the cutoff line forming portion 152 (in this example, the outer surface of the lower surface 5L of the front part of the light guide 15). Therefore, an image with its upper half cut off is incident on the rear focal plane of the projection lens 4. The projection lens 4 flips this image upside down and projects a light distribution pattern with its lower half cut off onto the projection screen. A high beam light distribution pattern is formed by the light distribution pattern formed by the light beams L11 and L12 emitted from the primary light source 2 and the light distribution pattern formed by the light beams L13 and L14 emitted from the secondary light source 3.

[0068] According to the lighting unit 10 of the present disclosure, similar to the lighting unit 1 of the first embodiment, the light emitted from the first light source 2 is first parallelized by the first optical element 51 and then totally reflected by the first reflecting surface 53, making it easy to control the light distribution and forming a wide low-beam light distribution pattern in the left-right direction.

[0069] In addition, the light that is totally reflected by the second reflecting surface 55 and reaches the underside of the cutoff line forming portion 152 is totally reflected by the metal reflecting layer, thereby preventing it from re-entering the light guide 15 from the cutoff line forming portion 152 and becoming stray light, and also preventing a decrease in the luminous intensity of the high beam light distribution pattern.

[0070] In the present embodiment, the light guide 15 integrally includes the first optical element 51, the cutoff line forming portion 152, the first reflecting surface 53, the second optical element 54, and the second reflecting surface 55. However, the first optical element 51 and the second optical element 54 may be formed of a material different from that of the other portions of the light guide 15.

[0071] Third Embodiment Fig. 5 is a vertical cross-sectional view illustrating the configuration of a lamp unit 20 according to a third embodiment. In Fig. 5, some light emitted from the light source is illustrated as light L21 to L23. In the description of this embodiment, components having the same functions as those in the first embodiment are given the same reference numerals, and for the sake of convenience, detailed description thereof will be omitted.

[0072] 5, the lighting unit 20 includes a plurality of primary light sources 2, a plurality of secondary light sources 3, a projection lens 4, and a light guide 25. The lighting unit 20 according to this embodiment differs from the lighting unit 1 according to the first embodiment in the shape of the light guide 25.

[0073] The light guide 25 has a plurality of first optical elements 51, a cutoff line forming portion 52, a first reflecting surface 53, a plurality of second optical elements 54, a second reflecting surface 55, an exit surface 56, and a third reflecting surface 58. In this example, the light guide 15 integrally has a plurality of first optical elements 51, a cutoff line forming portion 52, the first reflecting surface 53, a plurality of second optical elements 54, the second reflecting surface 55, and the third reflecting surface 58.

[0074] The third reflecting surface 58 is provided on the rear surface 5B of the light guide 5 above the second reflecting surface 55 and below the notch elements 57. That is, the third reflecting surface 58 is located below the cutoff line forming portion 52. The third reflecting surface 58 extends in the left-right direction along the plurality of first optical elements 51. The third reflecting surface 58 is located behind the first reflecting surface 53 and ahead of the second reflecting surface 55. The third reflecting surface 58 is configured to totally reflect the light emitted from the first light source 2 so that the light passes below the notch elements 57 and enters the projection lens 4. That is, the third reflecting surface 58 is configured to totally reflect a portion of the parallel light formed by the first optical elements 51 so that the light passes below the cutoff line forming portion 52 and heads toward the projection lens 4.

[0075] In the lamp unit 20 configured in this manner, as in the above-described embodiment, when the first light source 2 is turned on, a low beam light distribution pattern is formed, and when both the first light source 2 and the second light source 3 are turned on, a high beam light distribution pattern is formed.

[0076] When the light beams L21 and L22 emitted from the first light source 2 enter the first optical element 51, they are refracted or reflected by the first optical element 51 and travel toward the first reflecting surface 53 and the third reflecting surface 58 as parallel light beams.

[0077] The first reflecting surface 53 totally reflects the light L21 from the first light source 2, which has been converted into parallel light by the first optical element 51, diagonally downward and forward toward the rear focal point F1 of the projection lens 4. The light L21 totally reflected by the first reflecting surface 53 heads toward the vicinity of the rear focal point F1 of the projection lens 4. A portion of the light L21 heading toward the vicinity of the rear focal point F1 of the projection lens 4 passes above the cutout element 57. On the other hand, a portion of the light totally reflected by the first reflecting surface 53 and heading toward the vicinity of the rear focal point F1 of the projection lens 4 is totally reflected by the total reflecting surface of the cutoff line forming portion 52. Therefore, an image with its lower half cut off is incident on the rear focal plane of the projection lens 4. The projection lens 4 flips this image upside down and projects a light distribution pattern with its upper half cut off onto the projection screen.

[0078] The third reflecting surface 58 totally reflects a portion of the light L22 from the first light source 2, which has been converted into parallel light by the first optical element 51, so that the light passes below the cutoff line forming portion 52 and heads toward the rear focal point F1 of the projection lens 4. The light totally reflected by the third reflecting surface 58 passes below the rear focal point F1 of the projection lens 4, and the projection lens 4 upside down inverts the image incident on the rear focal plane. As a result, a light distribution pattern is projected above the projection screen.

[0079] That is, the light L21, L22 emitted from the first light source 2 forms a low-beam light distribution pattern including a light distribution pattern including a cutoff line and a light distribution pattern formed in an OHS (Over Head Sign) region above the light distribution pattern.

[0080] On the other hand, when light L23 emitted from the second light source 3 enters the second optical element 54, it is refracted or reflected by the second optical element 54 and travels as parallel light toward the second reflecting surface 55. The second reflecting surface 55 totally reflects the light from the second light source 3, which has been converted into parallel light by the second optical element 54, obliquely forward and upward toward the rear focal point F1 of the projection lens 4.

[0081] Since the second light source 3 is located behind the first light source 2 and the second reflecting surface 55 is located behind and below the first reflecting surface 53, the light L23 from the second light source 3 that is totally reflected by the second reflecting surface 55 intersects with the light L21, L22 from the first light source 2 at a position after the light L21, L22 from the first light source 2 has passed through the first optical element 51 and before it is incident on the first reflecting surface 53.

[0082] The light L23 totally reflected by the second reflecting surface 55 travels toward the vicinity of the rear focal point F1 of the projection lens 4. A portion of the light L23 traveling toward the vicinity of the rear focal point F1 of the projection lens 4 passes below the notch element 57. On the other hand, a portion of the light totally reflected by the second reflecting surface 55 and traveling toward the vicinity of the rear focal point F1 of the projection lens 4 is totally reflected by the lower surface 57L of the notch element 57. Therefore, an image with its upper half cut off is incident on the rear focal plane of the projection lens 4. The projection lens 4 inverts this image upside down and projects a light distribution pattern with its lower half cut off onto the projection screen. A high-beam light distribution pattern is formed by the light distribution pattern formed by the light emitted from the first light source 2 and the light distribution pattern formed by the light emitted from the second light source 3.

[0083] According to the lighting unit 20 of the present disclosure, similar to the lighting unit 1 of the first embodiment, the light emitted from the first light source 2 is first parallelized by the first optical element 51 and then totally reflected by the first reflecting surface 53, making it easy to control the light distribution and forming a wide low-beam light distribution pattern in the left-right direction.

[0084] In addition, the third reflecting surface 58 can totally reflect a portion of the light L22 that has been converted into parallel light by the first optical element 51, thereby forming an OHS light distribution pattern that illuminates above the cutoff line of the low beam light distribution pattern.

[0085] In the present embodiment, the light guide 25 integrally includes a plurality of first optical elements 51, a cutoff line forming portion 52, a first reflecting surface 53, a plurality of second optical elements 54, a second reflecting surface 55, and a third reflecting surface 58. However, the first optical elements 51 and the second optical elements 54 may be formed of a material different from that of the other portions of the light guide 25. Alternatively, the portions above and below the notch elements 57 may be made of different materials.

[0086] In the present embodiment, the light guide 25 has the notch element 57. However, as in the second embodiment, the lower surface of the front part of the light guide 25 may be configured to function as a cutoff line forming portion instead of the notch element 57. In this case, the third reflection surface 58 is formed below the lower surface of the front part of the light guide 25.

[0087] 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.

[0088] In the first to third embodiments described above, the lamp unit includes a plurality of first light sources and a plurality of second light sources. However, the lamp unit may be configured to include one first light source and one second light source. In this case, the lamp unit is configured to include one first optical element and one second optical element.

[0089] The configurations described in each item listed below also constitute part of this disclosure. Item 1: A lamp unit comprising: a first light source that emits light to form a low-beam light distribution pattern and a high-beam light distribution pattern including a cutoff line; a second light source that emits light to form the high-beam light distribution pattern; a projection lens that projects the light emitted from the first light source and the second light source forward; and a light guide that guides the light emitted from the first light source and the second light source to the projection lens, wherein the light guide has: a first optical element that converts the light emitted from the first light source into parallel light; a cutoff line forming portion that totally reflects a portion of the light emitted from the first light source to form the cutoff line of the low-beam light distribution pattern; a first reflecting surface that totally reflects the parallel light formed by the first optical element so that it passes above the cutoff line forming portion and heads toward the projection lens; a second optical element that converts the light emitted from the second light source into parallel light; and a second reflecting surface that totally reflects the parallel light formed by the second optical element so that it passes below the cutoff line forming portion and heads toward the projection lens. Item 2: The lighting unit according to item 1, wherein the light guide has a notch element formed between the first reflecting surface and an exit surface from which light totally reflected by the first reflecting surface exits, the notch element including a surface extending rearward from near the focal point of the projection lens, the surface forming the cutoff line forming portion. Item 3: The lighting unit according to item 2, wherein a portion of the light guide above and a portion below the notch element are made of different materials. Item 4: The lighting unit according to item 1, wherein the cutoff line forming portion includes a surface extending rearward from near the focal point of the projection lens, and a metal reflective layer is formed on a lower surface of the cutoff line forming portion. Item 5: The lighting unit according to item 1, item 2 or item 4, wherein the first optical element and the second optical element are made of a material different from that of other portions of the light guide.Item 6: The lamp unit according to any one of items 1 to 5, wherein the light guide has a third reflecting surface that totally reflects a portion of the parallel light formed by the first optical element so that the light passes below the cutoff line forming portion and heads toward the projection lens. Item 7: The lamp unit according to any one of items 1 to 6, wherein the second light source is located rearward of the first light source. Item 8: The lamp unit according to any one of items 1 to 7, wherein the first light source and the second light source are located below the cutoff line forming portion. Item 9: The lamp unit according to item 3, wherein the heat resistance of a material constituting a portion below the cutoff line forming portion is superior to the heat resistance of a material constituting a portion above the cutoff line forming portion. Item 10: The lamp unit according to item 4, wherein an area on the underside of the cutoff line forming portion through which the light totally reflected by the second reflecting surface passes is covered with a vapor deposition film. Item 11: The lamp unit according to item 2, wherein the first light source and the second light source are provided below the cutout elements, the first reflecting surface is provided on the rear surface of the light guide above the cutout elements, and the second reflecting surface is provided on the rear surface of the light guide below the cutout elements. Item 12: The lamp unit according to item 11, wherein light from the first light source that is totally reflected by the first reflecting surface passes above the cutout elements, and light from the second light source that is totally reflected by the second reflecting surface passes below the cutout elements. Item 13: The lamp unit according to item 11 or 12, further comprising a third reflecting surface that is provided on the rear surface of the light guide above the second reflecting surface and below the cutout elements, and that totally reflects a portion of the parallel light formed by the first optical element so that the light passes below the cutout elements and heads toward the projection lens. Item 14: The lighting unit according to any one of items 1, 2, 4, 6 to 8, and 10 to 13, wherein the light guide integrally includes the first optical element, the cutoff line forming portion, the first reflecting surface, the second optical element, and the second reflecting surface.Item 15: The lamp unit according to any one of items 1 to 14, wherein the light from the second light source that is totally reflected by the second reflecting surface intersects with the light from the first light source at a position after the light from the first light source has passed through the first optical element and before the light is incident on the first reflecting surface. Item 16: The lamp unit according to any one of items 1 to 15, wherein the first reflecting surface totally reflects the light from the first light source so as to diffuse the light in left and right directions.

[0090] This application is based on Japanese Patent Application No. 2024-148250, filed on August 30, 2024, the contents of which are incorporated herein by reference.

Claims

1. A lamp unit comprising: a first light source that emits light to form a low-beam light distribution pattern and a high-beam light distribution pattern including a cutoff line; a second light source that emits light to form the high-beam light distribution pattern; a projection lens that projects the light emitted from the first light source and the second light source forward; and a light guide that guides the light emitted from the first light source and the second light source to the projection lens, wherein the light guide has: a first optical element that collimates the light emitted from the first light source; a cutoff line forming portion that totally reflects a portion of the light emitted from the first light source to form the cutoff line of the low-beam light distribution pattern; a first reflecting surface that totally reflects the collimated light formed by the first optical element so that it passes above the cutoff line forming portion and heads toward the projection lens; a second optical element that collimates the light emitted from the second light source; and a second reflecting surface that totally reflects the collimated light formed by the second optical element so that it passes below the cutoff line forming portion and heads toward the projection lens.

2. A lighting unit as described in claim 1, wherein the light guide has a notch element formed between the first reflecting surface and an exit surface from which light totally reflected by the first reflecting surface exits, the notch element including a surface extending rearward from near the focal point of the projection lens, the surface forming the cutoff line forming portion.

3. The lamp unit according to claim 2, wherein the light guide has a portion above the notch element and a portion below the notch element that are made of different materials.

4. A lamp unit as described in claim 1, wherein the cutoff line forming portion includes a surface extending rearward from near the focal point of the projection lens, and a metal reflective layer is formed on the underside of the cutoff line forming portion.

5. A lamp unit as set forth in claim 1, claim 2 or claim 4, wherein the first optical element and the second optical element are formed from a material different from that of the other portions of the light guide.

6. A lighting unit as described in claim 1, wherein the light guide has a third reflecting surface that totally reflects a portion of the parallel light formed by the first optical element so that the portion passes below the cutoff line forming portion and is directed toward the projection lens.

7. The lamp unit according to claim 1, wherein the second light source is located rearward of the first light source.

8. The lamp unit according to claim 1, wherein the first light source and the second light source are positioned below the cutoff line forming portion.

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