Vehicle headlight

Abstract

A vehicle headlight (1) has a plurality of light source units (30) each including a light source (31), a light guide body (32), and a reflector (33). Each of the light guide bodies (32) has: a cut-off line formation part that forms a cut-off line in a low-beam light distribution pattern; and an emission surface (42). The plurality of light source units (30) are arranged so as to be displaced in the front-rear direction, and the light sources (31) of the light source units (30) are mounted on a common substrate (2) extending in the front-rear direction.

Description

Vehicle headlamp

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

[0002] For example, Patent Document 1 discloses a vehicle headlamp in which a plurality of optical units are linearly arranged.

[0003] Japanese Patent Application Laid-Open No. 2004-241349

[0004] Vehicle headlamps are often provided at corners such as the left end or right end of the front part of a vehicle. In recent years, due to the demand for a rounded design of the vehicle at such corners, for example, at the left corner, it has an inclined shape that slopes backward toward the left. Therefore, a shape adapted to such an inclined shape is also required for the vehicle headlamp. However, for example, when arranging a plurality of optical units in the left-right direction, if the normal direction of the substrate on which the light source is mounted extends in the front-rear direction, it is necessary to prepare a plurality of substrates, which increases the cost.

[0005] An object of the present disclosure is to provide a vehicle headlamp with reduced substrate cost.

[0006] The vehicle headlamp according to one aspect of the present disclosure has a plurality of light source units each including a light source, a light guide, and a reflector that reflects the light of the light source to the light guide. Each light guide has a cut-off line forming portion having a total reflection surface extending in the front-rear direction, and an emission surface provided in front of the cut-off line forming portion. The cut-off line forming portion forms a cut-off line in the low beam light distribution pattern by totally reflecting a part of the reflected light from the reflector by the total reflection surface and not directly incident on the emission surface. The plurality of light source units are arranged so as to be displaced in the front-rear direction, and the light sources of each light source unit are mounted on a common substrate extending in the front-rear direction.

[0007] According to the present disclosure, a vehicle headlamp with reduced substrate cost is provided.

[0008] Figure 1 is a top view of a vehicle headlight according to this embodiment. Figure 2 is a side view of the light source unit. Figure 3 is a top view of the common circuit board. Figure 4 is a top view of a vehicle headlight according to a reference example. Figure 5 is a side view of the light source unit of the vehicle headlight according to a reference example.

[0009] The embodiments of this disclosure will be described below with reference to the drawings. For the sake of clarity, the descriptions of components having the same reference numerals as those already described will be omitted.

[0010] In the drawing, arrow U indicates the upward direction of the illustrated structure. Arrow D indicates the downward direction of the illustrated structure. Arrow F indicates the forward direction of the illustrated structure. Arrow B indicates the rearward direction of the illustrated structure. Arrow R indicates the rightward direction of the illustrated structure. Arrow L indicates the leftward direction of the illustrated structure. These directions are relative directions set for the vehicle headlight 1 shown in Figure 1, with the direction of light emission from the vehicle headlight 1 being the forward direction.

[0011] Figure 1 is a top view of a vehicle headlight 1 according to this embodiment. As shown in Figure 1, the vehicle headlight 1 comprises a housing 10, an outer lens 20, three light source units 30, and a common substrate 2. The housing 10 is open to the front. The outer lens 20 closes the opening of the housing 10. The outer lens 20 and the housing 10 form a lamp chamber S inside each other.

[0012] The outer lens 20 of the illustrated vehicle headlight 1 has a front section that slopes backward from left to right. The housing 10 has a rear section that does not slope in the front-to-back direction but extends in the left-to-right direction. Therefore, when viewed from above, the lamp chamber S is a roughly trapezoidal space whose length in the front-to-back direction shortens towards the right.

[0013] The light source unit 30 is installed inside the lamp chamber S. The illustrated light source unit 30 is a light source unit 30 capable of emitting a low beam light distribution pattern. The vehicle headlight 1 may also have a light source unit 30 capable of emitting a high beam light distribution pattern, or it may include a light source unit 30 that functions as a DRL (Daytime Running Lamp) or turn signal.

[0014] The three light source units 30 each have the same configuration. Each light source unit 30 includes a light source 31, a light guide 32, and a reflector 33. The light source units 30 illuminate the front of the lamp with light emitted from each light source 31. In the illustrated example, the light emitted from the three light source units 30 forms a low-beam light distribution pattern. A common substrate 2 is also provided below the three light source units 30.

[0015] Figure 2 is a side view of the light source unit 30. As shown in Figure 2, the light source 31 is mounted on the common substrate 2 and emits light upwards. The light source 31 includes, for example, a light-emitting element such as an LED (Laser Emitting Diode) or an LD (Laser Diode), and a light source module that controls the turning on and off of the light-emitting element.

[0016] The reflector 33 is fixed on the common substrate 2. The reflector 33 is a so-called elliptical reflector. The reflector 33 has a reflective surface that is approximately an ellipsoid. The reflector 33 is positioned such that the major axis of the ellipsoid extends in the front-to-back direction. The light source 31 is located at the first focal point f1 of the ellipsoid. The second focal point f2 of the ellipsoid is located in front of the first focal point f1. By employing an elliptical reflector, the reflector 33 can focus the light and direct it into the light guide 32, making the left-to-right dimensions of the light guide 32 more compact.

[0017] The light guide 32 is a component made of a transparent material such as transparent resin or glass. The light guide 32 is a long component that is elongated in the longitudinal direction. An incident surface 41 is provided on the rear surface of the light guide 32. An exit surface 42 is provided on the front surface of the light guide 32.

[0018] The lower surface of the light guide 32 is provided with a total reflection surface 43 extending forward from the lower end of the incident surface 41, a flat surface 44 extending backward from the lower end of the exit surface 42, and a stepped surface 45 connecting the total reflection surface 43 and the flat surface 44. The total reflection surface 43 is located above the flat surface 44, and the stepped surface 45 extends in the vertical direction. In this embodiment, the total reflection surface 43 and the stepped surface 45 form a cutoff line forming portion. Although not shown, the corner 46 formed by the total reflection surface 43 and the stepped surface 45 has a stepped shape corresponding to the cutoff line of the low beam light distribution pattern when viewed from above.

[0019] The incident surface 41 is a lens surface that is concave toward the front. The incident surface 41 is a lens surface that controls light to focus in front of the second focal point f2 of the reflector 33. The incident surface 41 has a focal point near the corner 46 formed by the total reflection surface 43 and the stepped surface 45.

[0020] The emission surface 42 is a lens surface that is convex toward the front. The emission surface 42 emits light that has been emitted from the light source 31 and guided through the light guide 32 toward the front. The focal point of the emission surface 42 is located near the corner 46 formed by the total reflection surface 43 and the stepped surface 45.

[0021] Light emitted from the light source 31 is reflected by the reflector 33 and focused by the incident surface 41 to approximately the vicinity of the corner 46. At this time, the light L1 emitted from the light source 31 that passes above the corner 46 reaches the emission surface 42 and illuminates the area below the cutoff line of the low beam light distribution pattern.

[0022] On the other hand, of the light emitted from the light source 31, the light L2 that travels below the corner 46 would, if emitted as is, illuminate an area above the cutoff line of the low beam light distribution pattern. However, in reality, this light L2 enters the light guide 32 from the incident surface 41 and is totally reflected diagonally upward by the totally reflecting surface 43, and does not reach an area above the cutoff line of the low beam light distribution pattern. In this way, the cutoff line forming section forms the cutoff line of the low beam light distribution pattern by totally reflecting a portion of the light reflected from the reflector 33 by the totally reflecting surface 43, preventing the reflected light from directly entering the emission surface 42.

[0023] Returning to Figure 1, the three light source units 30 are positioned at offset locations in the front-to-back direction. In the illustrated example, the three light source units 30 are arranged so that they gradually shift backward from left to right, so that multiple light source units 30 fit within the roughly trapezoidal lamp chamber S. Furthermore, the multiple light source units 30 are not offset in the vertical direction; their vertical positions are common to each other.

[0024] In the illustrated example, the light guides 32 of the light source unit 30 are joined together to form a single light guide unit. The single light guide unit may be formed by integral molding, or the light guides 32 of each light source unit 30 may be formed separately and then bonded together with adhesive to form a single light guide unit. In addition, unlike the illustrated example, multiple light guides 32 may be formed separately.

[0025] Here, the light source unit 30 located at the left end will be called the first light source unit 30a, the light source unit 30 located at the right end will be called the third light source unit 30c, and the light source unit 30 located between the first light source unit 30a and the third light source unit 30c will be called the second light source unit 30b.

[0026] Figure 3 is a top view of the common substrate 2. As shown in Figure 3, the common substrate 2 is composed of a single substrate. The illustrated common substrate 2 extends in the front-to-back direction and the left-to-right direction. The top surface of the common substrate 2 is the mounting surface. The common substrate 2 includes a first region 2a located below the first light source unit 30a, a second region 2b located below the second light source unit 30b, and a third region 2c located below the third light source unit 30c.

[0027] The first region 2a, the second region 2b, and the third region 2c are each rectangular in shape. The common substrate 2 is stepped when viewed from above. It is offset backward in a stepped manner from the first region 2a to the third region 2c. The light source 31a of the first light source unit 30a is mounted on the upper surface of the first region 2a, the light source 31b of the second light source unit 30b is mounted on the upper surface of the second region 2b, and the light source 31c of the third light source unit 30c is mounted on the upper surface of the third region 2c.

[0028] As shown in Figure 2, the reflectors 33 of each light source unit 30 are also mounted on the common circuit board 2. The support members for the reflectors 33 are also shared with the support members for the light source 31, and since the support members for the reflectors 33 of each light source unit 30 are also shared, the number of parts is reduced.

[0029] Figure 4 is a top view of a vehicle headlight 100 according to a reference example. Figure 5 is a side view of the light source unit 130 of the vehicle headlight 100 of the reference example shown in Figure 4. In the reference examples shown in Figures 4 and 5, light emitted from the light source 131 toward the rear is incident on the light guide 132 from the upper surface by a reflector 133 provided behind the light source 131, passes through the cutoff line forming section and is emitted from the emission surface 142, forming a low beam light distribution pattern.

[0030] In the reference example of the vehicle headlight 100, the first substrate 102a, the second substrate 102b, and the third substrate 102c on which the light source 131 is mounted extend in the vertical and horizontal directions. Therefore, the second substrate 102b of the second light source unit 130b cannot be shared with the first substrate 102a of the first light source unit 130a or the third substrate 102c of the third light source unit 130c, which are adjacent to the second light source unit 130b in the horizontal direction. In other words, the first substrate 102a, the second substrate 102b, and the third substrate 102c cannot be arranged on the same plane, so it is not possible to share the substrates 102 of multiple light source units 130 and use a single substrate. For this reason, in the reference example of the vehicle headlight 100, it is necessary to use multiple substrates, which is a factor that increases costs.

[0031] In contrast, according to the vehicle headlight 1 of this embodiment shown in Figure 1, the light source 31 of each light source unit 30 is mounted on a common substrate 2 that extends in the front-rear direction. Therefore, multiple light sources 31 can be mounted on a single common substrate 2, which reduces costs. In particular, in recent vehicle headlights 1 that use multiple small lens components to form a light distribution pattern, it is necessary to use a large number of light source units 30. In such vehicle headlights 1 that include a large number of light source units 30, the cost reduction effect of using a common substrate 2 is significant.

[0032] In the vehicle headlight 1 of the above-described embodiment, the light guide 32 has an incident surface 41 into which reflected light from the reflector 33 enters. This incident surface 41 focuses the reflected light from the reflector 33 forward of the second focal point f2. However, when a light guide with a short front-to-back dimension is used, the distance between the exit surface and the focal point of the reflector tends to be short, so a reflector with a short focal length is adopted. When such a reflector with a short focal length is used, the light spreads out at a large angle from the focal point of the reflector. On the other hand, in recent years, lamps with a linear exit surface (lens surface) with a small vertical dimension have become popular with users. Therefore, when a light guide with a linear exit surface and a short front-to-back dimension is adopted, a problem arises in that it is difficult to direct the light that spreads out at a large angle from the focal point of the reflector into the exit surface of the light guide, which has a short vertical dimension. Therefore, a common solution is to increase the distance between the emission surface and the reflector's focal point, thereby lowering the angle at which the light spreads from the focal point, and directing the light onto the emission surface with a shorter vertical dimension. However, this design approach makes it difficult to miniaturize the front-to-back dimensions of the light source unit.

[0033] Therefore, in the vehicle headlight 1 of the above-described embodiment, the focal point is shifted forward by the incident surface 41, thereby keeping the angle of light incident on the exit surface 42 low. This makes it possible to efficiently incident light even when a light guide 32 having a linear exit surface 42 and a short front-to-back dimension is used. Needless to say, this disclosure can also be applied when a light guide 32 having a wide exit surface 42 or a long front-to-back dimension is used.

[0034] While embodiments of this disclosure have been described above, it goes without saying that the technical scope of this disclosure should not be interpreted restrictively by the description of these embodiments. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications to the embodiments are possible within the scope of the invention described in the claims. The technical scope of this disclosure should be determined based on the scope of the invention described in the claims and the scope of its equivalents.

[0035] For example, the above-described embodiment illustrates an example where the light source units are arranged in the left-right direction when viewed from the front, but this disclosure is not limited to this. For example, even when the light source units are arranged in the up-down direction when viewed from the front, a common substrate extending in both the up-down and front-to-back directions can be used. Alternatively, the light source units may be arranged in a straight line or a curved line when viewed from the front. In this case, a common substrate extending in both the arrangement direction and the front-to-back direction can be used. Furthermore, the light source units may be arranged in multiple rows when viewed from the front. In this case, a common substrate would be used for each row.

[0036] Furthermore, although the above-described embodiment illustrates an example in which three light source units cooperate to form a low-beam light distribution pattern, the disclosure is not limited thereto. For example, two light source units may cooperate to form a low-beam light distribution pattern, and one light source unit may form a high-beam light distribution pattern. Also, light source units that do not form a low-beam light distribution pattern, such as a light source unit that forms a high-beam light distribution pattern, do not need to have a cutoff line forming section. The light source of a light source unit including a light guide that does not have such a cutoff line forming section may be mounted on a common substrate.

[0037] The configurations described in each of the following items also constitute part of this disclosure. Item 1: A vehicle headlight having a plurality of light source units, each including a light source, a light guide, and a reflector that reflects the light from the light source to the light guide, wherein each light guide has a cutoff line forming portion having a total reflective surface extending in the front-rear direction, and an exit surface provided in front of the cutoff line forming portion, the cutoff line forming portion forms a cutoff line in the low beam light distribution pattern by total reflecting a portion of the light reflected from the reflector with the total reflective surface, preventing it from directly incident on the exit surface, the plurality of light source units are arranged so as to be offset in the front-rear direction, and the light source of each light source unit is mounted on a common substrate extending in the front-rear direction. Item 2: The vehicle headlight according to Item 1, wherein the reflector is an elliptical reflector having a first focal point at the position of the light source and a second focal point located in front of the first focal point. Item 3: The headlight for a vehicle according to Item 2, wherein the light guide has an incident surface into which reflected light from the reflector is incident, and the incident surface focuses the reflected light from the reflector forward of the second focal point. Item 4: The headlight for a vehicle according to any one of Items 1 to 3, wherein the light guides of each of the light source units are coupled together to form a single light guide unit. Item 5: The headlight for a vehicle according to any one of Items 1 to 4, wherein the reflector of each of the light source units is mounted on the common substrate. Item 6: The headlight for a vehicle according to any one of Items 1 to 5, wherein the common substrate is stepped when viewed from above.

[0038] This application is based on Japanese Patent Application No. 2024-228555, filed on 25 December 2024, the contents of which are incorporated herein by reference.

Claims

1. A vehicle headlight having a plurality of light source units, each including a light source, a light guide, and a reflector that reflects the light from the light source to the light guide, each light guide having a cutoff line forming portion having a fully reflective surface extending in the front-rear direction, and an exit surface provided in front of the cutoff line forming portion, the cutoff line forming portion forms a cutoff line in the low beam light distribution pattern by totally reflecting a portion of the light reflected from the reflector with the fully reflective surface and preventing it from directly entering the exit surface, the plurality of light source units are arranged so as to be offset in the front-rear direction, and the light source of each light source unit is mounted on a common substrate extending in the front-rear direction.

2. The headlight for a vehicle according to claim 1, wherein the reflector is an elliptical reflector having a first focal point at the position of the light source and a second focal point located in front of the first focal point.

3. The headlight for a vehicle according to claim 2, wherein the light guide has an incident surface into which reflected light from the reflector is incident, and the incident surface focuses the reflected light from the reflector forward of the second focal point.

4. The headlight for a vehicle according to claim 1, wherein the light guides of each of the light source units are coupled to each other to form a single light guide unit.

5. The vehicle headlight according to claim 1, wherein the reflector of each of the light source units is mounted on the common circuit board.

6. The vehicle headlight according to claim 1, wherein the common substrate is stepped when viewed from above.

Images