JPH11126503A - Headlamp for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control generation of glaring light without losing the brightness of the irradiation beam in a headlamp for a dipped beam incorporated with a thermal feedback type light source having a tubular spherical form. SOLUTION: The bulb 20b of a light source bulb 20 is formed of a cylinder part A and a pair of convex surfaces B so as to improve the bulb efficiency by light converging heat produced by returning the reflecting light without passing through the bulb 20b of direct light from a filament 20a to the filament 20a. In this case, light converging parts formed on near both ends of the filament 20a generate glaring light. Therefore, by forming an upper reflecting surface area 18a1 and a lower reflecting surface area 18a2 of a reflector 18 directed lower than a side reflecting surface area forming a cutoff line so as to prevent the irradiation beam from a secondary light source G from being irradiated above the light distribution pattern of a dipped beam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicular headlamp for passing beams, and more particularly to a vehicular headlamp incorporating a so-called heat-return type bulb-shaped light source bulb. It is.

[0002]

2. Description of the Related Art Heretofore, as a vehicle headlight for a low beam, a vehicle headlight having a light source bulb having a filament extending in the front-rear direction and a reflector for reflecting light from the light source bulb forward has been known. But in recent years,
As the light source bulb, one having a heat return type bulb shape has been proposed.

[0003] That is, in this light source bulb, the bulb has a cylindrical portion surrounding the filament such that the central axis substantially coincides with the axis of the filament, and the cylindrical portion extends from both ends of the cylindrical portion toward the central axis. A pair of convex curved surface portions that are curved, and of the direct light from the filament, light reflected by the cylindrical portion and each convex curved surface portion without passing through the tube is reflected on the filament. The light is returned and collected, and the heat of the collected light increases the temperature of the filament to increase the valve efficiency.

[0004] In a headlamp incorporating such a light source bulb, the brightness of the irradiation beam can be increased.

[0005]

However, the light source bulb having such a heat-return type bulb shape has the following problems.

That is, in the light source bulb, since the filament has a predetermined length, all of the light emitted from each position of the filament and reflected by the cylindrical portion and each convex curved surface portion of the tube is used. Does not return onto the filament, but a part of the light reflected by each of the convex curved surface portions is condensed in a space near both ends of the filament to form a secondary light source.

Further, since the above-mentioned tube is usually formed by subjecting a cylindrical glass tube to thermal deformation processing, it is difficult to obtain a highly accurate tube shape. The light to be reflected by the light and returning to the filament may also be condensed in a space near both ends of the filament to form a secondary light source.

For this reason, in the low beam headlamp incorporating the light source bulb, the light from the secondary light source is reflected by the reflector and irradiated above the low beam distribution pattern, thereby causing glare. Causes a problem.

The present invention has been made in view of such circumstances, and a low beam headlamp incorporating a light source bulb having a heat-returning tube shape is provided.
It is an object of the present invention to provide a vehicular headlamp capable of suppressing generation of glare light without impairing the brightness of an irradiation beam.

[0010]

According to the present invention, the above object is achieved by devising the shape of the reflecting surface of the reflector.

That is, according to the present invention, there is provided a light beam for a low beam, comprising: a light source bulb having a filament extending in the front-rear direction; and a reflector for reflecting light from the light source bulb forward. In a vehicle headlamp headlamp, the bulb of the light source bulb surrounds the filament so that the central axis substantially coincides with the axis of the filament, and the central axis extends from both ends of the cylindrical part. And a convex curved surface portion curved toward the light source, and the upper reflecting surface region of the reflector located above the light source bulb is directed downward from the side reflecting surface region located on the side of the light source bulb. , Is characterized in that

The above-mentioned "reflector" may have a light distribution control function like a so-called step reflector or free-form surface reflector, or may not have a light distribution control function like a rotating parabolic reflector. It may be something.

As long as each of the “convex curved surface portions” is formed so as to be curved from the end of the cylindrical portion toward the central axis, the specific curved surface shape is not particularly limited. Instead, for example, a curved surface shape such as an elliptical sphere or a spherical surface can be adopted.

The degree of the downward direction is not particularly limited as long as the "upper reflective surface area" is formed to be lower than the "side reflective surface area".

[0015]

As described above, in the vehicle headlamp according to the present invention, the bulb of the light source bulb surrounds the filament such that the central axis substantially coincides with the axis of the filament. Since it has a cylindrical portion and a convex curved surface portion curved from both ends of the cylindrical portion toward the central axis, the cylindrical portion of the direct light from the filament does not pass through the tube. In addition, the light reflected by each convex curved surface portion is returned to the filament and condensed, and the heat of the condensed light increases the temperature of the filament to increase the valve efficiency.

Therefore, in the above-mentioned vehicle headlamp incorporating such a light source bulb having a heat-return type tube shape, the brightness of the irradiation beam can be increased.

Since the vehicular headlamp according to the present invention is a low beam headlamp, an irradiation beam having a condensing portion formed near both ends of the filament as a secondary light source is glare. It is required to avoid light.

In this respect, in the present invention, the upper reflecting surface region of the reflector located above the light source bulb is formed to be lower than the side reflecting surface region located on the side of the light source bulb. Therefore, it is possible to prevent or minimize the light from the secondary light source from being irradiated above the passing beam light distribution pattern. The reason is as follows.

That is, the vehicle headlamp according to the present invention is premised on incorporating a light source bulb having a filament extending in the front-rear direction. The image of the filament formed by the light reflected on the side reflection surface region has a shape extending substantially in the horizontal direction, whereas the image of the filament formed by the light reflected on the upper reflection surface region is substantially vertical. The shape extends in the direction. Since the secondary light source is based on the light condensing portions formed near both ends of the filament, the image of the secondary light source due to the light reflected on the side reflection surface region becomes an image of the filament. On the other hand, it is located in the left-right direction, and the possibility of glare light is small. On the other hand, the image of the secondary light source due to the light reflected on the upper reflecting surface region is positioned vertically with respect to the image of the filament, and is likely to be glare light. Therefore, if the upper reflecting surface region is formed to be lower than the side reflecting surface region, the image of the secondary light source by the reflected light in the upper reflecting surface region is, together with the image of the filament by the reflected light,
The irradiation angle can be reduced. Thus, it is possible to prevent or minimize the irradiation of the light from the secondary light source above the passing beam light distribution pattern.

In addition, the reflected light from the upper reflective surface region is not merely shielded from light because its irradiation angle is directed downward, but it is used as light for irradiating a short-distance road surface in front of the vehicle. Can be used.

As described above, according to the present invention, glare light can be generated without impairing the brightness of an irradiation beam in a low-beam headlight incorporating a light source bulb having a heat-return type bulb shape. Can be suppressed.

The above operation and effect can be obtained by forming the upper reflecting surface region downwardly than the side reflecting surface region. If it is formed downward by 2 ° or more with respect to the side reflection surface region, generation of glare light can be suppressed more effectively.

Further, the "upper reflection surface area" is not particularly limited as long as it is a reflection surface area located above the light source bulb. 1 from the vertical plane passing through the axis of the filament
If the angle is set to a range including the reflection surface region within 5 ° (30 ° on both sides), generation of glare light can be suppressed sufficiently effectively. If the angle range is larger than the above-mentioned “15 °” (for example, “30 °”), the glare light generation suppressing effect can be further enhanced.

By the way, in the reflector of the vehicular headlamp for the low beam, the lower reflecting surface area located below the light source bulb is configured such that light from the light source bulb does not enter due to a shade or the like. There is a light source and a light source configured to receive light from the light source bulb. In the latter case, the image of the secondary light source due to the light reflected by the lower reflecting surface area is reflected by the upper reflection. Similar to that in the surface area, since the filament is located in the vertical direction with respect to the image of the filament, glare light is likely to occur. Therefore, in such a case, as described in claim 4, if the lower reflective surface region is also formed to be lower than the side reflective surface region, the generation of glare light can be effectively prevented. Can be suppressed.

The light source bulb may have only a heat-return type bulb shape provided with the cylindrical portion and a pair of convexly curved surface portions.
If an infrared reflective film is formed on the tube, the infrared light is reflected on the tube spherical surface without losing visible light useful for the low beam light distribution pattern, and the temperature of the filament is reduced by the condensing heat. It can be increased dramatically, thereby greatly improving the valve efficiency. In this case, the infrared reflecting film may be formed on the outer surface or the inner surface of the bulb.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view showing a vehicle headlamp according to one embodiment of the present invention, and FIGS.
FIG. 3 is a sectional view taken along lines II-II and III-III.

As shown in these figures, a vehicle headlamp (lamp) 10 according to the present embodiment is a headlamp for a low beam, and is provided in a space formed by a lens 12 and a lamp body 14. In addition, a reflector unit 16 is provided so as to be tiltable in the vertical and horizontal directions.

The lens 12 is a transparent lens,
The reflector unit 16 is provided with a light distribution control function, and the reflector unit 16 forms a passing beam light distribution pattern. The reflector unit 16 has a light source bulb 20 inserted into a reflector 18 having an optical axis Ax extending in the front-rear direction. Strictly speaking, the optical axis Ax is a small angle α (for example, α = 0.57) with respect to a horizontal axis Lh extending in the front-rear direction.
°) It is set downward.

The light source bulb 20 is constituted by a halogen bulb having a filament 20a extending in the front-rear direction, and is inserted into the reflector 18 so that the axis of the filament 20a coincides with the optical axis Ax. Have been done.

FIG. 4 is a side sectional view showing the main part of the light source bulb 20 in detail.

As shown in FIG. 4, the bulb 20b of the light source bulb 20 is made of glass, and has a cylindrical portion A and a pair of convex curved surface portions B. The cylindrical portion A is formed so as to surround the filament 20a so that the central axis thereof substantially coincides with the axis (Ax) of the filament 20a, and each of the convex curved surface portions B is formed of the cylindrical portion A. Are formed so as to be curved from both ends toward the central axis. Each of these convex curved surface portions B is formed of an elliptical spherical surface having a focal point on the central axis.

The light source bulb 20 converts the direct light from the filament 20a reflected by the inner and outer surfaces of the cylindrical portion A and the convex curved portions B without passing through the tube 20b. The light is condensed by returning to the top of the filament 20a, and the heat of the condensed light raises the temperature of the filament 20a to increase the bulb efficiency. However, not all the light emitted from each position of the filament 20a and reflected by the cylindrical portion A and each convex curved surface portion B of the tube 20b returns to the filament 20a. A part of the light reflected by the light source is collected in a space near both ends of the filament 20a. Thus, the secondary light source G is formed. Although FIG. 4 shows only the optical path of light reflected on the inner surface of the tube 20b, the optical path of light reflected on the outer surface of the tube 20b is substantially the same.

An infrared reflecting film 22 is formed on the outer surface of the tube 20b. And this infrared reflection film 22
Thus, the infrared rays are reflected without obstructing the transmission of visible light, and the heat of the condensed light dramatically increases the temperature of the filament 20a, thereby greatly improving the valve efficiency.

As shown in FIGS. 1 to 3, the reflector 1
8 has a reflecting surface 18a composed of a plurality of reflecting surface elements 18s, and the light source bulb 20 is provided by the reflecting surface 18a.
Light is diffusely reflected or deflected forward. Further, a shade 24 surrounding the light source bulb 20 is attached to the reflector 18 so that direct light from the light source bulb 20 is incident only on the reflection surface 18a of the reflector 18 by the shade 24. I have. Further, an extension 26 is provided in front of the reflector 18 along the periphery of the reflector 18.

The upper reflecting surface area 18a1 and the lower reflecting surface area 18a2 located above and below the light source bulb 20, which are indicated by oblique lines in FIG. It is formed lower than the side reflection surface region 18a3 located on the side. The upper reflecting surface region 18a1 and the lower reflecting surface region 18a2 are set to a range including a reflecting surface region within 30 ° (60 ° on both sides) from a vertical plane passing through the axis of the filament.

As shown in FIG. 2, the upper reflective surface area 1
The vertical cross-sectional shape of 8a1 is configured by a curve in which a parabola having a focus on a point F1 near the back of the filament 20a on the optical axis Ax is directed downward by a predetermined angle β (β = 0.25 °). The vertical cross-sectional shape of the lower reflecting surface region 18a2 is formed by a curve in which a parabola having a focus on a point F2 near the front of the filament 20a on the optical axis Ax is directed downward by the angle β.

The image I (20a) of the filament 20a formed by the light reflected by the upper reflecting surface region 18a1 and the lower reflecting surface region 18a2 has a shape extending in a substantially vertical direction or a direction slightly inclined from the vertical direction. . At this time, the image I (G) of the secondary light source G is formed on the upper and lower ends of the image I (20a) of the filament 20a. The images I (20a) and I (G) correspond to the upper reflective surface area 18a1 and the lower reflective surface area 18a2.
Is directed downward by the angle β, so that it is formed at a position downward by the angle β with respect to the image formed by the normal reflector reflecting surface.

FIG. 5 is a diagram showing a low-beam light distribution pattern P formed by the reflector unit 16.

In FIG. 5, a light distribution pattern P indicated by a solid line is shown.
1 is an upper reflective surface area 18a of the reflective surface 18a.
1 and a light distribution pattern formed by light reflected from a reflection surface region other than the lower reflection surface region 18a2, and a light distribution pattern P2 indicated by a broken line is a light distribution pattern from the upper reflection surface region 18a1 and the lower reflection surface region 18a2. And the light distribution patterns P
The passing beam light distribution pattern P is formed as a combined pattern of 1 and P2.

In FIG. 5, a light distribution pattern P indicated by a solid line is shown.
2 'is formed by the upper reflecting surface region 18a1 and the lower reflecting surface region 18a2 when the left and right diffusion angles of the respective reflecting surface elements 18s of the upper reflecting surface region 18a1 and the lower reflecting surface region 18a2 are assumed to be zero. The light distribution pattern P2 ′ is formed by diffusing the light distribution pattern P2 ′ right and left. In the light distribution pattern P2 ', a part P (20a) indicated by oblique lines rising to the right is an image I of the filament 20a.
This is the filament image pattern formed by (20a), and a portion P (G) indicated by oblique lines rising to the left is a secondary light source image pattern formed by the image I (G) of the secondary light source G.

In FIG. 5, the light distribution pattern P2'o indicated by a two-dot chain line is formed when the upper reflection surface area 18a1 and the lower reflection surface area 18a2 are not turned downward. It is a light distribution pattern corresponding to P2 '. The secondary light source image pattern P (G) o of the light distribution pattern P2'o is a cut-off line CL of the low-beam light distribution pattern P (a bright-dark boundary formed by light reflected from the side reflection surface area 18a3). ), The light distribution pattern P2 ′.
The secondary light source image pattern P (G) is formed at a position hidden below the cutoff line CL.

As described in detail above, the vehicle headlamp 10 according to the present embodiment includes the bulb 20 b of the light source bulb 20.
Is provided with the cylindrical portion A and the convex curved surface portion B, so that the cylindrical portion A and each convex curved surface portion B of the direct light from the filament 20a do not pass through the tube 20b. The reflected light is returned to the filament 20a and collected, and the heat of the collected light increases the temperature of the filament 20a to increase the valve efficiency. In addition, since an infrared reflecting film is formed on the outer surface of the tube 20b, the infrared light is reflected on the tube spherical surface without losing visible light useful for the passing beam light distribution pattern P, and the heat is collected by the collected heat. The temperature of the filament 20a can be drastically increased, thereby greatly improving the valve efficiency. Therefore,
The brightness of the irradiation beam of the vehicle headlamp 10 can be greatly increased.

Since the vehicular headlamp 10 is a low beam headlamp, an irradiation beam having a condensing portion formed near both ends of the filament 20a as a secondary light source G is formed as glare light. However, in the present embodiment, the upper reflective surface area 18a1 and the lower reflective surface area 18a2 of the reflector 18 are required.
Is formed downward by 2 ° or more from the side reflection surface region 18a3, it is possible to prevent the light from the secondary light source G from being irradiated above the passing beam distribution pattern P.

Moreover, the reflected light from the upper reflecting surface area 18a1 and the lower reflecting surface area 18a2 is not merely shielded from light because the irradiation angle is directed downward, but is not reflected near the front of the vehicle. It can be used as light for illuminating a distance road surface.

As described above, according to this embodiment, in a low beam headlamp incorporating a light source bulb having a heat-return type bulb shape, generation of glare light can be achieved without impairing the brightness of the irradiation beam. Can be suppressed.

The upper reflecting surface region 18a1 and the lower reflecting surface region 18a2 are aligned with the axis (Ax) of the filament.
Is set to a range including the reflection surface region within 30 ° (60 ° on both sides) from the vertical plane passing through the lens, it is possible to sufficiently effectively suppress the generation of glare light.

[Brief description of the drawings]

FIG. 1 is a front view showing a vehicle headlamp according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III of FIG. 1;

FIG. 4 is a side sectional view showing a main part of the light source bulb of the embodiment in detail.

FIG. 5 is a diagram showing a low-beam light distribution pattern formed by the reflector unit of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Vehicle headlamp (lamp) 12 Lens 14 Lamp body 16 Reflector unit 18 Reflector 18a Reflection surface 18a1 Upper reflection surface region 18a2 Lower reflection surface region 18a3 Side reflection surface region 18s Reflection surface element 20 Light source bulb 20a Filament 20b Tube Reference Signs List 22 Infrared reflective film 24 Shade 26 Extension A Cylindrical part Ax Optical axis of reflector (axial line of filament) B Convex curved surface part CL Cutoff line F1, F2 Focus G Secondary light source I (20a) Filament image I (G) Secondary Light source image Lh Horizontal axis P Passing beam light distribution pattern P (20a) Filament image pattern P (G), P (G) o Secondary light source image pattern β Downward angle

Claims (5)

[Claims] 1. A vehicular headlamp for a low beam, comprising: a light source bulb having a filament extending in the front-rear direction; and a reflector for reflecting light from the light source bulb forward. Comprises a cylindrical portion surrounding the filament so that the central axis substantially coincides with the axis of the filament, and a pair of convex curved portions curved from both ends of the cylindrical portion toward the central axis. Wherein the upper reflecting surface area of the reflector located above the light source bulb is formed to be lower than the side reflecting surface area located on the side of the light source bulb. Headlight. 2. The vehicular headlamp according to claim 1, wherein the upper reflecting surface region is formed to be downward by 2 ° or more with respect to the side reflecting surface region. 3. The vehicle according to claim 1, wherein the upper reflecting surface region is set to a range including a reflecting surface region within 15 ° from a vertical plane passing through the axis of the filament. Headlights. 4. The reflector according to claim 1, wherein a lower reflecting surface area of the reflector located below the light source bulb is formed to face downward with respect to the side reflecting surface area. Vehicle headlight according to the above. 5. The vehicle headlight according to claim 1, wherein an infrared reflective film is formed on the bulb.