GB2308648A

GB2308648A - Headlamp for motor vehicle

Info

Publication number: GB2308648A
Application number: GB9625875A
Authority: GB
Inventors: Norikazu Saito
Original assignee: Koito Manufacturing Co Ltd
Current assignee: Koito Manufacturing Co Ltd
Priority date: 1995-12-22
Filing date: 1996-12-12
Publication date: 1997-07-02
Anticipated expiration: 2016-12-12
Also published as: JPH09180508A; DE19653179A1; DE19653179B4; GB2308648B; JP3133246B2; GB9625875D0

Description

2308648 HEADLAMP FOR MOTOR VEHICLE The present invention relates to a

headlamp for a motor vehicle, and more particularly to the structure of a shade thereof.

is Headlamps for motor vehicles are generally constructed so that a required luminous intensity distributing pattern can be obtained by controlling the luminous intensity distribution of light from a light source body (filament) of a bulb by a reflector and a lens. Further, recently developed are headlamps that are designed to obtain a required luminous intensity distributing pattern only by the reflector using no lens.

By the way, when rays of light are injected upward in the front of a headlamp, glare occurs with respect to the drivers of motor vehicles running on the opposite lane or pedestrians walking on the opposite sidewalk. Therefore, it is essential that a luminous intensity distributing pattern including minimal upward rays of light at the time of lighting the auxiliary lamp be obtained. On the other hand, if it is designed so that upward rays of light are not provided at all, there exists a problem that overhead signs in the upper front such as guide signs and road signs are hard to see at the time the motor vehicle is travelling with the auxiliary lamp lit.

To overcome this problem, required upward rays of light have heretofore been produced in the following ways. As shown in Fig. 7A, if lens steps 2s are formed on a lens 2, a part 2sA of the lens steps 2s is used for overhead sign irradiation. Further, as shown in Fig. 7B, if luminous intensity distribution control steps 4s are formed on a reflector 4 with a lens 2 being transparent, a part 4sA of the luminous intensity distribution control steps 4s is used for overhead sign irradiation.

- 1 nIi However, the headlamps having the aforementioned conventional overhead sign irradiation structures have addressed the following problems.

That is, as shown in Fig. 7A, when the part 2sA of the lens steps 2s is used for overhead sign irradiation, transmitted light through the part 2sA becomes a loss in forming a desired luminous intensity distributing pattern. In addition, it is difficult to harmonize the part 2sA with other part of the lens steps 2s in aesthetic terms, which in turn impairs the outward appearance of the headlamp.

On the other hand, as shown in Fig. 7B, when the part 4sA of the luminous intensity distribution control steps 4s is used for overhead sign irradiation, light reflected at the part 4sA becomes a loss in forming the desired luminous intensity distributing pattern. In addition, not only it is difficult to harmonize the part 4sA with other part of the luminous intensity distribution Control steps 4s in aesthetic terms, but also the lens is transparent, which in turn impairs the outward appearance of the headlamp. If the luminous intensity distribution control steps 4s are designed to be stepless in order to improve the outward appearance of the headlamp in particular, it is not desirable to arrange the part 4sA because stepped portions are formed disadvantageously and this contradicts the aforementioned attempt to improve the outward appearance of the headlamp.

The invention has been made in view of the aforementioned circumstances. The object of the invention is therefore to provide a headlamp for a motor vehicle which can provide predetermined overhead sign irradiation without reducing the quantity of light for forming a luminous intensity distributing pattern nor impairing the outward appearance of the headlamp.

Attaching importance to the fact that many headlamps have a shade for cutting harmful light produced during the - 2 formation of a luminous intensity distributing pattern of the auxiliary lamp thereof, the invention has achieved the above object by providing overhead sign irradiating light while taking advantage of reflection of light at the inner surface of the shade.

The invention may be applied to a headlamp for a motor vehicle having a bulb with a light source body, a reflector reflecting rays of light from the light source body frontward, a lens disposed in the front of the reflector, and a shade enclosing the bulb, wherein a reflectance of a predetermined area out of an inner surface of the shade is set to a higher value than a reflectance of an area other than the predetermined area.

With respect to the "predetermined area", the position, size, and the like are not particularly limited, as long as overhead sign irradiating light can be provided by reflected light from the predetermined area.

As described in the aforementioned construction, the invention is characterized as setting the reflectance of the predetermined area out of the inner surface of the shade arranged so as to enclose the bulb to a value larger than the reflectance of the other area. Therefore, the invention can provide the following advantages.

Light beams emitting from the light source body reflected at the predetermined area whose reflectance is relatively high is reflected at the reflecting surface of the reflector and transmitted through the lens, so that the light necessary for overhead sign irradiation can be obtained without having to redesign the reflector and the lens. On the other hand, since the reflectance of the area other than the predetermined area is set to a relatively low value, negative effects of the reflected light from such other area upon the formation of a luminous intensity distributing pattern can be minimized.

Therefore, according to the invention, required overhead sign irradiation can be provided without reducing 3 - p is the quantity of light necessary for forming the luminous intensity distributing pattern nor impairing the outward appearance of the headlamp.

While a specific method for giving a higher reflectance to the predetermined area than the other area is not particularly limited in the aforementioned construction, a method in which the predetermined area is subjected to a reflection treatment and the other area is subjected to a nonreflection treatment may be employed. It is as a result of this positive method that a very high reflectance can be given to the predetermined area and a very low reflectance can be given to the other area. Hence, both a requirement that the overhead sign irradiating light be provided by reflection at the inner surface of ihe shade and a requirement that the negative effects of the reflection at the inner surface of the shade upon the formation of a luminous intensity distributing pattern be blocked can be met at the same time with ease.

While types of headlamps to which the invention is applied are not particularly limited, in the case of a headlamp having luminous intensity distribution control steps formed on the reflecting surface of the reflector and having no lens steps formed on the lens, the reflecting surface of the reflector inside the headlamp is seen well through the lens disadvantageously. Therefore, when a part of the luminous intensity distribution control steps is used for overhead sign irradiation, such part becomes planar in form which is greatly different from the other part of the luminous intensity distribution control steps. As a result, the outward appearance of the headlamp is impaired. However, if the headlamp is constructed in accordance with the invention, there is no likelihood that the outward appearance will be impaired. Hence, this is an advantage provided by the invention. If the reflecting surface has no stepped portions between the luminous intensity distribution control steps, then the stepped portions are formed only at a part of 1,1, the luminous intensity distribution control steps dedicated to overhead sign irradiation and it is only such stepped portions that is conspicuous. Therefore, the invention is particularly advantageous.

Further, while the shape of the shade is not particularly limited, if the shade is so shaped that direct light from the light source body is injected only onto the reflecting surface, it is particularly advantageous to apply the construction of the invention to a headlamp. That is, when the shade is shaped in the aforementioned manner, stray light unnecessary for the formation of a luminous intensity distributing pattern can be cut completely to reliably prevent glare, but at the same time overhead sign irradiating light cannot be obtained, which is disadvantage.

is Therefore, the invention is advantageous in that overhead sign irradiation can be provided by taking advantage of light reflected at the inner surface of'the shade because the irradiating direction of such reflected light is defined. As a result, overhead sign irradiating light can be provided while controlling production of stray light.

The position at which to set the predetermined area is not particularly limited as described above. If a luminous intensity distributing pattern is to be formed while cutting stray light, it is advantageous to set the predetermined area to such a position as to allow the light reflected at the predetermined area to be irradiated upward on the side of the opposite lane through both the reflecting surface and the lens,because the upper region on the opposite lane tends to be particularly dark.

Further, the shade is usually constructed of the shade main body and the leg portions that support the shade main body on the reflector. In this case, if the predetermined area is arranged at a position close to the leg portions of the shade main body, the reflectance of the predetermined area can be set to a relatively higher value than that of the other area with ease.

1 ' I- ' In the accompanying drawings:

Fig. 1 is a side sectional view showing a headlamp for motor vehicles. which is a mode of embodiment of the invention; Fig. 2 is a diagram showing a reflector unit of the aforementioned headlamp as viewed from the arrow II in Fig. 1; Fig. 3 is a sectional view taken along a line III-III of Fig. 2; Fig. 4A is a diagram thereof as viewed from the arrow IVa of Fig. 2, and Fig. 4B is a diagram thereof as viewed from the arrow IVb of Fig. 2; Fig. 5 is a luminous intensity distributing pattern showing an operation of the aforementioned mode of is embodiment; Fig. 6 is a luminous intensity distributing pattern showing the operation of a modification of the aforementioned mode of embodiment; and Figs. 7A and 7B are perspective views showing conventional lamps.

A headlamp 10, which is the mode of embodiment of the invention, is a socalled two-lamp type headlamp to be mounted on a two-wheel motor vehicle (corresponding to a four-lamp type headlamp to be mounted on a four-wheel motor vehicle). The headlamp 10 has a main lamp reflector unit and an auxiliary lamp reflector unit arranged in a lamp chamber formed of a lens 12 and a body 14 so that these reflector units can aim. A reflector unit 16 shown in the drawing is 1 ' -- 1, the auxiliary lamp reflector unit. The reflector unit 16 includes: a bulb 18; a reflector 20; and a shade 22.

A portion of the lens 12 corresponding to the front of the reflector unit 16 is formed into a transparent lens having no luminous intensity distribution control function.

This lens 12 is stepped so that an effective portion thereof 12a is coplanar with motor vehicle body side cowls 102. The lens 12 comes in contact with the motor vehicle body side cowls 102 at both top and bottom of the effective portion 12a through end covers 24, respectively. Further, on the inner surface side of the lens 12 are inner covers 26. The inner covers 26 are designed to conceal portions other than a reflecting surface 20a of the reflector 20 inside the headlamp. The lens. 12 and the inner covers 26 are attached to the body 14 through seal agents 28. A socket cover 30 is attached to an opening in the rear of the body 14.

The bulb 18 has a single'filament 18a. An adaptor 32 is attached to this bulb 18. Further, the socket cover 30 is attached to the adaptor 32.

The reflector 20 is a reflector made of FRP. The reflecting surface 20a has partially slightly curved striped luminous intensity distribution control steps 20s (for luminous intensity distribution on the right) formed as shown in Fig. 2. As shown in Fig. 3, these luminous intensity distribution control steps 20s are wave-shaped without stepped portions in cross section. This reflector 20 is designed to form such a luminous intensity distributing pattern P for the right as shown by the solid line in Fig. 5 by controlling the luminous intensity distribution of light injected onto the reflecting surface 20a from the filament 18a of the bulb 18 (light source body) through the luminous intensity distribution control steps 20s. Further, as shown in Fig. 2, a pair of shade mounting portions 20b and a hole 20c are formed in a position close to the rear apex of the reflecting surface 20a. The hole 20c allows a bulb fixing spring holding portion to be formed.

1 The shade 22 is constructed of a shade main body 22a and a pair of leg portions 22b. As shown in Figs. 2 and 4, the shade 22 is designed to be attached and fixed to the reflector 20 so as to bring a pair of claws 22c of each leg portion 22b into contact with the corresponding shade attaching portion 20b. The shade main body 22a is umbrella shaped so as to enclose the bulb 18, and the rear end face thereof 22d is so shaped as to allow direct light from the filament 18a to be injected only onto the reflecting surface 20a. As a result of this construction, harmful stray light produced during the formation of a luminous intensity distributing pattern such as direct.light injected onto the front of the headlamp, reflected light from the upper and lower inner wall surfaces of the reflector 20, and reflected is light from the inner covers 26 can be reliably cut.

The shade 22 is chromium-plated in the entire part thereof so that the outward appearance of the headlamp can be improved. However, an inner surface area A of the shade main body 22a (the area shaded in Figs. 1 and 4) is subjected to a heat-resistant black coating treatment over the chromium plated layer. As is apparent from Fig. 4, an area B other than the inner surface area A of the shade main body 22a (i.e., the area not subjected to the black coating treatment) is set to a position not only close to the rear end face 22d of the shade main body 22a but also close to the pair of leg portions 22b. That is, the area B is formed so that the chromium-plated layer is left substantially rectangular. As a result of this construction, the area A constitutes a nonreflection treated area, whereas the area B constitutes a reflection treated area. out of rays of light injected onto the inner surface of the shade main body 22a from the filament 18a, most of rays injected onto the area A are absorbed so that no reflected light is produced. on the other hand, those rays injected onto the area B are reflected at a certain reflectance so as to be injected onto the reflecting surface 20a of the reflector 20. As shown in Fig.

8 - 1, the rays of light reflected at the area B and injected onto the reflecting surface 20a are irradiated onto the front of the headlamp while transmitted through the lens 12 in the form of slightly upward rays. The thus irradiated rays of light become rather weak overhead sign irradiating light (irradiating light at about 50 to 400 cd) Pohs. That is, as shown by the broken line in Fig. 5, the irradiating rays extend slightly toward the opposite lane while stretching over a line V-V (a perpendicular line passing through the central axis Ax of the headlamp) in a region slightly above an HH line (a horizontal line passing through the central axis Ax of the headlamp). As a result of this overhead sign irradiating light Pohs, the overhead sign OHS arranged above in the upper front of the motor vehicle in one's one lane is irradiated. It may be noted that reference character L1 in Fig. 5 denotes the centerline of a road; and L2 and L3 denote a sideline of the lane along which one's own motor vehicle is running and that of the opposite lane, respectively.

As described in detail in the foregoing, this embodiment is characterized as subjecting the area B, out of the inner surface of the shade main body 22a of the shade 22 arranged so as to enclose the bulb 18, to a chromium-plating reflection treatment and as subjecting the area A to a blackcoated nonreflection treatment. Therefore, this embodiment can provide the following advantages.

The rays of light from the filament 18a reflected at the area B having a high reflectance are irradiated in the upper front of the headlamp while reflected at the reflecting surface 20a of the reflector 20 and transmitted through the lens 22. Therefore, rays of light required for overhead sign irradiation can be obtained without redesigning the reflector 20 and the lens 22. On the hand, few rays are reflected at the area A. Therefore, negative effects of such rays from the area A upon the formation of a luminous intensity distributing pattern can be checked.

/1 11 Therefore, according to this embodiment, predetermined overhead sign irradiation can be provided without reducing the quantity of light required for forming a luminous intensity distributing pattern nor impairing the outward appearance of the headlamp.

In the reflector 20 of this embodiment in particular, the reflecting surface 20a thereof has no stepped portions between the luminous intensity distribution control steps 20s. Therefore, even if a part of the luminous intensity distribution control steps 20s is used for overhead sign irradiation, stepped portions are formed only for that particular part, making the stepped-portions very conspicuous through the transparent lens 12 disadvantageously. However, there is no such impairment of the outward appearance in this is embodiment.

Further, the headlamp 10 according to this embodiment has the shade main body 22a of the shade 22 thereof shaped so as to allow direct light from the filament 18a to be injected only onto the reflecting surface 20a, and this means that there is few possibility that a part of stray light happens to be overhead sign irradiating light. Therefore, the construction of this embodiment in which overhead sign irradiation can be provided utilizing direction-defined light reflected at the inner surface of the shade is especially advantageous.

In this embodiment, the area B is set to a position close to the leg portions 22b of the shade main body 22a, constituting the chrQmium-plated treated portion continuous to the leg portions 22b. As a result of this construction, masking operation or the like for subjecting the area A to a black coating treatment can be facilitated.

While the filament 18a is used as a light source body in the aforementioned embodiment, other light source body (e.g., discharge lightemitting portion of a metal halide lamp) can, of course, be employed.

- Further, while a two-lamp headlamp for two-wheel motor vehicles has been described in the aforementioned embodiment, the same construction can be applied not only to a single lamp headlamp, but also to headlamps for four-wheel motor vehicles. In these cases, advantages similar to those provided by the aforementioned embodiment can be obtained.

Still further, while a headlamp for right luminous intensity distribution has been described in the aforementioned embodiment, the same construction can be applied to a headlamp for left luminous intensity distribution. In this case, a left luminous intensity distributing pattern P and overhead.sign irradiating light Pohs such as shown in Fig. 6 can be obtained, and advantages similar to those provided by the aforementioned embodiment can be obtained.

is 1 2 3 4 5 6 7 8 9 1 2 3 4 1 2 3 4 1 2 3 1 2 3 4 1 2

Claims

1. A headlamp for a motor vehicle, comprising:

bulb having a light source body; reflector reflecting rays of light from said light source body frontward; lens disposed in the front of the reflector; and shade enclosing the bulb, a reflectance of a predetermined area out of an inner surface of said shade being higher value than a reflectance of an area other than said predetermined area.

2. A headlamp for a motor vehicle according to claim 1, wherein said predetermined area is subjected to a reflection treatment, and the area other than said predetermined area is subjected to a nonreflection treatment.

3. A headlamp for a motor vehicle according to claim 1 or 2, wherein luminous intensity distribution control steps are formed on the reflecting surface, and no lens steps are formed on the lens.

4. A headlamp for a motor vehicle according to claim 3, wherein said reflecting surface has no stepped portions between the luminous intensity distribution control steps.

5. A headlamp for a motor vehicle according to any one of claims 1 to 4, wherein said shade is shaped so that direct light from the light source body is injected only onto said reflecting surface.

6. A headlamp for a motor vehicle according to any one of claims 1 to 5, wherein said predetermined area is set 3 to such a position as to allow rays of light from the light source body to irradiate upward on the side of an opposite lane, the rays of light being reflected at the predetermined 6 7 area, reflected at the reflecting surface, and then transmitted through the lens.

1 2 3 4 7. A headlamp for a motor vehicle according to any one of claims 1 to 6, wherein said shade comprises a shade main body and leg portions for supporting the shade main body on the reflector, and said predetermined area is set to a position close to the leg portions of said shade main body.

1 - 13 A (.\- Amendments to the claims have been filed as follows CLAIMS 1. A headlamp for a motor vehicle, the headlamp comprising: a bulb having a light source body; a reflector for reflecting rays of light from the light source body frontward; a lens disposed in the front of the reflector; and a shade enclosing the bulb, a reflectance of a predetermined area out of an inner surface of the shade being higher value than a reflectance of an area other than the predetermined area; the predetermined area having been subjected to a reflection treatment, and the area other than the predetermined area having been subjected to a nonreflection treatment.

2. A headlamp according to claim 1, wherein luminous intensity distribution control steps are formed on the reflecting surface, and no lens steps are formed on the lens.

3. A headlamp according to claim 2, wherein the reflecting surface has no stepped portions between the luminous intensity distribution control steps.

4. A headlamp according to any one of claims 1 to 3, wherein the shade is shaped so that direct light from the light source body is injected only onto the reflecting surface.

5. A headlamp according to any one of claims 1 to 4, wherein the predetermined area is set to such a position as to allow rays of light from the light source body to irradiate upwards on the side of an opposite lane, the rays of light being reflected at the predetermined area, reflected at the reflecting surface, and then transmitted through the lens.

X 6. A headlamp according to any one of claims 1 to 5, wherein the shade comprises a shade main body and leg portions for supporting the shade main body on the reflector, and the predetermined area is set to a position close to the leg portions of the shade main body.

7. A headlamp for a motor vehicle substantially as described with reference to Figs. 1 to 6 of the accompanying drawings