Information
-
Patent Grant
-
6354718
-
Patent Number
6,354,718
-
Date Filed
Friday, May 19, 200024 years ago
-
Date Issued
Tuesday, March 12, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
- O'Shea; Sandra
- Alavi; Ali
Agents
-
CPC
-
US Classifications
Field of Search
US
- 362 351
- 362 303
- 362 343
- 362 522
- 362 529
- 362 539
- 362 523
- 362 518
-
International Classifications
-
Abstract
A vehicular headlamp utilizing a light source bulb of the H4 type and which provides a low-beam light distribution pattern which makes it easy for the driver to drive and reduces the possibility of oncoming drivers being dazzled by glare. A light source bulb is securely supported by a reflector so that left and right upper edges of a shade are located at substantially the same height and an axis of a filament is upwardly offset from an optical axis of the reflector at a predetermined angle. A reflecting surface of the reflector is provided with a downward deflective reflection zone which downwardly deflects and reflects the light that has traveled from the filament past the right upper edge of the shade and impinged on a traveling-lane-side reflection zone. Thereby a low-beam light distribution pattern is obtained wherein an oncoming-lane-side horizontal cut-off line formed of light reflected from the traveling-lane-side reflection zone is at a lower level than a traveling-lane-side horizontal cut-off line formed of light reflected from an oncoming-lane-side reflection zone.
Description
FIELD OF THE INVENTION
The present invention relates to a vehicular headlamp having a light source bulb of the “H4” type.
BACKGROUND OF THE INVENTION
Many conventional vehicular headlamps employ a low-beam light distribution pattern P′ as shown in
FIG. 10
, which has a horizontal cut-off line CL
1
′ and a diagonal cut-off line CL
2
′ rising from the horizontal cut-off line CL
1
′ at an angle of 15°. In this low-beam light distribution pattern P′, the horizontal cut-off line CL
1
′ is arranged on the side of the oncoming lane and the diagonal cut-off line CL
2
′ is arranged on the side of the is lane in which the vehicle is traveling, whereby forward visibility for the driver is ensured while preventing the vision of drivers of oncoming vehicles from being dazzled by glare.
To obtain such a low-beam light distribution pattern, a light source bulb of the H4 type is often employed, which has a longitudinally extending filament
18
a
and a shade
18
c
covering the filament
18
a
around its axis at a central angle of approximately 165° so that light beams emitted from the filament
18
a
in the downward direction are blocked. Due to the light-blocking effect of the shade
18
c
, light from the filament
18
a
does not impinge on a lower zone of a reflecting surface indicated by broken lines in FIG.
10
.
In a vehicular headlamp designed to obtain the low-beam light distribution pattern described above, vertical aiming (beam adjustment) is carried out in the low-beam mode of the headlamp with respect to the horizontal cut-off line CL
1
′. For this reason, the contrast in luminosity of the horizontal cut-off line CL
1
′ should be sufficiently enhanced.
However, if the contrast in luminosity of the horizontal cut-off line CL
1
′ is enhanced excessively, long-distance visibility tends to decrease to such an extent that the driver may experience difficulty in driving in situations where the road ahead suddenly becomes dark, for example, in a case where the vehicle is approaching a flat road at the end of the descent of a slope. Also, even if the horizontal cut-off line CL
1
′ is slightly displaced upwards or downwards due to pitching of the vehicle or the like, there is a concern that oncoming drivers could be dazzled by glare.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of such circumstances. It is an object of the present invention to provide a vehicular headlamp employing an H4 type light source bulb and which is capable of providing a low-beam light distribution pattern which makes it easy for a driver to drive and reduces the possibility of oncoming drivers being dazzled by glare.
The present invention achieves the above-stated object by the provision of an improved structure for securely supporting a light source bulb on a reflector, and by providing the reflector or a front lens with a suitable downward deflective reflection zone or a downward deflective transmission zone.
More specifically, a vehicular headlamp according to a first aspect of the present invention includes a light source bulb having a longitudinally extending filament and a shade covering the filament around its longitudinal axis at a central angle of approximately 165° so that light traveling downward from the filament is blocked, a reflector securely supporting the light source bulb and having a reflecting surface forwardly reflecting light from the filament, and a front lens disposed forwardly of the reflector. The light source bulb is securely supported by the reflector so that left and right upper edges of the shade are at substantially the same height and the longitudinal axis of the filament is offset upward from the optical axis of the reflector at a predetermined angle. The reflecting surface of the reflector is provided with a downward deflective reflection zone which deflects downward and reflects light that has traveled from the filament past the vicinity of the upper edges of the shade and impinges on a traveling-lane-side reflection zone of the reflecting surface.
A vehicular headlamp according to a second aspect of the present invention includes a light source bulb having a longitudinally extending filament and a shade covering the filament around its axis at a central angle of approximately 165° so that light beam traveling downward from the filament is blocked, a reflector securely supporting the light source bulb and having a reflecting surface forwardly reflecting light beam from the filament, and a front lens disposed forwardly of the reflector. The light source bulb is securely supported by the reflector so that left and right upper edges of the shade are at substantially the same height and the longitudinal axis of the filament is offset upward from the optical axis of the reflector at a predetermined angle. The front lens is provided with a downward deflective transmission zone which downwardly deflects and transmits light that has traveled from the filament past the vicinity of the upper edges of the shade and impinges on a traveling-lane-side reflection zone of the reflecting surface.
The aforementioned “predetermined angle” means an angle is required to transform a generally sectorial light distribution pattern formed of light beams reflected from the reflecting surface of the reflector to a pattern where a pair of left and right cut-off lines constituting upper edges of the pattern at a central angle of approximately 195° are both substantially horizontal, under the condition that the reflecting surface is a paraboloid of revolution extending around the optical axis of the reflector.
In the above-described vehicular headlamp of the present invention which has the light source bulb securely supported by the reflector so that the left and right upper edges of the shade are located at substantially the same height and that the longitudinal axis of the filament is offset upward from the optical axis of the reflector at the predetermined angle, under the condition that the reflecting surface of the reflector is a paraboloid of revolution extending around the optical axis of the reflector, a low-beam light distribution pattern is obtained which has horizontal cut-off lines formed of light beams reflected from the reflecting surface on laterally opposed sides of a vertical line perpendicular to the reference axis of the lighting fixture, hereinafter referred to as “line V”.
In addition, with the reflecting surface of the reflector provided with the downward deflective reflection zone which downwardly deflects and reflects light that has traveled from the filament past the vicinity of the upper edges of the shade and impinges on the traveling-lane-side reflection zone of the reflecting surface, the front lens is provided with the downward deflective transmission zone which downwardly deflects and transmits light that has traveled from the filament past the vicinity of the upper edges of the shade and impinges on the traveling-lane-side reflection zone of the reflecting surface. Thus, in the aforementioned low-beam light distribution pattern, the oncoming-lane-side horizontal cut-off line formed of light reflected from the traveling-lane-side reflection zone is at a lower level than the traveling-lane-side horizontal cut-off line formed of light reflected from the oncoming-lane-side reflection zone.
In such a low-beam light distribution pattern, since vertical aiming can be carried out with respect to the traveling-lane-side horizontal cut-off line, the contrast in luminosity of the oncoming-lane-side horizontal cut-off line can be reduced.
This prevents long-distance visibility from being reduced when the road ahead of the vehicle suddenly darkens, for example, when the vehicle approaches a flat road after having traveled down a slope. As long as the horizontal cut-off line is just slightly displaced upward or downward due to pitching of the vehicle or the like, the luminosity of the upward light beams can be prevented from reaching a high level. Hence, the possibility of oncoming drivers being dazzled by glare is reduced.
In this manner, in a vehicular headlamp having a light source bulb of H4 bulb type, the present invention makes it possible to obtain a low-beam light distribution pattern which makes the vehicle easy to drive and reduces the possibility of oncoming drivers being dazzled by glare.
Moreover, since vertical aiming can be carried out with respect to the traveling-lane-side horizontal cut-off line as described above, it is also possible to set the target aiming position to a position where the horizontal cut-off line coincides with a horizontal line perpendicular to the lighting fixture reference axis, hereinafter referred to as “line H”. By thus setting the target position, even without the use of special equipment for carrying out an aiming measurement, it becomes possible to carry out vertical aiming by means of a simple operation of making the traveling-lane-side horizontal cut-off line coincide with the height of the lighting fixture reference axis above ground level in a low-beam light distribution pattern directed onto a wall surface or the like in front of the vehicle.
As to the first aspect of the present invention, if the downward deflective reflection zone of the reflecting surface of the reflector is composed of a plurality of downward deflective reflecting elements having different downward deflection angles, the contrast in luminosity of the oncoming-lane-side horizontal cut-off line can be reduced sufficiently. Therefore it is possible to more effectively reduce the possibility of oncoming drivers being dazzled by glare.
In accordance with the first aspect of the present invention, if the reflecting surface of the reflector is provided with a horizontally deflective reflection zone which horizontally deflects and reflects light that has traveled from the filament past the vicinity of the upper edges of the shade and impinges on an oncoming-lane-side reflection zone of the reflecting surface, and if the horizontally deflective reflection zone forms a long-distance radiation light distribution pattern wherein oncoming-lane-side ends are substantially located on the line V, the long-distance visibility of the driver can be enhanced.
Further concerning the first aspect of the present invention, although the front lens may be formed of a translucent lens with all the functions of light distribution control allotted to the reflector, a plurality of lens elements may be formed in a predetermined zone of the front lens so that the front lens also performs the function of light distribution control. In the latter case, each of the lens elements may be designed to perform the function of downward deflective transmission or horizontally deflective transmission for compensating for the function of downward deflective reflection or horizontally deflective reflection performed by the reflecting surface of the reflector. Alternatively, each of the lens elements may be designed to exclusively perform another function (e.g., the function of lateral diffusion).
On the other hand, as to the second aspect of the present invention, if the downward deflective transmission zone is composed of a plurality of downward deflection lens elements having different downward deflection angles, the contrast in luminosity of the oncoming-lane-side horizontal cut-off line can be reduced sufficiently. Thus, it is possible to more effectively reduce the possibility of oncoming drivers being dazzled by glare.
Further concerning the second aspect of the present invention, if the front lens is provided with a horizontally deflective transmission zone which horizontally deflects and transmits light that has traveled from the filament past the vicinity of the upper edges of the shade and been reflected by an oncoming-lane-side reflection zone of the reflecting surface, and if the horizontally deflective transmission zone forms a long-distance radiation light distribution pattern wherein oncoming-lane-side ends are substantially located on a line V, the long-distance visibility of the driver can be enhanced.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a side sectional view of a vehicular headlamp constructed according to a first embodiment of the present invention.
FIG. 2
is a detailed sectional view taken along a line II—II shown in FIG.
1
.
FIG. 3
shows a low-beam light distribution pattern formed by the vehicular headlamp of the first embodiment, together with a reflector unit, in a perspective view seen from the side of a rear surface of the reflector unit.
FIG. 4
shows a light distribution pattern formed by a downward deflective reflection zone of the vehicular headlamp of the first embodiment, together with the reflector unit, in a perspective view seen from the side of the rear surface of the reflector unit.
FIG. 5
shows a long-distance radiation light distribution pattern formed by a horizontally deflective reflection zone of the vehicular headlamp of the first embodiment, together with the reflector unit, in a perspective view seen from the side of the rear surface of the reflector unit.
FIG. 6
shows a low-beam light distribution pattern formed by a vehicular headlamp according to a second embodiment of the present invention, together with a front lens and a reflector unit, in a perspective view seen from the side of a rear surface of the reflector unit.
FIG. 7
shows a light distribution pattern formed by a downward deflective transmission zone of the vehicular headlamp of the second embodiment, together with the front lens and the reflector unit, in a perspective view seen from the side of the rear surface of the reflector unit.
FIG. 8
shows a long-distance radiation light distribution pattern formed by a horizontally deflective transmission zone of the vehicular headlamp of the second embodiment, together with the front lens and the reflector unit, in a perspective view seen from the side of the rear surface of the reflector unit.
FIG. 9
shows a low-beam light distribution pattern formed by a vehicular headlamp according to a third embodiment of the present invention, together with a front lens and a reflector unit, in a perspective view seen from the side of the rear surface of the reflector unit.
FIG. 10
, otherwise similar to
FIG. 3
, shows a conventional example of a vehicular headlamp.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1
is a side sectional view of a vehicular headlamp
10
constructed according to the first embodiment, and
FIG. 2
is a detailed sectional view taken along a line II—II in FIG.
1
.
As shown in
FIG. 1
, the vehicular headlamp
10
of this embodiment has a reflector unit
16
mounted in a lighting chamber formed by a front lens and a lamp body
14
in such as manner as to be vertically and laterally tiltably adjustable.
The reflector unit
16
has a light source bulb
18
, a reflector
20
and an outer shade
22
. The reflector unit
16
is supported by the lamp body
14
so that the optical axis Ax
1
of the reflector
20
substantially coincides with a lighting fixture reference axis Ax (a horizontal line longitudinally extending past a reference
10
position of the lighting fixture).
The light source bulb
18
is an HB2 bulb (a halogen bulb of the H4 type). The light source bulb
18
has two filaments
18
a
,
18
b
which extend longitudinally, and a shade
18
c
which covers the front filament
18
a
at a central angle of approximately 165° is extending around an axis Ax
2
of the filament
18
a
. The light source bulb
18
is securely supported by the reflector
20
by attachment to a bulb insertion-attachment portion
20
b
provided at the rear apex of the reflector
20
.
The light source bulb
18
is securely supported by the
20
reflector
20
in such a manner that the two upper edges
18
c
L,
18
c
R of the shade
18
c
are at substantially the same height (at left and right angular positions diagonally downward from the axis Ax
2
at an angle of approximately 7.5° respectively) as shown in
FIG. 2
, and that the axis Ax
2
is slightly upwardly offset from the optical axis Ax
1
of the reflector
20
as shown in FIG.
1
. The offsetting of the axis Ax
2
is achieved by slantingly forming the bulb insertion-attachment portion
20
b
of the reflector
20
.
The reflector
20
has a reflecting surface
20
a
having a plurality of reflecting elements
20
s
formed on a paraboloid of revolution extending around the optical axis Ax
1
. The reflecting surface
20
a
is designed to diffusively and deflectively reflect light from the filament
18
a
or
18
b
forwardly. When lit, the filament
18
a
forms a low-beam light distribution pattern, while the filament
18
b
when lit forms a high-beam light distribution pattern. The front lens
12
is made of a translucent material.
The outer shade
22
, which is disposed in front of the light source bulb
18
, is designed to block direct light emanating from the filament
18
a
towards the front of the lighting fixture.
FIG. 3
shows a low-beam light distribution pattern P formed by the vehicular headlamp
10
together with the reflector unit
16
is in a perspective view seen from the side of the rear surface of the reflector unit
16
.
In this embodiment, the upper edges
18
c
L,
18
c
R of the shade
18
c
are at substantially the same height (at respective left and right angular positions diagonally downward from the axis Ax
2
at an angle of approximately 7.5°), and the axis Ax
2
of the filament
18
a
is slightly upwardly offset from the optical axis Ax
1
of the reflector
20
. Light from the filament
18
a
impinges on a reflection zone of the reflecting surface
20
a
of the reflector
20
. The reflection zone is somewhat larger than the upper half of the reflecting surface
20
a
. Due to the light-blocking effect of the shade
18
c
, light from the filament
18
a
does not impinge on a lower zone of the reflecting surface indicated by broken lines in FIG.
3
.
Assuming that the reflecting surface
20
a
is a paraboloid of revolution extending around the optical axis Ax
1
, the light reflected from the reflecting surface
20
a
forms a basic light distribution pattern Po, which is a generally semicircular and slightly flattened light distribution pattern with its upper edge substantially located on a line H, as indicated by broken long-and-two-short dashed lines in FIG.
3
. Referring to
FIG. 3
, a long-and-short dashed line indicates a generally sectorial light distribution pattern Po′ which is obtained for a case where the axis Ax
2
of the filament
18
a
is not upwardly offset from the optical axis Ax
1
of the reflector
20
. The light distribution pattern Po′ has left and right upper edges extending diagonally upwardly at an angle of approximately 7.5°.
In this embodiment, the basic light distribution pattern Po is transformed by the diffusive and deflective reflection performed by the reflecting elements
20
s
formed on the reflecting surface
20
a
to the low-beam light distribution pattern P as indicated by a solid line in FIG.
3
.
The low-beam light distribution pattern P, which is designed for right-side light distribution, has horizontal cut-off lines CL
1
and CL
2
which are located at different levels on laterally opposed sides of a line V. The right horizontal cut-off line CL
2
is located on the line H and formed directly on the right upper edge of the basic light distribution pattern Po. On the other hand, the left horizontal cut-off line CL
1
is located slightly below the line H and is formed by downwardly displacing part of the left upper edge of the basic light distribution pattern Po. To form the left horizontal cut-off line CL
1
, the reflecting surface
20
a
is provided with a downward deflective reflection zone (a zone with diagonal lines extending upwardly to the right)
20
a
1
which downwardly deflects and reflects the light that has traveled from the filament
18
a
past the vicinity of the right upper edge
18
c
R of the shade
18
c
and impinges on a traveling-lane-side reflection zone
20
a
R of the reflection zone
20
a.
As shown in
FIG. 4
, a plurality of reflecting elements
20
s
1
(downward deflection reflecting elements) constituting the downward deflective reflection zone
20
a
1
do not form a unique downward deflection angle. Namely, reflecting elements (a) located on the outer peripheral side of the reflecting surface
20
a
form a large angle, reflecting elements (c) located on the inner peripheral side of the reflection zone
20
a
form a small angle, and reflecting elements (b) located therebetween form an intermediate angle. This arrangement serves to form a plurality of segmented light distribution patterns Pa, Pb and Pc having vertically offset upper edges from a plurality of segmented light distribution patterns Pao, Pbo and Pco, respectively, which have upper edges at the same level. With this arrangement, the contrast in luminosity of the horizontal cut-off line CL
1
on the side of the oncoming lane is sufficiently reduced.
As shown in
FIG. 5
, the reflecting surface
20
a
is provided with a horizontally deflective reflection zone (a zone with diagonal lines extending upwardly to the left)
20
a
2
which horizontally deflects and reflects the light that has traveled from the filament
18
a
past the vicinity of the left upper edge
18
c
L of the shade
18
c
and impinged on an oncoming-lane-side reflection zone
20
a
L of the reflection zone
20
a
. The horizontally deflective reflection zone
20
a
2
forms a long-distance radiation light distribution Pf whose left end (the end on the side of the oncoming lane) is located substantially on the line V. To realize this, a plurality of reflecting elements
20
s
2
constituting a horizontally deflective reflection zone
20
a
2
do not form a unique horizontal deflection angle. Namely, reflecting elements (d) located on the outer peripheral side of the reflecting surface is
20
a
form a small angle, and reflecting elements (f) located on the inner peripheral side of the reflecting surface
20
a
form a large angle, and reflecting elements (e) located therebetween form an intermediate angle. This serves to form a plurality of segmented light distribution patterns Pd, Pe and Pf having left ends located substantially on the line V out of a plurality of segmented light distribution patterns Pdo, Peo and Pfo, respectively, which have left ends offset from one another.
As has been described in detail, in the vehicular headlamp
10
of this embodiment the light source bulb
18
is securely supported by the reflector
20
so that the left and right upper edges
18
c
L,
18
c
R of the shade
18
c
are located at the same height and that the axis Ax
2
of the filament
18
a
is upwardly offset from the optical axis Ax
1
of the reflector
20
at a predetermined angle. The reflecting surface
20
a
of the reflector
20
is provided with the downward deflective reflection zone
20
a
1
which downwardly deflects and reflects the light that has traveled from the filament
18
a
past the vicinity of the right upper edge
18
c
R of the shade
18
c
and impinged on the traveling-lane-side reflection zone
20
a
R. Accordingly, it is possible to obtain a low-beam light distribution pattern P wherein the oncoming-lane-side horizontal cut-off line CL
1
formed of light reflected from the traveling-lane-side reflection zone
20
a
R is at a lower level than the traveling-lane-side horizontal cut-off line CL
2
formed of light beams reflected from the oncoming-lane-side reflection zone
20
a
L.
Because the low-beam light distribution pattern P makes it possible to carry out vertical aiming with respect to the traveling-lane-side horizontal cut-off line CL
2
, the contrast in luminosity of the oncoming-lane-side horizontal cut-off line CL
1
can be reduced. Thus, the low-beam light distribution pattern P makes it easy for the driver to drive the vehicle while reducing the possibility of oncoming drivers being dazzled by glare.
Moreover, since the downward deflective reflection zone
20
a
1
is composed of a plurality of reflecting elements
20
s
1
having different downward deflection angles, the contrast in luminosity of the oncoming-lane-side horizontal cut-off line CL
1
can be reduced sufficiently. Thereby it becomes possible to more effectively reduce the possibility of oncoming drivers being dazzled by glare.
In this embodiment, since the light source bulb
18
is offset upwardly, the basic light distribution pattern Po is flattened and made closer in shape to the low-beam light distribution pattern P in comparison with the case where the light source
18
is not upwardly offset. Thus, it is possible to facilitate the diffusive and deflective reflection control of the reflector
20
which is performed to transform the basic light distribution pattern Po into the low-beam light distribution pattern P.
In addition, according to this embodiment, the reflecting surface
20
a
of the reflector
20
is provided with the horizontally deflective reflection zone
20
a
2
forming the long-distance radiation light distribution pattern Pf whose left end is substantially located on the line V. With this arrangement it is possible to enhance the long-distance visibility of the driver.
In this embodiment, the target position for vertical aiming is set to a position where the traveling-lane-side horizontal cut-off line CL
2
coincides with the line H. Thus, even without special equipment for carrying out aiming measurement, it is possible to effect vertical aiming by means of a simple operation of making the traveling-lane-side horizontal cut-off line CL
2
coincide with a height of the lighting fixture reference axis Ax above ground level in the low-beam light distribution pattern P radiated onto a wall surface or the like in front of the vehicle. Moreover, it is also possible to easily carry out lateral aiming if the target position of lateral aiming is set to a position where the left end of the long-distance radiation light distribution pattern Pf substantially coincides with the line V.
Next, a second embodiment of the present invention will be described.
FIG. 6
shows a low-beam light distribution pattern P formed by a vehicular headlamp
30
of the second embodiment, together with a front lens
32
and a reflector unit
36
in a perspective view seen from the side of the rear surface of the reflector unit
36
.
The vehicular headlamp
30
of this embodiment is constructed basically in the same manner as that of the first embodiment. However, the second embodiment differs from the first embodiment in the structures of the reflecting surface
40
a
of a reflector is
40
and the lens surface
32
a
of the front lens
32
.
Namely, in this embodiment, the reflecting surface
40
a
of the reflector
40
is formed as a paraboloid of revolution extending around the optical axis Ax
1
of the reflector
40
. The reflecting surface
40
a
forwardly reflects light from a filament
18
a
as a generally parallel light beam slightly deflected towards the optical axis Ax, thus forming a basic light distribution pattern Po. The second embodiment is identical to the first embodiment in that the axis Ax
2
of the filament
18
a
is slightly upwardly offset from the optical axis Ax
1
of the reflector
40
to form the basic light distribution pattern Po. Due to the light-blocking effect of a shade
18
c
, light from the filament
18
a
does not impinge on the lower zone of the reflecting surface indicated by broken lines in FIG.
6
.
In this embodiment, a plurality of lens elements
32
s
are formed on the lens surface
32
a
of the front lens
32
, and the basic light distribution pattern Po is transformed into a low-beam light distribution pattern P by the diffusive and deflective transmission performed by the lens elements
32
s
. Referring to
FIG. 6
, long-and-two-short dashed lines indicate extensions of light beams reflected from the reflecting surface
40
a
, and solid lines indicate light beams diffusively and deflectively transmitted through the lens elements
32
s.
The low-beam light distribution pattern P has horizontal cut-off lines CL
1
, CL
2
on laterally opposed sides of a line V. To form the left horizontal cut-off line CL
1
at a lower level than the right horizontal cut-off line CL
2
, the lens surface
32
a
of the front lens
32
is provided with a downward deflective transmission zone
32
a
1
which downwardly deflects and transmits light that has traveled from the filament
18
a
past the right upper edge
18
c
R of the shade
18
c
and been reflected by a traveling-lane-side reflection zone
40
a
R of the reflecting surface
40
a.
As shown in
FIG. 7
, a plurality of lens elements
32
s
1
(downward deflective transmission elements) constituting the downward deflective transmission zone (a zone with diagonal lines extending upwardly to the right)
32
a
1
do not form a unique downward deflection angle. Namely, lens elements (a) located on the outer peripheral side of the reflecting surface
40
a
form a large angle, lens elements (c) located on the inner peripheral side of the reflecting surface
40
a
form a small angle, and lens elements (b) located therebetween form an intermediate angle. This serves to form a plurality of segmented light distribution patterns Pa, Pb and Pc having vertically offset upper edges out of a plurality of segmented light distribution patterns Pao, Pbo and Pco, respectively, which have upper edges at the same level. Thus, the contrast in luminosity of the horizontal cut-off line CL
1
on the side of an oncoming lane is sufficiently reduced.
As shown in
FIG. 8
, the lens surface
32
a
of the front lens
32
is provided with a horizontally deflective transmission zone (a zone with diagonal lines extending upwardly to the left)
32
a
2
which horizontally deflects and transmits the light that has traveled from the filament
18
a
past the vicinity of the left upper edge
18
c
L of the shade
18
c
and been reflected by an oncoming-lane-side reflection zone
40
a
L of the reflection zone
40
a
. The horizontally deflective transmission zone
32
a
2
forms a long-distance radiation light distribution Pf whose left end (the end on the side of the oncoming lane) is located substantially on the line V. To realize this, a plurality of lens elements
32
s
constituting a horizontally deflective transmission zone
32
a
2
do not form a unique horizontal deflection angle. Namely, lens elements (d) located on the outer peripheral side of the reflecting surface
40
a
form a small angle, lens elements (f) located on the inner peripheral side of the reflecting surface
40
a
form a large angle, and lens elements (e) located therebetween form an intermediate angle. This serves to form a plurality of segmented light distribution patterns Pd, Pe and Pf having left ends located substantially on the line V out of a plurality of segmented light distribution patterns Pdo, Peo and Pfo, respectively, which have left ends offset from one another.
As has been described in detail, the vehicular headlamp
30
of this embodiment has the light source bulb
18
which is securely supported by the reflector
40
so that the left and right upper edges
18
c
L,
18
c
R of the shade
18
c
are located at the same height and the axis Ax
2
of the filament
18
a
is upwardly offset from the optical axis Ax
1
of the reflector
40
at a predetermined angle. The reflecting surface
32
a
of the front lens
32
is provided with the downward deflective transmission zone
32
a
1
which downwardly deflects and transmits the light that has traveled from the filament
18
a
past the vicinity of the right upper edge
18
c
R of the shade
18
c
and been reflected by the traveling-lane-side reflection zone
40
a
R. With this construction, it is possible to obtain a low-beam light distribution pattern P wherein the oncoming-lane-side horizontal cut-off line CL
1
formed of light reflected from the traveling-lane-side reflection zone
40
a
R is at a lower level than the traveling-lane-side horizontal cut-off line CL
2
formed of light reflected from the oncoming-lane-side reflection zone
40
a
L.
Because the low-beam light distribution pattern P makes it possible to easily carry out vertical aiming with respect to the traveling-lane-side horizontal cut-off line CL
2
, the contrast in luminosity of the oncoming-lane-side horizontal cut-off line CL
1
can be reduced. Thus, the low-beam light distribution pattern P can make it easy for the driver to drive and reduce the possibility of oncoming drivers being dazzled by glare.
Moreover, since the downward deflective transmission zone
32
a
1
is composed of a plurality of lens elements
32
s
1
having different downward deflection angles, the contrast in luminosity of the oncoming-lane-side horizontal cut-off line CL
1
can be reduced sufficiently. Thereby it becomes possible to more effectively reduce the possibility of oncoming drivers being dazzled by glare.
In this embodiment, since the light source bulb
18
is upwardly offset, the basic light distribution pattern Po is flattened and made closer in shape to the low-beam light distribution pattern P, in comparison with the case where the light source
18
is not upwardly offset. Thus it is possible to facilitate the diffusive and deflective transmission control of the front lens
32
which is performed to transform the basic light distribution pattern Po into the low-beam light distribution pattern P.
In addition, according to this embodiment, the lens surface
32
a
of the front lens
32
is provided with the horizontally deflective transmission zone
32
a
2
forming the long-distance radiation light distribution pattern Pf whose left end is substantially located on the line V. Therefore it is possible to enhance the long-distance visibility of the driver.
In this embodiment, the target position of vertical aiming is set to a position where the traveling-lane-side horizontal cut-off line CL
2
coincides with the line H. Thus, even without special equipment for carrying out aiming measurement, it is possible to effect vertical aiming by means of a simple operation of making the traveling-lane-side horizontal cut-off line CL
2
coincide with a height of the lighting fixture reference axis Ax above ground level in a low-beam light distribution pattern P radiated onto a wall surface or the like in front of the vehicle. It is also possible to easily carry out lateral aiming if the target position of lateral aiming is set to a position where the left end of the long-distance radiation light distribution pattern Pf substantially coincides with the line V.
Next, a third embodiment of the present invention will be described.
FIG. 9
shows a low-beam light distribution pattern P formed by a vehicular headlamp
50
of the third embodiment together with a front lens
52
and a reflector unit
56
in a perspective view seen from the side of a rear surface of the reflector unit
56
.
The vehicular headlamp
50
of this embodiment is also constructed basically in the same manner as that of the first embodiment. However, the third embodiment is different from the first embodiment in the structures of a reflecting surface
60
a
of a reflector
60
and a lens surface
52
a
of the front lens
52
. Namely, in this embodiment, the reflecting surface
60
a
of the reflector
60
is formed as a paraboloid of revolution extending around the optical axis Ax
1
of the reflector
60
. A downward deflective reflection zone (a zone with diagonal lines extending upwardly to the right)
60
a
1
and a horizontally deflective reflection zone (a zone with diagonal lines extending upwardly to the left)
60
a
2
, which are similar to those of the first embodiment, are formed on the paraboloid of revolution. A plurality of reflecting elements
60
s
,
60
s
2
, similar to those of the first embodiment, are formed on the downward deflective reflection zone
60
a
1
and the horizontally deflective reflection zone
60
a
2
respectively. A zone in the reflecting surface
60
a
of the reflector
60
above the deflective reflection zones
60
a
1
,
60
a
2
is formed as a paraboloid of revolution extending around the optical axis Ax
1
of the reflector
60
.
The lens
52
a
of the front lens
52
is made of a translucent material in a section in front of the deflective reflection zones
60
a
1
,
60
a
2
, and has a plurality of lens elements
52
s
in a section in front of the zone above the deflective reflection zones
60
a
1
,
60
a
2
.
This embodiment is also designed such that the axis Ax
2
of the filament
18
a
is slightly upwardly offset from the optical axis Ax
1
of the reflector
60
to form a basic light distribution pattern Po. Due to the light-blocking effect of the shade
18
c
, light from the filament
18
a
does not impinge on a lower zone of the reflecting surface indicated by broken lines in FIG.
9
.
In this embodiment, the basic light distribution pattern P is transformed by the function of diffusive and deflective reflection performed by a plurality of reflecting elements
60
s
1
,
60
s
2
formed on the reflecting surface
60
a
of the reflector
60
and the function of diffusive and deflective transmission performed by a plurality of lens elements
52
s
formed on the lens surface
52
a
of the front lens
52
, whereby the low-beam light distribution pattern P as indicated by a solid line in
FIG. 9
is formed. In this process, a long-distance light distribution pattern extending along horizontal cut-off lines CL
1
, CL
2
is formed by the function of diffusive and deflective reflection performed by the reflector
60
, whereas a light distribution pattern short thereof is formed by the function of diffusive and deflective transmission performed by the front lens
52
.
As has been described in detail, this embodiment also makes it possible to obtain the low-beam light distribution pattern P wherein the oncoming-lane-side horizontal cut-off line CL
1
formed of light beams reflected from a traveling-lane-side reflection zone
60
a
R is at a lower level than the traveling-lane-side horizontal cut-off line CL
2
formed of light reflected from an oncoming-lane-side reflection zone
40
a
L.
Accordingly, this embodiment also makes it possible to achieve an operation and effects similar to those of the first and second embodiments. Moreover, since the lens surface
52
a
of the front lens
52
of this embodiment is made up of the section formed of the translucent lens and the section formed of the lens elements
52
s
, the three-dimensional design of the lighting fixture can be readily carried out. In particular, since the lens elements
52
s
are formed in the upper zone of the lens surface
52
a
, the lighting chamber can be prevented from becoming easily visible from viewing points in front of the lighting fixture.
Although the horizontal cut-off lines CL
1
, CL
2
in this embodiment are formed by the function of diffusive and deflective reflection performed by the reflector
60
, it is also possible to form the horizontal cut-off lines CL
1
, CL
2
by adding the function of diffusive and deflective transmission to the functions performed by the front lens
52
.
Although the description of the aforementioned embodiments has been made with reference to a lighting fixture structure in which a low-beam light distribution pattern P for right-side light distribution is obtained, it is possible to obtain a low-beam light distribution pattern for left-side light distribution, which is laterally symmetrical to the low-beam light distribution pattern P, by laterally inverting the lighting fixture structure of the aforementioned embodiments. In such a case, an operation and effects similar to those of the aforementioned embodiments can be achieved.
It should further be apparent to those skilled in the art that various changes in form and detail of the invention as shown and described above may be made. It is intended that such changes be included within the spirit and scope of the claims appended hereto.
Claims
- 1. A vehicular headlamp comprising:a light source bulb comprising a longitudinally extending filament and a shade covering a bottom area of the filament around a longitudinal axis of said filament at a central angle of approximately 165° so that light downwardly travelling from said filament is blocked by said shade; a reflector supporting said light source bulb and having a reflecting surface forwardly reflecting light from said filament, said light source bulb being supported by said reflector so that left and right upper edges of said shade are at substantially the same height and so that said longitudinal axis of said filament is upwardly offset from an optical axis of said reflector at a predetermined angle; a front lens disposed forward of said reflector; and means for downwardly deflecting light that has traveled from said filament past the upper edges of said shade and impinged on a traveling-lane-side reflection zone of said reflecting surface.
- 2. A vehicular headlamp comprising:a light source bulb comprising a longitudinally extending filament and a shade covering a bottom area of the filament around a longitudinal axis of said filament at a central angle of approximately 165° so that the light downwardly travelling from said filament is blocked by said shade; a reflector supporting said light source bulb and having a reflecting surface forwardly reflecting light from said filament; and a front lens disposed forward of said reflector, said light source bulb being supported by said reflector so that left and right upper edges of said shade are at substantially the same height and so that said longitudinal axis of said filament is upwardly offset from an optical axis of said reflector at a predetermined angle; and said reflecting surface of the reflector being provided with a downward deflective reflection zone which downwardly deflects and reflects light that has traveled from said filament past the upper edges of said shade and impinged on a traveling-land-side reflection zone of said reflecting surface.
- 3. The vehicular headlamp according to claim 2, wherein: said downward deflective reflection zone comprises a plurality of downward deflection reflecting elements having respective different downward deflection angles.
- 4. The vehicular headlamp according to claim 2, wherein said reflecting surface of said reflector is provided with a horizontally deflective reflection zone which horizontally deflects and reflects light that has traveled from said filament past upper edges of said shade and impinged on an oncoming-lane-side reflection zone of said reflecting surface; andwherein said horizontally deflective reflection zone forms a long-distance radiation light distribution pattern wherein oncoming-lane-side ends are located substantially on a vertical line perpendicular to a lighting fixture reference axis.
- 5. The vehicular headlamp according to claim 2, wherein a plurality of lens elements are formed in a predetermined zone of said front lens.
- 6. The vehicular headlamp according to claim 3,wherein said reflecting surface of said reflector is provided with a horizontally deflective reflection zone which horizontally deflects and reflects light that has traveled from said filament past upper edges of said shade and impinged on an oncoming-lane-side reflection zone of said reflecting surface; and wherein said horizontally deflective reflection zone forms a long-distance radiation light distribution pattern wherein oncoming-lane-side ends are located substantially on a vertical line perpendicular to a lighting fixture reference axis.
- 7. The vehicular headlamp according to claim 3, wherein a plurality of lens elements are formed in a predetermined zone of said front lens.
- 8. The vehicular headlamp according to claim 4, wherein a plurality of lens elements are formed in a predetermined zone of said front lens.
- 9. A vehicular headlamp comprising:a light source bulb having a longitudinally extending filament and a shade covering a bottom area of said filament around a longitudinal axis of said filament at a central angle of approximately 165° so that light travelling downward from said filament is blocked; a reflector supporting the light source bulb and having a reflecting surface forwardly reflecting light from said filament; and a front lens disposed forwardly of the reflector, said light source bulb being supported by said reflector so that left and right upper edges of said shade are at substantially the same height and said longitudinal axis of said filament is upwardly offset from an optical axis of said reflector at a predetermined angle; and said front lens being provided with a downward deflective transmission zone which downwardly deflects and transmits light that has traveled from said filament past upper edges of said shade and impinged on a traveling-lane-side reflection zone of said reflecting surface.
- 10. The vehicular headlamp according to claim 9, wherein said downward deflective transmission zone comprises a plurality of downward deflection lens elements having respective different downward deflection angles.
- 11. The vehicular headlamp according to claim 9,wherein said front lens is provided with a horizontally deflective transmission zone which horizontally deflects and transmits light that has traveled from said filament past said upper edges of said shade and been reflected by an oncoming-lane-side reflection zone of said reflecting surface; and wherein said horizontally deflective transmission zone forms a long-distance radiation light distribution pattern wherein oncoming-lane-side ends are located substantially on a vertical line perpendicular to a lighting fixture reference axis.
- 12. The vehicular headlamp according to claim 10,wherein said front lens is provided with a horizontally deflective transmission zone which horizontally deflects and transmits light that has traveled from said filament past upper edges of said shade and been reflected by on an oncoming-lane-side reflection zone of said reflecting surface; and wherein said horizontally deflective transmission zone forms a long-distance radiation light distribution pattern wherein oncoming-lane-side ends are located substantially on a vertical line perpendicular to a lighting fixture reference axis.
Priority Claims (1)
Number |
Date |
Country |
Kind |
11-147782 |
May 1999 |
JP |
|
US Referenced Citations (5)