Information
-
Patent Grant
-
6312147
-
Patent Number
6,312,147
-
Date Filed
Monday, December 21, 199825 years ago
-
Date Issued
Tuesday, November 6, 200122 years ago
-
Inventors
-
Original Assignees
-
Examiners
- O'Shea; Sandra
- Negron; Ismael
Agents
-
CPC
-
US Classifications
Field of Search
US
- 362 459
- 362 487
- 362 506
- 362 507
- 362 538
- 362 539
- 362 319
- 362 322
- 362 324
- 362 351
- 362 361
- 362 512
- 362 513
- 362 464
- 362 465
-
International Classifications
-
Abstract
A headlight for a vehicle operating in a projection principle has a light source, a reflector reflecting a light emitted by the light source, a lens arranged in a course of light reflected by the reflector, a first shade device located between the reflector and the lens and changeable between at least one first condition for a first operational position of the headlight and at least one second condition for a second operational position of the headlight, the first shade device in the first condition screening a part of the light reflected by the reflector and producing a bright-dark limit of a light bundle exiting the headlight, and in the second condition screening at least only a smaller part of a light reflected by the reflector than in the first condition, and a further shade device arranged in a direction of an optical axis offset relative to the first shade device and changeable between at least one first condition and at least one second condition, the further shade device in the first condition screening a part of a light reflected by the reflector and passing on the first shade device in the first condition so as to reduce a maximum illumination intensity value produced by a light bundle exiting the headlight in the first operational position, the further shade device in the second condition screening at least only a smaller part of a light reflected by the reflector.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a headlight for vehicle in accordance with a projection principle.
Headlights of the above mentioned general type are known in the art. One of such headlights is disclosed for example in the German patent document DE 40 02 576 A1. The headlights serves for selectively producing a low beam or a high beam. The headlight has a light source and a reflector for reflecting the light emitted by the light source. A lens is arranged in a beam course of the reflector and a shade device is arranged between the reflector and the lens. The shade device is changeable between a first condition for the operational position of the headlight for the low beam, and a second condition for the operational position for the high beam. The shade device screens in the first condition a part of the light reflected by the reflector and produces a bright-dark limit of the low beam bundle exiting the headlight. In the second condition the shade device shades at least a small part of the light reflected by the reflector. The change of the shade device between its first and second condition can be performed by its movement or the shade device can have at least locally a changeable light permeability, so that the light permeability in the first condition of the shade device is low and in the second condition is high.
The above described known headlight has the disadvantage that it can be optimal either for producing the low beam or for producing the high beam. However, no design is possible for optimal production of both light functions, since the requirements for them are partially contradictory. If the headlight is optimal for the production of the low beam, with the shade device in the first condition, then in the operational position for the high beam with the shade device in the second condition no efficient high beam is produced, since the high beam bundle exiting the headlight can be produced with very low maximum illumination intensities. If to the contrary the headlight is designed so that in its operational condition for high beam with the shade device in its second condition an efficient high beam bundle with its maximum illumination intensities is emitted, then the shade device in its first condition for the operational position of the headlight for low beam must be arranged so that a greater part of light reflected by the reflector is shades, since otherwise the low beam can be produced with impermissibly high illumination intensities. With the arrangement of the shade device required for this in the first condition, moreover substantial image forming error by the lens occurs, such as color edge or over radiation which jointly negatively affects the quality of the low beam bundle. Moreover, the headlight in the operational condition for the low beam is adjusted so that the bright-dark limit assumes the prescribed position, but in the operational position for the high beam the regions with the maximum illumination intensities are located too high.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a headlight for a vehicle which avoids the disadvantages of the prior art.
In keeping with these objects and with others which become apparent hereinafter, one feature of present invention resides, briefly stated in a headlight for a vehicle in accordance with the projection principle in which a further shade device is arranged offset in direction of the optical axis of the first shade device and is changeable between at least a first condition and at least a second condition wherein the further shade device in its first condition screens a part of the light reflected by the reflector and passing on the first shade device in its first condition, in order to reduce maximum illumination intensity values produced by the light bundle exiting the headlight in its first operational condition, and the further shade device in its second condition screens only a small part of the light reflected by the reflector.
When the headlight is designed in accordance with the present invention, the production of the bright-dark limit in the first operational condition of the headlight is performed by the first shade device in its first condition and the position of the regions with maximum illumination intensity values can be selected as required for the light bundle emitted by the reflector in the second operational condition, without taking into consideration of the low maximum illumination intensity values which are permitted from the light bundle emitted in the first operational position of the headlight, which are maintained by the second shade device by screening of a part of the light produced with the maximum illumination intensity value.
In accordance with a further feature of the present invention, the further shade device is arranged after the first shade device is considered in a light outlet direction. This provides the advantage that the bright-dark limit is produced by the further shade device without being influenced by the first shade device.
In accordance with still another feature of the present invention the further shade device is curved in direction of an optical axis preferably concavely. This has the advantage that during shading with a further shade device, a homogenous transition is produced.
In still another embodiment of the invention, the further device is formed so that in the first condition the light which passes on the first shade device and illuminating the opposite traffic side in front of the vehicle is screened in a greater part than the light passing on the first shade device which illuminations the traffic light itself in front of the vehicle. This provides an improved illumination of a traffic side in front of the vehicle.
Finally, in accordance with still another feature of the present invention, the shade devices are coupled with one another and together are movable between the first and second conditions. This provides for a simple construction of the headlight, since both shade devices can move with a single adjusting element.
The novel features which are considered as characteristic for the present invention are setforth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a view showing a headlight in accordance with the present invention in a vertical longitudinal section with shade devices in accordance with a first embodiment in a first condition for a low beam;
FIG. 2
is a view showing a headlight with the shade devices in a second condition for a high beam;
FIG. 3
is a view showing a section of the shade devices in accordance with a modified embodiment;
FIG. 4
is a view showing a headlight in a horizontal position section with the shade devices in accordance with a further modified embodiment;
FIG. 5
is a view showing a shade device in a cross-section along the line V—V in
FIG. 1
;
FIG. 6
is a view showing the shade devices of the headlight in a perspective in accordance with a second embodiment,
FIG. 7
is a view showing a measuring screen arranged in front of the headlight during illumination by a low beam bundle exiting the headlight; and
FIG. 8
is a view showing a measuring screen during illumination by the high beam bundle exiting the headlight.
DESCRIPTION OF PREFERRED EMBODIMENTS
A headlight as shown in
FIGS. 1-6
operates in accordance with the projection principle and is used for a vehicle, in particular a motor vehicle. It serves for selective generation of different light bundles. In particular, a headlight for selected generation of a low beam and a high beam will be described herein below. The headlight has a concave curved reflector
10
with a light source
12
arranged in its apex region. The light source
12
can be an in condensate lamp or preferably a gas-discharge lamp and its light body, or in other words its in condensate coil or its light arc is arranged substantially parallel to its optical axis
11
of the reflector
10
. The reflector
10
is formed so that the light emitted by the light source
12
is reflected by the reflector is a converging light bundle. The reflector
10
can have at least approximately ellipsoidal shape, or any other shape, for example numerically determined shape. The light source
12
is arranged approximately in a first focal point F
1
of the reflector
10
a surface which at least approaches its shape.
A lense
16
is arranged after the reflector
10
at a distance from it as considered in a light outlet direction
14
. The lens
16
is formed as a collecting lens and has for example a substantially flat side
17
opposite to the light outlet direction
14
and facing the reflector
10
and a convex curve side
18
facing in the light outlet direction
14
. The side
18
of the lens
16
can be spherical or preferably aspherical, so that the aspherical curvature the image forming error of the lens
16
can be corrected. The curvature of the side
18
of the lens
16
is determined so that the light reflector
10
is deviated during passage through the lens
16
in a predetermined manner. The lens
16
can be composed of glass or light-permeable synthetic plastic and held in a not shown manner, for example on a supporting element connected with the reflector
10
.
A first shade device
20
is arranged between the lens
16
and the reflector
10
. In the first embodiment shown in
FIGS. 1 and 2
the first shade device
20
is light-impermeable and composed for example of a metal sheet or synthetic plastic. The first shade device
20
is arranged substantially under the optical axis
11
and is flat. The first shade device
20
has an upper edge
22
. It is movable between a first position which it assumes in the operational position of the headlight for a low beam, and a second position which it assumes in the operational position of the headlight for high beam. The first shade device
20
is arranged preferably in the region of a focal point F
3
of the lens
16
or a spherical lens at least approaching the lens
16
.
In its first position for low beam the first shade device
20
is arranged as shown in
FIG. 1
substantially perpendicular to the optical axis
11
and its upper edge
22
is arranged substantially at the height of the optical axis
11
. The upper edge
22
of the first shade device
20
can be arranged substantially under or substantially over the optical axis
11
. In its first position for low beam in accordance with
FIG. 1
, a part of the light reflected by the reflector
10
is screened by the shade device
20
and thereby a bright-dark limit of the light which then passes through the lens
16
is produced. The position and the course of the bright-dark limit is therefore determined by the upper edge
22
of the first shade device
20
. The bright-dark limit produced by the upper edge
22
of the first shade device
20
is formed through the lens
16
.
A second shade device
30
is laterally offset relative to the first shade device
20
in direction of the optical axis
11
. In the shown embodiment the second shade device
30
is arranged after the first shade device
20
in the light outlet direction
14
and is composed of a light impermeable material, such as for example metal sheet or synthetic plastic. The second shade device
30
is also movable between a first position for the operational position of the headlight for a low beam and a second position for the operational position for the headlight for high beam. In
FIG. 1
the second shade device
30
is arranged in its first position for low beam, in which its upper edge
32
is located substantially at a height of the optical axis
11
or substantially under or above it. Due to the second shade device
30
, a part of the light reflected by the reflector
10
and passing on the first shade device
20
is screened. Due to the arrangement of the second shade device
30
laterally offset in the light outlet direction
14
relative to the first shade device
20
, no sharp bright-dark limit is produced, but instead a weakening of the light passing through the lens
16
is provided.
FIG. 4
shows the devices
20
,
30
in their second positions for the operational position of headlight for high beam. The shade devices
20
,
30
are arranged somewhat farther in the beam course of the light reflected by the reflector
10
when compared with their first positions, so that they screen only a smaller part of the light reflected by the reflector
10
. Preferably, the shade devices
20
,
30
move completely from the beam course of the light reflected by the reflector
10
so that the total light reflected by the reflector
10
can pass through the lens
16
.
The shade devices
20
,
30
can move between their both positions, for example transversely to the optical axis
11
or around an axis
34
which extends transversely to the optical axis
11
. The movements of the shade devices
20
,
30
are actuated by at least one adjusting element
36
which engages them and is activated by a control device
38
. The adjusting element
36
can be for example an electric motor, an electromagnet, a hydraulic or pneumatic adjusting drive, or any other device. Both shade devices
20
,
30
can be arranged separately from one another. In this case for the movement between their both positions, a joint adjusting element
36
which engages both shade devices
20
,
30
can be provided, or separate adjusting element
36
can be provided. In the case of separate adjusting element
36
, an independent movement of the shade devices
20
,
30
between their first and second positions is possible. Preferably, both shade devices,
20
,
30
are coupled with one another, so that their movement can actuated by a joint adjusting element
36
and only one support for the shade devices
20
,
30
in the headlight is needed. The adjusting element
36
is activated by the control device
38
during the switching of the headlight between its operational position for low beam and its operational position for high beam.
For example it is possible to support the first shade device
20
in the headlight so that the movement between both positions is possible, while the second shade device can be fixedly connected with the first shade device
20
or formed of one piece with it. In the embodiment shown in
FIGS. 1 and 2
the second shade device
30
is connected on its lower edge with a spacer piece which extends from the first shade device
20
in the light outlet direction
14
to support the second shade device
30
at a distance from the first shade device
20
substantially perpendicular to the optical axis
11
until its upper edge
32
. In this exemplary embodiment the substantially parallel shade devices
20
,
30
are rotated jointly between their low beam and high beam positions, as indicated by arrows
33
. In the modified embodiment shown in
FIG. 3
the second shade device
30
is directly connected at its lower edge with the first shade device
20
and extends from there inclinedly upwardly and in the light outlet direction
14
until its upper edge
32
is opposite the upper edge
22
of the first shade device.
FIG. 4
shows the headlight in a horizontal longitudinal section, in which the reflector
10
with the light source
12
and the lens
16
and the shade devices
20
,
30
are shown in their first position for low beam. The first shade device
20
extends substantially perpendicular to the optical axis
11
. The second shade device
30
can also extend substantially perpendicular to the optical axis
11
as shown in a broken line in FIG.
4
. However, as shown in
FIG. 4
in a solid line, in accordance with a modified embodiment, it can be curved in direction of the optical axis
11
. The second shade device
30
extends in particular with a concave curvature in the light outlet direction
14
. The advantage of this curved embodiment of the second shade device
30
will be explained herein below in connection with the operation of the headlight.
FIG. 5
shows the second shade device
30
in direction of the optical axis
11
. The upper edge
32
of the second shade device
30
can be substantially horizontal in the first position for low beam and, as described above, located at the height of the optical axis
11
or substantially under or over the same. Alternatively, the upper edge
32
as shown in
FIG. 5
in a broken line, can have a course which deviates from the horizontal direction. For example, the upper edge
32
on a side, on which the light reflected by the reflector
10
and illuminating the opposite traffic side passes, can have a substantially horizontal portion
32
a
extending at a height of the optical axis
11
or substantially below or above the same. In the shown embodiments of the headlight for the right traffic, the counter traffic side is the left side in front of the vehicle and due to the side image forming of the upper edge
32
through the lens
16
, the horizontal portion
32
a
of the upper edge as seen in the light outlet direction
14
in
FIG. 5
is arranged right of the optical axis
11
. At the side of the second shade device
30
, at which the light reflected by the reflector
10
and illuminating the traffic side passes, the upper edge has an inclined portion
32
b
extending from the horizontal portion
32
a
inclinedly downwardly. In the shown embodiment of the headlight for the right traffic, the inclined portion
32
b
of the upper edge is arranged left of the optical axis
11
. When the headlight is designed for the left traffic, the arrangement of both portions
32
a,
32
b
of the upper edge is mirror-symmetrical relative to the optical axis
11
with respect to the arrangement shown in FIG.
5
.
The first shade device
20
and/or the second shade device
20
additionally to the above described movement possibilities between the first and second conditions for the switching between low beam and high beam, can be also movable in a different way. For example, a turning around the optical axis
11
or around an axis substantially parallel to it can be provided. Thereby a change of the position of the upper edges
22
and
32
of the shade devices
20
,
30
can be performed. For example a switching between the right traffic and the left traffic can be performed, so that the shade devices
20
,
30
are arranged to produce the bright-dark limit on the counter traffic side by the high regions of their upper edges
22
,
32
. Alternatively, the whole headlight unit with the reflector
10
, light source
12
lens
16
and the shade devices
20
,
30
can be turnable about the optical axis
11
or an axis extending parallel to it.
FIG. 6
shows both shade devices
120
,
130
in accordance with a second embodiment. The basic construction of the headlight is not changed with respect to the first embodiment, but both shade devices
120
,
130
are arranged immovably and stationary in the headlight. The shade devices
120
,
130
have at least regions
125
,
135
with changeable light permeability, which are arranged as the above described shade devices
20
,
30
in their first position for low beam. The regions
125
,
135
are arranged substantially under the optical axis
11
and extend up to the height of the optical axis
11
and/or substantially above or below the same. The changeable light permeability of the region
125
of the shade device
120
can be arranged by providing a light permeable base body in form of a disc
121
with a coating
127
. Under the action of an electrical voltage, it can change its light permeability between a condition of higher light permeability and a condition of lower light permeability. The coating
127
can be composed of so-called electro chromic materials. The disc
121
can be provided only in the region
125
or extends over a greater part of the beam course of the light reflected by the reflector
10
and have a coating
127
only in the region
125
.
The second shade device
130
can be formed in the same way. Alternatively. the shade device
130
in the region
135
can be provided with two light permeable discs
131
arranged at a distance from one another in direction of the optical axis
11
and a material
137
which has a changeable light permeability for example under the action of an electrical voltage can be provided between them. The material
137
can be formed for example by liquid crystals which change their orientation under the action of an electrical voltage, so that the material is switchable between a condition of a higher light permeability and a condition of a lower light permeability. The disc
131
can be provided only in the region
135
, or extend over a greater part of the beam course reflected by the reflector
10
. The material
137
is however arranged only in the region
135
. The first shade device
120
can be formed in the same manner.
In the operational position in the headlight for low beam, the regions
125
,
135
of the shade devices
120
,
130
are located in their condition of lower light permeability or they are light-impermeable, so that a part of the light reflected by the reflector
10
is screened by them as in the first embodiment. The bright-dark limit of the low beam bundle is produced by the upper
122
of the region
125
of the first shade
120
, and a part of the light passing on the region of the first shade device
120
is screened by the region
135
of the second shade device
130
, to reduce the maximum illumination intensity value. In the operational position in the headlight for high beams, the regions
125
,
135
of the shade devices
120
,
130
are located in their condition of high light permeability, so that the light reflected by the reflector
10
can pass through them and through the lens
16
. The dispersion of the electrical voltages applied to the regions
125
,
135
of the shade devices
120
,
130
is performed by a control device
136
, which is controlled with the switching between the operational position for low beam and the operational position for high beam.
As explained in connection with the first embodiment, the position and the course of the bright-dark limit of the low beam bundle exiting the headlight in the operational position for low beam is determined by the upper edge
22
of the first shade
20
or the upper edge
122
of the region
125
of the first shade device
120
.
FIG. 6
shows a course of the upper edge
122
of the region
125
of the first shade device
120
. The edge on the side of the optical axis
11
, on which the light reflected by the reflector
10
and illuminating the counter traffic side passes, has a substantially horizontally extending portion
122
extending at the height of the optical axis
11
or substantially under it. As explained above, the edge
122
is formed by the lens
16
at the traffic side, so that the portion
122
a
in the shown embodiment for the right traffic at the right optical axis
11
. At the side of the optical axis
11
, at which the light reflected by the reflector
10
and illuminating the traffic side or in other words the left side, the edge
122
has a portion
122
b
which extends from the horizontal portion
122
a
to the left and falls downwardly. When the headlight is designed for the light traffic, the arrangements of the portions
122
a,
122
b
relative to the optical axis
11
is mirror-symmetrical to the arrangement shown in FIG.
6
. As described in connection with the first embodiment, also at least one of the shade devices
120
,
130
in accordance with the second embodiment can be provided with the regions
125
and
135
formed so that the higher located portion
122
a
or
132
a
of the edges
122
or
132
produces the bright-dark limit at the counter traffic side, and therefore a switching between right traffic and left traffic is possible.
When the low beam bundle exiting the headlight in the operational position for low beam must have a differently shaped bright-dark limit, the corresponding shaping of the edge
122
of the first shade device
120
can provide the same. For example, the edge
122
at both sides of the optical axis
11
can be provided with a substantially horizontal portion, and the portions are connected with one another by an inclined portion, wherein the edge at the side, on which the light illuminating the counter traffic side passes, is arranged higher than at the other side. The upper edge
132
of the region
135
of the second shade device
130
can extend as before horizontally, or can have portions extending at different heights as shown in FIG.
5
.
In the first embodiment, in the second embodiment the total headlight unit with the reflector
10
, light source
12
, lens
16
and the shade devices
120
,
130
can be turnable about the optical axis
11
or an axis which extends parallel to it, for changing the length of the shade devices
120
,
130
for example for switching between right and left traffic.
The characteristics of the light bundles emitted by the headlight and their operational positions for low beam and high beam are explained herein below. A measuring screen
80
is arranged at a distance from the headlight as shown in
FIGS. 7 and 8
, and illuminated by the light bundles emitted by the headlight. The vertical central plane of the measuring screen
80
is identified as VV and its horizontal central plane is identified as HH. The vertical central plane VV and the horizontal central plane HH intersect in a portion HV. The optical axis
11
of the reflector
10
is inclined relative to the point HV downwardly by an angle of approximately 1%.
In the operational position of the headlight for low beam with the shade devices
20
,
30
or
120
,
130
in their first position or in their first condition, a low beam bundle is emitted by the reflector and illuminates at a region
82
on the measuring screen
80
. The region
82
is limited from above by a bright-dark limit which is produced by the upper edge
22
of the first shade device
20
or the upper edge
122
of the portions
122
a,
122
b
of the second shade device
120
. The bright-dark limit has correspondingly the upper edge
22
or the upper edge
122
on the counter traffic side which for the right traffic is the left side of the measuring screen
80
, a substantially horizontal extending portion
84
substantially under the horizontal central plane HH, and the portion
86
which extends at the traffic side or in other words for the right traffic at the right side of the measuring screen
80
from the horizontal portion
84
raising to the right. The portion
84
of the bright-dark limit is produced by the portion
122
of the edge
120
and the portion
86
is produced by the portion
122
b.
The highest illumination intensity values are available in the region
82
closesly under the bright-dark limit
84
,
86
substantially right of the vertical central plane VV in a zone
88
. In accordance with the standards accepted in Europe, they can amount maximum to substantially 40-70 lux. This maximum permissible illumination values are obtained so that a part of the light reflected by the reflector
10
and passing on the first shade device
20
or
120
is screened by the second shade device
30
or
130
, which illuminates the measuring screen
80
in the zone
88
. The illumination intensity values increase to the edges of the region
82
starting from the maximum values available in the zone
88
. In the region
82
several lines
83
of the same illumination intensity or so-called isolux lines are plotted to illustrate the distribution of the illumination intensity. The region
82
extends in a horizontal direction to approximately 30-40° as both sides of the vertical central plane VV, where the illumination intensity values are available of approximately one lux.
In the operational condition of the headlight for high beam with the shade devices
20
,
30
or
120
,
130
in their second position or their second, light-permeable condition, a high beam bundle is emitted by the headlight and illuminates the measuring screen
80
of
FIG. 8
in a region
92
. In the region
92
the highest illumination intensity values are available in a zone
98
around the point HV, which amounts to approximately 100-180 lux. In the region
92
several isolux lines
93
are again plotted for illustration of the distribution of the illumination intensity. The region
92
extends in a horizontal direction to approximately 30-40° at both sides of the vertical central plane VV, where the illumination intensity values of approximately one lux are available. The extension of the region
92
in a horizontal direction corresponds at least substantially to the extension of the region
82
in a horizontal direction since it is not influenced by the shape devices
20
,
30
or
120
,
130
. Since the first shade device
20
in its second position or the first shade device
120
in its second, light-permeable condition is located, the region
92
however does not have the bright-dark limit
84
,
86
of the region
82
and since the second shade device
30
in its second position was the second shade device
130
in its second light-permeable condition is located, the zone
98
of the maximum illumination intensity value of the region
92
is higher and arranged around the point HV than the zone
88
of the maximum illumination intensity value of the region
82
.
The inventive headlight can be designed so that in the operational position for high beam a high beam bundle is emitted which illuminates the measuring screen
80
of
FIG. 8
in the region
92
, in which as prescribed by the regulations in the zone
92
around the point HV the maximum illumination intensity values of a sufficient height are available. In the operational position for low beam due to the first shade device
20
or
120
the bright-dark limit
84
,
86
of the region
82
in
FIG. 7
, and by the second shade device
30
or
130
the maximum illumination intensity values at the height are weakened as permitted for the low beam in accordance with the regulations. Because of the curved course of the second shade device
30
shown in
FIG. 4
in direction of the optical axis
11
a homogenous transition of the illumination intensity values in the region
82
is obtained, so that here no disturbing abrupt weakenings of the illumination intensity values are available. Because of the arrangement of said second shade device
30
or
130
which is displaced in direction of the optical axis
11
to the focal point F
3
of the lens
16
, its upper edge
32
or its upper edge
132
is not projected sharply through the lens
16
. Due to the course of the upper edge
32
of the second shade device
30
shown in
FIG. 5
, a strong retraction of the illumination intensity values on the counter traffic side or in other words at the left side of the measuring screen
80
in
FIG. 7
is provided as desired, whereby for the low beam only low illumination intensity values are available.
It is also possible that the first shade device
20
,
120
and the second shade device
30
,
130
are formed differently. The shade device in accordance with the first embodiment is designed movably, and the shade device in accordance with the second embodiment is designed stationary with changeable light-permeability. The reflector carrier of the light source
12
as well as the lens
16
and the shade devices
20
,
30
, or
120
,
130
can be arranged in a not shown housing of the headlight. In the course of beam of the light extending through the lens
16
, a further disc can be arranged which can serve as a cover disc of the headlight and can be formed smooth, so that light passing through it without being influenced. On the other hand, the optical profile can be provided so that the passing light is deviated and/or dispersed. It is to be understood that more two shade devices
20
,
30
or
120
,
130
can be provided in the headlight.
The inventive headlight has been described as operating for selectively producing the low beam and the high beam. However, the use of the inventive headlight is not limited to this, but instead it is possible to provide a selected emission of different light bundles, with the shade devices
20
,
30
or
120
,
130
in its first condition emitting a light bundle with a bright-dark limit produced by the first shade device
20
or
120
, and with the shade device
20
,
30
, or
120
,
130
in their second condition emitting a light bundle with a greater range and higher maximum illumination intensities. It is also possible to switch the second shade device
30
or
130
independently from the first shade device
20
or
120
between its first and second condition, so that also when the first shade device
20
or
120
is located in its first condition and produces the bright-dark limit, the second shade device
30
or
130
is located in its second condition and the light bundle exiting the headlight has a bright-dark limit but higher maximum illumination intensities.
It is also possible that the second shade device
30
has several parts or the second shade device
130
has several regions
135
, which are movable independently from one another or switchable between their light-permeable and light-impermeable condition so as to provide a desired partial screening of the light reflected by the reflector
10
. Moreover, it is also possible that at least one of the shade devices
20
,
30
or
120
,
130
is changeable not only between two conditions, but instead are changeable steplessly or in several steps between various conditions, in order to vary the part of the light reflected by the reflector
10
which is screened by the shade devices
20
,
30
or
120
,
130
. For example, the illumination intensities the traffic side and the counter traffic side can be varied in a different manner. Also, the expansion of the regions
82
or
92
of the measuring screen
80
illuminated by the light bundle emitted by the reflector can be expanded between a concentration and a wider expansion. A one-side wide expansion can be adjusted, preferably during drive over a curve and in the direction of the roadway course. A wide expansion is preferably during a drive over a curve or poor visibility, while a concentration is advantageous in particular at high speeds. It can be also provided that a fog light bundle with throughgoing horizontal bright-dark limit and a greater dispersion width can be emitted by the headlight in the first position of the shade devices
20
,
30
or
120
,
130
.
It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.
While the invention has been illustrated and described as embodied in headlight for vehicle in accordance with the projection principle, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.
What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.
Claims
- 1. A headlight for a vehicle operating in accordance with a projection principle, comprising a light source; a reflector reflecting in a direction of an optical axis a light emitted by said light source; a lens arranged in a course of light reflected by said reflector; at least one first shade device located between said reflector and said lens and changeable between at least one first condition for a first operational position of the headlight and at least one second condition for a second operational position of the headlight, said at least one first shade device in said first condition screening a part of the light reflected by said reflector and producing a bright dark limit of a light bundle exiting the headlight, and in said second condition screening at most only a smaller part of a light reflected by said reflector than in said first condition; and at least one further shade device changeable between said first condition and said second condition, said at least one further shade device in said first condition being laterally offset in the direction of said optical axis relative to said at least one first shade device, thus screening a part of a light reflected by said reflector past said first shade device in said first condition so as to reduce a maximum illumination intensity value produced by a light bundle exiting the headlight in said first operational position without producing a further sharp bright-dark limit in said bundle, said at least one further shade device in said second condition screening at most only a smaller part of a light reflected by said reflector.
- 2. A headlight as defined in claim 1, wherein said at least one further shade device is arranged in a light outlet direction after said first shade device.
- 3. A headlight as defined in claim 1, wherein said at least one first shade device and said at least one further shade device are changeable independently from one another between said first and second conditions.
- 4. A headlight as defined in claim 1, wherein said at least one further shade device is formed so that a light which passes through said at least further shade device in said first condition on said at least one first shade device which illuminates a counter traffic side in front of the vehicle is screened to a greater part than the light passing on said at lest one first shade device which illuminates a traffic side in front of the vehicle.
- 5. A headlight as defined in claim 1, wherein at least one of said shade devices at least partially has a changeable light permeability and switchable between said first condition with a lower light permeability and is said second condition with a higher light permeability.
- 6. A headlight as defined in claim 1, wherein said shade devices are formed so that in said first operational condition with said shade devices in said first condition a low beam bundle is emitted, and in said second operational condition with said shade devices in said second condition a high beam light is emitted.
- 7. A headlight as defined in claim 1, wherein said light source is a gas discharge lamp.
- 8. A headlight as defined in claim 1, wherein said at least one further shade device is curved in direction of said optical axis.
- 9. A headlight as defined in claim 8, wherein said at least one further shade device is concavely curved.
- 10. A headlight as defined in claim 1, wherein at least one of said shade devices is light-impermeable and is movable between said first and second conditions.
- 11. A headlight as defined in claim 10, wherein said shade devices are coupled with one another and jointly movable between said first and second conditions.
- 12. A headlight for a vehicle operating in accordance with a projection principle, comprising a light source; a reflector reflecting a light emitted by said light source; a lens arranged in a course of light reflected by said reflector; at least one first shade device located between said reflector and said lens and changeable between at least one first condition for a first operational position of the headlight and at least one second condition for a second operational position of the headlight, said at least one first shade device in said first condition screening a part of the light reflected by said reflector and producing a bright-dark limit of a light bundle exiting the headlight, and in said second condition screening at least only a smaller part of a light reflected by said reflector than in said first condition; and at least one further shade device arranged in a direction of an optical axis offset relative to said at least one first shade device and changeable between at least one first condition and at least one second condition, said at least one further shade device in said first condition screening a part of a light reflected by said reflector and passing on said first shade device in said first condition so as to reduce a maximum illumination intensity value produced by a light bundle exiting the headlight in said first operational position, said at least one further shade device in said second condition screening at least only a smaller part of a light reflected by said reflector, said shade devices are formed so that in said first operational condition with said shade devices in said first condition a low beam bundle is emitted, and in said second operational condition with said shade devices in said second condition high beam light is emitted, said shade devices are being so that the high beam bundle emitted by the headlight in said second operational condition with said shade devices in their second operational position illuminates a measuring screen arranged in front of the headlight in a region in which in a central zone of said measuring screen maximum illumination intensity values are provided for approximately 100-200 lux, and in said first operational position with said shade devices in said first condition the emitted low beam bundle illuminates said measuring screen in a region which is limited above by the bright-dark limit produced by said first shade device, and in a zone under the bright-dark limit and at the traffic side of the measuring screen maximum illumination intensity values of 40-80 lux are provided.
Priority Claims (1)
Number |
Date |
Country |
Kind |
198 7 153 |
Feb 1997 |
DE |
|
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
5161875 |
Sekiguchi et al. |
Nov 1992 |
|
5339226 |
Ishikawa |
Aug 1994 |
|
Foreign Referenced Citations (1)
Number |
Date |
Country |
40 02 576 A1 |
Aug 1991 |
DE |