Note: Descriptions are shown in the official language in which they were submitted.
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FIELD OF THE INVENTION
(00011 The present invention relates to headlight systems for automotive
vehicles and the like.
More specifically, the present invention relates to headlight systems which re-
aim the headlights to
achieve desired operating conditions such as beam patterns, when the headlight
systems are used in
different modes of operation.
BACKGROUND OF THE INVENTION
(00021 Lighting systems for automotive vehicles have undergone significant
changes in the last
decade. Improved lamp technologies, design techniques and stricter regulatory
requirements have
resulted in brighter, better-focused lighting systems that provide better
illumination for vehicle drivers,
enhancing safety and driver comfort, while also reducing the glare and other
undesired artifacts the
headlight system may have on the drivers of other vehicles.
(OO031 Modern headlight systems often use multiple lamps and/or much brighter
lamps, such as
Halogen and/or High Intensity Discharge (H1D) lamps, to provide an increased
intensity of light for
night driving. Also, in addition to convenrional reflector headlights, wherein
the light source is placed
at the focal point of a parabolic reflector, projector headlights have been
created. In a projector
headlight, the light source is placed at the focal point of an elliptical
reflector, which is more efficient at
collecting useful light from the light source than a parabolic reflector, and
one or more focusing lenses
are employed in the light path downstream of the reflector to appropriately
focus the light into the
desired pattern. In any case, the increased amount of light provided by modern
headlight systems offers
a safer night time driving experience compared to headlight systems in use
even just a few years ago.
(00041 However, along with the advantages of the increased intensity of light
provided by such
modern headlight systems, the possible detrimental effects of such intense
light on other drivers, in
vehicles approaching a vehicle equipped with a modern headlight system or in
vehicles being overtaken
by a vehicle equipped with a modern headlight system, are greatly increased
and could result in
oncoming driver discomfort, at best or even unsafe driving conditions, at
worst.
(00051 Accordingly, various regulatory bodies specify both the maximum amount
of light which
can be produced by a headlight system and the beam patterns in which the light
can be emitted by the
headlight system. For example, the ECE, FMVSS, JIS and other regulatory bodies
have various
regulations which specify the beam pattern (both intensity and distribution)
of the light produced by a
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headlight system when running in low beam (passing beam) mode and a different
beam pattern of the
headlight system when running in high beam mode (driving beam).
Manufacturing an effective headlight system which produces good illumination
and still
meets the standards and limitations set by regulatory bodies is a challenge.
When combined with the
requirements of vehicle design aesthetics and cost considerations, the
difficulties are further increased.
(0007) It is desired to have a headlight system which provides good
illumination while meeting
relevant regulatory limitations in a reasonable manner.
SUMMARY OF THE INVENTION
(o0os) It is an object of the present invention to provide a novel headlight
system which obviates or
mitigates at least one disadvantage of the prior art.
(0009) According to a first aspect of the present invention, there is provided
a headlight system,
each side of the headlight system comprising: a low beam illuminator being
horizontally and vertically
aimable; a high beam illuminator; an actuator operable to alter the vertical
aim of the low beam
illuminator; and the system including a control means operaring the actuator
for each side to aim the
low beam illuminator at a first vertical aim target position when the
headlight system is operating in
low beam mode and operating to aim the low beam illuminator at a second
vertical aim target position
when the headlight system is operating in high beam mode wherein both the high
beam and low beam
illuminators are operating.
(0010) Preferably, the actuators are part of a headlight leveling system which
operates to aim the
low beam illuminator at a vertical aim target position.
(0011) The present invention provides a headlight system which can be adapted
to comply with a
variety of different headlight regulatory regimes while providing effective
illumination.
According to another aspect of the invention, there is provided a headlight
system a low beam
illuminator and a high beam illuminator. An actuator is operable to alter
aiming of the hot spot of
the low beam. A controller effects the actuator to move the low beam
illuminator aiming the low
beam hot spot between a first target when the headlight system is operating in
a low beam mode
wherein only said low beam illuminator is energized, and a second target when
the headlight system
is operating in a high beam mode wherein both the high beam and low beam
illuminators are
energized.
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BRIEF DESCRIPTION OF THE DRAWINGS
[00121 Preferred embodiments of the present invention will now be described,
by way of example
only, with reference to the attached Figures, wherein:
Figure 1 shows a schematic representation of one side of a four-bulb-burn
headlight system with
an actuator and a controller to adjust the vertical aim of a low beam
illuminator to a vertical aim target
position;
Figure 2 shows a low beam pattern permitted by one regulatory body;
Figure 3a shows the low beam pattern produced by the low beam illuminator of
Figure 1;
Figure 3b shows the high beam pattern produced by the high beam illuminator of
Figure 1;
Figure 4 shows the high beam pattern of Figure 3b combined with the low beam
pattern of
Figure 3a without the benefit of the present invention; and
Figure 5 shows the combined high beam pattern and low beam pattern produced
with the benefit
of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
100131 One side (driver or passenger side) of a modern headlight system 20 is
schematically in
Figure I. Each side of system 20 includes a high beam illuminator 24 and a low
beam illuminator 28.
Each illuminator 24 and 28 can comprise an assembly of a reflector and/or one
or more lenses and a
light source, such as an incandescent, H1D or Halogen bulb. System 20 is a
four-bulb-burn headlight
system, wherein each high beam illuminator 24 is only powered (and thus
illuminating) when system 20
is in high beam mode but each low beam illuminator 28 is powered when system
20 is operating in both
low beam and high beam modes. In other words, both of illuminators 24 and
illuminators 28 are
operating when system 20 is in high beam mode while only the low beam
illuminators 28 are operating
when system 20 is in low beam mode. This is in contrast to two-bulb-burn
headlight systems wherein
only the appropriate one of high beam illuminators 24 and low beam
illuminators 28 are powered in
either respective mode.
(0014) Each side of system 20 includes an actuator 32 which is operable to
alter the vertical aim of
low beam illuminator 28 in response to signals from a controller 36. Actuators
32 can be a linear DC
stepping motor or any other suitable electrical or mechanical means for
vertically altering the aim of a
low beam illuminator 28, as will occur to those of skill in the art.
Typically, actuator 32 mechanically
tilts the housing of a low beam illuminator 28 to alter its aim, although
other techniques such as moving
the reflector or lens of a low beam illuminator 28 can also be employed, as
will be apparent to those of
skill in the art.
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(0015) As indicated by the dashed lines in Figure 1, depending upon the
mounting configuration of
illuminators 24 and 28 on a vehicle, the actuator 32 on each side may
vertically alter the aim of just low
beam illuminator 28 or of both low beam illuminators 28 and high beam
illuminators 24.
(0016) System 20 includes a controller 36, which can be a digital controller
such as a
microprocessor, microcontroller, PIC, or other suitable digital or analog
processing device as will occur
to those of skill in the art, receives inputs from one or more sensors 40
which can indicate any changes
in the positioning of the vehicle body with respect to the road surface due to
static (cargo and/or
passengers) andlor dynamic (acceleradon/deceleration and/or cornering) loads,
and controller 36
generates appropriate control signals for actuators 32 to alter the vertical
aim of low beam illuminators
28, as required. In Figure 1, the dashed signal line from controller 36 would
connect to the actuator 32
of the other side (not shown) of system 20. An example of a known headlight
leveling system is
discussed in U.S. Patent 6,183,118 to Toda et al.
(00171 Under ECE regulations, for example, if a low beam illuminator 28 has an
Hll~ light source,
means to adjust the vertical aim of the low beam illuminator 28 must be
provided. At a minimum,
these means can comprise a manual adjustor to allow a driver to manually
adjust the vertical aim of the
low beam illuminators to compensate for static loading of the vehicle.
However, it is increasingly
common that an automatic system is provided as a safety enhancement, even in
countries/regions where
the ECE regulation, or similar regulations, do not apply, and thus headlight
leveling systems similar to
that shown in Figure 1 are becoming increasingly common. Such automatic
systems include a
predefined vertical aim target position at which the system operates to
maintain the illuminator aimed.
(0018] In a present embodiment of the instant invention, Iow beam illuminators
28a, 28b comprise
projector headlight assemblies, each with an H>D light source. High beam
illuminators 24a, 24b
comprise projector headlight assemblies with a Halogen light source. This
configuration is a high
performance headlight system in that it is intended to produce illumination
approaching or meeting the
maximum illumination (intensity and distribution) permitted by the appropriate
regulatory bodies.
(00191 In this particular embodiment, the reflectors for the left two
projector assemblies share a
common frame as do the reflectors for the right two projector assemblies.
Thus, when actuators 32a,
32b alter the vertical aim of the respective low beam illuminators 28a, 28b,
the vertical aim of the
corresponding high beam illuminators 24a, 24b are also altered. As will be
apparent to those of skill in
the art, such a configuration is not required by the present invention and
high beam illuminators 24a,
24b can have a fixed vertical position while low beam illuminators 28a, 28b
are re-aimable by actuators
32a, 32b. Similarly, there are no requirement that either high beam
illuminators 24a, 24b nor low beam
illuminators 28a, 28b be projector assemblies.
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(00201 As mentioned above, various regulatory bodies impose regulations on the
intensity and
distribution (beam pattern) of headlight systems. Figure 2 shows an ECE
mandated beam pattern for
low beam headlights. In the Figure, the illustrated axes are the horizontal
(H) axis and the vertical (V)
axis which are centered about the center of the illuminator and the shaded
portion of the Figure
indicates generally where the largest amount of illumination from the low beam
illuminator is located.
The actual configuration and testing of beam patterns is well known to those
of skill in the art and need
not be discussed further herein.
(0021) As can be seen, to prevent blinding oncoming traffic, the permitted
beam pattern generally
only allows light to be projected somewhat (about 0.6 degrees) below the H
axis in the left hand region
of the beam and allows for light to be projected above the H axis on the right
hand region of the beam at
a height above the H axis that increases generally linearly with the distance
from the V axis. As will be
apparent to those of skill in the art, this pattern will be reversed in
jurisdictions in which vehicles travel
on the left-hand side of the road. In either case, the pattern is intended to
mitigate the creation of glare
for oncoming drivers while providing illumination of the side of the road
and/or sidewalks, etc.
(00221 One technique often employed to make the beam pattern of an illuminator
comply with a
permitted pattern is to include a metal shield in the internal light path of
the illuminator to block light
from the prohibited regions of the beam pattern and such a technique is
employed with low beam
illuminator 28 of system 20.
(00231 Figure 3a shows, at the shaded region 100, the actual beam pattern
achieved, including
region 104 of maximum intensity of the beam pattern. Figure 3b shows, at
shaded region 106, the beam
pattern which high beam illuminator 24 produces, including region 108 of
maximum intensity of the
pattern.
(00241 High beam illuminator 24 produces a beam pattern 106 which is generally
an elliptical in
shape with an approximately circular region 108 of high-intensity centered at
the intersection of the H
and V axes as shown in Figure 3b.
(OO251 As system 20 is a four-bulb-burn system, when headlight system 20 is
operating in high
beam mode the beam patterns of low beam illuminator 28 and high beam
illuminator 24 are combined
and Figure 4 shows a combined low beam pattern 100 and the high beam pattern
106 which would be
achieved without the present invention.
(00261 However, section 6.3 of ECE regulation #112 requires that the light
intensity measured at
the intersection of the H and V axes of the high beam pattern be at least
80°~ as intense as the
maximum intensity found anywhere else in the beam pattern. As can be seen, low
beam maximum
intensity area or hot spot 104 and high beam maximum intensity area or hot
spot 108 overlap in region
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112 which, in a system 20 not employing the present invention, is not located
at the intersection of the
H and V axes and which is sufficiently bright, due to the overlap, that the
80°!o regulation is not met by
this pattern.
(002'7] Conventional techniques for addressing such an overly bright area
include intentionally mis-
focusing one or both of the low and high beam illuminators and/or employing a
metal shield in the high
beam illuminator 24 to make it not illuminate the area beneath the H axis.
However, both of these
techniques will result in a headlight system which performs less than
optimally.
(OO28) The dilemma the present inventors faced was that, if region 112 was the
brightest region, it
should be moved to the intersection of the H and V axes. However, moving the
vertical aim of low
beam illuminator 28 upwards would, in low beam mode, violate the low beam
pattern required by
regulation as the illumination would impermissibly approach or cross above the
H axis. Alternatively,
moving the vertical aim of the high beam illuminator 24 upwards (to avoid the
creation of overlap
region 108) or relocating the maximum intensity region of the low beam
illuminator 28 downwards, but
would result in a much lower performance of the headlight system. Also,
relocating the vertical aim of
low beam illuminator 28 when in low beam mode, whether upwards or downwards,
results in a
violation of the ECE regulatory requirements and thus is not permitted.
(0029] The present inventors determined that if the vertical aim target
position for low beam
illuminator 28 was moved when headlight system 20 is in high beam mode, then
the low beam
illuminator 28 would be vertically re-aimed and the desired performance could
be obtained and the
regulatory requirements for the low beam pattern could still be met.
(0030] According, sensor 40i connected to controller 36 determines whether
headlight system 20 is
in high beam mode or low beam mode. Sensor 40i can comprise an additional
signal lead from the high
beam/low beam selection system or any other means suitable for determining the
operating mode of
headlight system 20 as will occur to those of skill in the art. Controller 36
accepts the signal from
sensor 40i and, depending upon the indicated mode of headlight system 24,
selects one of two vertical
aim target positions for low beam illuminator 28.
(0031) In low beam mode, controller 36 operates actuator 32 to vertically aim
low beam illuminator
28 at the vertical aim target position which is at a height required to
achieve the low beam pattern
illustrated in Figure 3a. In high beam mode, controller 36 operates actuator
32 to vertically aim low
beam illuminator 28 at the higher vertical aim target position which is at a
height required to achieve
the high beam pattern illustrated in Figure 5, wherein the maximum intensity
region 112 resulting from
the overlap of the maximum intensity region 104 of low beam pattern 100 and
the maximum intensity
region 108 of high beam pattern 106 is approximately centered at the
intersection of the H and V axis as
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desired, and the performance of headlight system 20 in high beam mode is
enhanced, rather than
degraded.
100321 In a present embodiment, the vertical aim target position for low beam
illuminator 28 in
high beam mode is about 0.9 degrees higher than the vertical aim target
position in low beam mode. As
will be apparent to those of skill in the art, the vertical aim target
positions for other embodiments of
headlight system 20 will vary, depending upon the applicable regulatory
requirements, the actual
construction of high beam illuminator 24 and low beam illuminator 28, the
metal shields employed in
the illuminator(s), if any, and other parameters. However, as will be readily
apparent, the vertical aim
target positions for other embodiments can easily be determined empirically,
as needed.
(00331 The present invention is not limited to headlight systems with two
modes of operation. For
example, it is contemplated that a headlight system further including fog
lamps, and thus having three
modes of operation (high beam, Iow beam and fog) can also employ the present
invention. When
providing night time driving illumination in fog, it is desired to avoid
distributing light in the region
close to horizontal to the driver's sight lines as reflections from the water
particles in the fog can create
significant glare for the driver of the vehicle. Accordingly, many vehicles
provide fog lamps which are
mounted below the headlight system of the vehicle in an attempt to provide
sufficient illumination with
a reduced risk of reflected glare impeding the vehicle driver's vision. It is
contemplated by the present
inventors that system 20 can be constructed such that sensor 40i will also
indicate to controller 36 when
system 20 is in fog lamp mode in addition to indicating low beam and high beam
modes. Upon
detecting that system 20 is in fog lamp mode, controller 36 will then employ a
vertical aim target
position which is lower than the vertical aim target position for low beam
mode, if permitted by the
relevant regulatory bodies. Controller 36 will then operate actuator 32 to
alter the vertical aim of low
beam illuminator 28 downwards from the normal low beam pattern vertical aim
target position to
further mitigate the possibility of reflected glare.
(0034] It is also contemplated that the present invention can be employed with
a headlight system
wherein combined fog and driving lights which are vertically aimable by
additional actuators 32 are
provided. In driving mode, the vertical aim target position for the combined
fog and driving lights will
be higher than the vertical aim target position when the lighring system is in
fog mode. It is also
contemplated that the present invention can be employed in headlight systems
wherein the low beam
illuminator 28 on each side and the high beam illuminator 24 on each side are
connected to different
separate actuators 32 and controller 36 operates to aim each of the low beam
illuminators 28 and high
beam illuminators 24 at different vertical aim target positions. Those of
skill in the art will be able to
think of other possible modes with other vertical aim points which will be
useful in various
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circumstances and such modes and vertical aim target aim positions are within
the scope of the present
invention.
(00351 It is also contemplated that the present invention can be employed to
address the issues of
different standards imposed by regulatory bodies, thus simplifying the
configuration issues faced by
manufacturers of headlight systems. Specifically, controller 36 can be
programmed with vertical aim
target positions which are customized for, and meet, particular regulatory
regimes. Such programming
can be performed when a manufacturer determines the regulations that an
installed headlight system
must meet, or can be programmed when the automobile in which the headlight
system is installed is
sold. Alternatively, controller 36 can be preprogrammed with sets of vertical
aim target positions for
each of multiple regulatory regimes and the appropriate set of vertical aim
target positions can be
selected as needed.
(00361 The above-described embodiments of the invention are intended to be
examples of the
present invention and alterations and modifications may be effected thereto,
by those of skill in the art,
without departing from the scope of the invention which is defined solely by
the claims appended
hereto.