The intensity, beam pattern and beam aim point of vehicle front lamp assemblies are regulated because of the impact they have on various safety issues. Sufficient light is needed under a variety of driving conditions so as to allow the operator of a vehicle to see the road being traveled upon as well as hazards that may present themselves. The concern with adequate lighting is balanced by safety concerns for others.
An operator of a vehicle may be blinded by the front lamps of an oncoming vehicle. Similarly, a pedestrian may be blinded by the front lamps of an oncoming vehicle. Typically, the blinding is a result of direct glare. That is, glare resulting from light emitted from the lamp assemblies directly into the eyes of the operator or pedestrian (also referred to as disability glare and discomfort glare). Concern for this type of glare has resulted in regulations regarding the shape of the upper portion of the emitted beam as well as the illumination level in that upper portion.
The problem of direct glare has been addressed in a number of ways. The most significant manner of addressing this issue is the use of two different beam patterns, high beam and low beam. Depending upon the situation, such as other traffic in the vicinity, the vehicle operator selects the desired beam in order to decrease the light emitted by the front lamp assemblies (“low beam”) or to increase the light emitted by the front lamp assemblies (“high beam”). Multiple beams may be realized by using multiple light sources and/or moving a cutoff shield, a reflector, the light source and or the lens of the lamp assembly.
While the problem of glare for other operators and pedestrians has been given a significant amount of attention, the problem of glare to the operator of the vehicle from the vehicles own front lamps has remained largely unaddressed. Glare to the operator of a vehicle, or reflective glare, typically occurs as a result of wet, snow-covered or icy road conditions. In this environment, light from the lowest portion of the emitted light beam, used to light the road immediately in front of the vehicle or the foreground area, can be reflected back at the vehicle, blinding the operator.
The problem of reflective glare can be addressed to some extent by the use of shaped light beams, either by using a square reflector or manufacturing a lamp assembly with a permanent foreground shield that eliminates foreground lighting. However, these approaches unnecessarily eliminate foreground lighting under conditions wherein reflective glare is not a concern (i.e. dry road conditions). Moreover, if a reflective foreground shield is used, the problem of direct glare may be exacerbated. By reflecting a beam back through the main reflector, the emitted beam may not be uniform since the light reflected from the shield will typically not be emitted in a direction parallel to light that has not been reflected by the shield.
The potential impact of any solution to the reflective glare issue should take into consideration potential design limitations. By way of example, designers of sports cars frequently attempt to design vehicles with a low-slung, sleek appearance. Such designs may require a headlamp to be mounted at or very near the upper portion of the front of the vehicle, with little if any freeboard above the headlamp. This presents a challenge when reducing reflective glare for headlamps wherein the upper portion of the light beam reflected off the reflector is the primary contributor to reflective glare. In such headlamps, any additional hardware cannot be mounted near the upper part of the headlamp.
Therefore, a need exists for an automotive lighting system that provides for the reduction and/or elimination of foreground lighting when reflective glare conditions exist (i.e. when roads are icy, snow-covered or wet), but that also allows more intense illumination of the foreground area when reflective glare conditions do not exist (i.e. when roads are dry). It would be beneficial if the lighting system did not require additional equipment to be placed above the headlamp assembly. It would be further beneficial if the system operated with a variety of light source, shield and reflector configurations.
In accordance with the present invention, a lamp assembly is provided which overcomes the disadvantages of the prior art by providing for reduced illumination of the foreground area when reflective glare is present. According to one embodiment, a rotating shield is located between the reflector and the lens of a lamp assembly. Initially, the shield is placed in a position where it does not block light from passing out of the lamp assembly. The shield may be opaque, translucent or transparent. When needed or desired, the shield is rotated into the beam of light coming from the reflector, such that illumination in the foreground is reduced.
In one embodiment, the shield includes an opaque obstruction generally in the form of a partial epicycloid. When rotated into a blocking position, the shield projects into the beam of light formed by the reflector, reducing the amount of light that is projected into the foreground area of the illumination field of the lamp assembly. In an alternative embodiment, the shield comprises a glass shield with areas of varying degrees of light transparency. In this embodiment, when reflective glare is sensed, the glass shield can be rotated to a position that reduces the emitted light in the foreground area. In another embodiment, a free-formed spreading lens with areas of varying curvatures redirect portions of light in the light beam pattern.
Upper portion 106 is bounded on the lower side by horizontal axis H. In a typical passing or low beam pattern in countries that drive in the right hand lane, upper portion 106 is generally limited to the right hand side of the beam pattern as viewed from a vehicle. This is done to avoid direct glare from the lamp assembly to the occupant of an oncoming vehicle and is shown in
Middle portion 104 is typically not a significant contributor to either reflective or direct glare. For purposes of discussion, middle portion 104 is defined to be the portion of the emitted beam of a lamp assembly that is above the foreground portion and below the horizontal axis H. Obviously, the aim point and mounting height of the lamp assembly when used in an operational situation will affect the extent to which each portion discussed above contributes to direct or reflective glare. Accordingly, the shape and size of the above defined portions may vary from embodiment to embodiment.
As is well known in the art, variations in the vertical extent of the emitted light beam, such as upper portion 106 of pattern 100 in
In accordance with one embodiment of the present invention, the foreground shield is rotatable into the forward beam of light so that the shield can be rotated into a position that blocks light during icy, snowy and wet road conditions and rotated into a position that does not block any light during dry road conditions.
Cutoff shield 608 blocks a portion of light from impinging on lens 610. When foreground shield 500 is placed in the position shown in
As will be appreciated by those of skill in the art, a number of alternative embodiments of rotatable foreground shield may be realized within the scope of the present invention. The following embodiments are provided by way of example, but not of limitation.
In yet another alternative embodiment shown in
Protuberances 908, 910 and 912 are pivotably connected to rotating ring 902 by spring loaded hinges such as hinge 914. In operation, hinge 914 biases protuberance 912 against stationary ring 904. Protuberances 908 and 910 are similarly held against stationary ring 904. As a protuberance is rotated over cutout 906, the protuberance is allowed to pivot toward the center of rotating ring 904. In
In accordance with other embodiments, the protuberance may be translucent, merely reducing the amount of light that passes through lens 610 to illuminate the foreground area. Alternatively, the protuberance may function as a lens, and redirect light passing through protuberance 506 to other portions of the light pattern by providing varying degrees of narrow angle light bending and/or spreading. This allows for a variable amount of illumination to be reduced in the foreground area. These and other embodiments are within the scope of the present invention.
Referring back to
Rotation of foreground shield 500 moves protuberance 506 from behind cutoff shield 608 into a blocking position wherein protuberance 506 extends into the beam of light reflected forward by reflector 604 and passing over cutoff shield 608. Thus, a portion of the light beam is blocked. Initially, the light blocked is at the edge of the emitted light beam. To avoid shadow areas immediately in front of the vehicle, it is preferred to rotate foreground shield 500 in a direction such that the edge of the emitted light beam away from the center of the vehicle is occluded. When protuberance 506 is rotated into its blocking position (shown in
Motor 614 may be energized in response to a sensed reflective glare condition. The energization may be a result of a switch or button activated by a driver. For example, a dedicated circuit may move the glare shield when a driver activates the circuit. Alternatively, activation of the circuit may be in response to activation of a vehicle's windshield wipers. Other sensors may include, alone or in combination with any of the others, light sensors and moisture sensors.
As shown in
Those of skill in the art will recognize that in accordance with the present invention, the shape and characteristics of the foreground shield could be varied to the desired glare reducing effects. The foreground shield may include as a means for reducing illumination in the foreground area of a headlamp a solid piece of opaque material or generally transparent material having translucent portions. Alternatively, the means for reducing illumination may comprise an area that functions as a filter, such as a color filter or a polarizing filter. Further, the shape of the protuberances of the foreground shield can take a variety of other forms.
Moreover, the foreground shield may be moved into and out of the blocking position in a variety of ways. By way of example but not of limitation, the means for receiving motive force may be teeth located on the inner or outer surface of the glare shield ring. Alternatively, the means for receiving motive force may be a bracket or an arm connected to the shield. Additionally, the glare shield may be moved by a worm gear, solenoid, or rack and pinion mechanism. These variations and others are considered to be within the scope of the present invention.
Those of skill in the art will realize that as described herein, the present invention provides significant advantages over the prior art. The invention provides a glare shield which reduces and/or eliminates foreground lighting when reflective glare conditions exist, but that also allows more intense illumination of the foreground area when reflective glare conditions do not exist. The glare shield does not require additional equipment to be placed above the headlamp assembly, and can be incorporated into a variety of light source, shield and reflector configurations.
While the present invention has been described in detail with reference to certain exemplary embodiments thereof, such are offered by way of non-limiting example of the invention, as other versions are possible. It is anticipated that a variety of other modifications and changes will be apparent to those having ordinary skill in the art and that such modifications and changes are intended to be encompassed within the spirit and scope of the invention as defined by the following claims.