BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a headlight assembly, more particularly to a projector-type vehicle headlight assembly.
2. Description of the Related Art
A vehicle headlamp assembly is configured to provide road illumination to suit different road conditions and road visibility requirements. Currently, there exists a projector-type, or Poly-Ellipsoid System (PES) headlamp assembly. FIG. 1 shows a conventional headlamp assembly, which includes a reflector 61 that defines a compartment 610, a light source 62 mounted in the compartment 610 and disposed on an optical axis (x), a lighting shielding plate 63 extending upwardly from a bottom edge of the reflector 61 and having a top edge that is flush with the optical axis (x), a housing (not shown) assembled in front of the reflector 61. By virtue of the shielding effect of the light shielding plate 63, the light beams reach and exit a region of the lens 64 that is below the optical axis (x). As a result, an illuminating pattern is formed. Even though the aforementioned vehicle headlamp assembly is capable of casting the illuminating pattern, the pattern cast thereby is heavily concentrated at a lower region (i.e., below the optical axis “x”) , and causes an adjacent upper region (i.e., above the optical axis “x”) to suffer from inadequate light illumination.
In order to adequately illuminate on upper region that is 18 meters in front of the headlamp assembly, the headlamp assembly must be able to provide at least 64 candela (cd) of light intensity thereat. However, the aforementioned conventional vehicle headlamp assembly does not have enough power to cast such light intensity, which is detrimental for drivers to be not able to discern the overhead signs when driving at nighttime.
FIG. 2 shows a plot of the light intensity obtained at 25 meters in front of the light source 62. It is evident from the plot that the light intensity in the upper region (above zero axis) is extremely low or non-existent.
As illustrated in FIG. 3, U.S. Pat. No. 6,736,533 discloses a vehicular headlamp that has an auxiliary plate 72 provided in front of a shield plate 71. The auxiliary plate 72 serves to reflect a portion of the descending light beams through a lens 73. As a result of passing through the lens 73, light beams Al radiate forwardly in an upward direction so as to enhance overall light intensity in the upper region. Referring to FIG. 4, U.S. Pat. No. 6,736,533 further teaches another vehicular headlamp that has an aperture 810 in the shield plate 81, and an auxiliary plate 82 provided on an inner side of the shield plate 81. This particular configuration can also achieve the effect of enhancing light intensity in the upper region. Another conventional headlight is disclosed in U.S. Patent Application Publication No. 2001/0019484, which discloses a screen configuration that permits limited upper region illumination.
SUMMARY OF THE INVENTION
The object of the present invention is to provide vehicle headlight assembly that can form two illuminating patterns.
According to the present invention, a vehicle headlight assembly includes a housing, a light source, a light shielding plate, and a light guiding plate. The housing defines a compartment, and includes a reflector and a lens disposed in front of the reflector. The light source is mounted in the compartment and is disposed on an optical axis. The light shielding plate is mounted in the housing between the light source and the lens. The light guiding plate is mounted in the housing and is disposed below the optical axis. A first portion of light beams emitted upwardly by the light source is reflected by the reflector, passes over the light shielding plate, and further passes through the lens, which refracts the first portion of the light beams to form a first illuminating pattern. A second portion of the light beams emitted by the light source passes through the light guiding plate and further passes through the lens, which refracts the second portion of the light beams to result in a second illuminating pattern that is directed forwardly and upwardly.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:
FIG. 1 is a cross-sectional view of a conventional vehicle headlamp assembly;
FIG. 2 shows a plot of light intensity obtained at 25 meters in front of the conventional vehicle headlamp assembly of FIG. 1;
FIG. 3 is a cross-sectional view of a conventional vehicle headlamp assembly disclosed in U.S. Pat. No. 6,736,533;
FIG. 4 is a cross-sectional view of another vehicle headlamp assembly disclosed in U.S. Pat. No. 6,736,533;
FIG. 5 is a perspective view of the preferred embodiment of a vehicle headlight assembly according to the present invention;
FIG. 6 is an exploded perspective view of the preferred embodiment;
FIG. 7 is a cross-sectional view of the preferred embodiment; and
FIG. 8 shows a plot of light intensity obtained at 25 meters in front of the vehicle headlight assembly of this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 5, 6, and 7, the preferred embodiment of a vehicle headlight assembly according to the present invention includes a housing 1, a light source 2, a heat-insulation plate 3, an elongated light shielding plate 4, and a light guiding plate 5. The housing 1 defines a compartment 10, and includes a reflector 11 and a lens 13 that is coupled to a lens holder 12 and that is disposed in front of the reflector 11. The light source 2 is mounted in the compartment 10 via mounting unit 14, and is disposed on an optical axis (L). The heat-insulation plate 3 is mounted in the housing 1 and is disposed below the light source 2. The light shielding plate 4 is mounted in the housing 1 between the light source 2 and the lens 13 and has opposite ends respectively fastened to the reflector 11. The light shielding plate 4 also has a top edge that is disposed at a same level as the optical axis (L) . The light guiding plate 5 is mounted in the housing 1 and is disposed below the optical axis (L).
As shown in FIG. 7, a first portion of the light beams emitted upwardly by the light source 2 is reflected by the reflector 11, passes over the light shielding plate 4, and further passes through the lens 13, which refracts the first portion of the light beams to form a first illuminating pattern that is positioned below the optical axis (L). The first illuminating pattern is a low-beam illuminating pattern. On the other hand, a second portion of the light beams emitted by the light source 2 passes through the light guiding plate 5 and further passes through the lens 13, which refracts the second portion of the light beams to result in a second illuminating pattern (B) that is directed forwardly and upwardly. The light guiding plate 5 has a light incident surface 51 that faces toward the light source 2 and where at the second portion of the light beams is incident, and a light exit surface 52 that is opposite to and spaced apart from the light incident surface 51 and that faces toward the lens 13.
In this embodiment, the heat-insulation plate 3 has upper and lower surfaces and a through-hole 31 formed through the upper and lower surfaces. The through-hole 31 allows the second portion of the light beams emitted by the light source 2 to pass therethrough and subsequently enter the light guiding plate 5. The light incident surface 51 is formed with saw-teeth protrusions, whereas the light exit surface 52 is formed with rounded protrusions. The light guiding plate 5 extends forwardly to the lens 13 with respect to the heat-insulation plate 3. In the preferred embodiment, the light guiding plate 5 is fastened to the heat-insulation plate 3 and is made of a plastic material but should not be limited thereto.
As shown in FIG. 6, the reflector 11 has inner and outer surfaces and is formed with a groove 111 that extends along a curve and that is indented from the inner surface toward the outer surface. The heat-insulation plate 3 is constructed to match the inner surface of the reflector 11. The heat-insulation plate 3 engages the groove 111 and is fixed to the reflector 11 by fasteners 112. The heat insulation plate 3 is utilized in the present invention to insulate heat radiated from the light source 2. It should be noted that the heat-insulation plate 3 can be omitted in other embodiments of the present invention.
FIG. 8 shows a plot of light intensity obtained at 25 meters in front of the light source 2. A horizontal axis of the plot represents lateral projection angles of the light source 2 of approximately −25 to 25 degrees. A left axis of the plot represents vertical projection angles of approximately −15 to 15 degrees, and a right axis of the plot indicates the light intensity. It is evident from the plot that the light intensity in an upper region with respect to the optical axis (L) can reach up to 100-200 candela (cd).
In the conventional Poly-Ellipsoid System (PES)/headlight assembly, a portion of the descending light beams emitted by the light source 62 is blocked and is not utilized. However, in the present invention, due to the light guiding property of the light guiding plate 5, such descending light beams can be utilized for further illumination. That is, the light guiding plate 5 directs the descending light beams that were previously unusable into usable light beams for forming the second illuminating pattern. With this structure of the present invention, the light beams are effectively utilized so that the illuminating efficiency of the headlight assembly is thus maximized.
It should be noted that while the preferred embodiment of the headlight assembly is exemplified as a low beam light module, this invention can also be applied to other headlight assemblies, such as a high beam light module or an integrated low/high beam light module.
While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
Patent Application
20090279318
