Patent Description:
A typical vehicle headlight assembly includes a reflector and a lamp placed with its light source at or near the focal point of the reflector. Currently, the majority of such lamps are of halogen type while some high end automobiles use High Intensity Discharge (HID) lamps and, in recent years, not only HID lamps, but also light-emitting diode (LED) retrofit bulbs have also been introduced to such assembly. The reflector commonly includes a poly-ellipsoid rear portion and flat wall sections between the rear portion and the front of the assembly. The front is usually covered with a transparent lens. Typically, the lens, the reflector, or a combination of both is designed to direct the light from the light source into a specified pattern.

Several prior art methods have been used to control the light emitted from the lamp in vehicle headlight assemblies. One common method is to mount a shuttle in front of the bulb, to make the bulb having a dual function - a high beam and a low beam function through setting down or raising the shuttle. However, such a method of controlling the light emitted by the lamp results in inefficiencies in the headlight assembly, particularly for the low beam function, because they prevent a large percentage of the light emitted by the lamp from being used by the headlight assembly for example through absorption by the raised shuttle.

<CIT> discloses a H7 retrofit lamp mountable at an automotive headlight which comprises a connector, a body, a plurality of light emitting diodes (LEDs) and a reflective element. The LEDs are arranged at the body and are adapted to emit light laterally. The reflective element is arranged at an end of the arrangement of LEDs opposite to the connector, i.e. at the end furthest away from the connector. The reflective element is adapted to reflect some light emitted by the LEDs.

Further lamp for a vehicle headlight is known from <CIT>.

Therefore, it is an object of the present invention to solve at least one of the above-mentioned problems.

According to one aspect of the invention, there is provided a lamp for a horizontal operating position within a vehicle headlight assembly of a vehicle. The lamp comprises: an LED light source for emitting light mainly to one side as seen with respect to the vehicle, i.e., to the left or the right side of the vehicle, when the lamp is mounted in the vehicle headlight assembly in a horizontal mounting position, and a reflective member for shielding, as seen with respect to the vehicle, front and lower parts of the light emitted by the LED light source when the lamp is mounted in the vehicle headlight assembly in the horizontal mounting position, and reflecting them to desired directions, wherein the reflective member has an "L" shaped cross section for its reflecting part, with one face to reflect forward side light of the LED light source, and one face to reflect down side light of the LED light source, as seen in the horizontal operating position of the lamp with respect to the vehicle.

According to another aspect of the invention, there is provided a vehicle headlight assembly. The headlight assembly comprises the above lamp, a reflector for shaping the light emitted by the LED light source into a beam, and a shuttle, adjustable between positions to shape the beam into a high beam or a low beam.

By scenarios or as a whole, the present invention will probably improve efficiencies of the vehicle headlight assembly or of the lamp integrated therein.

The invention will be described in detail by reference to the following drawings, in which:.

Embodiments of the present invention will be described more fully hereinafter with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth hereafter.

<FIG> is a cross-sectional side view of a vehicle headlight assembly <NUM> in accordance with the prior art.

As is shown in <FIG>, a lamp <NUM> is mounted within a cavity <NUM> of a reflector <NUM>. The cavity <NUM> is closed by a transparent lens <NUM>, which may have light-directing elements. The reflector <NUM> has a shaped, light-directing interior surface <NUM> that is usually poly-ellipsoid in shape, but may be parabolic or may have other shapes. The reflector <NUM> is configured for shaping light emitted by a light source of the lamp <NUM> into a high beam and a low beam, in combination with the lens <NUM> or not in combination with the lens <NUM>. The poly-ellipsoid reflecting surface <NUM> has a central axis <NUM> and a focal point <NUM>. The reflector <NUM> also may include walls <NUM>, including a top wall, a bottom wall, and side walls which extend between light-directing surface <NUM> and lens <NUM>. The walls <NUM> may have any suitable shape and may have a reflective coating, but are typically not designed for reflecting light in a desired direction.

The headlight assembly further comprises a shuttle <NUM> mounted in the lower part in front of the lamp <NUM>, to make the lamp <NUM> having a dual function, high beam and low beam, through setting down or raising the shuttle <NUM>. The shuttle is at least adjustable between a position in which the light from the light source is blocked across a maximum cross section and an essentially transmissive position in which this light is substantially allowed to pass through, i.e., to pass through for the high beam and to be blocked for the low beam. The reflector further includes a heel portion for mounting of the lamp <NUM>. Typically, the heel portion is located on the axis <NUM> of reflecting surface <NUM>. The lamp <NUM> can be mounted in reflector <NUM> by any suitable mounting structure as known in the art, for example the lamp <NUM> can be supported by a lamp base and a mounting strap. The lamp base is provided with electrical conductors for connecting the contact pins of the lamp <NUM> to a source of electrical energy in conventional fashion. The lamp <NUM> can be any suitable lamp, but is typically a halogen type lamp, such as the one shown in <FIG>, a LED retrofit lamp, a LED lamp, a laser lamp, or any new substitute. It is noted that a LED retrofit lamp refers to a lamp that is compatible with a mounting structure for a halogen type lamp and the lamp illuminates with light-emitting diodes. A LED lamp generally has a module of light-emitting diodes and is incompatible with a mounting structure for a halogen type lamp. A LED light source may be comprised in a LED lamp or a LED retrofit lamp. As the headlight assembly for vehicles evolves and LED technology develops, the LED lamp may be widely applied in the headlight assembly for vehicles.

The lamp <NUM> includes a hermetically sealed, light-transmissive lamp envelope <NUM> and a filament <NUM> sealed within the envelope <NUM>. The filament <NUM> functions as the light source. It is noted that a light source herein is referred to as a source for emitting light, i.e., does not include the envelope, and thus differs from a lamp e.g. in that a lamp may have an envelope.

The envelope <NUM> is preferably fabricated of a hard or quartz glass material such as borosilicate or aluminosilicate glass. It will be understood that the envelope and light source structure of the lamp <NUM> may have configurations other than that shown in <FIG>. The lamp <NUM> is preferably mounted in reflector <NUM> such that the longitudinal axis of filament <NUM> coincides with the central axis <NUM> of poly-ellipsoid reflecting surface <NUM> and such that the center of filament <NUM> is located at or near the focal point <NUM> of poly-ellipsoid reflecting surface <NUM> and at or near the central axis of envelope <NUM>. This ensures that light emitted by filament <NUM> and incident on poly-ellipsoid reflecting surface <NUM> is reflected through lens <NUM> as a light beam approximately originating from a single point.

As is shown in <FIG>, upward light such as light L1 and L2 is emitted out of the headlight assembly, while downward light such as light L3 and L4 is blocked by the shuttle <NUM> and thus light efficiencies are greatly reduced.

A vehicle headlight assembly <NUM> not claimed by the present invention is shown in <FIG>. As is shown in <FIG>, a lamp <NUM> is mounted within a cavity <NUM> of a reflector <NUM>. The cavity <NUM> is closed by a transparent lens <NUM>, which may have light-directing elements. The reflector <NUM> has a shaped, light-directing interior surface <NUM> that is usually poly-ellipsoid in shape, but may be parabolic or may have other shapes. The reflector <NUM> is configured for shaping light emitted by the light source into a high beam and a low beam, in combination with the lens <NUM> or not in combination with the lens <NUM>. The poly-ellipsoid reflecting surface <NUM> has a central axis <NUM> and a focal point <NUM>. The reflector <NUM> also may include walls <NUM>, including a top wall, a bottom wall, and side walls which extend between light-directing surface <NUM> and lens <NUM>. The walls <NUM> may have any suitable shape and may have a reflective coating, but are typically not designed for reflecting light in a desired direction.

The vehicle headlight assembly further comprises a shuttle <NUM> mounted in the lower part in front of the lamp <NUM>, to make the lamp <NUM> having a dual function, high beam and low beam functions, through setting down or raising the shuttle <NUM>. The shuttle is at least adjustable between a position in which the light from the light source is blocked across a maximum cross section and an essentially transmissive position in which this light is substantially allowed to pass through. In practice, the shuttle can be set down, but cannot completely disappear, therefore, still part of the light emitted by the light source is prevented from exiting from the headlight assembly and light inefficiency results.

The lamp <NUM> includes a hermetically sealed, light-transmissive lamp envelope <NUM> and a filament <NUM> sealed within the envelope <NUM>. The filament <NUM> functions as the light source. The envelope <NUM> is preferably fabricated of a hard or quartz glass material such as borosilicate or aluminosilicate glass.

Not claimed by the present invention, a reflective member <NUM> in front of and below the light source is provided.

Generally, the light source is located at or near the focal point <NUM> of the surface <NUM>, and preferably, the reflective member <NUM> is closely located to the light source, for example filament <NUM>, i.e., near the focal point <NUM> of the surface <NUM>, so that stray reflections and glare may be reduced.

The envelope <NUM> is formed as a cylinder in <FIG>, but actually it can be of any shape as appropriate. To ensure that as much as possible (i.e. substantially all) of the light emitted by filament <NUM> that will otherwise finally be blocked by the shuttle <NUM> is reflected by the reflective member <NUM> to the shaped, light-directing surface <NUM> of the reflector <NUM>, the reflective member <NUM> is mounted in front of and under the light source as is shown in <FIG>, to reflect the light going forward and downward to the upper part of the reflector <NUM>. As is seen from the side view of <FIG>, the reflective member <NUM> has an "L" shaped cross section for its reflecting part. As a result, the light is reflected by shaped, light-directing surface <NUM> in a desired direction, thereby increasing the useful output of the headlight assembly.

In a not claimed example, the reflective member <NUM> reflects light in a specular manner. Suitable specularly reflective materials include, but are not limited to, aluminum, silver, copper, chromium, nickel, gold, rhodium, palladium, platinum, and any combinations thereof.

As preferably the reflective member <NUM> is closely located to the light source, preferably the reflective member <NUM> is mounted inside the lamp envelope <NUM>. Therefore, the selected reflective material must be able to withstand operating conditions for the life of the lamp without melting, evaporating, subliming or oxidizing. Some materials which can survive these conditions without degradation in performance include gold, platinum, palladium and rhodium.

Another approach is to mount the reflective member <NUM> outside the lamp envelope but still as close to the light source as possible.

In case the lamp will be operated in air, one may also coat the outer surface of the reflective member <NUM> or make the reflective member <NUM> out of a more easily oxidized reflective material, such as aluminum or silver, and to overcoat the reflective areas with a protective film, such as silicon dioxide, to prevent these materials from degrading when the lamp is operated in air.

Alternatively, a more easily oxidized reflective material, such as silver or aluminum, may be used by mounting the lamp in a reflector assembly which is hermetically sealed and which is filled with an inert atmosphere, such as nitrogen.

The size of the reflective member <NUM> can be determined empirically or by the use of computer modeling or a CAD system. In a headlight assembly, it is desirable that all of the light which leaves the headlight is reflected from the poly-ellipsoid reflecting surface <NUM> of the reflector <NUM>, because the light is more controllable when it is reflected from the poly-ellipsoid surface. It is also desirable that the light be emitted from or near the focal point of the poly ellipsoid reflecting surface <NUM>, since this light is directed in a controlled and predictable manner. Preferably, design of the reflective member <NUM> should consider these aspects.

In a not claimed example, the reflective member <NUM> has an "L" shaped cross section for its reflecting part. In another not claimed example, the reflective member <NUM> has an arc shaped cross section for its reflecting part.

The size of the reflective member is preferably small to fit a light source of small size, for example, the width of the reflective member is <NUM> for a LED retrofit light source.

It is noted that the reflective member <NUM> is advantageous for both high beam and low beam scenarios, due to light blocking otherwise occurring both in high beam and low beam scenarios.

It is noted that the reflective member <NUM> is particularly advantageous for a LED light source. Compared with a halogen filament, a LED light source is less compact, which leads to a light beam not well focused behind the lens <NUM> and not contributing to a maximum intensity of the beam pattern. The reflective member <NUM>, which preferably is near the LED source, may help direct more light through the focus <NUM> behind the lens <NUM> and help get a higher maximum intensity.

<FIG> is a schematic view of a reflective member <NUM> usable for an embodiment of the present invention in a vehicle headlight assembly <NUM> very similar to that shown in <FIG>, in which the inventive reflective member <NUM> replaces the not claimed reflective member <NUM> in <FIG>. The reflective member <NUM> in <FIG> has an "L" shaped cross section for the reflecting part, with one face <NUM> to reflect forward side light of the LED light source of an inventive lamp, and one face <NUM> to reflect down side light of the light source, as seen in the horizontal operating position of the lamp with respect to the vehicle. The reflective member <NUM> also has two parts <NUM> and <NUM> for it to be mounted in an inventive vehicle headlight assembly on the left and right sides of the "L" shape respectively, as seen in <FIG>. Preferably, these two parts <NUM> and <NUM> will not further block desired light, or block it as little as possible to ensure high light efficiency.

A schematic illustration of an inventive lamp is shown in <FIG> in form of a H7 LED retrofit product.

The "L" shaped reflective member <NUM> is mounted close to the light emitting chips forming the LED light source <NUM>, only a very small distance away as required out of manufacturing reasons, such as mechanical mounting spaces.

It's vital for the invention that the LED light source <NUM> mainly emits its light to one side. , as seen in the horizontal mounting position of the inventive lamp in an inventive vehicle headlight assembly, the LED light source <NUM> mainly emits to one side, i.e., the left or the right side of the vehicle, and not upwards or downwards. In the illustration of <FIG>, such side direction is diagonal between the left and out of the drawing plane. In other words, on installing lamp <NUM>, in the orientation as shown in <FIG>, in a vehicle headlight assembly, LED light source <NUM> mainly emits to the left side of the vehicle.

In a preferred embodiment of the invention, lamp <NUM> of <FIG> has an other LED light source on the side of lamp <NUM> which cannot be seen in <FIG>, i.e., an other LED light source having a mirrored configuration to the LED light source <NUM> visible in <FIG>. This other LED light source then mainly emits light to the other side of the inventive lamp <NUM>, which, in the just discussed configuration of <FIG>, means that this other LED light source mainly emits light to the diagonal between the right and behind the drawing plane of <FIG>, i.e., to the right of the vehicle.

The mainly side emission of LED light source <NUM> allows direct utilization, i.e., without any intermediate redirection, of the main part of the emitted light by the side surfaces of reflector <NUM> in an inventive vehicle headlight assembly. Thus, by avoiding any intermediate redirections, e.g., by reflection at intermediate mirrors, any intermediate losses always connected with such redirections are avoided and the efficiency of lamp <NUM> is considerably increased. This allows for a compact LED light source with high luminance.

The latter is even further improved by using an other LED light source on the other side as explicated above. As all the LEDs of the two LED light sources can be placed very close to each other a very compact high luminance light source is obtained.

As said, the inventive concept of using mainly side emission avoids the necessity of redirecting the main part of the emitted light thus avoiding any loss mechanism for this part of the light. Furthermore, by using reflective member <NUM> in front of and below LED light source <NUM> further avoids loss of the otherwise unused part of the forward and downwards emitted light.

On using an other LED light source in mirrored configuration to LED light source <NUM>, in order to use its forward and downwards emitted light an other reflective member in mirrored configuration to reflective member <NUM> is used on the other side of lamp <NUM>.

<FIG> shows a simulation result of a prior art vehicle headlight assembly with a halogen bulb and <FIG> shows a simulation result of an inventive vehicle headlight assembly integrated with a reflective member in accordance with the invention, respectively. The scenario for <FIG> has a vehicle headlight assembly with a traditional halogen bulb, which was found to produce <NUM> lumen at <NUM> volts and to consume <NUM> watts. The scenario for <FIG> has a vehicle headlight assembly with an inventive retrofit LED product, which was found to produce <NUM> lumen at <NUM> volts and to consume <NUM> watts. <FIG> are all results for low beam patterns on a standardized vertical screen in front of the vehicle.

Based on the simulation results, it can be seen that the flux out of the inventive headlight assembly in the scenario of <FIG> is <NUM> lumen vs. <NUM> lumen for the prior art headlight assembly in the scenario of <FIG>, which shows an improved light efficiency by more than <NUM>% (<NUM>/<NUM>*<NUM>%=<NUM>%, despite using a lamp with lower light output, i.e., <NUM> instead of <NUM> lumen).

Such improvements can be obtained for headlight assemblies with H7, HIR2, H18 and similar retrofit products.

While the exemplary embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that various changes and modifications may be made, and equivalents may be substituted for elements thereof without departing from the true scope of the present invention. In addition, many modifications may be made to adapt to a particular situation and to the teaching of the present invention without departing from its central scope. Therefore it is intended that the present invention is not limited to the particular embodiments disclosed as the best modes contemplated for carrying out the present invention, but that the present invention includes all embodiments falling within the scope of the appended claims.

It will be further understood that the terms "comprises", "comprising", "includes" and/or "including" used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Claim 1:
A lamp (<NUM>) for a horizontal operating position within a vehicle headlight assembly (<NUM>) of a vehicle, comprising:
an LED light source (<NUM>) for emitting light mainly to one side as seen with respect to the vehicle, i.e., to the left or the right side of the vehicle, when the lamp (<NUM>) is mounted in the vehicle headlight assembly (<NUM>) in a horizontal mounting position, and
a reflective member (<NUM>) for shielding, as seen with respect to the vehicle, front and lower parts (L3, L4) of the light emitted by the LED light source (<NUM>) when the lamp (<NUM>) is mounted in the vehicle headlight assembly (<NUM>) in the horizontal mounting position, and reflecting them to desired directions,
wherein the reflective member (<NUM>) has an "L" shaped cross section for its reflecting part, with one face (<NUM>) to reflect forward side light of the LED light source (<NUM>), and one face (<NUM>) to reflect down side light of the LED light source (<NUM>), as seen in the horizontal operating position of the lamp (<NUM>) with respect to the vehicle.