1. Field of the Invention
The present invention relates, generally, to automotive lights and, more specifically, an automotive light and a method of manufacturing an automotive light.
2. Description of Related Art
The term “automotive light” as used in the related art is known to refer to either a rear automotive light or a front automotive light (also known as a “headlight”) for use as lighting and/or signaling devices of a vehicle, which includes at least one external automotive light having a lighting and/or signaling function towards the outside of the vehicle (such as, for example: a sidelight, an indicator light, a brake light, a rear fog light, a reverse light, a dipped beam headlight, a main beam headlight, etc.).
The automotive light generally includes a container body, a lenticular body, and at least one light source. The lenticular body is placed so as to close a mouth of the container body so as to form a housing chamber. The light source is arranged inside the housing chamber, which may be directed so as to emit light towards the lenticular body when powered with electricity.
In manufacturing automotive lights, once the various components have been assembled, there needs to be attachment and hermetic sealing of the lenticular body to the container body. Typically, sealing is effected by welding. It will be appreciated that welding may also be utilized for other components of a more complex automotive light, for example components arranged inside the housing chamber.
There are a number of different welding solutions known in the related art. From a mechanical point of view, the welds of the prior art make it possible to realise joints which are reliable over time both from the mechanical point of view, considering the continuous mechanical and thermal stresses (vibrations, and atmospheric conditions) to which an automotive light is continually subjected; and from the sealing point of view, for example preventing infiltration of water or dirt from the outside towards the inside of the light.
Assembly techniques known in the related art can be expensive because the welding processes of the lenticular bodies to the container body are rather complex and, thus, slow. For example, it is known of to use vibration welding techniques for the assembly of automotive lights. Conventional laser welding applications in automotive lights, with the techniques currently in use, are not very efficient given that it is necessary to weld together complex geometries such as those of automotive lights. Specifically, the lenticular bodies and the container bodies of automotive lights are made of polymeric materials with highly complex geometries and with curved or straight coupling surfaces having inclinations highly variable along the entire perimeter of the mutual coupling. Moreover, it will be appreciated that laser welding of polymeric bodies generally assumes localized supply of thermal energy capable of locally melting polymeric bodies respectively having sufficient transmittance and absorbance of electromagnetic radiation emitted by a laser source (such as a laser diode). More specifically, light energy of electromagnetic radiation emitted by the laser source is transformed into heat during absorption in the absorbent polymer body. The absorbent polymer body thus simultaneously melts locally and conducts heat to the transmissive polymer body in a defined welding area corresponding to an interface area between the bodies in contact. The softened polymeric bodies can consequently penetrate each other, connecting permanently once cooled.
In headlights, the polymeric bodies may include the lenticular body and the container body of the automotive light, where the lenticular body acts as a transmissive polymeric body and the container body serves as an absorbent polymeric body. However, the complex geometry of automotive lights or their components (such as the container body and the lenticular body) are ill-adapted for use with conventional laser welding techniques, which are in fact optimised for applications on flat walls, simple geometries, and relatively thin body thicknesses. Thus, laser welding techniques are currently little used on automotive lights in that there is no guarantee of satisfactory results and alternative welding techniques are more cost/time competitive.
In addition, certain complexities of automotive lights further discourages and makes current laser welding techniques inconvenient. By way of example, a component of the automotive light (such as the lenticular body) can be crossed by light emitted by the light source so as to effect lighting of the automotive light. The lenticular body may have a coloration so as ensure that the color of the light emitted by the light source complies with government-mandated regulations (for example, a stop light of the automotive light may be realised with a substantially white light source and a lenticular body tending to red). However, during the laser welding process, a red colored lenticular body absorbs a lot of light energy in comparison to a clear lenticular body to the detriment of the light energy provided by the laser source, which needs to be able to provide a predetermined light energy in the welding area. The increased absorption due to the presence of a colored lenticular body acting as the transmission element, which filters the radiation emitted, requires the use of higher power laser beams, which consequently results in high energy consumption and increased welding costs.
Because of the foregoing considerations, laser welding techniques are little used on conventional automotive lights since they are too complex, expensive, and inconvenient to implement when compared to alternative welding techniques, such as friction welding. Thus, there remains a need in the art for a laser welding method of polymeric bodies used in automotive lights able to reduce the power of the laser source.