1. Field of the Invention
The present invention relates to a lamp and is mainly aimed at vehicle lighting, such as a headlamp, a turn lamp, a front fog, spot or driving lamp and a reverse lamp. More particularly, it relates to a vehicle lamp including a plurality of LED lamps (or one or more LED lamps each with a plurality of LED chips mounted thereon) as light sources. A single LED lamp often provides an insufficient amount of light for particular applications.
2. Description of the Related Art
In a conventional vehicle lamp that employs LED lamps as light sources, the LED lamps are arranged such that each of their optical axes is directed to the apex of a cone. In addition, a cylindrical optical guide is attached to each LED lamp such that the light from all the LED lamps converges on the apex. A reflective surface of the hyperboloid of revolution is arranged near the apex to convert the light beams from the LED lamps into a single light beam, as if it is emitted from a single point. This is effective to form a light distribution pattern at a main reflective surface of the hyperboloid of revolution and compensate for an insufficient amount of light sometimes produced by a single LED lamp (see for example Japanese Patent Application Publication No.: JP-A-2002/100217).
In the above conventional configuration, however, in addition to the optical guide, a casing and others structures are attached to the LED chip contained in each of the LED lamps that are arranged in a ring. Accordingly, this configuration is limited in the number of LED lamps that can be integrated, and the lamp still produces an insufficient amount of light for certain applications. For example, there are problems and difficulties associated with incorporating the lamp into a vehicle lamp that requires a much larger amount of light, such as a headlight.
During manufacture and assembly, high accuracy is required to ensure the mutual positional accuracy of both the optical guide with the reflective surface of the hyperboloid of revolution, and the reflective surface of the hyperboloid of revolution with the main reflective surface. This requirement causes problems because it complicates the processing and manufacturing steps, which elevates the cost of the vehicle lamp.
If the number of the LED lamps is increased, the reflective surface combined with a plurality of light sources causes spots of light, resulting in a difficulty in the formation of proper light distribution characteristics. In addition, such a configuration causes variations in illumination on the road surface, deteriorating the illumination quality and lowering the visibility. These and other problems are considered as subjects to be solved.