Illumination – Supported by vehicle structure – Light modifier
Reexamination Certificate
2000-10-02
2002-03-26
O'Shea, Sandra (Department: 2875)
Illumination
Supported by vehicle structure
Light modifier
C362S517000, C362S516000, C362S297000, C362S346000
Reexamination Certificate
active
06361195
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicle lamp used in vehicles, such as automobiles and the like, and to a method of determining a reflective surface of a reflector thereof.
2. Related Background Art
The vehicle lamps need to meet (1) the conditions from the aspect concerning the function as lamps and, in addition thereto, (2) the conditions from the aspect concerning the shape (shape constraints) and (3) the conditions from the aspect concerning the appearance (appearance constraints) because of their use in a mounted state on the vehicles such as the automobiles and the like. It is thus necessary to realize lamps optimized as to the conditions from the functional aspect while satisfying the given constraints from the shape aspect and the appearance aspect.
The conditions from the functional aspect include light uniformity with which the entire lamp lights uniformly, light diffusibility with which light is properly diffused to be observed from various directions, and so on, depending upon types of lamps.
As for the constraints from the vehicle and body side, the shape constraints include conditions defined by the volume and shape of lamp receiving portions of the body, the continuous shape of the outer surface of the lamp (the outer surface of lens) from the other body portions, and so on. The appearance constraints include conditions resulting from harmony with the appearance of the other body portions, requirements from the design aspect of the body, and so on.
SUMMARY OF THE INVENTION
With the recent trend toward fascinating styling of cars, there are increasing needs for vehicle lamps matching further various body-side constraints, according to forms of individual vehicles, types of lamps including illumination lamps, marker lamps, etc., and so on. An example of such lamps is a marker lamp that appears transparent and deep, because the lens forming the outer surface of the lamp is one with see-through nature.
An example of the conventional marker lamps of this type is a structure in which the reflective surface of the reflector for reflecting the light from the light source is formed in a unifocal paraboloid shape, the reflective surface is divided into an array pattern of segments, and the segments are provided with diffuse reflection steps for diffusely reflecting the light from the light source. In this case, since the light is diffused at the reflector, the lens does not have to diffuse the light much. As a consequence, the lens can be a stepped lens or a stepless lens with see-through nature, which realizes transparency as one of the appearance constraints described above.
In the case of the lamp in the above structure, however, the thickness of the lamp can not be decreased, because the basic shape of the reflective surface is based on a single paraboloid. It is thus difficult to match the lamp with the shape constraint of decrease in the depth of the lamp according to the volume of the lamp receiving portion of the body. In addition, it also fails to assure sufficient light uniformity of emitted light in the functional aspect.
Another marker lamp is one constructed in such structure that the basic shape of the reflective surface is a free-formed surface determined from the shape constraints and that a plurality of paraboloids of revolution are arranged in order in an approximately concentric circle pattern about the light source and the optical axis on the free-formed surface. In this case, it is relatively easy to meet the shape constraints including the decrease in the depth of the lamp, because the structure provides sufficiently large degrees of freedom in designing (for example, reference is made to Japanese Patent Application Laid-Open No. H09-33708).
In the above structure, however, the light reflected by the reflective surface is nearly parallel light without diffuse reflection, because the reflection employed is one by the paraboloids of revolution. In addition, it is necessary to diffuse the light with a fish-eye stepped lens or the like as the lens, and thus the lens lacks of the see-through nature, so as to fail to obtain the transparency as one of the appearance constraints.
The present invention has been accomplished in view of the above problems and an object of the present invention is thus to provide a vehicle lamp of thin shape and appearance with transparency while being improved in the functional conditions of light uniformity and light diffusibility, and provide a method of determining a reflective surface of a reflector in the vehicle lamp, which permits efficient determination of the shape of the reflective surface of the reflector capable of realizing the lamp satisfying such conditions.
In order to accomplish the above object, a method of determining a reflective surface of a reflector used in a vehicle lamp according to the present invention is a method comprising: (1) a condition setting step of setting a light source position at which a light source is to be placed, and an optical axis passing the light source position and defining a direction into which light from the light source is to be reflected by the reflector; (2) an initial reference line setting step of setting a plurality of initial reference lines each extending radially from a predetermined position on the optical axis so that on each of the initial reference lines luminous exitances M, specified in the direction along the optical axis for respective portions of the initial reference line, are constant; (3) a surface reference line creating step of creating a plurality of surface reference lines by deforming the plurality of initial reference lines so as to satisfy the condition of Mmax/Mmin≦6 as to a maximum Mmax and a minimum Mmin on the plurality of initial reference lines out of luminous exitances M for the respective, entire, initial reference lines, and a predetermined shape constraint; (4) a free-formed surface creating step of creating a free-formed surface comprising the plurality of surface reference lines; and (5) a reflective surface determining step of dividing the free-formed surface into an array of segments and assigning a reflective surface element having a diffuse reflection region for diffusely reflecting the light from the light source position, to each of the segments, thereby determining a reflective surface comprising a plurality of reflective surface elements.
Also, a vehicle lamp according to the present invention is a vehicle lamp comprising a light source, a reflector having a reflective surface comprising a plurality of reflective surface elements for reflecting light from the light source into a direction along a predetermined optical axis, and a lens which transmits the light reflected by the reflector, wherein the reflective surface is formed by assigning the reflective surface elements to respective segments obtained by dividing a free-formed surface satisfying a predetermined shape constraint, into an array pattern, and each of the plurality of reflective surface elements has a diffuse reflection region for diffusely reflecting the light from the light source, and wherein the free-formed surface satisfies the condition of Mmax/Mmin≦6 as to a maximum Mmax and a minimum Mmin out of luminous exitances M specified in the direction along the optical axis for respective portions on the free-formed surface.
Another vehicle lamp according to the present invention is a vehicle lamp comprising a light source, a reflector having a reflective surface comprising a plurality of reflective surface elements for reflecting light from the light source into a direction along a predetermined optical axis, and a lens which transmits the light reflected by the reflector, wherein the reflective surface is formed by assigning the reflective surface elements to respective segments obtained by dividing a free-formed surface satisfying a predetermined shape constraint, into an array pattern, and each of the plurality of reflective surface elements has a diffuse reflection region for diffusely reflecting the
DelGizzi Ronald E.
Koito Manufacturing Co. Ltd.
O'Shea Sandra
LandOfFree
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