Illumination – Light source and modifier – Including reflector
Reexamination Certificate
1999-04-22
2002-11-05
Husar, Stephen (Department: 2875)
Illumination
Light source and modifier
Including reflector
C362S297000, C362S346000, C362S516000, C362S518000, C362S310000
Reexamination Certificate
active
06474845
ABSTRACT:
DETAILED DESCRIPTION OF THE INVENTION
1. Technical Field of the Invention
This invention relates to a vehicle lamp having a reflector for reflecting light from a light source and more particularly to a vehicle lamp whose reflector has a reflective surface coated with a reflective coating film containing aluminum flakes.
2. Description of the Related Art
There are generally known reflectors as members for use in forming vehicle lamps such as a reflector made by aluminum deposition provided on the surface of a reflector base so as to form a reflective surface with an aluminum deposited film (hereinafter called an aluminum deposited reflector), and a reflector made by applying a reflective coating to a reflector base so as to form a reflective surface with a reflective coating film (hereinafter called a reflective coated reflector).
As shown in
FIG. 7
, the aluminum deposited reflector is utilized mainly for a lamp, such as a headlamp, which has a greater luminous intensity because the aluminum deposited reflector has a specular reflectance of 50% or higher (the percentage of reflected rays of light at the incident and reflected angles equal to each other with respect to the incident ray) and a center luminous intensity (the maximum luminous intensity obtained by turning on a bulb of 12 V, 27 W and 400 lm for a parabolic reflector of F
25
) of 9,000 cd or greater when a predetermined bulb arranged for a parabolic reflector having a configuration of
FIG. 8
is lighted.
On the other hand, the reflective coated reflector is utilized for a beacon lamp and the like, which do not have as great a luminous intensity because the reflective coated reflector has a specular reflectance of about 40% or lower and a center luminous intensity of about 8,000 cd or less (200-8,000 cd). As is obvious from
FIG. 7
, the specular reflectance has a substantially proportional relationship to the center luminous intensity.
Further, although the aluminum deposited reflector provides a greater luminous intensity than the reflective coated reflector, the aluminum deposited reflector is costly because it requires large deposition facilities, many manufacturing steps and a great deal of time for production. On the contrary, although a great luminous intensity is not obtainable with the reflective coated reflector, it is less costly and can be manufactured efficiently, because it only requires simple coating facilities, and the steps of applying a reflective coating prepared by mixing a resin as a binder and aluminum flakes, and adding a volatile solvent to the mixture so as to adjust the viscosity.
In the case of recent beacon lamps such as tail lamps, clearance lamps, turn-signal lamps and the like, the interior of a lamp chamber is arranged so as to be seen through without providing any step for a front lens in order to make the lamps look solid. Consequently, the aluminum deposited reflector offering greater luminance instead of the reflective coated reflector, is employed for emphasizing the solidity. When the luminous intensity is too great for a specific beacon lamp as a result of using the aluminum deposited reflector, applying a smoke top coat onto the aluminum deposited surface or forming an emboss on the reflector base surface where the aluminum deposited film is formed, may be employed for reducing the luminous intensity whereby to provide a lower suitable luminous intensity for the beacon lamp.
Since the luminous intensity obtainable from the conventional reflective coated reflector is limited, such conventional reflective coatings are not used in the aforementioned beacon lamp of the see-through type, and thus, there is a problem arising from the necessity of using the expensive aluminum deposited reflector for a lamp which needs a substantially great luminous intensity.
In the aforementioned beacon lamp of the see-through type, it has been deliberately contrived to decrease the luminous intensity obtainable from the original aluminum deposited film as discussed above, resulting in the problem that the beacon lamp becomes costly to the extent that special labor and time are needed to make a reflector for this purpose.
With respect to the problems above, the present inventor has studied the possibility of increasing the center luminous intensity (specular reflectance) of the reflective coated reflector, as greater luminance may have the effect of providing more solidity and increasing the center luminous intensity (specular reflectance) of the reflective coated reflector without having to contrive a means of lowering the luminous intensity of the reflector.
The reflective coating film used to form the reflective surface of a reflector is structured as shown in FIG.
9
(
a
) so that an aluminum flake layer
3
in which aluminum flakes
4
having a mean particle diameter of 3 &mgr;m or greater and a thickness of 0.1 &mgr;m or greater are lined up continuously and formed in the surface layer portion of a resin layer
2
as a binder adhering to the surface of a reflector base
1
, the aluminum flake layer
3
forming a reflective surface for reflecting light.
The reflective coated reflector is formed by mixing the resin
2
as a binder and the aluminum flakes
4
, and adding a volatile solvent to the mixture so as to adjust the viscosity to a predetermined degree. In order to increase floatability with respect to the resin
2
as a binder, stearic acid is made to adhere to the aluminum flakes
4
in the reflective coating beforehand. Consequently, the aluminum flakes
4
are kept floating within the liquid resin (layer)
2
in the coating (coating film) immediately after the coating is applied to the reflector base
1
as shown in FIG.
9
(
b
). As the drying and hardening of the resin (layer)
2
progress, the aluminum flakes
4
are piled up and the aluminum flake layer
3
appears to be formed in the surface layer portion of the film as shown in FIG.
9
(
a
).
Therefore, the present inventor reasoned that the center luminous intensity be increased by increasing the smoothness of the surface of the aluminum flake layer
3
and studied a method of increasing the surface smoothness of the aluminum flake layer
3
.
First, the size (particle diameter) of the aluminum flakes
4
to be mixed in was reduced. As shown in
FIG. 10
, the finer (the smaller of the particle diameters) the aluminum flake, the greater the center luminous intensity became to some extent. However, the luminous intensity did not reach 8,000 cd.
Then it was attempted to reduce the thickness of the aluminum flake
4
without changing the size (particle diameter) of the aluminum flake
4
to be mixed in. As shown in
FIG. 11
, the thinner the aluminum flake
4
, the greater the center luminous intensity became. Thus, a center luminous intensity (specular reflectance) of not less than 8,000 cd was obtained, which had previously not been obtainable from any one of the conventional reflective coated reflectors.
Attention was also focussed on the softening point of the resin (layer)
2
as a binder for use in forming the reflective coating film and resins different in the softening point were used. It was proved that the lower the softening point of the resin, the greater the center luminous intensity became (see FIG.
5
).
SUMMARY OF THE PRESENT INVENTION
An object of the present invention, in view of the foregoing problems pertaining to the prior art and the present inventor's reasoning, is to provide a vehicle lamp fitted with a reflective coated reflector capable of obtaining a greater center luminous intensity (specular reflectance) that has not been obtainable from conventional reflective coated reflectors.
In order to accomplish the above object, a vehicle lamp comprises a light source, a reflector disposed behind the light source, used to reflect light from the light source forward, and a front lens disposed in front of the light source, wherein the reflective surface of the reflector is formed with a luminance reflective coating film having a center luminous intensity of 8,000-13,000 cd, the luminance reflective coating f
Mabe Michihiro
Nakamura Koichi
Husar Stephen
Koito Manufacturing Co. Ltd.
Sughrue & Mion, PLLC
Zeade Bertrand
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