Illumination – Supported by vehicle structure – Light modifier
Reexamination Certificate
2001-03-28
2003-10-28
Husar, Stephen (Department: 2875)
Illumination
Supported by vehicle structure
Light modifier
C362S346000, C362S806000, C362S293000, C362S307000
Reexamination Certificate
active
06637920
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a vehicular lamp of a type wherein light emitted from a light source bulb is reflected by a reflector to form an outward illuminating light beam. More particularly, the invention relates to such a vehicular lamp in which the reflector is coated with a tinted topcoat layer so as to allow for discrimination from the outer appearance of the vehicular lamp as to whether the lamp is in its ON or OFF state, and for brightening the outward light beam when the lamp is in the ON state.
In a vehicular lamp such as headlamp mounted on an automobile or a two-wheeled vehicle, the technique of reflecting light emitted by a light source bulb with a reflector to form an outward light beam has of course long been well known. In such a lamp, tinting the topcoat layer formed as the outermost layer of the reflecting surface has been conventionally employed both to protect the reflecting surface, which is formed on the upper layer of a lamp body by aluminum deposition, and to change the color of the emitted light.
This technique has been developed based on the phenomenon that when the light emitted from a light source bulb passes through the tinted topcoat layer, light having a specific wavelength is absorbed, so that the color of the reflected light is determined in dependence on the pigment contained in the tinted topcoat layer. Such a lamp is disclosed in Japanese Utility Model Laid-open Publication No. Hei. 2-18202.
According to this technique, for example, if a coating layer containing a blue-based pigment is used as the topcoat layer, in the ON state of the lamp while in use at night, the reddish light emitted by an incandescent bulb can be converted into, for example, white light, similar to the light emitted from a halogen bulb, or white light emitted from a halogen bulb can be converted into the pale blue light typical of a discharge lamp. Therefore, it is possible to facilitate visibility at longer distances and to provide an improved outer appearance for the lamp.
In addition to the above effects obtained when the lamp is in the ON state, in the OFF state during the daytime the tinted topcoat layer of the reflector causes the natural light reflected outward from the lamp chamber to give the lamp a distinctive appearance.
However, in such a lamp a certain portion of the light emitted from the bulb is absorbed due to the passage of the light through the tinted topcoat layer. As a result, the luminous intensity is reduced, causing a problem in light distribution.
If the density of the pigment of the tinted topcoat layer is increased so as to improve the outer appearance of the lamp, the reflection factor of the lamp is decreased, thus further reducing the luminous intensity of the lamp. It has been difficult in the conventional art to satisfy simultaneously the requirements of an improved outer appearance and high luminous efficiency.
FIG. 1
is a vertical sectional view of a vehicular lamp (headlamp) having a reflector provided behind a halogen bulb. The structure of the vehicular lamp
1
will be explained referring to the drawing.
The lamp
1
is formed with generally a cup-like shape. The lamp
1
includes a lamp body
2
with its rear top portion
2
a
provided with an opening
11
for mounting a light source bulb (halogen bulb)
3
, a rubber boot
8
having a predetermined shape for sealing the opening
11
, the light source bulb
3
disposed in a lamp chamber
4
inside the lamp body
2
, and a front lens
10
mounted so as to close the front opening of the lamp body
2
.
The reflector
5
includes a reflecting surface
504
(see
FIG. 2
) for reflecting bulb-emitted light P
1
from the light source bulb
3
forward of the vehicle to form an outward illuminating beam P
2
. An extension portion (extension reflector)
6
is also provided for covering a gap
7
formed between the reflector
5
and the lamp body
2
.
Reference numeral
301
represents a top portion which is painted black for shielding the forward light from the light source bulb
3
. In some cases, a shade member (not shown) having the same outer appearance color as that of the reflector
5
may be provided around the light source bulb
3
.
In addition to
FIG. 1
, referring to
FIG. 2
, which is a partial sectional view of the reflector
5
, the structure of the reflector
5
will be explained in detail.
The reflector
5
generally has a four-layer structure including a synthetic resin base body
501
defining the basic shape of the reflector
5
, an undercoat layer
502
provided on the upper layer of the base body
501
for smoothing any roughness in the surface of the base body
501
, a reflecting surface
504
including a surface formed by an aluminum-deposited layer
503
and provided on an upper layer of the undercoat layer
502
, and a topcoat layer
505
for protecting the reflecting surface
504
.
The reflector otherwise can be formed as a three-layer structure by omitting the undercoat layer
502
.
The reflector
5
has substantially a cup-shaped outer appearance. The reflector
5
is provided with a paraboloidal effective reflector portion (effective reflecting surface)
5
x
(see
FIG. 1
) which can effectively contribute to formation of the reflected light P
2
, and a non-effective reflector portion (non-effective reflecting surface)
5
y
having an extension wall (flat plate-like surface) extending from the end of the effective reflector portion
5
x
toward the front lens
10
. The non-effective reflector portion
5
y
does not directly contribute to the formation of the reflected light P
2
but is required for structural or design reasons.
Since one of the purposes of the topcoat layer of the reflector
5
is to protect the reflecting surface
504
, it is required that the bulb-emitted light P
1
pass through the topcoat layer without greatly lowering its luminous intensity, while reflected light (outward emitted light) P
2
having a desired light distribution is formed on the reflecting surface
504
, i.e., the transparent topcoat layer (not shown).
Recently, it has been proposed to form a transparent topcoat layer by “smoke coating” (also called “color clear coating”) wherein a pigment
505
a
is dispersed in a base medium to form a tinted topcoat layer
505
. With this reflected light coloring technique, the reflected light P
2
is converted into colored reflected light while reducing the amount by which the luminous intensity of the reflected light P
2
is lowered due to coloring.
For carrying out this reflected light coloring technique, there has been proposed a method for forming a five-layered structure wherein smoke coating is performed on an upper layer of a transparent topcoat layer in a separate step. However, since the number of steps is increased with such a technique, a method for combining the topcoat layer with the tinted topcoat layer
505
so as to not increase the number of layers is generally preferred.
With the reflected light coloring technique, by forming the tinted topcoat layer
505
as a blue coated layer, when the lamp is turned ON at night, the light P
1
from the light source bulb (halogen bulb)
3
is converted into colored reflected light of a pale blue color or the like, similar to the light from a discharge-type bulb. Also, using this technique the reddish light from an incandescent bulb can be converted into substantially white reflected light, similar to the light from a halogen bulb.
Thus, the reflected light coloring technique has merit in that it prevents a large reduction in the brightness of the light from the lamp
1
, preserving visibility over long distances, while enhancing the outward appearance of the lamp, without having to employ an expensive light source.
When the lamp is in the OFF state, due to the provision on the reflector
5
of the tinted topcoat layer
505
, light P
3
entering from outside the light chamber
4
is tinted. Therefore, the outer design of the lamp
1
can be distinguished in terms of coloration, and the visual recognition ability of the vehicle in the evening can be enhanc
Murakoshi Mamoru
Ono Shigeki
Husar Stephen
Koito Manufacturing Co. Ltd.
Payne Sharon
Sughrue & Mion, PLLC
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