Illumination – Light source and modifier – With sealing means or artificial atmosphere
Reexamination Certificate
1999-08-25
2001-11-20
Quach, Y. (Department: 2875)
Illumination
Light source and modifier
With sealing means or artificial atmosphere
C362S507000
Reexamination Certificate
active
06318883
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a lamp for vehicle, and more particularly, to a structure for sealing a space between a front lens and a lamp body of the lamp for the vehicle.
2. Prior Art
In general, a lamp for a vehicle is structured such that when joining a front lens to the lamp body, a sealing member is interposed therebetween to maintain a required sealing efficiency between the lamp body and the front lens so as to prevent introduction of water, dust or the like into the interior of the lamp.
Hitherto, as the sealing member, a hot melt
114
A as shown in FIG.
7
(
a
), an elastic cord
114
B as shown in FIG.
8
(
b
), and a foamed gasket
114
C as shown in FIG.
9
(
b
) have been known.
The hot melt
114
A is a thermoplastic adhesive having great adhesive strength and generating no repulsion force. Therefore, when a front lens
116
is secured to a lamp body
112
, a strong mechanical joining, for example, by using threaded fasteners such as screws, is not required. That is, the hot melt
114
A has an advantage that allows the usage of only engagement fastening as an effective means of mechanical joining. There, however, arises the following problem when the components of the lamp are intended to be recycled. That is, the hot melt
114
A having the great adhesive strength inhibits easy separation of the front lens
116
from the lamp body
112
. If the separation is forcibly performed, a cohesion failure (a phenomenon in which the structure of the hot melt
114
A is torn along random surfaces of breakage) occurs as shown in FIG.
7
(
b
) . Therefore, not only the hot melt
114
A encounters cohesion failure, but also the lamp body
112
, and a front lens
116
to which a chip of the hot melt
114
A is still adhered cannot be recycled.
Regarding FIGS.
8
(
a
) and
9
(
a
), the elastic cord
114
B and the foamed gasket
114
C are made of a thermosetting elastic material having no tackiness. Therefore, the front lens
116
can be attached to or detached from the lamp body
112
without elastic cord residue, allowing recycling of the lamp components. However, each of the elastic cord
114
B and the foamed gasket
114
C yields a great elastic repulsion force so as to maintain sealing efficiency. Therefore, as shown in FIGS.
8
(
b
) and
9
(
b
), the repulsion force constantly acts on the front lens
116
so as to be forced out. Therefore, simple fastening means such as engagement fasteners are insufficient as the mechanical fastening means for securing the front lens
116
to the lamp body
112
. Thus, strong fastening means such as threaded fasteners have to be additionally used as shown in
FIG. 10
(referring to the drawing, the symbol A represents engagement fastening portions and B represents threaded fasteners). As a result, the structure of the lamp becomes too complicated to improve workability in the process for assembling the lamp. In these foregoing cases, the elastic repulsion force also frequently causes failure such as deformation or a fracture of the front lens
116
.
Since the elastic cord
114
B is a complete product serving as the elastic sealing member, it is difficult to apply the elastic cord
114
B automatically to the sealing position on the lamp body
112
. Therefore, the elastic cord
114
B is applied by performing a manual bonding operation. As a result, there arises a problem of deteriorated workability in the process for assembling the lamp. As for the foamed gasket
114
C, the foamed gasket material can be automatically applied to the sealing position on the lamp body
112
. However, hardening of the applied foamed gasket material takes a long time. Also in this case, there arises the problem of deteriorated workability in the process for assembling the lamp.
SUMMARY OF THE INVENTION
In view of the foregoing, the present invention provides a lamp for a vehicle which incorporates a lamp body to which a front lens is joined through a sealing member so as to allow the front lens to be attached or cleanly detached, simplifies the structure of the lamp, and improves the workability in the process for assembling the lamp.
The present invention achieves the foregoing by improving the structure of the sealing member. That is, according to the present invention, there is provided a lamp for a vehicle having a lamp body to which a front lens is joined through a sealing member, wherein the sealing member is made of a low-adhesive hot melt in the gel state that causes surface exfoliation when the front lens is separated from the lamp body.
The expression “surface exfoliation” means the phenomenon in which the sealing member exfoliates at an interface with the front lens or the lamp body without causing cohesion failure.
The phrase “low-adhesive hot melt in the gel state”, means a thermoplastic adhesive similar to the usual hot melt, structured so as to maintain a low-adhesive gel state even when it is used as the sealing member. In order to obtain the foregoing property, the content of wax and so forth as the cause of the cohesion failure is reduced so that it is less than that of the usual hot melt. Further, an appropriate amount of plasticizer or the like may be added.
The expression “low-adhesive” means an adhesive strength that is low enough to allow the sealing member to cause surface exfoliation when the front lens is separated from the lamp body.
To realize the low-adhesive property, a structure is employed in which a separating force El required to separate the front lens from the lamp body satisfies a range of 0<F1≦1 kg/cm
2
. It is preferable that the sealing member yields a certain level of tackiness to improve sealing efficiency. Additionally, it is preferable to reduce the separating force in order to simplify the operation of removing the front lens from the lamp body. Therefore, it is preferable to reduce the range of the separating force F1. For example, a suitable structure for use as a sealing member satisfies the range of 0.05≦F1≦0.5 kg/cm
2
. Preferably, the structure for use as a sealing member satisfies the range of 0.1≦F1≦0.3 kg/cm
2
. According to the foregoing structure, the present invention has the structure in which the sealing member interposed between the front lens and the lamp body is made of a low-adhesive hot melt in the gel state which causes surface exfoliation when the front lens is separated from the lamp body. Therefore, the structure not only allows easy removal of the front lens from the lamp body, but also prevents the front lens, the lamp body and the sealing member from being damaged. As a result, the components of the lamp can effectively be recycled.
Since the sealing member is made of a low-adhesive hot melt in the gel state, it yields a certain level of elasticity. Unlike the sealing member formed as an elastic cord or a foamed gasket which depend on their elastic repulsion force, the aforementioned sealing member is capable of maintaining sealing efficiency between the front lens and the lamp body with its own adhesive strength. Therefore, the sealing member does not have to be strongly depressed. Accordingly, the mechanical fastening means for securing the front lens to the lamp body may be a simple fastening means, such as a hook fastening means. Thus, strong fastening means such as threaded fasteners such as screws do not have to be used, resulting in a simplified structure of the lamp and improved workability in the process for assembling the lamp. Moreover, the present invention prevents such failures as deformation or a fracture of the front lens which may occur due to elastic repulsion force.
The sealing member, which is made of a low-adhesive hot melt, can automatically be applied to a sealing position on the lamp body (or on the front lens). Moreover, only a substantially short time is required for cooling the sealing member at the sealing position into the low-adhesive hot melt in the gel state as compared with the time required for hardening a foamed gasket. Thus, workability in the process for assembling the lamp can also be
Otani Haruo
Sugiyama Fumihiko
Suzuki Michihiko
Yamazaki Kazuhiro
Fish & Richardson P.C.
Koito Manufacturing Co. Ltd.
Quach Y.
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