Coating processes – Direct application of electrical – magnetic – wave – or... – Pretreatment of substrate or post-treatment of coated substrate
Reexamination Certificate
2002-12-20
2004-10-12
Pianalto, Bernard (Department: 1762)
Coating processes
Direct application of electrical, magnetic, wave, or...
Pretreatment of substrate or post-treatment of coated substrate
C264S129000, C427S162000, C427S250000, C427S404000, C427S407100, C427S569000, C427S578000
Reexamination Certificate
active
06803079
ABSTRACT:
This patent application claims priority from a Japanese patent application No. 2002-003501 filed on Jan. 10, 2002, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a reflector and a method and an apparatus for manufacturing a reflector. More particularly, the present invention relates to a method of forming a hydrophilic layer on a surface of an ineffective area of the reflector economically and safely.
2. Description of Related Art
FIGS. 1A and 1B
are cross-sectional views of a conventional reflector used for a headlamp of a motor vehicle and the like. The reflector includes a base body
38
, undercoat
15
, reflective layer
10
, and water-repellent polymer layer
42
. The base body
38
is formed into a shape of the reflector out of material such as synthetic resin or metallic material. The undercoat
15
is formed on a surface of the base body
38
. The undercoat
15
is a layer for adhering the reflective layer
10
to the base body
38
. The reflective layer
10
is formed of material for reflecting light, such as aluminum, and is evaporated on a surface of the undercoat
15
. In order to protect the reflective layer
10
, the polymer layer
42
, which is a layer of a polymer, is formed on a surface of the reflective layer
10
. As shown in
FIGS. 1A and 1B
, in a case where the polymer layer
42
is formed of polymer with hexamethyldisiloxane (HMDSO), a layer
12
formed of silicon dioxide (SiO
2
) and a layer
14
formed of methyl group (CH3) are formed.
Since the polymer layer
42
includes the layer
14
of methyl group on the surface, the surface of the polymer layer
42
has high water repellence. Therefore, as shown in
FIG. 1A
, contact angle between a water drop and the polymer layer
42
is large. Therefore, when moisture condenses on the polymer layer
42
, shape of the water drop on the polymer layer
42
becomes spherical and the water drop appears to be a foreign matter adhering on the surface of the reflector. Furthermore, when a colored layer is to be formed on the surface of the polymer layer
42
by painting, there occurs a portion
18
on which paint
16
does not adhere. This phenomenon is called crawling and the crawling deteriorates the appearance of the reflector. Therefore, it is preferable that the surface of the polymer layer
42
is moderately hydrophilic.
FIG. 2
is a cross-sectional view of a conventional reflector where a hydrophilic layer is formed on the surface of the polymer layer
42
. A conventional method for manufacturing a reflector forms a hydrophilic layer
20
, such as silicon dioxide (SiO2), on the surface of the polymer layer
42
, in order to make the surface of the polymer layer
42
to be hydrophilic, as shown in FIG.
2
. However, since this hydrophilic layer
20
is formed in addition to the polymer layer
42
, expensive hydrophilic material is required and the manufacturing cost becomes high.
Moreover, since apparatus for forming the hydrophilic layer
20
is required in addition to apparatus for forming the polymer layer
42
, a configuration of the entire apparatus for manufacturing the reflector becomes complicated. Furthermore, since the silicon dioxide used as material of the hydrophilic layer is supplied in the form of tablets or powder, apparatus for supplying the material becomes complicated and consequently the configuration of the entire apparatus for manufacturing the reflector becomes complicated. Therefore, costs for manufacturing the reflector are very high.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide a reflector and a method and an apparatus for manufacturing a reflector which can solve the foregoing problem. The above and other objects can be achieved by combinations described in the independent claims. The dependent claims define further advantageous and exemplary combinations of the present invention.
According to the first aspect of the present invention, there is provided a method for manufacturing a reflector. The method includes steps of molding a base body of the reflector; forming reflective layer for reflecting light on a surface of the base body; forming layer of water-repellent polymer on a surface of the reflective layer; and performing hydrophilic treatment on a surface of the polymer layer using plasma of gaseous argon.
It is preferable that the reflective layer formation step includes a step of evaporating the reflective layer on a surface of the base body using the gaseous argon supplied from the same source as that of the gaseous argon used in the hydrophilic treatment step. Moreover, it is preferable that the reflective layer formation step evaporates the layer of aluminum on a surface of the base body. The polymer layer formation step may form the polymer layer by polymerizing hexamethyldisiloxane. The method for manufacturing a reflector may further include a step of forming a colored layer on a surface of the polymer layer, on which the surface is subjected to the hydrophilic treatment. It is preferable that the hydrophilic treatment step substitutes hydrophilic group for hydrophobic group on a surface of the polymer layer by plasma of the gaseous argon contacting a surface of the polymer layer. Furthermore, it is preferable that the hydrophilic treatment step controls the quantity of hydrophilic group which is substituted for hydrophobic group based on duration of the hydrophilic treatment.
According to the second aspect of the present invention, there is provided an apparatus for manufacturing a reflector. The apparatus includes a base body molding unit for molding a base body of the reflector; a first source for supplying gaseous argon; an evaporating unit for evaporating reflective layer for reflecting light on a surface of the base body by using the gaseous argon supplied from the first source; an RF generator for generating high-frequency current; a plasma generator, which connects with the RF generator and the first source, for generating plasma from the gaseous argon supplied from the first source using the high-frequency current; and a plasma reactor, which connects with the plasma generator, and includes a chamber for accommodating the base body.
It is preferable that the apparatus for manufacturing a reflector further includes a second source for supplying gas of a water-repellent monomer, and the plasma reactor generates plasma from the water-repellent monomer supplied from the second source using the plasma generator, and forms a layer of the water-repellent polymer on a surface of the reflective layer evaporated on a surface of the base body accommodated in the chamber. It is also preferable that the plasma reactor performs hydrophilic treatment on a surface of the polymer layer by generating plasma in the chamber from the gaseous argon supplied from the first source using the plasma generator, and by allowing plasma of the gaseous argon to contact with a surface of the polymer layer.
The summary of the invention does not necessarily describe all necessary features of the present invention. The present invention may also be a sub-combination of the features described above.
REFERENCES:
patent: 4085248 (1978-04-01), Zehender et al.
Koito Manufacturing Co. Ltd.
Osha & May L.L.P.
Pianalto Bernard
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