Horology: time measuring systems or devices – Displays or display device details – Dial or hand
Reexamination Certificate
1999-07-12
2001-09-25
Roskoski, Bernard (Department: 2859)
Horology: time measuring systems or devices
Displays or display device details
Dial or hand
Reexamination Certificate
active
06295251
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a timepiece dial plate and, more particularly, to a timepiece dial plate provided on its face with relief indices resembling characters and such.
2. Description of the Related Art
Referring to
FIG. 10
, a timepiece dial plate
100
is provided on its face with indices including hour markers
102
and a name marker
103
. The time piece dial plate
100
is fixedly provided with two positioning legs
101
so as to project from the back surface of the timepiece dial plate
100
. The two positioning legs
101
position and fix in place the timepiece dial plate
100
relative to a movement. Various finishing methods are applied to the manufacture of luxury timepieces to finish their indices including hour markers beautifully. For example, a timepiece dial plate
100
as shown in
FIG. 11
is provided with indices including hour markers
102
set on the face thereof by a setting method. The setting method forms hour markers
102
having various facets individually, and sets each of the hour markers
102
on a timepiece dial body by fitting legs
102
a
formed on the hour marker
102
in holes formed in the timepiece dial body of the timepiece dial plate
100
. The indices thus attached to the timepiece dial plate
100
assume a fully solid appearance.
Those indices, however, need high manufacturing costs because the indices must individually be subjected to many processes to form the facets. Since the facets are limited to flat surfaces, the indices are unable to assume a solid appearance having optional curved surfaces.
An electroforming method is another method of manufacturing a timepiece dial plate provided with fully solid indices. An electroforming method deposits a metal on a pattern by electrodeposition and separates a metal coating formed over the pattern from the pattern to obtain an electroformed article having a shape exactly resembling that of the surface of the pattern. Electroforming is capable of forming facets of indices, such as hour markers, not only in flat surfaces but also in optional curved surfaces.
An electroforming process for forming a timepiece dial plate will be described with reference to
FIG. 12
by way of example.
A model
110
(male pattern) as shown in FIG.
12
(
a
) exactly resembling a timepiece dial plate to be manufactured is formed. In FIG.
12
(
a
), indices including hour markers are represented typically by a protrusion
105
. As shown in FIG.
12
(
b
), a plastic mother
111
(female pattern) of a plastic material is formed by using the model
110
. The plastic mother
111
is separated from the model
110
as shown in FIG.
12
(
c
), and a plurality of stampers
112
(male patterns) are formed by depositing an alloy of Cu and Ni or the like on the plastic mother
111
by electroforming. Then, as shown in FIG.
12
(
d
), a number of plastic patterns
113
(female patterns) equal to the number of timepiece dial plates to be produced are formed by using the stampers
112
(male patterns). A timepiece dial body
115
for a timepiece dial plate
116
as shown in FIG.
12
(
f
) is formed by electroforming using the plastic pattern
113
. An electroformed member
114
is formed by using the plastic pattern
113
as shown in FIG.
12
(
e
). The electroformed molding is separated from the plastic pattern
113
, and the electroformed member
114
is cut along a cutting plane
114
a to obtain the timepiece dial body
115
.
Legs
117
for fixedly positioning the timepiece dial plate
116
relative to a movement must be welded or brazed to the timepiece dial body
115
. The electroformed member
114
must be cut along the cutting plane
114
a
to form the timepiece dial body
115
having a flat back surface and a thickness t. Then, the legs
117
are welded or brazed to the flat back surface of the timepiece dial body
115
to complete the timepiece dial plate
116
.
When manufacturing the timepiece dial plate
116
by the conventional electroforming method, the timepiece dial body
115
formed by an electroforming process secures rigidity and strength for the timepiece dial plate
116
, and the legs
117
are welded or brazed to the timepiece dial body
115
. Therefore, the back surface of the timepiece dial body
115
must be flat to facilitate welding or brazing the legs
117
thereto, and the timepiece dial body
115
must be relatively thick. However, the electroforming process needs several days to form a layer of several tens micrometers in thickness. Therefore, the electroforming process must be continued for several days, which increases the manufacturing costs of the timepiece dial plate greatly.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to solve those problems in the prior art and to provide a timepiece dial plate provided with indices having an excellent solidity and a luxurious appearance.
Another object of the present invention is to provide a method of manufacturing a timepiece dial plate provided with indices having an excellent solidity and a luxurious appearance.
According to a first aspect of the present invention, a timepiece dial plate comprises: an upper plate provided with holes, and positioning legs projecting from its lower surface so as to position the upper plate relative to a movement, and a lower plate provided on its upper surface with solid indices to be fitted in the holes of the upper plate so as to protrude from the upper surface of the upper plate and provided with holes through which the positioning legs of the upper plate are extended, in which the upper plate and the lower plate are superposed so that the solid indices of the lower plate are fitted in the holes of the upper plate, respectively, and protrude from the upper surface of the upper plate, and the positioning legs of the upper plate extend through the holes of the lower plate, respectively.
Preferably, the lower plate is formed by an electro-forming method, the indices are formed integrally with a main part of the lower plate, the lower plate has a flat lower surface, the upper plate has a flat upper surface and a flat lower surface, parts of the lower surface of the lower plate corresponding to the indices are recessed, the thickness of the upper plate is greater than that of the main part of the lower plate, and the thickness of the upper plate is at least twice as great as that of the main part of the lower plate.
According to a second aspect of the present invention, a timepiece dial plate manufacturing method comprises the steps of: forming an upper plate provided with holes and positioning legs projecting from its lower surface to position the upper plate relative to a movement; forming a lower plate provided on its upper surface with solid indices to be fitted in the holes of the upper plate so as to protrude from the upper surface of the upper plate and provided with holes through which the positioning legs of the upper plate are extended; and superposing the upper plate and the lower plate so that the solid indices of the lower plate are fitted in the holes of upper plate, respectively, and protrude from the upper surface of the upper plate, and the positioning legs of the upper plate extend through the holes of the lower plate, respectively.
Preferably, the lower plate is formed by using a pattern having on it surface with protrusions corresponding to the indices and provided with holes corresponding to the holes through which the positioning legs are extended. Preferably, the lower plate is formed by an electroforming process using a pattern having on it surface with protrusions corresponding to the indices and provided with holes corresponding to the holes through which the positioning legs are extended. The indices are formed integrally with a main part of the lower plate. The lower plate has a flat lower surface, and the upper plate has a flat upper surface. Both the upper and the lower surface of the upper plate are flat. Regions of the lower surface of the lower plate corresponding to the indices are recessed, the
Ishiguro Katsuhiko
Matsuzaki Masami
Sakai Shigeo
Roskoski Bernard
Seiko Kabushiki Kaisha
Stroock & Stroock & Lavan LLP
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