Glass manufacturing – Processes of manufacturing fibers – filaments – or preforms – With measuring – controlling – sensing – programming – timing,...
Reexamination Certificate
2002-06-03
2004-08-24
Hoffmann, John (Department: 1731)
Glass manufacturing
Processes of manufacturing fibers, filaments, or preforms
With measuring, controlling, sensing, programming, timing,...
C065S382000, C065S384000, C065S407000
Reexamination Certificate
active
06779362
ABSTRACT:
This patent application claims priority based on Japanese patent applications, H11-067366 filed on Mar. 12, 1999, H11-075129 filed on Mar. 19, 1999, H10-315856 filed on Nov. 6, 1998, H10-314564 filed on Nov. 5, 1998, H11-015293 filed on Jan. 25, 0.1999, H11-16840 filed on Jan. 26, 1999, H10-314574 filed on Nov. 5, 1998, H11-067199 filed on Mar. 12, 1999, H11-315849 filed on Nov. 6, 1998, H11-010197 filed on Jan. 19, 1999, H11-112354 filed on Apr. 20, 1999, H11-046141 filed on Feb. 24, 1999, H10-314553 filed on Nov. 5, 1998, H11-065819 filed on Mar. 12, 1999, H11-118094 filed on Apr. 26, 1999, H11-044902 filed on Feb. 23, 1999, and H11-064994 filed on Mar. 11, 1999, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to an optical fiber manufacture method, a preform manufacture method and a preform manufacture apparatus that can manufacture a preform and an optical fiber with reduced variation in their diameters.
2. Description of Related Art
FIG. 1
shows a conventional glass base material first elongating apparatus
400
. A glass base material
102
, which is a base material of an optical fiber, is usually elongated by the glass base material first elongating apparatus
400
. This reduces the diameter of the glass base material
102
, to produce a glass rod
106
. The glass rod
106
has a diameter from 3 mm to 5 mm larger than the most convenient diameter to draw an optical fiber. The most convenient diameter for drawing an optical fiber is 30 mm to 80 mm.
A glass base material first elongating apparatus
400
comprises a heating furnace
100
that heats the glass base material
102
and a drawing chuck
104
that holds and elongates the heated glass base material
102
. To elongate the glass base material
102
, the glass base material first elongating apparatus
400
supplies the glass base material
102
to the heating furnace
100
. Here the glass base material
102
is heated to approximately 2000° C. The first elongating apparatus
400
then holds the glass base material
102
by the drawing chuck
104
, and draws the glass base material
102
from the heating furnace
100
downward continuously to form a glass rod
106
.
FIG. 2
shows a configuration of a conventional glass lathe
110
. The glass rod
106
made by the glass base material first elongating apparatus
400
undergoes secondary elongation by the glass lathe
110
to produce a preform
107
. At this time, the diameter of the glass rod
106
is reduced to prescribed diameter. The glass lathe
110
comprises chucks
118
and
119
that hold the glass rod
106
, a tail stock
116
which moves the chuck
119
, and a heating source
122
which heats the glass rod
106
. One side of the chuck
118
is fixed, and the other side of the chuck
119
movable. A traction force can be applied to the chuck
119
. The glass rod
106
, which is held by the chucks
118
and
119
, is heated by the heating source
122
. The heated glass rod
106
is elongated by moving the tail stock
116
which pulls the glass rod
106
. The result is, the diameter of the glass rod
106
reduces to become the prescribed diameter.
There was the possibility of manufacturing bent glass rods
106
when using a conventional glass base material first elongating apparatus
400
to elongate the glass base material
102
. Also, when using a conventional glass lathe
110
to elongate the glass rod
106
to manufacture the preform
107
further problems often arose. These problems included variation in the diameter of the preform
107
because the amount of gas provided to the heating source
122
and the speed of moving the tail stock
116
differed for each preform
107
produced.
When elongating a bent glass rod
106
, which is made by a conventional glass base material first elongating apparatus
400
, to make a preform
107
by the glass lathe
110
, the diameter of the preform
107
varied. When manufacturing optical fibers by drawing a preform
107
with a varying diameter, the diameter of the optical fibers produced also varies. This makes it difficult to manufacture an optical fiber of high quality.
SUMMARY OF THE INVENTION
As stated, it is an object of the present invention to provide an optical fiber manufacture method, a preform manufacture method and a preform manufacture equipment that can solve the problems outlined above. The object of the present invention can be achieved by the combinations of features described in the independent claims of the present invention. The dependent claims define further advantageous embodiments of the present invention.
According to the first aspect of the present invention, a method for manufacturing an optical fiber can be provided which comprises setting a heating condition for heating a glass rod, which is a parent material of the optical fiber, and an elongating speed of the glass rod based on a prescribed numerical value which changes with a progress of elongation of the glass rod; heating and elongating the glass rod to generate a preform based on the heating condition and the elongating speed which are set by the setting; and drawing the preform to a filament-like form by further heating the preform to generate the optical fiber.
A method for manufacturing an optical fiber can be provided such that the setting sets the heating condition and the elongating speed based on a progress time of the elongation as the numerical value. The heating and elongating may include end drawing for reducing a diameter of an end of the glass rod, and the end drawing end-draws the end of the glass rod with heat and elongation based on the progress time of the end drawing.
A method for manufacturing an optical fiber can be provided such that the setting sets a location of a burner, which heats the glass rod, and an amount of gas supplied to the burner as the heating condition based on the progress time of the elongation. The setting may set a moving speed of a chuck, which holds the glass rod, as the elongating speed based on the progress time of the elongation.
A method for manufacturing an optical fiber can be provided such that the setting sets the heating condition and the elongating speed based on an elongation length of the glass rod in the elongation as the numerical value.
A method for manufacturing an optical fiber can be provided such that the heating and elongating includes end drawing for reducing a diameter of an end of the glass rod, and the end drawing end-draws the end of the glass rod with heat and elongation based on the elongation length of the glass rod. The setting may set a moving distance of a burner, which heats the glass rod, and an amount of gas supplied to the burner as the heating condition based on the elongation length of the glass rod. The setting can further set a moving speed of a chuck, which holds the glass rod, as the elongating speed based on the elongation length of the glass rod.
A method for manufacturing an optical fiber can be provided such that the setting uses a encoder, which is provided on a motor that drives the chuck, to measure a moving distance of the chuck by measuring a rotation angle of the motor.
A method for manufacturing an optical fiber can be provided such that the setting sets the heating condition and the elongating speed based on a tensile stress generated on the glass rod in the elongation as the numerical value.
A method for manufacturing an optical fiber can be provided such that a heating source, which heats the glass rod, moves along a longitudinal direction of the glass rod with a progress of the elongation, and the heating and elongating controls the elongating speed so that the tensile stress before the heating source moves prescribed distance becomes substantially 110 percent or below an average value of the tensile stress after the heating source moves the prescribed distance.
A method for manufacturing an optical fiber can be provided such that the heating and elongating controls the tensile stress so that the tensile stress before the heating source moves the
Hatayama Kazuhisa
Hirasawa Hideo
Moriya Jiro
Nagano Takaaki
Sakashita Mitsukuni
Hoffmann John
Shin-Etsu Chemical Co. , Ltd.
Smith Gambrell & Russell
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