Illumination – Light source and modifier – Including reflector
Reexamination Certificate
2001-06-21
2003-09-30
O'Shea, Sandra (Department: 2875)
Illumination
Light source and modifier
Including reflector
C362S346000, C362S350000, C250S50400H, C250S455110
Reexamination Certificate
active
06626561
ABSTRACT:
BACKGROUND
The present invention is directed to lamp structure having elliptical reflectors, and methods of use thereof, for more uniformly irradiating surfaces of at least one workpiece (for example, a continuous workpiece such as a continuous fiber and/or filament). The present invention is particularly directed to apparatus, and methods, for more uniformly irradiating optical fibers, cables and ribbons, which continuously pass by a bulb, of the lamp, generating the radiation, within an elliptical space formed by the reflectors.
The present invention is especially useful in connection with irradiating a workpiece passing along a lamp bulb producing, for example, infrared light, visible light or ultraviolet light, in the processing of workpieces to cure a photo-responsive coating (for example, ultraviolet light curable coatings, and coloring inks) on surfaces of the workpieces.
The present invention has uses within the optical fiber market, including methods for processing fibers, ribbons and cables of various widths and thickness cross-sections, multi-fiber coloring, strengthening members and other applications that require a pattern of radiant flux density to the workpieces being processed.
Conventional apparatus (systems) for irradiating a fiber or ribbon with ultraviolet light includes a lamp (for example, a modular lamp, such as a microwave-powered lamp having a microwave-powered bulb (e.g., tubular bulb) with no electrodes or glass-to-metal seals), the lamp having reflectors. The reflectors can desirably utilize a primary elliptical-shaped reflector and also a secondary elliptical-shaped reflector (which optionally can have a cylindrical back reflector). This reflector structure of primary and secondary elliptical-shaped reflectors is illustrated in
FIG. 1
, which shows the structure of “DRF Systems” (ultraviolet curing systems for optical fiber, coloring, ribbon and cable) of Fusion UV Systems, Inc.
Thus, shown in
FIG. 1
is bulb
1
(e.g., a tubular bulb), centered at first focal point
2
. Hereinafter, when it is stated herein that the bulb is positioned at a location, it is meant that the bulb is centered at such location. This first focal point
2
is one of the two focal points in elliptical space
4
surrounded by primary elliptical-shaped reflector
3
and secondary elliptical-shaped reflector
9
. The second focal point of this elliptical space
4
is designated by reference character
6
, at which point optical fiber
5
is centered. Also shown in
FIG. 1
is quartz tube
7
, through which optical fiber
5
passes. Quartz tube
7
is preferred in order to be able to provide a desired atmosphere (for example, an inert gas atmosphere) surrounding optical fiber
5
, without the need for filling the entire elliptical space
4
with such inert gas. Also shown in
FIG. 1
is cylindrical back (auxiliary) reflector
11
.
As seen in
FIG. 1
, light
12
from bulb
1
, either directly or more likely after being reflected by reflectors
3
,
9
and/or
11
, is transmitted through quartz tube
7
to be irradiated on, e.g., optical fiber
5
to perform a process thereon (for example, cure a coating on the optical fiber).
In the structure shown in
FIG. 1
, bulb
1
is positioned at first focal point
2
of elliptical space
4
formed by primary elliptical-shaped reflector
3
and secondary elliptical-shaped reflector
9
, and the workpiece runs through second focal point
6
of elliptical space
4
.
FIG. 2
shows a standard ray diagram for conventional “DRF Systems” of Fusion UV Systems, Inc., having primary and secondary elliptical-shaped reflectors
3
and
9
, but without a cylindrical back reflector
11
. Bulb
1
is positioned at first focal point
2
of the elliptical space
4
of the reflector, that is, a position 1.900 inches from a midpoint of the major axis of the elliptical space
4
.
That is,
FIG. 2
shows the standard I25X/I60X ray diagram for the apparatus having primary and second elliptical-shaped reflectors
3
and
9
, respectively with a distance of 4.271 inches between bulb
1
and fiber
5
and an entire distance between the ends of the primary and secondary elliptical-shaped reflectors being 6.000 inches. A maximum width of the reflectors is 4.214 inches. As shown in this standard ray diagram of
FIG. 2
, bulb
1
and fiber
5
are respectively at the primary and secondary focal points
2
,
6
of elliptical space
4
; light
12
from bulb
1
is substantially transmitted to fiber
5
passing through second focal point
2
of the elliptical space
4
.
However, various problems arise in connection with use of this conventional structure. For one thing, alignment of the fiber
5
at secondary focal point
6
is critical, but can be difficult to achieve.
In addition, focusing of light rays
12
at second focal point
6
can cause problems in uniformity when, for example, the fiber or fibers being treated are not solely at second focal point
6
. For example, where a ribbon is being processed which has a planar surface having a width perpendicular to the direction of motion of the ribbon (that is, in a width direction of elliptical space
4
shown in FIG.
1
), focusing of light rays
12
at second focal point
6
causes non-uniformity of light irradiating on the ribbon. Such non-uniformity is especially disadvantageously great for light irradiating the surface of the ribbon facing bulb a compared with light irradiating the surface of the ribbon facing away from bulb
1
.
In order to avoid the aforementioned problems of conventional structure, a proposed technique would be to position the workpiece slightly away from the second focal point
6
, so that a pattern of radiation spaced from second focal point
6
impinges on the workpiece. This is shown in
FIG. 3
, where ribbon
15
is displaced slightly from second focal point
6
, in a direction along major axis
22
of elliptical space
4
, toward secondary elliptical-shaped reflector
9
. However, this technique of moving the workpiece does not in and of itself provide sufficient uniformity of radiation pattern on surfaces of ribbon
15
.
Accordingly, it is desired to provide apparatus and methods of use of such apparatus, providing a more uniform irradiation of all surfaces of the workpiece, including workpiece surfaces facing the bulb and surfaces facing away from the bulb, using elliptical-shaped reflector structure. It is desired to provide such more uniform irradiation of surfaces of the workpiece, without the need for providing precise positioning of the workpiece at the second focal point, and wherein the apparatus can be utilized to process, e.g., fibers, ribbons and cables of various widths and thickness cross-sections.
SUMMARY
The present invention overcomes deficiencies of the above-described techniques, achieving a more uniform dispersion of light over the surfaces of the workpieces, by moving the bulb such that the bulb is spaced from the first focal point. That is, while, according to conventional techniques, the center of the bulb is at the first focal point, according to the present invention the center of the bulb is spaced from the first focal point of the ellipse. According to the present invention, the bulb is positioned spaced from the first focal point of the ellipse in the vicinity thereof, on the major axis of the ellipse.
Thus, according to one aspect of the present invention, structure of a lamp for irradiating at least one workpiece, this structure including reflector structure, is provided. The reflector includes primary and secondary elliptical-shaped reflectors, these two reflectors in combination forming substantially an ellipse, surrounding an elliptical space, with the ellipse having a major axis and first and second focal points, the first focal point being closer to the primary reflector than the second focal point is to this primary reflector, along the major axis. This structure of the lamp includes support structure for a bulb of this lamp, to support the bulb within the elliptical space, so that the bulb is spaced from the first focal point of the ellipse in the
Carter R. Sykes
Rhoades Robert L.
Wood Charles H.
Antonelli Terry Stout & Kraus LLP
Fusion UV Systems Inc.
O'Shea Sandra
Sawhney Hargobind S.
LandOfFree
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