U.S. patent application number 10/729048 was filed with the patent office on 2005-06-09 for optical horned lightpipe or lightguide.
Invention is credited to Caldwell, Scott, McNair, Hugh T..
Application Number | 20050121424 10/729048 |
Document ID | / |
Family ID | 34633834 |
Filed Date | 2005-06-09 |
United States Patent
Application |
20050121424 |
Kind Code |
A1 |
Caldwell, Scott ; et
al. |
June 9, 2005 |
Optical horned lightpipe or lightguide
Abstract
A laser welding apparatus having a laser source outputting a
laser beam and a light transmitting device, chosen from the group
consisting essentially of a lightpipe and a lightguide, positioned
downstream from the laser source. The light transmitting device
transmits the laser beam therethrough. An optical device receives
the laser beam exiting the light transmitting device and is
operable to converge light lobes exiting the light transmitting
device to define a final beam width. The final beam width being
narrower than a beam width exiting the light transmitting
device.
Inventors: |
Caldwell, Scott; (Fairport,
NY) ; McNair, Hugh T.; (Webster, NY) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Family ID: |
34633834 |
Appl. No.: |
10/729048 |
Filed: |
December 5, 2003 |
Current U.S.
Class: |
219/121.63 ;
219/121.64; 219/121.73 |
Current CPC
Class: |
B29C 65/1667 20130101;
B29C 65/1612 20130101; G02B 6/00 20130101; B29C 66/73921 20130101;
B29C 65/1687 20130101; B29C 66/1122 20130101; G02B 6/10 20130101;
B23K 26/064 20151001; B29C 65/1635 20130101; B29C 66/41
20130101 |
Class at
Publication: |
219/121.63 ;
219/121.73; 219/121.64 |
International
Class: |
B23K 026/20; B23K
026/06 |
Claims
What is claimed is:
1. A laser welding apparatus comprising: a laser source outputting
a laser beam; a light transmitting device chosen from the group
consisting essentially of a lightpipe and a lightguide, said light
transmitting device being positioned downstream from said laser
source, said light transmitting device operable to transmit said
laser beam therethrough; and an optical device positioned
downstream from said light transmitting device, said optical device
operable to converge light lobes exiting said light transmitting
device to define a final beam width, said final beam width being
narrower than a beam width exiting said light transmitting
device.
2. The laser welding apparatus according to claim 1 wherein said
light transmitting device is integrally formed with said optical
device to form a single unit.
3. The laser welding apparatus according to claim 1 wherein said
optical device is an optical horn having outwardly tapered bounce
planes.
4. The laser welding apparatus according to claim 3 wherein said
outwardly tapered bounce planes define a first angle therebetween
and said light lobes exiting said light transmitting device define
a second angle, said first angle being less than said second
angle.
5. A laser welding apparatus comprising: a laser source outputting
a laser beam; a light transmitting device chosen from the group
consisting essentially of a lightpipe and a lightguide, said light
transmitting device being positioned downstream from said laser
source, said light transmitting device operable to transmit said
laser beam therethrough; and an optical device integrally formed
with said light transmitting device, said optical device being
positioned downstream from said light transmitting device, said
optical device being operable to converge light lobes exiting said
light transmitting device to define a final beam width, said final
beam width being narrower than a beam width exiting said light
transmitting device.
6. The laser welding apparatus according to claim 5 wherein said
optical device is an optical horn having outwardly tapered bounce
planes.
7. The laser welding apparatus according to claim 6 wherein said
outwardly tapered bounce planes define a first angle therebetween
and said light lobes exiting said light transmitting device define
a second angle, said first angle being less than said second
angle.
8. A method of laser welding a first part to a second part, said
method comprising: outputting a laser beam; passing said laser beam
through a lightpipe to define a central light lobe and a side light
lobe; passing said laser beam exiting said lightpipe through an
optical horn such that said side light lobe is generally reflected
toward said central light lobe to define a combined light lobe; and
heating at least one of a first part and a second part with said
combined light lobe to create a weld therebetween.
9. A method of laser welding a first part to a second part, said
method comprising: outputting a laser beam; passing said laser beam
through a lightguide to define a central light lobe and a side
light lobe; passing said laser beam exiting said lightguide through
an optical horn such that said side light lobe is generally
reflected toward said central light lobe to define a combined light
lobe; and heating at least one of a first part and a second part
with said combined light lobe to create a weld therebetween.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to laser welding
and, more particularly, relates to lightpipes or lightguides having
an optical horn.
BACKGROUND OF THE INVENTION
[0002] Laser welding is commonly used to join plastic or resinous
parts, such as thermoplastic parts, at a welding zone. An example
of such use of lasers can be found in U.S. Pat. No. 4,636,609,
which is expressly incorporated herein by reference.
[0003] As is well known, lasers provide a semi-focused beam of
electromagnetic radiation at a specified frequency (i.e., coherent
monochromatic radiation). There are a number of types of lasers
available; however, infrared lasers or non-coherent sources provide
a relatively economical source of radiative energy for use in
heating a welding zone. One particular example of infrared welding
is known as Through-Transmission Infrared (TTIr) Welding. TTIr
welding employs an infrared laser capable of producing infrared
radiation that is directed by lenses, diffractive optics, fiber
optics, waveguides, lightpipes or lightguides through a first
plastic part and into a second plastic part. This first plastic
part is often referred to as the transmissive piece, since it
generally permits the laser beam from the laser to pass
therethrough. However, the second plastic part is often referred to
as absorptive piece, since this piece generally absorbs the
radiative energy of the laser beam to produce heat in the welding
zone. This heat in the welding zone causes the transmissive piece
and the absorptive piece to be melted and, with intimate contact,
welded together.
[0004] However, in the case of those TTIr welding systems that
employ a lightguide or lightpipe, the infrared laser light that
exits the lightguide or lightpipe is often outwardly dispersed in a
fan or cone shape as it passes through the transmissive piece. This
dispersion of light may lead to oversized welding zones. That is,
as the light exits the lightpipe or lightguide, the light fans
outwardly and impacts a larger area of the absorptive piece and
transmissive piece interface. This larger area is consequently
heated causing a larger welding zone.
[0005] Accordingly, there exists a need in the relevant art to
provide an apparatus for use with a lightpipe or lightguide that is
capable of minimizing the size of a weld zone. Furthermore, there
exists a need in the relevant art to provide an apparatus for use
with a lightpipe or lightguide that is capable of focusing the
laser light to a narrower area that could not otherwise be obtained
simply with a conventional lightpipe or lightguide. Lastly, there
exists a need in the relevant art to provide a lightpipe or
lightguide with an optical horn capable of overcoming the
disadvantages of the prior art.
SUMMARY OF THE INVENTION
[0006] According to the principles of the present invention, a
laser welding apparatus is provided having an advantageous
construction and method of using the same. The laser welding
apparatus includes a laser source outputting a laser beam and a
light transmitting device, chosen from the group consisting
essentially of a lightpipe and a lightguide, positioned downstream
from the laser source. The light transmitting device transmits the
laser beam therethrough. An optical device receives the laser beam
exiting the light transmitting device and is operable to converge
light lobes exiting the light transmitting device to define a final
beam width. The final beam width being narrower than a beam width
exiting the light transmitting device.
[0007] Further areas of applicability of the present invention will
become apparent from the detailed description provided hereinafter.
It should be understood that the detailed description and specific
examples, while indicating the preferred embodiment of the
invention, are intended for purposes of illustration only and are
not intended to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The present invention will become more fully understood from
the detailed description and the accompanying drawings,
wherein:
[0009] FIG. 1 is a schematic view illustrating a TTIr welding
apparatus employing a lightpipe according to the prior art;
[0010] FIG. 2 is a schematic view illustrating conventional light
distribution exiting the TTIr welding apparatus illustrated in FIG.
1;
[0011] FIG. 3 is a schematic view illustrating a TTIr welding
apparatus employing a lightpipe and optical horn according to the
principles of the present invention, including the resultant light
distribution;
[0012] FIG. 4 is a schematic view illustrating a TTIr welding
apparatus employing a lightguide and optical horn according to the
principles of the present invention, including the resultant light
distribution; and
[0013] FIG. 5 is a schematic view illustrating the TTIr welding
apparatus employing a lightpipe and optical horn according to the
principles of the present invention, including the resultant weld
zone.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] The following description of the preferred embodiment is
merely exemplary in nature and is in no way intended to limit the
invention, its application, or uses. Furthermore, it should be
understood that although the present invention is described in
connection with TTIr welding, the present invention is equally
applicable to other forms of welding and/or surface heating using
light energy being passed through lightpipes or lightguides. It
should also be understood that although the term lightguide will be
used here throughout, lightguides are also known as waveguides and,
thus, such terms should be understood as being interchangeable.
[0015] By way of background and with reference to FIGS. 1 and 2,
TTIr welding systems 100 often include a laser 102 outputting a
laser light to a conventional lightpipe 104. This laser light
transmitted along conventional lightpipe 104 and through a
transmissive piece 106. The laser light finally impacts an
interface between transmissive piece 106 and an absorptive piece
108 at a weld zone 110.
[0016] As can be seen in FIGS. 1 and 2, this laser light often fans
outwardly as it exits conventional lightpipe 104 and may further
fan outwardly due to the optical effects of transmissive piece 106.
Consequently, weld zone 110 is substantially larger than the exit
end of conventional lightpipe 104 due to this effect.
[0017] More particularly, as seen in FIG. 2, the angular
distribution of laser light exiting conventional lightpipe 104 can
be seen. Specifically, as laser light enters conventional lightpipe
104, it inherently has a certain amount of angular distribution.
This angular distribution is exaggerated by the tapered sides of
conventional lightpipe 104. Therefore, as the laser light exits
conventional lightpipe 104, the angular distribution is increased
causing a larger than desired weld zone 110. Still referring to
FIG. 2, the distribution typically forms a central lobe 112 and a
pair of side lobes 114.
[0018] Referring now to FIGS. 3-5, a lightpipe or lightguide
assembly 10 is illustrated in accordance with the principles of the
present invention. According to the present embodiment, lightpipe
or lightguide assembly 10 is adapted for use with a TTIr welding
system 12. As seen in FIG. 1, TTIr welding system 12 may include an
optional fiber optic bundle 14 comprised of a plurality of optical
fibers generally arranged in a circular pattern capable of carrying
or transmitting radiative energy in the form of a laser beam
therethrough. Fiber optic bundle 14 is operably coupled to a laser
source 18, such as an infrared laser, according to known
principles.
[0019] In order to limit the angular distribution of the laser
light, lightpipe or lightguide assembly 10 comprises a lightpipe 20
(FIG. 3) or a lightguide 22 (FIG. 4). With particular reference to
FIG. 3, lightpipe assembly 10 further comprises bounce planes 24
disposed at an exit end 26 of lightpipe 20. Bounce planes 24 form
an optical horn 25 that serves to "bounce" or otherwise reflect the
laser light exiting exit end 26 of lightpipe 20 such that side
lobes 114 are generally aligned with central lobe 112 to form a
combined light lobe 28. As can be seen in FIGS. 2 and 3, combined
light lobe 28 (FIG. 3) of the present invention is considerably
narrower than the conventional distribution (FIG. 2). As such,
combined light lobe 28 is transmitted through transmissive piece 30
(FIG. 5) and impacts absorptive piece 32 to define a narrower weld
zone 34 compared to conventional weld zone 110. Lightpipe 20 and
bounce planes 24 are preferably made of a dielectric that uses
total internal reflection (TIR) and/or mirrored surface to direct
light therethrough.
[0020] Similarly, as seen in FIG. 4, lightguide assembly 10 further
comprises bounce planes 36 disposed at an exit end 38 of lightguide
22. Bounce planes 36 form an optical horn 39 that serves to
"bounce" or otherwise reflect the laser light exiting exit end 38
of lightguide 22 such that side lobes 114 are generally aligned
with central lobe 112 to form a combined light lobe 40. As can be
seen in FIGS. 2 and 3, combined light lobe 40 (FIG. 3) of the
present invention is considerably narrower than the conventional
distribution (FIG. 2). As such, combined light lobe 40 is
transmitted through transmissive piece 30 (FIG. 5) and impacts
absorptive piece 32 to define a narrower weld zone 34 compared to
conventional weld zone 110. Preferably, lightguide 22 and bounce
planes 36 employ a void having mirrored walls to conduct light
therethrough.
[0021] As should be appreciated, the present invention enables a
laser welding apparatus, which employs a lightpipe or lightguide,
to produce a substantially narrower laser welding beam capable of
producing a narrower weld zone compared to conventional laser
welding apparatuses. Consequently, laser welding apparatuses using
lightpipes or lightguides may now be used for a greater range of
delicate welding operations and/or improved weld features.
Additionally, the reflecting of the side light lobes into a
concentrated combined light lobe provided improved welding
efficiency.
[0022] The description of the invention is merely exemplary in
nature and, thus, variations that do not depart from the gist of
the invention are intended to be within the scope of the invention.
Such variations are not to be regarded as a departure from the
spirit and scope of the invention.
* * * * *