U.S. patent application number 16/285841 was filed with the patent office on 2019-08-29 for optical receiving device including focusing lens and reflector mounted to housing body and collimating lens mounted to housing c.
The applicant listed for this patent is OPTOMIND INC.. Invention is credited to Sang Shin LEE, Yong-geon LEE, Yung-sung SON.
Application Number | 20190265422 16/285841 |
Document ID | / |
Family ID | 67684434 |
Filed Date | 2019-08-29 |
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United States Patent
Application |
20190265422 |
Kind Code |
A1 |
SON; Yung-sung ; et
al. |
August 29, 2019 |
Optical Receiving Device Including Focusing Lens And Reflector
Mounted to Housing Body And Collimating Lens Mounted To Housing
Cover
Abstract
Embodiments according to the present disclosure relate to an
optical transmitting device and an optical receiving device which
can minimize the alignment error between the light source and the
photodetector on the substrate, miniaturize the devices, and
require no separate guide member reducing manufacturing costs,
while satisfying the design requirements for sub-miniaturization,
and performing optical transmission and reception more
efficiently.
Inventors: |
SON; Yung-sung; (Yongin,
KR) ; LEE; Sang Shin; (Seoul, KR) ; LEE;
Yong-geon; (Seoul, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
OPTOMIND INC. |
Suwon-si |
|
KR |
|
|
Family ID: |
67684434 |
Appl. No.: |
16/285841 |
Filed: |
February 26, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16008774 |
Jun 14, 2018 |
10268007 |
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16285841 |
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PCT/KR2016/014737 |
Dec 15, 2016 |
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16008774 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 6/4214 20130101;
G02B 6/4244 20130101; G02B 6/423 20130101 |
International
Class: |
G02B 6/42 20060101
G02B006/42 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 15, 2015 |
KR |
10-2015-0179014 |
Dec 15, 2015 |
KR |
10-2015-0179030 |
Claims
1. An optical receiving device, comprising: a collimating lens
configured to collimate a light emitted from an optical fiber; a
reflector configured to reflect the collimated light from the
collimating lens; a focusing lens, disposed below in alignment with
the reflector, configured to concentrate the reflected light from
the reflector and to direct the concentrated light to a photo
detector provided in a substrate; and a housing configured to house
the collimating lens, the focusing lens, and the reflector,
wherein: the housing has a divided structure composed of a body at
a lower position and a cover at an upper position; the focusing
lens and the reflector are mounted to the body, the body includes a
reflector mount configured to mount the reflector and a focusing
lens mount configured to mount the focusing lens; the collimating
lens is mounted to the cover, and the cover includes a collimating
lens mount configured to mount the collimating lens; the housing
has a height less than 1 mm; the reflector mount stands vertically
from a bottom of the body, and the focusing lens mount is spaced
apart from the reflector mount by a predetermined distance and is
formed in front of the reflector mount, extending from the bottom
upward and then forward laterally; the focusing lens is installed
on an upper surface of the focusing lens mount with a convex
surface of the focusing lens facing downward, and the reflector is
obliquely installed across an end of the upper surface and an apex
of the reflector mount; the body comprises a left body side
coupling portion and a right body side coupling portion, each
extending from forwardly of the bottom to near a middle region of
the body, the left body side coupling portion and the right body
side coupling portion being symmetrical in structure, and
respectively including one or more flaps, one or more receiving
holes and one or more latch members; the flaps extend vertically
upward from the bottom to provide a protective frame for protecting
at least the focusing lens and the reflector laterally from the
outside; and the bottom has an open space behind the left body side
coupling portion and the right body side coupling portion, which
cooperates with the cover so as to provide a space through which an
optical fiber passes.
2. The optical receiving device of claim 1, wherein the cover is
formed with a hole for injecting epoxy resin or refractive index
matching oil.
3. The optical receiving device of claim 1, wherein the collimating
lens mount extends vertically downward from an upper surface of the
cover, and the collimating lens is installed on a front surface of
the collimating lens mount.
4. The optical receiving device of claim 1, wherein the cover
includes an upper side formed with a left cover side coupling
portion and a right cover side coupling portion corresponding to
the left body side coupling portion and the right body side
coupling portion, the left cover side coupling portion and the
right cover side coupling portion being symmetrical in structure,
and respectively including one or more flaps, one or more receiving
holes and one or more latch members.
5. The optical receiving device of claim 1, wherein the housing
comprises a first post and a second post installed extending
downward at predetermined front and rear positions in the bottom,
respectively.
6. The optical receiving device of claim 5, wherein the first post
and the second post are circular columns.
7. The optical receiving device of claim 6, wherein the first post
is a tapered column whose diameter decreases gradually downward by
minute degrees, and the second post is a straight column having a
constant diameter.
8. The optical receiving device of claim 7, wherein the first post
has the diameter larger than that of the second post near the
bottom of the body.
9. The optical receiving device of claim 1, wherein the collimating
lens is installed at a predetermined position to fully accommodate
the reflected light.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is a continuation-in-part of U.S.
Ser. No. 16/008,774, filed Jun. 14, 2018, which is a continuation
of International Application No. PCT/KR2016/014737, filed Dec. 15,
2016, and is based upon and claims the benefit of priorities from
Korean Patent Application Nos. 10-2015-0179014 and 10-2015-0179030,
filed on Dec. 15, 2015. The disclosures of the above-listed
applications are hereby incorporated by reference herein in their
entireties.
BACKGROUND OF THE INVENTION
Technical Field
[0002] The present disclosure in some embodiments relates to an
optical transmitting device and an optical receiving device for an
optical fiber cable and a method of aligning thereof.
Discussion
[0003] The statements in this section merely provide background
information related to the present disclosure and do not
necessarily constitute prior art.
[0004] Optical fiber-based signal transmission methods, which are
in extensive use for a long haul communication, have widespread
applications in a large-capacity digital media transmission
including a high-definition digital video display for which
high-speed and high-density data transmission is required, owing to
the operation characteristics unaffected by an electromagnetic
interference (EMI) and usefulness in a broad bandwidth of the
optical fiber.
[0005] These optical fiber-based signal transmission methods can be
implemented by arranging a lens and a reflector configured between
an optical fiber and an optical element. One possible way to
achieve such configuration is to install the optical fiber and a
structure affixed with the reflector and the lens on a substrate
mounted with the optical element to establish an optical
alignment.
[0006] This method of optical alignment can be incorporated into
manufacturing an optical transceiver, where a selected way of
aligning the optical element, the lens, the reflector and the
optical fiber dictates the structural simplification, manufacturing
cost reduction, and durability and precision enhancements, etc.,
which exhibits the paramount significance of the optical alignment
issue.
[0007] However, an optical transceiver manufactured by the optical
alignment of the conventional method is not only highly costly but
also too bulky to fit in a mobile communication device such as a
smartphone, and is troubled with instability issues due to a
complicated structure.
[0008] Korean Patent Application No. 2014-0168272 filed on Nov. 28,
2014 by this applicant proposed an apparatus for optical
transmitting and receiving as shown in FIGS. 1A and 1B.
[0009] The apparatus for optical transmitting and receiving or
optical transmitting and receiving device includes a baseplate
1210' and an optical-fiber fixing block 1300'. The baseplate 1210'
includes a set position for mounting an optical element 1215', a
first reference hole A', and a second reference hole B' spaced by a
first distance from the first reference hole A'. The optical-fiber
fixing block 1300' is configured to fixedly mount at least one of a
lens unit 1320' and an optical fiber 1340' optically linked with
the optical element 1215', and it includes a first post C'
configured to be inserted into the first reference hole A' and a
second post D' configured to be inserted into the second reference
hole B'.
[0010] The optical fiber 1340' is inserted along guide surfaces
1310'. The optical element 1215' and the lens unit 1320' are
arranged so that their centers are vertically aligned, and a
reflector 1330' is installed on the upper part of the lens unit
1320'. Light emitted from the optical fiber 1340' is deflected via
the reflector 1330', focused via the lens unit 1320' and thereby
made incident on the optical element 1215'. Conversely, light
emitted from the optical element 1215' is focused via the lens unit
1320' and deflected via the reflector 1330' such that the light is
incident on the optical fiber 1340'.
[0011] Such an optical transmitting and receiving device exhibits
excellent efficiency serving the two individual purposes of
transmission/reception, but has the following drawbacks.
[0012] Recent embedded system specifications require that the
overall height of the optical transmitting and receiving device be
1 mm or less to fit the standard IC package. The main issue in
designing and manufacturing in accordance with this requirement is
that reducing the diameter or thickness of the lens unit has its
light concentration ratio dropped correspondingly to inhibit a
designed performance of the optical transmission and reception. In
addition, reducing the external dimension of the device with the
size of the lens unit maintained causes an optical loss at the
reflector and an increased refraction angle of the light incident
on the optical fiber to inhibit a part of the light from being
guided through the optical fiber, resulting in structural
misalignment of the optical system.
[0013] Here, the present inventors have determined that there is a
limit to fulfilling a new specification with an existing device
that performs both transmission and reception of light, and found
that an optical transmitting device dedicated advantageously to
optical transmissions can satisfy design requirements for
sub-miniaturization as well as transmit light more efficiently.
[0014] At the same time, the present inventors have found an
improved method of aligning the lens of the optical transmitting
device and the light source on a substrate.
SUMMARY OF THE INVENTION
[0015] The following description of some embodiments of the present
disclosure is based on these findings.
[0016] Therefore, the first and second embodiments of the present
disclosure seek to provide an optical transmitting device and an
optical receiving device respectively suitable for the design
requirements for sub-miniaturization.
[0017] The first and second embodiments provide new types of
optical transmitting and receiving devices to reduce the tolerance
as well as the size of the devices which are economical, convenient
to manufacture and so on.
[0018] The first and second embodiments further seek to provide
aligning methods capable of limiting the alignment error between
the optical transmitting and receiving devices and the substrates
to within a few micrometers and minimizing the error.
[0019] Technical problems to be solved by the present disclosure
are not limited to the above, but other unmentioned technical
problems resolved will be clearly understood by a person of
ordinary skill in the pertinent art from the description below.
SUMMARY
[0020] According to one aspect of the first embodiment of the
present disclosure, an optical transmitting device is provided
including a first lens, a reflector disposed above and in alignment
with the first lens, a second lens disposed on a side of and in
alignment with the reflector so as to receive light reflected by
the reflector, and a housing configured to house the first lens,
the second lens, and the reflector. Here, the housing has a divided
structure composed of a body at a lower position and a cover at an
upper position, and the housing has a height less than 1 mm.
[0021] According to another aspect of the first embodiment, a
method of aligning the optical transmitting device is provided
including providing a substrate coupled to the optical transmitting
device and including a light source, and coupling a first post to a
first reference hole provided in the substrate, and coupling a
second post to a second reference hole provided in the substrate,
and aligning a first lens provided in the optical transmitting
device with the light source of the substrate.
[0022] According to one aspect of the second embodiment, an optical
receiving device.
[0023] The optical receiving device includes a focusing lens, a
reflector disposed above and in alignment with the focusing lens,
and a housing configured to house the focusing lens and the
reflector. Here, the housing has a height less than 1 mm, and the
housing has a bottom provided with a first post and a second post
extending downward at predetermined front and rear positions of the
bottom, respectively.
[0024] According to another aspect of the second embodiment, a
method of aligning an optical receiving device is provided,
including providing a substrate coupled to the optical receiving
device and including a photodetector, and coupling a first post to
a first reference hole provided in the substrate, and coupling a
second post to a second reference hole provided in the substrate,
and aligning a focusing lens provided in the optical receiving
device with the photodetector of the substrate.
[0025] According to yet another embodiment of the present
disclosure, an optical transmitting device includes a body and a
cover. The body includes a first lens configured to modify a
diverging beam of light emitted from a light source into a parallel
beam of light, and a reflector arranged above the first lens and
configured to reflect light from the first lens. The cover is
configured to be coupled with the body to form a housing and it
includes a second lens configured to collect the light from the
reflector and transmit the light to an optical fiber, and an
optical fiber guide unit configured to guide the optical fiber.
Here, the second lens is installed at a predetermined position to
fully accommodate the light reflected by the reflector and to
establish a seamless optical path running from the light source
through the first lens, the reflector and the second lens to the
optical fiber.
[0026] According to yet another embodiment of the present
disclosure, an optical communication assembly includes a body, a
cover and a substrate.
[0027] The body includes a collimating lens configured to modify a
diverging beam of light emitted from a light source into a parallel
beam of light, and a reflector arranged above the collimating lens
and configured to reflect light from the collimating lens. The
cover is configured to be coupled with the body to form a housing
and it includes a focusing lens configured to collect the light
from the reflector and transmit the light to an optical fiber, and
an optical fiber guide unit configured to guide the optical fiber.
The substrate is configured to be coupled to the light source and
the body. Here, the focusing lens is installed at a predetermined
position to fully accommodate the light reflected by the reflector
and to establish a seamless optical path running from the light
source through the collimating lens, the reflector and the focusing
lens to the optical fiber. The body comprises a first post and a
second post installed extending downward at predetermined front and
rear positions in a bottom of the body. The substrate comprises a
first reference hole and a second reference hole configured to be
coupled with the first post and the second post, respectively.
[0028] According to the first embodiment, by utilizing a lens group
including a plurality of lenses, an optical transmitter is provided
that can function as an optical transmitting device while
satisfying the design requirements for sub-miniaturization, and can
perform optical transmission more efficiently.
[0029] According to the second embodiment, an optical receiving
device is provided that can function as an optical receiver while
satisfying the design requirements for sub-miniaturization, and can
perform optical reception more efficiently.
[0030] Further, the optical transmitting device according to the
present alignment method minimizes the alignment error with a light
source on the substrate, provides for the miniaturization thereof,
and obviates the need for a separate guide member so as to reduce
the manufacturing cost of the device.
[0031] Further, the optical receiving device according to the
present alignment method minimizes the alignment error with a
photodetector on the substrate, provides for the miniaturization
thereof, and obviates the need for a separate guide member so as to
reduce the manufacturing cost of the device.
[0032] Besides, different embodiments of the present disclosure
exhibit a variety of corresponding effects such as the devices with
excellent durability, which will be clearly illustrated by the
embodiments described below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] FIG. 1A is a perspective view of a conventional apparatus
for transmitting and receiving light.
[0034] FIG. 1B is a side view of FIG. 1A.
[0035] FIG. 2 is a conceptual diagram for illustrating the
principle of optical transmission of an optical transmitting device
according to a first embodiment.
[0036] FIG. 3 is a perspective view of the overall appearance of
the optical transmitting device of the first embodiment.
[0037] FIGS. 4A and 4B are a left side view and a plan view of the
body of the optical transmitting device of the first
embodiment.
[0038] FIGS. 5A and 5B are a left side view and a plan view of a
cover of the optical transmitting device of the first
embodiment.
[0039] FIGS. 6A and 6B are a left side view and a plan view
illustrating that a housing made of the body and the cover of the
first embodiment is coupled with a substrate.
[0040] FIGS. 7A to 7C are conceptual diagrams illustrating a method
of aligning the optical transmitting device according to the first
embodiment on a substrate, of which FIG. 7B is a diagram of the
principle of the method where a first post is fixed, and FIG. 7C is
a diagram of the principle of the method illustrating a second post
is fixed.
[0041] FIG. 8 is a conceptual diagram illustrating the principle of
optical reception of the optical receiving device according to the
second embodiment.
[0042] FIG. 9 is a perspective view of the overall appearance of
the optical receiving device of the second embodiment.
[0043] FIGS. 10A and 10B are a left side view and a plan view of
the optical receiving device of the second embodiment.
[0044] FIG. 11 is a left side view illustrating that the housing of
the second embodiment is coupled to the substrate.
[0045] FIGS. 12A to 12C are conceptual diagrams illustrating a
method of aligning the optical receiving device according to the
second embodiment on a substrate, of which FIG. 12B is a diagram of
the principle of the method where the first post is fixed, and FIG.
12C is a diagram of the principle of the method illustrating a
second post is fixed.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0046] Hereinafter, some embodiments of the present disclosure will
be described in detail with reference to the accompanying drawings.
In the following description, like reference numerals designate
like elements, although the elements are shown in different
drawings. Further, in the following description of the at least one
embodiment, a detailed description of known functions and
configurations incorporated herein will be omitted for the purpose
of clarity and for brevity.
[0047] Additionally, various terms such as first, second, A, B,
(a), (b), etc., are used solely for the purpose of differentiating
one component from the other but not to imply or suggest the
substances, the order or sequence of the components. Throughout
this specification, when a part "includes" or "comprises" a
component, the part is meant to further include other components,
not excluding thereof unless specifically stated to the
contrary.
[0048] If any component is described as `connected`, `coupled` or
`fastened` to another component, the components are not only meant
to be directly `connected`, `coupled`, or `fastened` but also are
indirectly `connected`, `coupled`, or `fastened` via one or more
additional components.
[0049] In addition, the size, shape, etc. of the components
illustrated in the drawings can be exaggerated for clarity of
explanation and convenience. The terms specifically defined in
consideration of the configuration and operation of the present
disclosure are only for explaining some embodiments of the present
disclosure and are not intended to limit the scope of the present
disclosure.
[0050] The transmission/reception apparatus for an optical fiber
cable, according to some embodiments of the present disclosure may
be manufactured as two different modules. One module is a
transmitting device that performs an electric-optical signal
conversion and transmits the converted optical signal via an
external optical fiber cable. The other module is a receiving
device that receives an optical signal via an external optical
fiber cable and performs an optical-electric signal conversion. A
transmitting device for an optical fiber cable according to at
least one embodiment of the present disclosure will be described in
the first embodiment, and a receiving device for an optical fiber
cable will be described in a second embodiment.
[0051] Hereinafter, the principle, structure and then alignment
method of an optical transmitting device 1 presented as the first
embodiment of the present disclosure will be explained.
[0052] 1. Principle of Optical Transmission
[0053] First, referring to FIG. 2, the principle of optical
transmission will be described concentrating on the optical
structure of the optical transmitting device 1 of the first
embodiment of the present disclosure.
[0054] The optical transmitting device 1 faces a substrate 10
installed with a light source 12 as an optical element, and
includes a lens group 20, a reflector 14 and an optical cable 30.
The lens group 20 has a first lens 22 installed between the light
source 12 and the reflector 14, and a second lens 24 installed
between the reflector 14 and the optical cable. An optical fiber 32
is inserted in the optical cable 30. The reflector 14 includes, but
is not limited to, a prism.
[0055] The light source 12, the first lens 22 and the reflector 14
are aligned so that the centers of the three members are aligned in
the vertical direction. Likewise, the reflector 14, the second lens
24 and the optical cable 30 are laterally aligned so that the
centers of the reflector 14 and the second lens 24 coincide with
the center point of the light receiving portion of the optical
cable 30. Methods for aligning the light source 12 and the first
lens 22 are disclosed in applicant's earlier Korean Patent
Application Nos. 2014-0168272 and 2013-0146599, which are hereby
incorporated by reference into the contents of this
application.
[0056] The first lens 22 is preferably a collimating lens and the
second lens 24 is preferably a focusing lens. Light that has passed
through a collimating lens becomes collimated light, and light that
has passed through a focusing lens is focused. Therefore, as shown
in the drawing, the light emitted from the light source 12 is
collimated by passing through the first lens 22, propagates towards
the reflector 14, is reflected by the reflector 14, travels towards
and passes through the second lens 24, and then coupled into the
core of the optical fiber 32 where the light is focused.
[0057] Multiples of the light source 12 may be aligned in a row on
the substrate. In this case, multiple first lenses 22 and second
lenses 24 are installed in a row in alignment with the respective
light sources 12.
[0058] The adoption of the lens group 20 including the plurality of
lenses of the first lens 22 and the second lens 24 is a feature of
some embodiment of the present disclosure. Maintaining a
single-lens structure with only a focusing lens displaced between a
light source and a reflector while meeting the design requirement
for sub-miniaturization of a submillimeter height limit leads to a
reduced size of the lens and a shortened optical path, particularly
where light needs to propagate through its micro heights. Thereby,
the light emitted from the light source fails to gather accurately
on the reflector, and part of the light reflected by the reflector
is incident on the optical fiber at an angle with the fiber axis
exceeding the fiber's total reflection critical angle to disable
its propagation through the optical fiber, resulting in an optical
loss with the light scattering outside the fiber cladding. To the
contrary, with the adoption of the lens group 20 made of the
plurality of lenses including the first lens 22 and the second lens
24, the optical transmitting device 1 of some embodiments of the
present disclosure functions exclusively as an optical transmitter
different from the conventional optical apparatus for both
transmission and reception operations. At the same time, the
optical transmitting device 1 satisfies the design requirements for
sub-miniaturization, and performs optical transmission more
efficiently.
[0059] The main function of the first lens 22 is to reduce the beam
divergence of light emitted from the light source 12, to alleviate
the burden of the second lens 24 with the duty to focus the light
and at the same time to increase the optical alignment tolerance.
The distributed duties between the lens with respect to the
coupling of the optical signal reduces the influence of the
numerical aperture (NA) which is a constraint of the optical
waveguide of the optical fiber. This means that the refractivity of
the lens can be adjusted according to the divergence of the light.
In particular, using the second lens 24 to focus the collimated
beam of light from the first lens 22 facilitates to maximally focus
the light into the optical fiber that has a predetermined NA.
[0060] 2. Structure of Optical Transmitting Device
[0061] FIG. 3 is a perspective view of the overall appearance of
the optical transmitting device 1 including the structure of FIG. 2
of the present disclosure.
[0062] The optical transmitting device 1 includes a housing 2 in
which the lens group 20 and the reflector 14 are installed. The
optical transmitting device 1 is coupled face-to-face to the
substrate 10 on which the light source 12 is installed.
[0063] The housing 2 is approximately quadrangular and has a
divided structure of a body 3 and a cover 4. The cover 4 has its
upper surface provided with a hole 40 for injecting an adhesive
such as epoxy, and has at its rear a trapezoidal cut to provide a
guide 41 for the optical cable 30.
[0064] The height (H) of the housing 2 is on a sub-millimeter, or
sub-miniature, scale. This is a smaller thickness than a typical
electronic chip, and the optical transmitting device 1 of some
embodiments of the present disclosure is useful for application to
devices with small thickness or small form factor.
[0065] The optical transmitting device 1 of some embodiments has a
molded article for optical alignment removed, and it is suffice to
perform the optical alignment with the housing 2 and the substrate
10 themselves and thereby reduces the alignment error generated by
using the molded article. The housing 2 is manufactured by plastic
injection molding to facilitate mass production and assembly
thereof.
[0066] FIGS. 4A and 4B are a left side view and a plan view of the
body 3 of the optical transmitting device 1.
[0067] The body 3 has a bottom 300 of a long rectangle, a left side
coupling portion 310 and a right side coupling portion 312, each
having a height larger than the bottom 300 and extending from near
the front of the tip of the bottom 300 to near a middle region
thereof. The bottom 300 is centrally positioned and enclosed by the
left coupling portion 310 and the right coupling portion 312 from
both sides. Starting from the front to the rear, the left coupling
portion 310 includes a first flap 315 projecting upward, a first
receiving hole 313 and a first latch member 316 projecting upward.
Likewise, the right coupling portion 312 includes a second flap
317, a second receiving hole 314 and a second latch member 318
projecting upward. Generally, the left coupling portion 310 and the
right coupling portion 312 are symmetrical structures of the same
shape.
[0068] The first flap 315 and the second flap 317 extend vertically
upward from the bottom 300, and protect the first lens 24 and the
reflector 14 from the left and right, respectively. The latch
members 316, 318 and the receiving holes 313, 314 are members to be
coupled with corresponding elements of the cover 4. In this
arrangement, the left coupling portion 310 and the right coupling
portion 312 provide a protective frame for the lens and the
reflector and provide a fastening structure for cooperating with
the cover 4. Therefore, as long as their functions are offered, the
above members may have their size, shape and position arbitrarily
changed.
[0069] The bottom 300 and the coupling portions 310, 312 may be
integrated with one another, although their formation is not
necessarily limited thereto.
[0070] The bottom 300 has an open space 300S behind the left and
right coupling portions 310, 312, which cooperates with the cover 4
so as to provide a space through which the optical fiber passes.
This optical fiber space is closed by the cover 4 at its third flap
403 and fourth flap 408 described below to provide an optical fiber
guiding structure which is impervious to external impacts and
vibrations.
[0071] The bottom 300 is formed with a first post 302 and a second
post 303 in predetermined positions forward and rearward
respectively along the longitudinal center line thereof, which
extend downward toward the substrate. The first post 302 and the
second post 303 are circular columns protruding downward. In the
example shown in FIG. 4A, in order to tolerate the error of optical
alignment, the first post 302 is a tapered column having its
diameter gradually reduced downward by minute degrees, and the
second post 303 is a straight column having a constant diameter.
The diameter of the first post 302 is larger than that of the
second post 303 in the vicinity of the top of the first post 302,
that is, adjacent to the bottom 300. This means that with respect
to the second post 303, the diameter of the first post 302 may be
larger on its upper side of a reference point in the vertical
direction and smaller on its lower side of the reference point.
[0072] Then, the body 3 of some embodiments of the present
disclosure utilizes a reflector mount 301 and a first lens mount
304 for installing the reflector 14 and the first lens 22,
respectively. As shown in FIG. 4A, the reflector mount 301 rises
vertically from the tip of the bottom 300. The first lens mount 304
is spaced apart from the reflector mount 301 by a predetermined
distance and is formed in front of the reflector mount 301, and it
extends from a lower end portion of the bottom 300 to a height
slightly higher than the start point of the reflector mount 301
until it is redirected to extend forward laterally to generally
form an inverted L-shape. The reflector mount 301 and the first
lens mount 304 may be made to be integrated with the bottom 300 or
they may be separately manufactured in a unitized module and
coupled to the bottom 300.
[0073] The first lens 22 is installed on an upper surface 304a of
the first lens mount 304 with its convex surface facing downward.
The reflector 14 is obliquely installed across the end of the upper
surface 304a and the apex of the reflector mount 301. When
multiples of the first lens 22 are installed, as shown in FIG. 4B,
the first lenses 22 are installed in a row along the upper surface
304a with a certain interval therebetween. In this case, the
reflector 14 may be a single prism installed for providing a
constant reflecting surface.
[0074] As long as the reflector mount 301 and the first lens mount
304 perform the optical transmission function described with
reference to FIG. 2 and serve to house the first lens 22 and the
reflector 14 so as to provide an optical path suitable for the
optical transmitting device 1 of some embodiments of the present
disclosure, they may be freely modified in shape, size and
position.
[0075] As described above, the present disclosure in some
embodiments adopts a divided structure wherein the first lens 22
and the reflector 14 are installed in the body 3, and the second
lens 24 is installed in the cover 4, which facilitates designing
and manufacturing of a suitable compact optical transmitting device
for sub-miniaturization requirements.
[0076] FIGS. 5A and 5B are a left side view and a plan view of the
cover 4 of the optical transmitting device 1.
[0077] The cover 4 has an elongated rectangular shape and includes
an upper side 400 wider than the bottom 300. On the lower part of
the upper side 400, a left coupling portion 420 is formed to
correspond to the left side contour of the body 3 and a right
coupling portion 430 is formed to correspond to the right side
contour of the body 3. Starting from the front to the rear, the
left coupling portion 420 includes a third latch member 401
projecting downward, a third receiving hole 402, and a third flap
403 projecting downward. Similarly, the right coupling portion 430
includes a fourth latch member 406 projecting downward, a fourth
receiving hole 407, and a fourth flap 408 projecting downward from
the front.
[0078] As long as the left coupling portion 420 and the right
coupling portion 430 serve the purpose of providing a protection
frame of the optical fiber cable and fastening with corresponding
elements of the body 3, they may be arbitrarily modified in size,
shape and position. In some embodiments, the upper side 400 and
these coupling portions 420, 430 are integrated, but are not
necessarily limited thereto.
[0079] As described above, the upper side 400 is provided with the
hole 40 for injecting an adhesive such as epoxy at the midpoint in
the width direction in front of the upper side 400. The epoxy resin
injected through the hole 40 securely binds the optical fiber and
the cover 4 together, fills the gap between the wall surface of the
second lens 24 and the optical fiber end in the coupling process,
so as to reduce the reflection that may occur from the surface
through which the light is transmitted. Some embodiments of the
present disclosure inject, in addition to epoxy, other highly
viscous materials enabling optical communication in cooperation
with optical fibers and plastic molded parts. For example, as a
replacement or addition to the epoxy, refractive index matching oil
may be injected to desirably reduce the NA of the light incident on
the optical fiber.
[0080] In some embodiments of the present disclosure, the cover 4
utilizes a second lens mount 404 for mounting the second lens 24.
The second lens mount 404 extends vertically downward from the
front portion of the upper surface 300, as shown in FIG. 5A. The
second lens 24 is installed on a front surface 404a of the second
lens mount 404. The second lens 24 is installed at an elevation set
according to the position of the reflector 14 so as to fully
accommodate the light reflected by the reflector 14. When there are
multiples of the first lens 22, as shown in FIG. 5B, the matching
number of second lenses 24 are installed.
[0081] The portion where the second lens 24 and the second lens
mount 404 are installed remains in the cover 4 as an open space 40S
which, however, is laterally closed by the first flap 315 and the
second flap 317 to provide a structure of the lens system which is
impervious to external impact and vibration.
[0082] As long as the second lens mount 404 serves its purpose of
housing the second lens 24 described with reference to FIG. 2 so as
to provide an optical path suitable for the optical transmitting
device 1 of some embodiments of the present disclosure, it may be
freely modified in shape, size and position.
[0083] As described above, the present disclosure in some
embodiments adopts a divided structure between the body 3 and the
cover 4, which facilitates designing and manufacturing of a
suitable compact optical transmitting device for
sub-miniaturization requirements.
[0084] In addition, relocating the second lens 24 installed on the
cover 4 alone without adjustment of the body 3 may adjust the
distance to the optical fiber or provide an alignment with the path
of the reflected light from the reflector 14, which facilitates the
operation of optical alignment and calibration.
[0085] FIGS. 6A and 6B are a left side view and a plan view
illustrating that the housing 2 made of the body 3 and the cover 4
described above is coupled with the substrate 10. For convenience
of explanation, FIG. 6A presents a reference numeral of each left
side member, accompanied by its right side counterpart in
parentheses.
[0086] The first flap 315 and the second flap 317 of the body 3 are
fastened to the cover 4 so as to be in contact with the upper side
400 of the cover 4, to provide a protective frame for laterally
protecting the optical system including the first lens 22, the
reflector 14 and the second lens 24.
[0087] In the first receiving hole 313 and the second receiving
hole 314 of the body 3, the third latch member 401 and the fourth
latch member 406 of the cover 4 are accommodated, respectively.
Additionally, in the third receiving hole 402 and the fourth
receiving hole 407 of the cover 4, the first latch member 316 and
the second latch member 318 of the body 3 are accommodated,
respectively. Repetitive fastening of these continuous
concavo-convex structures provides secure and accurate fastening of
the body 3 and the cover 4, and it can minimize misalignment after
assembly.
[0088] Further, the third flap 403 and the fourth flap 408 of the
cover 4 are coupled with the body 3 abutting against the bottom 300
while closing the space 300s thereof so as to provide an optical
fiber guiding structure which is impervious to external impacts or
vibrations.
[0089] One of the structural features of the housing 2 of the
optical transmitting device of some embodiments is that the body 3
is provided with the first lens 22 and the reflector 14 and the
cover 4 has the second lens 24 and the optical fiber guide unit
installed therein. Thus, while maintaining this feature, the
present disclosure is capable of various modifications at the level
of those skilled in the art, including, for example, providing the
first flap and the second flap on the cover 4 with the third flap
and the fourth flap provided on the body 3, or inversely forming
the latch members and the receiving holes between the body 3 and
the cover 4, or switching the order of forming the latch members
and the receiving holes.
[0090] Further, although the explanation has been made on the
premise that the light source 12 is arranged outside the first post
302 and the second post 303, the light source 12 when relocated
halfway between the first post 302 and the second post 303 as
disclosed in Korean Patent Application No. 2014-0168272 may be
accommodated by the present disclosure with an appropriate
adaptation of the housing structure.
[0091] Referring again to FIGS. 6A and 6B, the housing 2 of the
present disclosure is coupled to the substrate 10.
[0092] The substrate 10 is formed with a first reference hole 302a
and a second reference hole 303a for accommodating the first post
302 and the second post 303 of the housing 2. The first post 302
and the second post 303 are inserted into the first reference hole
302a and the second reference hole 303a, respectively. The first
post 302 which is the tapered column is initially inserted into the
first reference hole 302a with a minute clearance remaining
therebetween. As the insertion progresses gradually, the first post
302 is fixed in a position where it comes into contact with the
first reference hole 302a without gaps.
[0093] As described later, the optical transmitting device 1 of
some embodiments having such coupling structure can minimize a
misalignment that may occur in the process of assembling with the
substrate 10.
[0094] 3. Alignment Method of Optical Transmission Device
[0095] The principle of the alignment method of the optical
transmitting device of the present disclosure will be described
with reference to FIGS. 7A to 7C, which mainly shows the plan view
of the substrate 10.
[0096] With respect to the light source 12 provided on the
substrate 10, the first reference hole 302a and the second
reference hole 303a are formed in a line. The light source 12,
first reference hole 302a and second reference hole 303a
respectively have center lines 111, 112 and 113 in the widthwise
direction (vertical direction in the drawing), and the light source
12, first reference hole 302a and second reference hole 303a have a
longitudinal (horizontal direction in the drawing) center line as
indicated by 114. "A" is the gap between center line 111 and center
line 112, and "B" is the spacing between center line 112 and center
line 113.
[0097] In the small form factor optical transmitting device 1 with
a height of less than 1 mm, correction of assembling tolerance
means eliminating errors of several micrometers, so a sophisticated
aligning operation is required. Typically, the substrate 10 is
completed and supplied in advance according to specifications. The
principal interest in the assembly of the substrate 10 and the
optical transmitting device 1 is the alignment of the first lens 22
with the least possible deviation with respect to the light source
12 located on the substrate 10. The ideal assembly for this purpose
provides a perfect alignment of the centers of the respective
reference holes with the centers of the respective posts free of
deviation of even several .mu.m. However, it is difficult to make a
complete intermeshing of members in the actual assembly process. A
solution to this problem is to minimize the error by having either
one of the first post 302 and the second post 303 fixed to
eliminate the tolerance issue, and having the tolerance of the
other post to exclusively affect the position of the first lens 22
to be aligned with the light source 12.
[0098] FIG. 7B is a diagram of the principle of the method where
the first post 302 is fixed immovably. It is assumed that A:B=1:8
and the second post 303 is located deflected upward by 20 .mu.m
from the center of the second reference hole 303a. In this case,
the first lens 22 is deviated from the light source 12 downwardly
by 2.5 .mu.m by proportional expression.
[0099] FIG. 7C is a diagram of the principle of the method
illustrating the second post 303 is fixed immovably. It is assumed
that A:B=1:8 and the first post 302 is located deflected upward by
20 .mu.m from the center of the first reference hole 302a. In this
case, the first lens 22 is deviated from the light source 12
upwardly by 22.5 .mu.m by proportional expression.
[0100] Therefore, when the light source 12 is arranged outside with
respect to all the reference holes, fixing the first post 302 in
proximity to the light source 12 can eventually reduce the
nine-fold error than when the second post 303 is fixed. The above
principle is applied not only to the case where the post deviates
to the upward direction from the center of the reference hole but
also to the case where the post deviates in the downward or
left/right direction.
[0101] Those skilled in the art will appreciate that assembly
errors can be minimized as the proportional relationship of A:B
increases, that is, as the distance between posts increases or the
first post is closer to the light source or the first lens.
[0102] In order to fix the first post 302 to the first reference
hole 302a, the optical transmitting device 1 of some embodiments of
the present disclosure has the first post 302 designed as a tapered
column so that it is inserted into the first reference hole 302a
initially with minute degrees of clearance provided, and as the
insertion gradually progresses, the first post 302 is fixed at a
position where it is in contact with the first reference hole 302a
without gaps.
[0103] The fixed position may be a point where the diameters of the
first post 302 and the first reference hole 302a coincide. However,
since the post is molded with, for example, a plastic material, it
has a property that, when depressed, it is inserted by being
compressed and deformed, and when pressure is released, returns to
the original shape by elastic restoring force. Therefore, the fixed
position may be a position where the diameter of the first post 302
is slightly larger than that of the first reference hole 302a,
which is a margin for facilitating the fixation of the first post
302.
[0104] From the above, one can see that it is desirable to design
the first post 302 as a tapered column having its diameter
continuously increased from a range larger than the diameter of the
first reference hole 302a to a range smaller than the same.
[0105] When the position of the first post 302 is fixed, only the
position of the second post 303 affects the alignment of the light
source and the lens, but the latter effect is very small compared
to the effect on the lens by the deviation of either the first post
302 or both posts 302, 303 from the centers of all the reference
holes. Therefore, it becomes possible to restrict the alignment
error of the light source and the lens to within a few micrometres
to minimize it.
[0106] The structure of the optical transmitting device described
in the first embodiment can also be applied to an optical receiving
device. In such an optical receiving device, the second lens 24
collimates a light emitted from the optical fiber 32, the reflector
14 reflects the collimated light from the collimating lens, and the
first lens 22 concentrates the reflected light from the reflector
14 and directs the concentrated light to a photo detector (not
shown) provided in the substrate 10. The photo detector would be
installed at a position on the substrate 10 where the light source
12 is installed.
[0107] The following describes the principle, structure and then
the alignment method of an optical receiving device 1' presented as
the second embodiment of the present disclosure.
[0108] 1. Principle of Optical Reception
[0109] Referring first to FIG. 8, the principle of optical
reception will be described concentrating on the optical structure
of the optical receiving device 1' of the second embodiment of the
present disclosure.
[0110] The light receiving device 1' according to some embodiments
of the present disclosure faces a substrate 10 installed with a
photodetector 12' as an optical receiving element, and includes a
lens 20', a reflector 14' and an optical cable 30'. The lens 20' is
provided between the photodetector 12' and the reflector 14'. An
optical fiber 32' is inserted in the optical cable 30'. The
reflector 14' includes, but is not limited to, a prism.
[0111] The photodetector 12', lens 20' and reflector 14' are
aligned so that the centers of the three members are at the same
elevation. Likewise, the reflector 14' and the optical cable 30 are
laterally aligned so that both members are aligned such that the
reflector 14' coincide with the center point of the light
transmitting portion of the optical cable 30'.
[0112] The lens 20' is preferably a focusing lens. The light having
passed through the focusing lens is focused. Therefore, as shown in
the drawing, the light emitted from the optical fiber 32' is
incident on the reflector 14', is reflected by the reflector 14' at
right angle, travels downward in the drawing and passes through the
lens 20' where the light is focused and then incident on the
photodetector 12'.
[0113] Multiples of the photodetector 12' may be aligned in a row
on the substrate. In this case, multiple lenses 20' are installed
in a row in alignment with the respective photodetectors 12'.
[0114] It is very difficult to design an optical transceiver that
performs both optical transmission and optical reception while
satisfying the design requirements for sub-miniaturization of a
submillimeter height limit. However, it has been found that the
single-lens structure with the lens size reduced for use as an
optical receiving device exhibits an excellent optical receiving
efficiency over prior art. On the other hand, the optical
transmitting device needs to adopt a lens group for transmitting
light by focusing the same to the optical fiber at the precise
point.
[0115] 2. Structure of Optical Receiving Device
[0116] FIG. 9 is a perspective view of the overall appearance of
the optical receiving device 1' including the structure of the
optical receiving device of FIG. 8 according to some
embodiments.
[0117] The optical receiving device 1' includes a housing 2' in
which a lens 20' and a reflector 14' are installed. The optical
receiving device 1' is coupled face-to-face to the substrate 10' on
which the photodetector 12' is installed.
[0118] The height (H) of the housing 2' is on a sub-millimeter, or
sub-miniature, scale. This is a smaller thickness than a typical
electronic chip, and the optical receiving device 1' of some
embodiments of the present disclosure is useful for application to
devices with small thickness or small form factor.
[0119] The optical receiving device 1' of some embodiments has a
molded article for optical alignment removed, and it is suffice to
perform the optical alignment with the housing 2' and the substrate
10' themselves and thereby reduces the alignment error generated by
using the molded article. The housing 2' is manufactured by plastic
injection molding to facilitate mass production and assembly
thereof.
[0120] The housing 2' has guide surfaces 41' adapted to guide the
optical fiber 32' to the inner center of the housing 2'.
[0121] FIGS. 10A and 10B are a left side view and a plan view of
the housing 2' of the optical receiving device 1'.
[0122] The optical fiber 32' which has passed through a space
defined by the guide surfaces 41' of the housing 2' further passes
through a space defined by central guide surfaces 411' into a
position where it faces the reflector 14'. Under the reflector 14',
four lenses 20' are arranged in a row along the width direction of
the housing 2' in the illustrated example. This arrangement is
advantageous in that flexibility and design freedom can be
increased when, for example, multiples of the optical fiber 32' are
disposed between the guide surfaces 41' or even if the position of
any one of optical fibers 32' is somewhat misaligned because the
light emitted from the optical fibers 32' can be deflected by the
reflector 14' and directed to one of the lenses 20'.
[0123] The housing 2' has a bottom 200' formed with a first post
302' and a second post 303' in predetermined positions forward and
rearward respectively along the longitudinal center line thereof,
which extend downward toward the substrate. The first post 302' and
the second post 303' are circular columns protruding downward. In
the example shown in FIG. 10A, in order to tolerate the error of
optical alignment, the first post 302' is a tapered column having
its diameter gradually reduced downward by minute degrees, and the
second post 303' is a straight column having a constant diameter.
The diameter of the first post 302' is larger than that of the
second post 303' in the vicinity of the top of the first post 302',
that is, adjacent to the bottom 200'. This means that with respect
to the second post 303', the diameter of the first post 302' may be
larger on its upper side of a reference point in the vertical
direction and smaller on its lower side of the reference point.
[0124] FIG. 11 is a left side view illustrating that the housing 2'
is coupled to the substrate 10'.
[0125] The substrate 10' is formed with a first reference hole
302a' and a second reference hole 303a' for accommodating the first
post 302' and the second post 303' of the housing 2'. The first
post 302' and the second post 303' are inserted into the first
reference hole 302a' and the second reference hole 303a',
respectively. The first post 302' which is the tapered column is
initially inserted in first reference hole 302a' with a minute
clearance remaining therebetween. As the insertion progresses
gradually, the first post 302' is fixed in a position where it
comes into contact with the first reference hole 302a' without
gaps.
[0126] As described later, the optical receiving device 1 of some
embodiments having such coupling structure can minimize a
misalignment that may occur in the process of assembling with the
substrate 10'.
[0127] 3. Method of Arranging Optical Receiving Device
[0128] The principle of the alignment method of the optical
receiving device of the present disclosure will be described with
reference to FIGS. 12A to 12C which mainly show the plan view of
the substrate 10.
[0129] With respect to the photodetector 12' provided on the
substrate 10', the first reference hole 302a' and the second
reference hole 303a' are formed in a line. The photodetector 12',
first reference hole 302a' and second reference hole 303a'
respectively have center lines 111', 112' and 113' in the width
direction (vertical direction in the drawing), and the
photodetector 12', first reference hole 302a' and second reference
hole 303a' have a longitudinal (horizontal direction in the
drawing) center line as indicated by 114'. "K" is the gap between
center line 111' and center line 112', and "L" is the spacing
between center line 112' and center line 113'.
[0130] In the small form factor optical transmitting device 1' with
a height of less than 1 mm, correction of assembling tolerance
means eliminating errors of several micrometers, so a sophisticated
aligning operation is required. Typically, the substrate 10' is
completed and supplied in advance according to specifications. The
principal interest in the assembly of the substrate 10' and the
optical receiving device 1' is the alignment of the lens 20' with
the least possible deviation with respect to the photodetector 12'
located on the substrate 10'. The ideal assembly for this purpose
provides a perfect alignment of the centers of the respective
reference holes with the centers of the respective posts free of
deviation of even several .mu.m. However, it is difficult to make a
complete intermeshing of members in the actual assembly process. A
solution to this problem is to minimize the error by having either
one of the first post 302' and the second post 303' fixed to
eliminate the tolerance issue, and having the tolerance of the
other post to exclusively affect the position of the lens 20' to be
aligned with the photodetector 12'.
[0131] FIG. 12B is a diagram of the principle of the method where
the first post 302' is fixed immovably. It is assumed that K:L=1:8
and the second post 303' is located deflected upward by 20 .mu.m
from the center of the second reference hole 303a'. In this case,
the first lens 20' is deviated from the photodetector 12'
downwardly by 2.5 .mu.m by proportional expression.
[0132] FIG. 12C is a diagram of the principle of the method
illustrating the second post 303' is fixed immovably. It is assumed
that K:L=1:8 and the first post 302' is located deflected upward by
20 .mu.m from the center of the first reference hole 302a'. In this
case, the lens 20' is deviated from the photodetector 12' upwardly
by 22.5 .mu.m by proportional expression.
[0133] Therefore, when the photodetector 12' is arranged outside of
all the reference holes, fixing the first post 302' in proximity to
the photodetector 12' can eventually reduce the nine-fold error
than when the second post 303' is fixed. The above principle is
applied not only to the case where the post deviates to the upward
direction from the center of the reference hole but also to the
case where the post deviates in the downward or left/right
direction.
[0134] Those skilled in the art will appreciate that assembly
errors can be minimized as the proportional relationship of K:L
increases, that is, as the distance between posts increases or the
first post is closer to the light source or the first lens.
[0135] In order to fix the first post 302' to the first reference
hole 302a', the optical receiving device 1' of some embodiments of
the present disclosure has the first post 302' designed as a
tapered column so that it is inserted into the first reference hole
302a' initially with minute degrees of clearance provided, and as
the insertion gradually progresses, the first post 302' is fixed at
a position where it is in contact with the first reference hole
302a' without gaps.
[0136] The fixed position may be a point where the diameters of the
first post 302' and the first reference hole 302a' coincide.
However, since the post is molded with, for example, a plastic
material, it has a property that, when depressed, it is inserted by
being compressed and deformed, and when pressure is released,
returns to the original shape by elastic restoring force.
Therefore, the fixed position may be a position where the diameter
of the first post 302' is slightly larger than that of the first
reference hole 302a', which is a margin for facilitating the
fixation of the first post 302'.
[0137] From the above, one can see that it is desirable to design
the first post 302' as a tapered column having its diameter
continuously vary increasing from a range larger than the diameter
of the first reference hole 302a' to a range smaller than the
same.
[0138] Once the position of the first post 302' is fixed, only the
position of the second post 303' affects the alignment of the light
source and the lens, but the latter effect is very small compared
to the effect on the lens by the deviation of either the first post
302' or both posts 302', 303' from the centers of all the reference
holes. Therefore, it becomes possible to restrict the alignment
error of the light source and the lens to within a few micrometres
to achieve the sub-miniaturization thereof.
[0139] Although exemplary embodiments of the present disclosure
have been described for illustrative purposes, those skilled in the
art will appreciate that various modifications, additions and
substitutions are possible, without departing from the idea and
scope of the claimed invention. The scope of the technical idea of
the present embodiments is not limited by particular illustrations.
Accordingly, one of ordinary skill would understand the scope of
the claimed invention is not to be limited by the explicitly
described above embodiments but by the claims and equivalents
thereof.
* * * * *