U.S. patent application number 15/978731 was filed with the patent office on 2018-11-22 for optical connector.
This patent application is currently assigned to Yazaki Corporation. The applicant listed for this patent is Yazaki Corporation. Invention is credited to Motonori MIYANARI.
Application Number | 20180335592 15/978731 |
Document ID | / |
Family ID | 64176461 |
Filed Date | 2018-11-22 |
United States Patent
Application |
20180335592 |
Kind Code |
A1 |
MIYANARI; Motonori |
November 22, 2018 |
OPTICAL CONNECTOR
Abstract
An optical connector includes an optical filter 36 that is
disposed between an end surface and a lens, and includes a
through-hole that transmits part of the output light, when an inner
diameter of the through-hole of the optical filter is denoted by B,
a distance from the end surface to the optical filter in the
optical axis direction is denoted by L, a maximum transmitted light
output angle of transmitted light that passes through the
through-hole and has a smaller angle than a maximum output angle
.alpha. of output light is denoted by .alpha.', and an outer
diameter of a core of an optical fiber is denoted by A,
B=2.times.L.times.tan .alpha.'-A, and L>A/tan .alpha.'/2 are
satisfied.
Inventors: |
MIYANARI; Motonori;
(Shizuoka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Yazaki Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
Yazaki Corporation
Tokyo
JP
|
Family ID: |
64176461 |
Appl. No.: |
15/978731 |
Filed: |
May 14, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 6/4215 20130101;
G02B 6/4206 20130101; G02B 6/4292 20130101; G02B 6/3893
20130101 |
International
Class: |
G02B 6/42 20060101
G02B006/42 |
Foreign Application Data
Date |
Code |
Application Number |
May 19, 2017 |
JP |
2017-099707 |
Claims
1. An optical connector comprising: an optical fiber; a light
receiving member that is disposed to face an end surface in an
optical axis direction of the optical fiber, and receives an output
light emitted from the end surface; and an optical filter that is
disposed between the end surface and the light receiving member,
and includes a through-hole that transmits a part of the output
light, wherein when an inner diameter of the through-hole is
denoted by B, a distance from the end surface to the optical filter
in the optical axis direction is denoted by L, a maximum
transmitted light output angle of a transmitted light that passes
through the through-hole and has a smaller angle than a maximum
output angle .alpha. of the output light is denoted by .alpha.',
and an outer diameter of a core of the optical fiber is denoted by
A, following formulae (1) and (2) are satisfied.
B=2.times.L.times.tan .alpha.'-A (1) L>A/tan .alpha.'/2 (2)
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] The present application claims priority to and incorporates
by reference the entire contents of Japanese Patent Application No.
2017-099707 filed in Japan on May 19, 2017.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The present invention relates to an optical connector.
2. Description of the Related Art
[0003] In recent years, in a vehicle such as an automobile,
high-speed communication is achieved by replacing a communication
system provided between various electronic devices, with the one
using an optical fiber (for example, Japanese Patent Application
Laid-open No. 2002-23025).
[0004] In the optical fiber, light that has entered a core
propagates while repeating reflection at a boundary between the
core and a clad. Among the light that propagates in the optical
fiber, light with a large incident angle (hereinafter, also
referred to as "higher-order light") proceeds while being reflected
at a high angle, whereas light with a small incident angle
(hereinafter, also referred to as "low-order light") proceeds while
being reflected at a low angle. Because the higher-order light
repeats reflection in the optical fiber a larger number of times,
the higher-order light has an optical path length longer than that
of the low-order light. For example, if a refractive-index
distribution of the core is made constant, speeds of light
proceeding in the optical fiber become the same. Thus, there arises
a difference between the higher-order light and the low-order light
in propagation time of light from an entrance end to an exit end of
the optical fiber.
[0005] As mentioned above, output light emitted from the optical
fiber includes both higher-order light and low-order light that
have a difference in propagation time. This causes such a problem
that a waveform of an optical signal deteriorates, and high-speed
communication cannot be achieved.
SUMMARY OF THE INVENTION
[0006] A purpose of the present invention is to provide an optical
connector that can achieve high-speed communication.
[0007] According to one aspect of the present invention, an optical
connector includes: an optical fiber; a light receiving member that
is disposed to face an end surface in an optical axis direction of
the optical fiber, and receives an output light emitted from the
end surface; and an optical filter that is disposed between the end
surface and the light receiving member, and includes a through-hole
that transmits a part of the output light. When an inner diameter
of the through-hole is denoted by B, a distance from the end
surface to the optical filter in the optical axis direction is
denoted by L, a maximum transmitted light output angle of a
transmitted light that passes through the through-hole and has a
smaller angle than a maximum output angle .alpha. of the output
light is denoted by .alpha.', and an outer diameter of a core of
the optical fiber is denoted by A, following formulae (1) and (2)
are satisfied.
B=2.times.L.times.tan .alpha.'-A (1)
L>A/tan .alpha.'/2 (2)
[0008] The above and other objects, features, advantages and
technical and industrial significance of this invention will be
better understood by reading the following detailed description of
presently preferred embodiments of the invention, when considered
in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a perspective view illustrating a schematic
configuration of an optical connector according to an
embodiment;
[0010] FIG. 2 is a perspective view illustrating a schematic
configuration of the optical connector according to the
embodiment;
[0011] FIG. 3 is a cross-sectional view illustrating a schematic
configuration of the optical connector according to the
embodiment;
[0012] FIG. 4 is a schematic diagram for describing a function of
an optical filter according to the embodiment;
[0013] FIG. 5 is a perspective view for describing a function of
the optical filter according to the embodiment; and
[0014] FIG. 6 is diagram illustrating a distribution of maximum
transmitted light output angles of transmitted light transmitted
through the optical filter according to the embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] An embodiment of an optical connector according to the
present invention will be described in detail below with reference
to the drawings. In addition, the present invention is not limited
by the following embodiment. In addition, components in the
following embodiment include the ones that can be replaced by those
skilled in the art, and are easy, or the ones that are
substantially identical.
Embodiment
[0016] FIGS. 1 and 2 are perspective views illustrating a schematic
configuration of an optical connector according to an embodiment.
FIG. 3 is a cross-sectional view illustrating a schematic
configuration of the optical connector according to the embodiment.
FIG. 4 is a schematic diagram for describing a function of an
optical filter according to the embodiment. FIG. 5 is a perspective
view for describing a function of the optical filter according to
the embodiment. FIG. 6 is diagram illustrating a distribution of
maximum transmitted light output angles of transmitted light
transmitted through the optical filter according to the embodiment.
In addition, FIG. 1 illustrates an optical connector in a fitted
state of a male connector and a female connector. FIG. 2
illustrates the optical connector in a non-fitted state of the male
connector and the female connector. FIG. 3 is a cross-sectional
view of an A-A cross section in FIG. 1. In FIG. 6, a vertical axis
indicates EAF (EAF: Encircled Angular Flux), and a horizontal axis
indicates Angle [.degree.].
[0017] An optical connector 1 according to the present embodiment
is mounted on a vehicle such as an automobile, for example, and
connects an optical fiber used as a communication cable, and an
electronic device. As illustrated in FIGS. 1 and 2, the optical
connector 1 is formed by fitting a male connector 2 and a female
connector 3, and optically connects, by the fitting, a pair of
optical fibers 4 connected to the male connector 2, and an
electronic device (not illustrated) connected to the female
connector 3.
[0018] As illustrated in FIG. 3, the male connector 2 includes the
pair of optical fibers 4, a pair of ferrules 21, a housing 22, and
a spacer 23.
[0019] One of the pair of optical fibers 4 is for transmission and
the other one is for reception. For example, a plastic optical
fiber (POF: Plastic Optical Fiber) that uses transparent plastic is
used as the optical fibers 4. The optical fibers 4 each have a
structure in which a core wire called a core (core) 41 serving as a
transmission path of light is surrounded by a clad (clad) 42 being
made of the same material but having a different refractive index,
and the clad is covered by a nontransparent protective coating 43.
An outer diameter A [mm] of the core 41 is about 0.9 mm to 1 mm,
for example. The optical fibers 4 are formed of multi mode fibers
(MMF: Multi Mode Fiber), for example.
[0020] The pair of ferrules 21 is formed of metal material,
synthetic resin material, or the like, into a cylindrical shape,
and has through-holes in an optical axis direction. The ferrules 21
are provided at leading ends of the optical fibers 4 as connecting
end portions, and hold the optical fibers using the
through-holes.
[0021] The housing 22 is formed of insulating material such as
synthetic resin, and has a substantially rectangular parallelepiped
shape. A pair of through-holes penetrating in the optical axis
direction is formed in the housing 22, and the optical fibers 4 to
which the ferrules 21 are attached are respectively inserted into
the through-holes.
[0022] Similarly to the housing 22, the spacer 23 is formed of
insulating material such as synthetic resin. The spacer 23 is
provided separately from the housing 22, and fixes the pair of
optical fibers 4 to the housing 22 by assembling the pair of
optical fibers 4 to the housing 22.
[0023] The female connector 3 includes a pair of FOTs 31, a shield
case 32, an aligning plate 33, a housing 34, a lens unit 35, and an
optical filter 36.
[0024] One of the pair of fiber optic transceivers (FOTs) 31 is for
transmission and the other one is for reception. The FOT 31 is made
of synthetic resin and has a substantially rectangular
parallelepiped shape, and has a built-in light-emitting element and
a built-in light receiving element thereinside.
[0025] The shield case 32 is formed as a hollow cover member having
a substantially rectangular parallelepiped shape with two opened
surfaces, by pressing a metal thin plate having electrical
conductivity. The shield case 32 shields the pair of FOTs 31 by
covering the peripheries of the pair of FOTs 31 so as not to leak
electromagnetic wave noises to the outside.
[0026] The aligning plate 33 is formed of insulating material such
as synthetic resin, and on the inner side, has an internal space
for accommodating the shield case 32. The aligning plate 33 is
latched to the housing 34 by a latch portion provided on the
housing 34 side.
[0027] The housing 34 is formed of insulating material such as
synthetic resin, and has a substantially rectangular parallelepiped
shape. In an internal space, the housing 34 has a pair of
cylindrical sleeves 34a for holding the pair of optical fibers 4
and the lens unit 35.
[0028] The lens unit 35 is made of transparent resin having optical
characteristics by integrally forming a flat-plate substrate, and a
pair of lenses 35a vertically installed from the substrate. One of
the pair of lenses 35a is a light receiving member, and collects
light from the optical fibers 4 to the light receiving elements of
the FOTs 31, and the other one collects light from the
light-emitting elements of the FOTs 31 to the optical fiber 4
side.
[0029] The optical filter 36 is formed of insulating material such
as synthetic resin that does not pass optical signals in a
wavelength band (e.g., 400 nm to 1800 nm) used by a general
communication fiber, and disposed between end surfaces 4a in the
optical axis direction of the optical fibers 4 and the lenses 35a.
The optical filter 36 is disposed at a position distant from the
end surface 4a of the optical fiber 4 by a distance L [mm] in the
optical axis direction. The optical filter 36 includes a
through-hole 36a that transmits part of output light, and has a
ring shape when viewed from the optical axis direction. The shape
of a cross section of the through-hole 36a that is orthogonal to
the optical axis direction is circular, and the through-hole 36a
has an inner diameter (diameter) B [mm]. The optical filter 36 is
fixed to inner peripheral surfaces of the sleeves 34a of the
housing 34.
[0030] Next, a function of the optical connector 1 will be
described. As illustrated in FIG. 4, when an inner diameter of the
through-hole 36a is denoted by B, a distance from the end surface
4a to the optical filter 36 in the optical axis direction is
denoted by L, a maximum transmitted light output angle of
transmitted light that passes through the through-hole 36a and has
a smaller angle than a maximum output angle .alpha.[.degree.] of
output light is denoted by .alpha.'[.degree.], and an outer
diameter of the core 41 of the optical fiber 4 is denoted by A, the
optical connector 1 preferably satisfies the following formulae (1)
and (2).
B=2.times.L.times.tan .alpha.'-A (1)
L>A/tan .alpha.'/2 (2)
[0031] As illustrated in FIG. 5, output light of the optical fiber
4 includes both higher-order light 51 and low-order light 52. Thus,
the higher-order light 51 is emitted at a large output angle, and
the low-order light 52 is emitted at a small output angle. In other
words, the output light of the optical fiber 4 reaches the lens 35a
of the lens unit 35 while spreading from the end surface 4a toward
the optical axis direction within a range of the maximum output
angle .alpha. (2.alpha. in reality) illustrated in FIG. 4. The
output light that has reached the lens 35a is collected by the lens
35a, and is emitted onto a light receiving surface of the FOT 31
having a built-in light receiving element. In the optical connector
1 of the present embodiment, the optical filter 36 is disposed on
an optical path between the end surface 4a and the lens 35a. By
using the through-hole 36a of the optical filter 36, part of the
optical path is shielded, and part of output light is transmitted.
The inner diameter B of the through-hole 36a is defined by the
above formula (1) based on the distance L, the outer diameter A of
the core 41, and the maximum transmitted light output angle
.alpha.' of transmitted light that passes through the through-hole
36a and has a smaller angle than the maximum output angle .alpha.
of output light. The distance L is defined by the above formula (2)
based on the outer diameter A of the core 41 and the maximum
transmitted light output angle .alpha.'. In this manner, by the
inner diameter B of the through-hole 36a and the distance L in the
optical axis direction from the end surface 4a to the optical
filter 36 satisfying the above formulae (1) and (2), the optical
filter 36 can block or reduce the transmission of the higher-order
light 51 of the output light.
[0032] As described above, the optical connector 1 according to the
present embodiment includes the optical fibers 4, the lenses 35a
that are disposed to face the end surfaces 4a in the optical axis
direction of the optical fibers 4, and receive output light emitted
from the end surfaces 4a, and the optical filter 36 that is
disposed between the end surfaces 4a and the lenses 35a, and
includes the through-hole 36a that transmits part of output light.
When an inner diameter of the through-hole 36a of the optical
filter 36 is denoted by B, a distance from the end surface 4a to
the optical filter 36 in the optical axis direction is denoted by
L, a maximum transmitted light output angle of transmitted light
that passes through the through-hole 36a and has a smaller angle
than a maximum output angle .alpha. of output light is denoted by
.alpha.', and an outer diameter of the core 41 of the optical fiber
4 is denoted by A, the following formulae (1) and (2) are
satisfied.
B=2.times.L.times.tan .alpha.'-A (1)
L>A/tan .alpha.'/2 (2)
[0033] The optical connector 1 according to the present embodiment
that has the above configuration can block or reduce the
transmission of the higher-order light 51 from output light passing
on the optical path between the end surfaces 4a in the optical axis
direction of the optical fibers 4 and the lenses 35a of the lens
unit 35. Thus, deterioration of a waveform of an optical signal
that is caused by mixture of the higher-order light 51 and the
low-order light 52 can be reduced or suppressed, and high-speed
communication can be achieved.
[0034] In addition, in the above embodiment, the inner diameter B
of the through-hole 36a may be defined using a graph illustrated in
FIG. 6, for example. The EAF illustrated in FIG. 6 is a value
obtained by integrating an intensity distribution of output angles
of output light emitted from the end surfaces 4a of the optical
fibers 4, toward a spreading direction of the output angles from
the center. In the graph illustrated in FIG. 6, the EAF also
increases in accordance with the increase in output angle. For
example, in the graph illustrated in FIG. 6, the EAF becomes 0.4
when the output angle is 10[.degree.], the EAF becomes 0.84 when
the output angle is 20[.degree.], and the EAF becomes about 1.0
when the output angle is 30[.degree.]. The inner diameter B of the
through-hole 36a of the present embodiment is preferably defined so
that the maximum transmitted light output angle .alpha.' falls
within a range corresponding to a shaded portion on the graph
illustrated in FIG. 6.
[0035] In addition, in the above embodiment, the shape of the cross
section of the through-hole 36a that is orthogonal to the optical
axis direction is circular. The shape, however, is not limited to
this. For example, the cross-sectional shape may be an ellipse
shape. In addition, part of an inner circumferential surface of the
through-hole 36a may have recesses and protrusions.
[0036] In addition, in the above embodiment, the optical filter 36
is fixed to the inner peripheral surfaces of the sleeves 34a of the
housing 34. Nevertheless, the optical filter 36 may be formed
integrally with the sleeves 34a, or may have a configuration
assembled to the sleeves 34a as a separate member.
[0037] In addition, in the above embodiment, the optical connector
1 has been described as connecting the optical fibers 4 and an
electronic device. Nevertheless, the optical connector 1 is not
limited to this, and the present invention may be applied to an
optical connector that connects optical fibers.
[0038] According to the optical connector according to the present
embodiment, such an effect that high-speed communication can be
achieved is caused.
[0039] Although the invention has been described with respect to
specific embodiments for a complete and clear disclosure, the
appended claims are not to be thus limited but are to be construed
as embodying all modifications and alternative constructions that
may occur to one skilled in the art that fairly fall within the
basic teaching herein set forth.
* * * * *