Patent Application
20140086541
The present invention relates to an optical module in which a connector unit is provided at an end portion of an optical cable.
An optical module that carries out a photoelectric conversion of an optical signal transmitted through an optical cable has been known (for example, see Patent Literature 1). The aforementioned optical module is, for example, configured to include a metal casing (metal housing) of which an outside is covered by a resin housing, the metal casing accommodating a circuit substrate where an element or the like that carries out the photoelectric conversion of an optical signal is provided.
[Patent Literature 1] JP-A-2010-010254
However, in an optical module of Patent Literature 1, dusts may enter a gap between an outside resin housing and an inside metal housing. Accordingly, there is concern that dusts enter the inner part of the housing from the gap of the metal housing and adhere onto a circuit substrate or the like.
The present invention is to provide an optical module that can prevent dusts, which have entered the gap between the inner housing accommodating the circuit substrate and the outer housing, from intruding further into the depth of the gap.
An optical module according to the invention is an optical module in which a connector unit is provided at an end portion of an optical cable including an optical fiber,
wherein the connector unit includes
wherein a step portion is provided on the inner housing,
wherein an internal space on a side of the front end portion from the step portion of the inner housing is narrower than an internal space on a side of a rear end portion from the step portion of the inner housing, and
Further, in the optical module according to the invention, it is preferable that an optical coupling member optically connecting the optical fiber and the optical element, which have different optical axes from each other, is provided on the circuit substrate, and the height of the optical coupling member is greater than the distance between the circuit substrate and the inner housing on the side of the front end portion.
Furthermore, in the optical module according to the invention, it is preferable that a sealing member, which has a smaller young's modulus than that of the inner housing, is attached between the inner housing and the electrical connector, and the inner housing and the electrical connector are provided being in contact with the sealing member.
Further, in the optical module according to the invention, it is preferable that a cut-and-raised second engagement portion engaging with a first engagement portion provided on an inner surface of the outer housing is provided on a wall surface of the inner housing, the step portion is provided on the side of the front end portion from a cut-and-raised hole formed due to the second engagement portion, and a gap between the wall surface and the outer housing on a side of a rear end portion of the connector unit from the step portion is narrower than a gap between the wall surface and the outer housing on a side of a front end portion of the connector unit from the step portion.
Furthermore, in the optical module according to the invention, it is preferable that the step portion is provided on a wall surface of the inner housing on the side of the front end portion from the accommodation space where the optical element is provided.
Further, in the optical module according to the invention, it is preferable that a heat radiation member, thermally connecting the circuit substrate and the inner housing, is provided on the inner side of the wall surface including the cut-and-raised hole in the inner housing.
According to the optical module of the invention, it is possible to prevent dusts, which have entered the gap between the inner housing accommodating the circuit substrate and the outer housing, from intruding further into the depth of the gap.
Hereinafter, an example of an embodiment of an optical module according to the present invention will be described in reference to the views.
As illustrated in
The optical module 10 can be employed in transmitting of signals (data) in optical communication technology so as to be electrically connected to an electronic device such as a personal computer at an access point, and convert an input/output electrical signal into an optical signal, thereby transmitting the optical signal.
As illustrated in
An interposing layer 24 formed of bundles of tensile strength fibers is provided around the inner tube 23. A metal layer 25 formed of a plurality of metal element wires is provided on the outer periphery of the interposing layer 24. A jacket 26 formed of an insulating resin is provided on the outer periphery of the metal layer 25.
As the coated optical fiber 22, an optical fiber of which a core and a cladding are made of silica glass (All Glass Fiber: AGF), an optical fiber of which the cladding is made of rigid plastic (Hard Plastic Clad Fiber: HPCF) can be employed. If a thin diameter HPCF having a glass core diameter of 80 μm is employed, the coated optical fiber 22 is difficult to be broken, even when the coated optical fiber 22 is bent in a circle having a small diameter.
It is possible to accommodate a plurality of coated optical fibers 22 that are not tape-type but in single fibers inside the inner tube 23. However, if the coated optical fibers are tape-type, it is possible to prevent a microbending loss from being generated due to an exerted lateral pressure of the coated optical fiber 22 in the single fibers crossing each other. Further, the optical fiber ribbon 21 may be provided in a plural number.
The inner tube 23 is made of an insulating resin such as, for example, polyvinylchloride (PVC) which is a non-halogen flame retardant resin. For example, the inner tube 23 has an outer diameter of 2.0 mm and a thickness of 0.55 mm.
The interposing layer 24 is, for example, an aramid fiber having an ultrafine diameter, and built in the optical cable 20 in a bundled assembly state. The interposing layer 24 has a tensile strength function with respect to the optical cable 20.
The metal layer 25 is, for example, a layer braided with a plurality of tin-plated lead wires and has a function as a heat radiation layer. The metal layer 25 is equal to or more than 70% in braid density, and 45° to 60° in a braid angle. The outer diameter of the metal element wire configuring the metal layer 25 is approximately 0.05 mm. Thermal conductivity of the metal layer 25 is, for example, 400 W/m·K. It is preferable that the metal layer 25 be arranged at high density to secure satisfactory thermal conductivity. As an example, it is preferable that the thermal layer 25 be configured with a rectangular tin-plated lead wire.
The jacket 26 is formed of an insulating resin such as, for example, polyolefin. For example, the jacket 26 has the outer diameter of 4.2 mm and the thickness of 0.5 mm.
The optical cable 20 having the above-described configuration excels in a lateral pressure characteristic of the coated optical fiber 22 and flexibility as a cable, and excels in heat radiation as well.
As illustrated in
As illustrated in
The metal housing 311 has a cross-sectional U-shaped accommodation portion main body 311a open downward and a cross-sectional U-shaped base plate 311b open upward to form an internal space S accommodating the circuit substrate 33 or the like. In addition, the electrical connector 32 is provided on the side of the front end portion of the circuit substrate 33 to be accommodated on the side of the front end portion of the metal housing 311. The fixing member 35 is attached on the side of the rear end portion of the metal housing 311. In the embodiment, the metal housing 311 is made of a metal material having high thermal conductivity (preferably equal to or more than 100 W/m·K) such as steel (Fe-based), tin (tin-plated copper), stainless steel, copper, brass or aluminum, thereby serving to outwardly radiate heat generated from the circuit substrate 33 or the like.
As illustrated in
Moreover, a sealing member 50, which is formed of a material having a smaller young's modulus than that of the metal housing 311, is attached between the metal housing 311 and the electrical connector 32. Both the metal housing 311 and the electrical connector 32 are provided being in contact with the sealing member 50. In the aforementioned configuration, dusts are prevented from intruding between the metal housing 311 and the resin housing 312. Further, even though an external force is added to the optical module 10 in a state where the electrical connector 32 is connected to an external device, since the external force is absorbed by the elastic sealing member 50 having a smaller young's modulus, it is possible to prevent damage to the metal housing 311. However, in this case, a gap may occur between the metal housing 311 and the electrical connector 32, and the resin housing 312 such that dusts may enter between the metal housing 311 and the resin housing 312. A further advantageous effect of the invention in the aforementioned case will be described below.
In the embodiment, the step portion 343 of the metal housing 311 is provided on the top plate 34 on the side of the front end portion from a below-described lens array component 41 (one example of an optical coupling member) accommodated in the internal space S (one example of an accommodation space) of the metal housing 311. In this way, the step portion 343 can prevent dusts, having entered the space between the metal housing 311 and the resin housing 312 from the side of the front end portion, from further intruding while the internal space S to accommodate the lens array component 41 is enlarged. That is, even in a case where the height of the lens array component 41 is greater than the distance (typically, distance from the circuit substrate 33 to upper end of electrical connector 32) from the circuit substrate 33 to the metal housing 311 on the side of the front end portion, it is possible to secure enough internal space to accommodate the lens array component 41, while maintaining the entire size to be small.
In addition, it is desirable that a radiation member 44, thermally connecting the circuit substrate 33 and the metal housing 311, be provided on the inner side of the top plate 34 including the cut-and-raised hole 342 in the metal housing 311. In this way, even in a case where dusts, having entered a gap between the metal housing 311 and the resin housing 312, reach the cut-and-raised hole 342 of the engagement convex portion 341, intrusion of dusts and the like can be prevented by the radiation member 44 provided in the inner side of the cut-and-raised hole 342. In addition, if the radiation member 44 is provided between the circuit substrate 33 and the metal housing 311, it is possible to release heat generated by the lens array component 41 and the like to the metal housing 311.
As illustrated in
The fixing member 35 has a plate-shaped base portion 351 and a cylindrical tube portion 352. A boot 36 to be connected to the resin housing 312 is provided in rear of the fixing member 35.
The tube portion 352 has a substantially cylindrical shape, and is provided so as to protrude rearward from the base portion 351. The tube portion 352 holds the optical cable 20 together with a caulking ring 37.
The procedure to hold the optical cable 20 using the fixing member 35 is, for example, as follows. That is, first, after peeling off the jacket 26, the optical fiber ribbon 21 of the optical cable 20 is inserted through the inside of the tube portion 352, while arranging the interposing layer 24 along the outer periphery surface of the tube portion 352. Then, the caulking ring 37 is arranged on the interposing layer 24 arranged on the outer periphery surface of the tube portion 352, thereby caulking the caulking ring 37. In this way, the interposing layer 24 is clamped to be fixed between the tube portion 352 and the caulking ring 37, and then the optical cable 20 is held to be fixed by the fixing member 35. Meanwhile, as described above, it is desirable that the optical cable 20 be fixed to the fixing member 35 so as to be further adhered thereto.
An end portion of the metal layer 25 of the optical cable 20 is, for example, bonded to the base portion 351 by soldering. Specifically, the metal layer 25 is arranged to cover the outer periphery of the caulking ring 37 (tube portion 352) in the fixing member 35 such that the end portion thereof is extended to one surface (rear surface) of the base portion 351 so as to be bonded by soldering. In this way, the fixing member 35 and the metal layer 25 are thermally connected to each other. Moreover, the rear end portion of the metal housing 311 is coupled with the fixing member 35 such that the metal housing 311 and the fixing member 35 are physically and thermally connected to each other. In other words, the metal housing 311, and the metal layer 25 of the optical cable 20 are thermally connected to each other, thereby further being thermally connected to the radiation member 44 via the top plate 34 of the metal housing 311.
As illustrated in
The boot 36 is linked to the rear end portion of the resin housing 312, thereby covering the fixing member 35 attached to the rear end portion of the metal housing 311. The rear end portion of the boot 36 and the jacket 26 of the optical cable 20 are adhered to each other by an adhesive (not illustrated).
The electrical connector 32 is inserted into a connecting subject (personal computer and the like), while being an electrically connecting part to the connecting subject. The electrical connector 32 is arranged on the side of the front end portion (left end in
The circuit substrate 33 is accommodated in the internal space S of the metal housing 311. As illustrated in
The controlling semiconductor 38 includes a driving integrated circuit (IC) 381, or a clock data recovery (CDR) device 382 which is a waveform shaper. The controlling semiconductor 38 is arranged on the side of the front end of the mounting surface 331 on the circuit substrate 33. The controlling semiconductor 38 is electrically connected to the electrical connector 32.
As illustrated in
The light receiving and emitting elements 39 are optically connected to the coated optical fiber 22 of the optical cable 20. Specifically, as illustrated in
Tip end portions of the plurality (four in the example) of coated optical fibers 22 separated from the optical fiber ribbon 21 into single fibers are fixed onto the connector component 42. More specifically, the tip end portions of the coated optical fibers 22, which are respectively inserted one by one into a plurality (four in the example) of through holes provided in the connector component 42, are adhesively fixed to a concave portion (not illustrated) provided on a surface of the connector component 42. Further, in parts inserted at least into the through hole of the connector component 42 at the end portion 221 of the coated optical fiber 22, coating resins are removed so as to expose the optical fibers.
In the lens array component 41, a plurality of lens surfaces 412 are formed on an opposite surface of the connector component 42 and on an opposite surface of the light emitting elements 391 and the light receiving elements 392. In addition, in the upper surface center portion of the lens array component 41, a reflective surface 411 is formed along the width direction. Light emitted from the light emitting elements 391 is incident on the lens array component 41 through the lens surface 412 formed on the opposite surface. Then, after the light incident on the lens array component 41 is reflected by the reflective surface 411, the light is optically coupled with the end surface of the corresponding coated optical fiber 22 fixed to the connector component 42 by the lens surface 412 formed on the opposite surface of the connector component 42.
Meanwhile, light emitted from the end surface of the coated optical fiber 22 is incident on the lens array component 41 through the corresponding lens surface 412. Then, after the light incident on the lens array component 41 is reflected by the reflective surface 411, the light is received by the light receiving elements 392 through the lens surface 412 formed on the opposite surface of the light receiving elements 392. That is, the plurality of coated optical fibers 22 fixed to the connector component 42, and the light receiving and emitting elements 39 are optically connected to each other via the lens array component 41. Further, the plurality of lens surfaces 412 formed on the respective surfaces in the lens array component 41, for example, emit diffused light incident thereon as parallel light, and the lens surfaces 412 are collimate lenses condensing the parallel light incident thereon to be emitted. The aforementioned lens array component 41 is, for example, integrally molded by injection molding of a resin.
In the optical module 10 having the above configuration, if an electrical signal is input via the electrical connector 32, the controlling semiconductor 38 receives the electrical signal via wiring of the circuit substrate 33. The electrical signal input to the controlling semiconductor 38 is output to the light receiving and emitting elements 39 via the wiring of the circuit substrate 33 from the controlling semiconductor 38, after waveform shaping and the like is carried out by level adjustment or the CDR device 382. The electrical signal is converted into an optical signal in the light receiving and emitting elements 39 to which the electrical signal is input, thereby emitting the optical signal from the light emitting elements 391 to the coated optical fiber 22.
In addition, an optical signal transmitted through the optical cable 20 is incident on the light receiving elements 392. An optical signal incident thereon is converted into an electrical signal in the light receiving and emitting elements 39 so as to output the electrical signal to the controlling semiconductor 38 via the wiring of the circuit substrate 33. In the controlling semiconductor 38, the electrical signal is processed by a predetermined treatment, and then the electrical signal is output to the electrical connector 32.
The radiation sheet 43 is arranged between the circuit substrate 33 and the metal housing 311 (see
As in the above, in the optical module 10 according to the embodiment of the invention, since the step portion 343 is provided on the side of the front end portion of the top plate 34 of the metal housing 311 in the connector module 30 as described above, even though dusts enter from a gap between the top plate 34 of the metal housing 311 and the resin housing 312, it is difficult for dusts to intrude into the side of the rear end portion from the step portion 343.
In addition, in the optical module 10 according to the embodiment of the invention, since the engagement convex portion 341, engaging with the engagement concave portion 313 provided on the inner surface of the resin housing 312, is provided by cutting and raising a part of the top plate 34 of the metal housing 311, the cut-and-raised hole 342 is formed at the part cut and raised. However, the above-mentioned step portion 343 is provided on the side of the front end portion of the connector module 30 from the cut-and-raised hole 342. Accordingly, a gap between the top plate 34 and the resin housing 312 on a side of the cut-and-raised hole 342 (a side of rear end portion of connector module 30) from the step portion 343 is narrower than a gap between the top plate 34 and the resin housing 312 on the side of the front end portion from the step portion 343. Consequently, even though dusts enter from a gap between the top plate 34 of the metal housing 311 and the resin housing 312, it is difficult for dusts to intrude into the side of the rear end portion from the step portion 343. Therefore, it is difficult for dusts to enter the internal space S from the cut-and-raised hole 342.
In addition, in the embodiment, since the step portion 343 is provided on the side of the front end portion from the internal space S (accommodation space) where the lens array component 41 is provided, it is difficult for dusts to enter the internal space S where the lens array component 41 is arranged due to the above-mentioned effect. Moreover, since the radiation member 44 is provided inside the cut-and-raised hole 342, even in a case where dusts, having entered a gap between the metal housing 311 and the resin housing 312, supposedly intrude into the cut-and-raised hole 342 of the engagement convex portion 341, it is possible to prevent dusts from intruding into the internal space S from the cut-and-raised hole 342 by the radiation member 44. In addition, since the aforementioned radiation member 44 is provided between the circuit substrate 33 and the metal housing 311, it is possible to radiate heat generated by the lens array component 41 and the like to the metal housing 311.
In addition, in the embodiment, the light receiving and emitting elements 39 and the coated optical fiber 22 are respectively different from each other in optical axis such that an optical signal emitted from one thereof is converted in the optical axis direction so as to be optically coupled to the other thereof by the reflective surface 411 of the lens array component 41 which is the optical coupling member. In addition, the positioning pins 413 formed on the lens array component 41 are formed to protrude toward a direction substantially parallel to an optical axis of the coated optical fiber 22. The positioning pins 413 of the lens array component 41 are fit into the connector component 42 so as to cause the coated optical fiber 22 and the light receiving and emitting element 39 to be optically coupled with each other by moving the connector component 42 holding the coated optical fiber 22 in a direction substantially parallel to the optical axis of the coated optical fiber 22. Since the protruding direction of the positioning pins 413 is substantially parallel to a surface direction of the circuit substrate 33, the connector component 42 can be connected to the positioning pins 413 along the surface of the circuit substrate 33, thereby obtaining improvement in efficiency (workability) of assembly work.
Further, as described above, the configuration, in which the lens array component 41 causes a light signal emitted from one of the light receiving and emitting elements 39 and the coated optical fiber 22, each of which has a different optical axis from the other, to be optically coupled with the other, is not limited to the embodiment employing the lens array component 41. A modified example is illustrated in
The above-described configuration can be arbitrarily chosen as a configuration of the optical coupling member. However, in a configuration where a light receiving and emitting element and a coated optical fiber, each of which has a different optical axis from the other, are optically coupled, the height of the optical coupling member may be greater than that of the electrical connector 32. In the aforementioned case, it is advantageous to have the configuration of the embodiment of the invention in a point where enough internal space can be secured to accommodate the aforementioned optical coupling member, while maintaining the small size of a module in its entirety.
Further, the optical module in the invention is not limited to each embodiment described above, and appropriate modifications and improvements can be made.
The present application is based on Japanese Patent Application No. 2011-289476, filed Dec. 28, 2011, the content of which is incorporated herein by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-289476 | Dec 2011 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2012/080619 | 11/27/2012 | WO | 00 | 11/26/2013 |
