JP2004096054A - Optical transmission module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably ground a light receiving element to a case and to decrease a crosstalk. <P>SOLUTION: A conductive member 10 is put between the light receiving element 2 and the case 4. The conductive member 10 comprising an elastic tube with a conductive material mixed in it and cut in a predetermined length is formed flat by flattening the cut tube. The flat member is attached on the upper surface of the metal can 2b as well as on the lower surface of the metal can 2b of the light receiving element 2. Bulding the light receiving element 2 in the case 4 makes the member 10 stay between the lower case 5 and the uppper case 6 of the case 4 and the light receiving element 2. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical transmission module used for a switch or a repeater in an optical transmission path.
[0002]
[Prior art]
FIG. 5 shows an example of this type of conventional optical transmission module. In the optical transmission module 1 shown in FIG. 1, for example, a light receiving element 2 composed of a photodiode and a light emitting element 3 also composed of a photodiode are disposed adjacent to a case 4.
The case 4 includes a lower case 5 having an open upper part and an upper case 6 having an open lower part. A board 7 on which electronic components are mounted is mounted inside the lower case 5. The light receiving element 2 is inserted through a notch 5 a provided on one side of the lower case 5, and is electrically connected by soldering the terminal 2 a to the substrate 7. The light emitting element 3 is inserted through a notch 5 b provided at a position adjacent to the notch 5 a of the lower case 5, and its terminal 3 a is electrically connected to the substrate 7 by soldering. Adjacent and arranged in the same direction. In this case, mounting arms 3c made of the same material as the metal can 3b are provided on both sides of the metal can 3b of the light emitting element 3. Notches 6a and 6b are also provided on one side of the upper case 6 corresponding to the notches 5a and 5b of the lower case 5.
[0003]
As described above, the light receiving element 2 and the light emitting element 3 are inserted into one side of the lower case 5 so as to be adjacent to each other in the same direction, and connected to the substrate 7 by soldering. The light receiving element 2 and the light emitting element 3 are assembled in the case 4 by being fitted. At this time, since the metal can 3b and the mounting arm 3c of the light emitting element 3 need to be insulated from the case 4, an insulating material (not shown) is provided between the lower case 5 and the upper case 6. . The mounting arm 3c is originally provided integrally with the metal can 3b so that the light emitting element 3 can be screwed.
In FIG. 5, reference numeral 8 denotes an optical fiber connected to the input side of the light receiving element 2, and 9 denotes an optical fiber connected to the output side of the light emitting element 3.
[0004]
[Problems to be solved by the invention]
Meanwhile, in the conventional optical transmission module 1 described above, commercially available products are adopted as the light receiving element 2 and the light emitting element 3 in order to reduce the cost and the like, and the case 4 including the lower case 5 and the upper case 6 is formed by pressing or the like. The two elements 2 and 3 are automatically assembled in the case 4.
[0005]
However, when the light receiving element 2 and the light emitting element 3 are incorporated in the case 4, the light emitting element 3 is provided with the mounting arm 3c on the metal can 3b. However, since nothing is provided in the metal can 2b of the light receiving element 2, the terminal 2a of the light receiving element 2 is mounted in a state of being soldered to the substrate 7, so that the light receiving element 2 However, there is a problem that the ground is unstablely grounded to the case 4.
[0006]
In addition, while the power of the light receiving element 2 is about several μW and its current value is several μA, the power of the light emitting element 3 is several mW, which is much larger than the power of the light receiving element 2. Electric radiated power is generated from the element 3 and acts as disturbance noise on the light receiving element 2, and the distance between the light emitting element 3 and the light receiving element 2 is further reduced by the mounting arm 3 c provided on the light emitting element 3. As a result, the mounting arm 3c functions as an antenna, and as a result, there is a problem that the crosstalk of the light receiving element 2 is increased and the characteristics are adversely affected.
[0007]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the related art, and has as its object to provide an optical transmission module capable of reducing crosstalk and improving characteristics by incorporating a light receiving element in a case in a stable state. Is to do.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the present invention employs the following solutions.
The invention according to claim 1 is a light receiving element that captures an optical signal, a light emitting element that outputs an optical signal based on the optical signal captured by the light receiving element, and a case where the light receiving element and the light emitting element are assembled adjacent to each other. Wherein a conductive member is interposed between the light receiving element and the case.
According to the optical transmission module of the present invention, since the light receiving element is incorporated in the case via the conductive member, the light receiving element can be grounded in a stable state with respect to the case, and the light receiving element can be properly grounded. It can be carried out.
[0009]
The invention according to claim 2 is the optical transmission module according to claim 1, wherein the conductive member has elasticity.
ADVANTAGE OF THE INVENTION According to the optical transmission module which concerns on this invention, since a conductive member has elasticity, when a light receiving element is built in a case, the light receiving element is reliably inserted into a case through a member by the elastic force of a conductive member. Contact can be made, and the grounding of the light receiving element with respect to the case can be accurately stabilized.
[0010]
According to a third aspect of the present invention, in the optical transmission module according to the first or second aspect, the conductive member includes at least one of a first case and a second case constituting the case, and a light receiving element. And a metal can.
According to the optical transmission module of the present invention, since the conductive member is interposed between one of the first case and the second case constituting the case and the metal can of the light receiving element, the light receiving element Can be satisfactorily grounded.
[0011]
According to a fourth aspect of the present invention, in the optical transmission module according to any one of the first to third aspects, the conductive member includes a first case and a second case that constitute the case on a peripheral surface of a metal can of the light receiving element. It is characterized in that it is attached at a position where it contacts the two cases.
According to the optical transmission module of the present invention, the conductive member is attached to a position in contact with the first and second cases on the peripheral surface of the metal can of the light receiving element, so that the metal can and the case of the light receiving element can be mounted. Can be contacted in a stable state, so that the light receiving element can be grounded well.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 3 are views showing an optical transmission module according to a first embodiment of the present invention. FIG. 1 is a perspective view showing a main part of the optical transmission module, and FIG. FIG. 3 is a cross-sectional view when the case corresponding to the line is closed, and FIG. 3 is an explanatory view showing the light receiving element and a conductive member provided between the cases.
The optical transmission module 1 of this embodiment shown in FIG. 1 includes a light receiving element 2, a light emitting element 3, and a case 4 in which these elements are incorporated. It is configured to output an optical signal. The light receiving element 2 and the light emitting element 3 are commercially available, and the mounting arm 3c is provided at the tip of the metal can 3b of the light emitting element 3. This is the same as in the prior art, and the same parts as in the prior art are denoted by the same reference numerals.
[0013]
This embodiment differs from the prior art in that a conductive member 10 is interposed between the light receiving element 2 and the case 4.
That is, as shown in FIG. 3A, the conductive member 10 is formed by cutting a tube 11 into which a conductive material is mixed into a predetermined length, and has elasticity. 11 is squashed as shown by a solid line from a chain line shown in FIG. Then, a flat plate is attached to the upper surface of the metal can 2b of the light receiving element 2 as shown in FIGS. 1 and 2, and also attached to the lower surface of the metal can 2b as shown in FIG. When the light receiving element 2 is assembled in the case 4, the member 10 is interposed between the lower case (first case) 5, the upper case (second case) 6, and the light receiving element 2 of the case 4. I have.
In FIG. 2, reference numeral 12 denotes an insulating material provided on the light emitting element 3 and interposed between the lower case 5 and the upper case 6. 1 to 3, the same parts as those in FIG. 5 are denoted by the same reference numerals.
[0014]
In the optical transmission module 1 of the present embodiment, when an optical signal is captured by the light receiving element 2, an optical signal is output from the light emitting element 3 based on the captured optical signal.
In this case, while the light emitting element 3 outputs at several mW, the light receiving element 2 outputs at several μW, and since the mounting arms 3c are provided on both sides of the metal can 3b of the light emitting element 3, light emission is performed. Radiation energy from the element 12 is emitted particularly through the mounting arm 3c, and may adversely affect the light receiving element 2 as disturbance noise.
[0015]
However, in the case 4, the conductive member 10 is interposed between the lower case 5 and the lower portion of the metal can 2 b of the light receiving element 2, and the conductive member 10 is provided between the upper portion of the metal can 2 b and the upper case 6. Since the light receiving element 10 is interposed, the light receiving element 2 can be stably grounded to the case 4 by incorporating the light receiving element 2 into the case 4 via the conductive member 10.
[0016]
Moreover, since the member 10 has elasticity, when the lower case 5 and the upper case 6 are closed to form the case 4, the member 10 can be reliably brought into contact between the two cases 5, 6. , The light receiving element 2 can be accurately grounded.
As a result, the ground impedance of the light receiving element 2 can be reduced, so that crosstalk generated in the light receiving element 2 can be reliably reduced.
[0017]
Therefore, since the crosstalk generated in the light receiving element 2 can be reduced, the sensitivity of the light receiving element 2 to an optical signal can be increased, and the characteristics of the optical transmission module 1 can be improved.
[0018]
The conductive member 10 interposed between the lower case 5 and the upper case 6 of the case 4 and the metal can 2b of the light receiving element 2 is formed in a plate shape by crushing a tube cut to a desired length. Therefore, not only can it be completed with a commercially available tube, but also it can be easily attached to the metal can 2b, and automatic assembly can be favorably performed.
In the illustrated embodiment, an example is shown in which the conductive member 10 or the light receiving element 2 is attached to the upper surface side and the lower surface side of the metal can 2b, however, it may be attached to any one of them. The member 10 may be attached to a position on the peripheral surface of the metal can 2b where the member 10 can come into contact with either the lower case 5 or the upper case.
[0019]
FIG. 4 shows an optical transmission module according to a second embodiment of the present invention.
In this embodiment, the difference from the first embodiment is that the conductive member 10 penetrates the metal can 2b of the light receiving element 2, and the metal can 2b and the lower case 5 and the upper case 6 of the case 4 The member 10 is interposed between them.
Therefore, the member 10 is configured to attach a conductive tube cut to an appropriate length to the metal can 2b of the light receiving element 2.
[0020]
According to this embodiment, since the conductive member 10 is used, basically the same operation and effect as those of the first embodiment can be obtained.
[0021]
【The invention's effect】
As described above, according to the present invention, the light receiving element is incorporated into the case via the conductive member, and the light receiving element is configured to be stably grounded to the case. As a result, it is possible to reduce the crosstalk generated in the element and to increase the sensitivity of the light receiving element to the optical signal. As a result, it is possible to obtain the effect of improving the characteristics of the optical transmission module.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an optical transmission module according to a first embodiment of the present invention, and is a perspective view illustrating a main part of the optical transmission module.
FIG. 2 is a cross-sectional view when a case corresponding to line AA in FIG. 1 is closed.
FIG. 3 is an explanatory view showing a conductive member provided between a light receiving element and a case.
FIG. 4 is a diagram illustrating an optical transmission module according to a second embodiment of the present invention, and is an explanatory diagram illustrating a conductive member attached to a light receiving element.
FIG. 5 is an explanatory diagram of a main part showing a conventional optical transmission module.
[Explanation of symbols]
Reference Signs List 1 light transmission module 2 light receiving element 2b light receiving element metal can 3 light emitting element 3b light emitting element metal can 4 case 5 lower case (first case)
6 Upper case (second case)
10 Conductive part

Claims (4)

A light receiving element that captures an optical signal, a light emitting element that outputs an optical signal based on the optical signal captured by the light receiving element, and an optical transmission module including a case where the light receiving element and the light emitting element are assembled adjacent to each other;
An optical transmission module, wherein a conductive member is interposed between the light receiving element and the case. The optical transmission module according to claim 1,
The optical transmission module according to claim 1, wherein the conductive member has elasticity. The optical transmission module according to claim 1 or 2,
The optical transmission module, wherein the conductive member is interposed at least between one of the first case and the second case constituting the case and a metal can of a light receiving element. The optical transmission module according to any one of claims 1 to 3,
The optical transmission module according to claim 1, wherein the conductive member is mounted on a peripheral surface of the metal tube of the light receiving element at a position in contact with the first case and the second case constituting the case.

Images