Optical waveguides – With disengagable mechanical connector – Optical fiber to a nonfiber optical device connector
Reexamination Certificate
1998-12-03
2001-05-22
Font, Frank G. (Department: 2877)
Optical waveguides
With disengagable mechanical connector
Optical fiber to a nonfiber optical device connector
C385S094000
Reexamination Certificate
active
06234686
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a light-receiving module for converting an optical signal propagating through an optical fiber into an electric signal and outputting thus obtained electric signal, a light-emitting module for converting the electric signal to an optical signal and transmitting thus obtained optical signal to the optical fiber, and an optical data link comprising these optical modules.
2. Related Background Art
As conventional data links, those disclosed in Japanese Patent Application Laid-Open Nos. 57-91571, 57-91572, and 2-61921 have been known, for example.
In Japanese Patent Application Laid-Open Nos. 57-91571 and 57-91572, an optical device for converting an optical signal to an electric signal and an electronic circuit for processing the electric signal outputted from this optical device are transfer-molded with a transparent resin so as to form an intermediate component, which is accommodated in a housing provided with a mechanism for joining it with an optical fiber, thus constituting an optical module. Further, a predetermined assembling jig is used for placing this intermediate component at a predetermined position, and a resin opaque to the optical signal is injection-molded, thereby forming a housing which can block off external light.
The optical data link disclosed in Japanese Patent Application Laid-Open No. 2-61921 has a configuration in which an optical device is mounted to a base part of an optical connector made of a metal. This optical connector is provided with a joint mechanism for connecting a ferrule accommodating a tip portion of an optical fiber. When mounting the optical device to the base part, an optical signal is actually introduced in the optical fiber and, while the electric signal outputted from the optical device in response thereto is being observed, the optical axes of optical fiber and optical device are adjusted with respect to each other, such that the optical device is mounted at its optimal position where a predetermined level of electric signal is attained. Further, the metal connector mounted with the optical device and a hybrid IC board equipped with an electronic circuit for processing the electric signal are integrally molded with a resin, thereby forming an optical data link.
SUMMARY OF THE INVENTION
Having studied the conventional optical data links, the inventors have found the following problems. Namely, in the optical data links disclosed in Japanese Patent Application Laid-Open Nos. 57-91571 and 57-91572, when adjusting the optical axes of an optical fiber and a transfer-molded optical device, their centering accuracy has not been high since it is influenced by various factors such as the accuracy in installation of the jig used when molding the housing, the accuracy in installation of the intermediate component, and the form of the intermediate component.
Also, the optical axes of the optical fiber and optical device are only indirectly matched by way of the housing. Therefore, even when the optical axes of the optical fiber and optical device are matched in a centering operation during a manufacturing step, they may shift from each other if a mechanical stress is applied to the housing during a later manufacturing step or the like.
Further, for forming a transmitter-receiver optical data link in which a light-emitting module incorporating an electricity-to-light conversion device (optical device) therein and a light-receiving module incorporating a light-to-electricity conversion device (optical device) therein are integrally assembled therein, the distance between these optical modules must be adjusted with the axis-to-axis distance of the jig for adjusting the optical axes of the optical fiber and these optical devices. Hence, the microscopic adjustment of optical axes of the optical fiber and these optical devices and the macroscopic adjustment of the positions of the light-emitting and light-receiving modules must be effected concurrently in the same step with the same jig. It has been very hard to effect both adjustments at the same time.
Further, due to restrictions on the dimension of lead frames, it has been very difficult to install a large-scale electronic circuit for performing complicated signal processing in response to the demand for higher-grade optical communications. Namely, when the lead frame is made larger, the volume of the intermediate component also increases, thereby making the optical axis adjustment harder, and the optical axes are likely to shift after the completion.
The optical data link disclosed in Japanese Patent Application Laid-Open No. 2-61921 is advantageous in that the optical axis adjustment and the axis-to-axis adjustment can be effected separately from each other as the metal optical connector and the hybrid IC are integrated together as being sealed with a resin. On the other hand, it must use an expensive connector made of a metal. Further, a separate condenser lens must be mounted in the metal connector, and the electronic circuit has to be subjected to a two-step manufacturing process in which it is once prepared as a hybrid IC and then is mounted on a lead frame, thereby increasing the number of parts and complicating the manufacturing process.
In view of such problems of the prior art, it is an object of the present invention to provide an optical data link that is quite easy to manufacture at a low cost and achieves high optical/mechanical accuracy and high reliability.
The optical data link according to the present invention connects an optical fiber transmission line and an electric signal transmission line to each other. In order to attain the above-mentioned object, the optical data link according to the present invention comprises a housing, light-receiving and light-emitting modules at least partly accommodated in the housing, and an insulating substrate having a main surface on which the light-receiving and light-emitting modules are mounted in a state separated from each other by a predetermined distance.
Each of the light-receiving and light-emitting modules has a head portion being provided such that an optical component including one of light-receiving and light-emitting devices and a first support portion on which the optical component is mounted are integrally resin-molded; a body portion being provided such that an electronic device and a second support portion on which the electronic device is mounted are integrally resin-molded; and a neck portion coupling the first support portion to the second support portion and, in a state where the optical component and the electronic device are electronically connected to each other, supporting the head portion at a predetermined position with respect to the body portion.
As a consequence of the configuration mentioned above, the optical data link of the present invention does not need an expensive connector made of a metal. Once adjusted, optical axes would not shift during a later manufacturing step or the like. For attaining higher functions, it would neither increase the number of electronic devices nor influence the optical axis adjustment. Further, the positions of the light-emitting and light-receiving modules are accurately controlled by the substrate.
The optical data link can also be modified to overcome the following structural problem. Namely, since a large current is switched for driving the light-emitting element (optical device) of the light-emitting module, the electromagnetically induced noise generated upon this switching influences the light-receiving module handling minute signals, thereby lowering the minimum input sensitivity.
In typical optical data links, the input amplitude is very low, i.e., on the order of several mV in terms of voltage. By contrast, a switching current exceeds several ten mA. Hence, when the light-emitting and light-receiving modules are disposed close to each other in order to reduce the size of optical data link, the influence of electromagnetically induced noise increases.
The above-mentioned problem can b
Irie Takeshi
Mizue Toshio
Tonai Ichiro
Font Frank G.
Pillsbury Madison & Sutro LLP
Punnoose Roy M.
Sumitomo Electric Industries Ltd.
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