Optical waveguides – With optical coupler – Switch
Reexamination Certificate
1999-10-12
2001-03-27
Palmer, Phan T. H. (Department: 2874)
Optical waveguides
With optical coupler
Switch
C385S019000, C385S020000
Reexamination Certificate
active
06208777
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to optical switches, and more particularly, to an actuator assembly for optical switches.
2. Background
Optical switches have been developed for switching optical networks in broadband telecommunications systems. Because of increasing demand for high speed broadband data communications, optical wavebands including infrared and visible light wavelengths are increasingly being used as data carriers in telecommunications systems to satisfy the demand for high speed broadband data transmission. Conventional optical switches have been implemented in a typical optical fiber telecommunications network to switch the optical paths of information-carrying light to different optical fiber cables.
Conventional optical switches typically fall into two broad categories of non-integrated optical switches and integrated optical switches. Among the non-integrated optical switches, moving fibers have been used to change optical paths between different input or output fibers. In a conventional moving fiber switch, either the input optical fibers or the output optical fibers are moved mechanically to switch the optical path between different input or output optical fibers.
However, conventional moving fiber switches typically suffer from alignment problems because it is difficult to align the input and output fibers with a high degree of accuracy and repeatability. Alignment of single mode fibers can be especially difficult because of their small diameters. Even a slight misalignment between the selected input and output fibers through which optical transmission supposedly occurs may result in an unacceptably high insertion loss because the output fiber is not in the perfect position on the optical path to receive the light transmitted from the input fiber.
In order to avoid the problem of misalignment in a typical fiber moving switch, expensive and complicated mechanisms are usually required to move either the input or the output optical fibers to achieve acceptable alignment accuracy and repeatability. Furthermore, conventional moving fiber switches typically have slow switching speeds which may limit their applications in optical fiber communications networks which require high-speed switching operations.
Moving reflectors have also been used in conventional non-integrated optical switches to switch optical paths between different input or output optical fibers instead of moving the input or output fibers for optical alignment. Moving reflector switches are usually capable of faster switching operations than conventional moving fiber switches. However, conventional reflector switches typically also suffer from the problems of mechanical stability and repeatability. After a large number of repeated on and off switching operations, the optical reflectors in a conventional reflector switch may deviate from their designed reflection angles because of the problems with mechanical stability and repeatability. Even a slight deviation of reflection angle may cause the optical path of reflected light to be misaligned with a respective output fiber or another reflector which is supposedly positioned to receive the reflected light.
Therefore, there is a need for an optical switch with a high degree of reliability after a large number of repeated on and off switching operations which are typically required in modern optical fiber communications networks. Furthermore, there is a need for an inexpensive mechanical assembly which allows optical switches to maintain a high degree of reliability and accuracy after a large number of repeated switching operations.
SUMMARY OF THE INVENTION
The present invention provides a mechanical assembly for an optical switch, roughly comprising:
(a) an actuator capable of generating repetitive movements in opposite directions;
(b) an axle assembly, comprising:
(i) a hollow cylindrical shaft rotatable about a center axis, the cylindrical shaft comprising an exterior sidewall and an interior sidewall defining a hollow interior and an open end;
(ii) a screw fastened to the interior sidewall of the cylindrical shaft through the open end;
(iii) first and second ball bearings each comprising an inner annulus, an outer annulus and a plurality of balls movably positioned between the inner and outer annuli, the inner annuli of the ball bearings attached to the exterior sidewall of the cylindrical shaft; and
(iv) a spacer positioned between the first and second ball bearings;
(c) a lever connected to the actuator and the axle assembly, the lever pivoted about the center axis of the cylindrical shaft; and
(d) an optical switching element, connected to the lever, capable of moving repetitively in opposite directions in response to repetitive movements generated by the actuator.
In an embodiment, the mechanical assembly according to the present invention further comprises a flexible connector between the actuator and the lever to transfer mechanical movements from the actuator to the lever. In a further embodiment, the flexible connector comprises at least two bent metal wires to avoid or at least to reduce the possibility of resonance induced by the mechanical forces generated by the actuator.
In an embodiment in which the optical switch is supported by a perforated support plate, a portion of the lever adjacent the optical switching element is movably positioned through the aperture to drive the optical switching element between its on and off positions. In a further embodiment, the mechanical assembly further comprises first and second blocks fixedly connected to the support plate for stopping further movements of the lever to set the optical switching element in its on and off positions.
In an embodiment, the actuator comprises a relay switch to provide repetitive movements for the optical switching element through the lever and the flexible connector. In an embodiment, a fixed member is attached to the support plate to support the axle assembly. In a further embodiment, the actuator is connected to the fixed member which also supports the axle assembly. In an alternate embodiment, the actuator is directly connected to the support plate.
Advantageously, the mechanical assembly according to the present invention can be used to move an optical switching element either to intercept an optical path when it is switched to an on position or to move away from the optical path when it is switched to an off position, with a high degree of mechanical reliability for accurate optical alignment even after a large number of repeated on and off switching operations. Furthermore, a high degree of mechanical stability can be maintained even if an inexpensive conventional solenoid relay switch is implemented as the actuator in the mechanical assembly according to the present invention, thereby allowing the cost of the optical switch to be reduced.
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Palmer Phan T. H.
Primawave Photonics, Inc.
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