Optical: systems and elements – Optical modulator – Light wave temporal modulation
Reexamination Certificate
2003-03-12
2004-12-07
Schwartz, Jordan M. (Department: 2873)
Optical: systems and elements
Optical modulator
Light wave temporal modulation
C359S237000
Reexamination Certificate
active
06829076
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an actuator apparatus, and more particularly, to an actuator, which is used in an optical communications system or the like, and which, for example, is applicable to a driven-type mechanical optical switch, for arranging a pair of optical fibers by aligning them with an optical axis, and moving either a mirror or a shielding plate in and out of the gap therebetween.
2. Description of the Related Art
In recent years, actuator apparatus capable of achieving high-speed, high-precision displacement are desired for use in optical switching devices and so forth in optical transmission systems, such as optical LAN (local area networks) in particular. In order to apply these actuator apparatus to optical switches in particular, the actuator apparatus must have a moving speed of about eleven to nineteen milliseconds, and must possess accuracy of around ±1 &mgr;m, and various methods for achieving this have been proposed. Among these systems, the mechanical optical switch is advantageous in that, since the direction of propagation of direct light can be changed by mechanically driving a fiber or mirror (or shielding plate) using a mechanical switch, there is less loss of light and cross-talk inside the switch than there is with optical switches of other systems, and commercialization of mechanical optical switches is being pushed forward as the most promising technology capable of being applied to optical switches.
As mechanical optical switching technology in this technical field, a mirror drive-type mechanical 2×2 optical switch is disclosed in Japanese Patent Laid-open No. 2001-75026. This prior art will be explained using a diagram of the prior art.
First, the optical fiber portion constituting an optical switch will be explained initially. In this optical fiber portion, there is disposed a first collimator lens assembly
105
, which arranges a pair of optical fibers
101
,
103
symmetrically with the optical axis of the lens, and a second collimator lens assembly
111
, which arranges a pair of optical fibers
107
,
109
symmetrically with the optical axis of this collimator lens, and these first and second collimator lens assemblies
105
,
111
are placed opposite one another, and their optical axes are aligned. At this time, the first and second collimator lens assemblies
105
,
111
are arranged such that optical fiber
101
and optical fiber
109
, and optical fiber
103
and optical fiber
107
mutually cross over to form optical connections, and these assemblies are supported by alignment block
113
. Then, the above-mentioned first and second collimator lens assemblies
105
,
111
are constituted from a pair of optical fibers not shown in the figure, and a ferrule for supporting the optical fibers, and an approximately 0.25-pitch rod lens, which is connected to the optical fibers and ferrule tip.
Next, the actuator apparatus in the prior art will be explained. A shaft opening provided parallel to the optical axis of the lens is disposed in the above-mentioned alignment block
113
, and a reflecting mirror shaft
115
is inserted into this shaft opening.
Since a reflecting mirror
117
must accurately reflect light being emitted from the above-mentioned optical fibers
101
,
103
, a reflecting mirror reference plane
119
is machined into the alignment block
113
perpendicular to the optical fibers, and reflecting mirror
117
makes contact with the surface of this reflecting mirror reference plane
119
, and its perpendicularity is defined. According to this constitution, it is a state in which the surface of the reflecting mirror
117
is made perpendicular to the optical axis of the above-mentioned optical fibers, and the reflecting mirror
117
can rotate together with the above-mentioned reflecting mirror shaft
115
.
In addition, this reflecting mirror
117
is capable of moving between a first position, in which the reflecting mirror
117
is perpendicular to the optical axis of the lens at the lens focal plane, and reflects light from the respective optical fibers, and a second position, in which the reflecting mirror
117
allows light to pass through, and this operation is carried out by a motor (DC micromotor
121
), which is driving means. This specific driving means is capable of arbitrarily moving the above-mentioned reflecting mirror
117
from the first position to the second position having the above-mentioned reflecting mirror shaft
115
as the supporting point, in accordance with a bushing
123
and an eccentric pin
125
mounted to the motor shaft of DC micromotor
121
.
Further, since the above-mentioned reflecting mirror
117
is precisely moved in and out of the gap of the above-mentioned pair of optical fibers
101
,
103
by the above-mentioned actuator apparatus, a mechanism is required to define the above-mentioned first position and second position. This mechanism is constituted such that the above-mentioned eccentric pin
125
is inserted into a notched groove
127
(for example, a V shape) formed in a specified shape in the above-mentioned alignment block
113
, and the constitution is such that rotating the above-mentioned motor shaft in one direction determines the first position by bringing this eccentric pin
125
into contact with a face of this notched groove
127
, and, in addition, rotating the motor shaft in the other direction determines the second position by bringing this eccentric pin
125
into contact with the opposite face of the notched groove
127
.
Furthermore, a permanent magnet
129
is embedded inside the alignment block
113
in a location close to the reflecting mirror shaft
115
, and by virtue of this permanent magnet
129
biasing reflecting mirror shaft
115
, which comprises a magnetic substance, in one direction in the first position, at which light from the optical fibers is reflected, the slow moving mirror rotation shaft
115
is constantly set in the same position. Accordingly, in addition to causing the light emitted from the optical fibers to be accurately reflected, subsequent to moving the reflecting mirror
117
to the intended position, the position of this reflecting mirror
117
can be maintained as a self-hold state, wherein this position is held by the magnetic attracting force of the permanent magnet
129
without energizing the DC motor
121
.
Combining a conventional actuator apparatus constituted in this manner with the above-mentioned optical fiber portion realized the moving speed and precision of the actuator apparatus of the above-mentioned optical switch, and resulted in a compact mechanical optical switch, which also featured good repeatability, and was not susceptible to the effects of external forces, such as vibrations and impacts.
Furthermore, the above-mentioned reflecting mirror
117
was constituted by coating a metal base material, such as a stainless steel, on both sides with Ti—N of a hardness of MHv 1800 or greater, and, in addition, attaching a high reflectivity coating of gold (Au), platinum (Pt) or the like via either sputtering or electroless plating.
However, although a conventional actuator apparatus excels from the aspects of moving speed and precision, it has the following disclosed problems.
To operate an optical switch normally, conventional actuator apparatus specified the perpendicularity of the reflecting mirror
117
by causing surface contact between the alignment block
113
and the reflecting mirror
117
, and moved the reflecting mirror
117
in and out of the optical fiber portion in a state, wherein the reflecting mirror
117
was constantly perpendicular to the optical axis of the above-mentioned optical fibers. However, when rotating this reflecting mirror
117
between the first position and the second position, this reflecting mirror
117
had to be rotated as-is with surface contact between the alignment block
113
and reflecting mirror shaft
115
, and between the alignment block
113
and the reflecting mirror
117
. Accordingly, there are problems
Abe Takashi
Fukushima Toshiaki
Futakami Shigeru
Kawada Takahiro
Suzuki Kazuo
Citizen Watch Co. Ltd.
Schwartz Jordan M.
Smith , Gambrell & Russell, LLP
Stultz Jessica
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