JPH02176616A - Optical switch - Google Patents

Abstract

PURPOSE:To consume electric power only for optical path switching and to prevent electric power consumption for holding by holding an electromagnetic conversion type actuator for the optical path switching only with the detent torque even at 1st and 2nd stop positions. CONSTITUTION:When no exciting current flows to the exciting coil 18 of the electromagnetic conversion type actuator, a rotor 5 is held by a stopper 18 at a point A which is the 1st stop position. When an exciting current flows to the exciting coil 18, on the other hand, driving torque is generated and the rotor 5 stops by abutting on a 2nd stopper 9 after rotating by thetas' and is held at a point C. Here, when the exciting current is interrupted, only the detent torque is left, the rotor is held at a point D with the torque to a next stable point F, and this is the 2nd stop position. In this state, an optical path is formed from a 1st optical fiber 1 to a 3rd optical fiber 3 through a right-angled prism 4. Thus, even when the exciting current is interrupted, the rotor 5 is stably held at the 1st and 2nd stop positions and no electric power is consumed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical switch for switching optical paths used in optical fiber communications.

(Prior Art) In optical communications, optical switches are used to switch the optical path of information light transmitted through optical fibers. Conventionally known optical switches include, for example, Japanese Patent Application Laid-Open No. 56-107.
As disclosed in No. 201, a right-angle prism is provided to face the input/output terminals of three optical fibers installed in the same plane, and this right-angle prism is connected to the three optical fibers. It is known to switch the optical coupling between optical fibers by moving them in a direction orthogonal to these fibers within the same plane as the provided optical fibers.

Further, as another optical switch, as shown in FIG. 7, fiber collimators la and 2a are installed at the input and output terminals of three optical fibers 1, 2, and 3 arranged in parallel.

3a is provided, and a right angle prism 4 having a rotation axis 100 coaxially with the central optical fiber l is provided, and this right angle prism 4 is rotated 180 degrees within a plane orthogonal to the plane in which the optical fibers 1 to 3 are provided. By this, each optical fiber 1
It is known that the optical coupling between and 2 or 1 and 3 is switched.

The former optical switch performs switching by linearly reciprocating a rectangular prism, so the stop 1-
The direction of the inertial force acting at this position coincides with the adjustment direction of the right angle prism with respect to the optical axis, so there is a disadvantage that it is easy to fall into this adjustment position with use, and it is not affected by gravity due to its mounting orientation. This has the disadvantage that there is likely to be a difference in switching time between the two.

A common drawback of both is that since the input/output terminal surface of the optical fiber and the input/output surface of the prism are installed parallel to each other, they are easily affected by the reflected light from both entrance surfaces.

Therefore, the present inventors developed an optical switch whose principle is shown in FIG. 8 in order to solve the above two drawbacks. That is, in FIG. 8, optical fibers 1 to 3 are arranged in parallel in the same plane, and fiber collimators la to 3a are provided at the input/output terminal portions of the optical fibers. Reference numeral 4 denotes a right-angled prism serving as an optical path changing means, subnumbered so as to face the fiber collimators la to 3a. This right angle prism 4
The optical fiber 1 is provided with an entrance/exit surface 4a, a first reflective surface 4b, and a second reflective surface 4C, and has a swing rotation radius of radius r.
- 3 are arranged in parallel in the same plane. This swing rotation angle is approximately an angle α on the left and right sides, centering on the human output optical axis A by the central optical fiber l,
The first optical fiber 1 and the second optical fiber 2 are optically coupled in the swinging stopped state shown by the solid line when the first optical fiber 1 and the second optical fiber 2 are swung toward one side, and the swinging stopped state shown by the broken line when the first optical fiber 1 and the second optical fiber 2 are swung toward the other. In the step, the first optical fiber 1 and the third optical fiber 3 are optically coupled.

The driving torque for swinging and rotating the right angle prism 4 is obtained by magnetic force using a permanent magnet and an electromagnet.

FIG. 9 shows the structure of a main part of an electromagnetic conversion actuator for swinging and rotating the rectilinear prism 4. As shown in FIG. In the figure 5
is a rotor made of a permanent magnet that rotates the rectangular prism 4; on the other hand, 6 and 7 are sunken stators that face each other with the rotor 5 in between, and the stators 6 and 7 are rotated as needed by excitation coils, which will be described later. magnetized. This rotor 5
The gap between the rotor 5 and the stator 6.7 is formed so that the gap gradually changes so that the stator parts 6a and 7a are relatively narrow and the stators 6b and 7b are relatively wide. The magnetic field between 6.7 and 6.7 is strongest near the stator parts 6a and 7a. Therefore, even if the stators 6 and 7 are not magnetized by the excitation coil, a torque (this torque is called detent torque) acts between the rotors 5 and 6, 7 in the direction of rotating the rotor 5. The N pole 5a and the S pole 5b of the rotor 5 move in the direction connecting the stator parts 6a and 7a, and the rotor 5 moves in a direction that connects the stator parts 6a and 7a, so that the N pole and the S pole are lined up on the x'-x' line as shown in FIG.
The torque of becomes 0. This position is the stable resting position of the rotor 5.

The curve Ta in FIG.
The angle 0 when the N and S poles of the angle coincide with the X'X' line shown in FIG. 9 is shown as 0. On the other hand, the curve Tb in FIG. 10 shows the driving torque Tb acting on the rotor 5 and its rotation angle O when the excitation coil is energized to magnetize the stator 6.7.
Indicates the relationship between In FIG. 10, assuming that positive torque acts to rotate the rotor 5 clockwise and negative torque acts to rotate the rotor 5 counterclockwise, the rotation angle θ of the rotor 5 is 0°. Between 〈θ〈90°, when the stator 6.7 is not magnetized, the detent torque Ta is high and negative, so the rotor 5 is rotated counterclockwise toward the stable point O by the force 1 ]0<, when the stator 6.7 is magnetized, a driving torque Tb is generated which overcomes the detent torque Ta, causing the rotor 5 to rotate clockwise.

In an actuator having such a structure, the stator 6
．． 7 is not magnetized, the rotor 5 or detent torque T
a slightly before reaching the stable resting position (corresponding to point O in Figure 10) by rotating counterclockwise (point 1 O).
A protrusion 1 provided on a part of the rotor 5 (corresponding to point A in the figure)
A first stopper 8 abutting the stator 7b is provided, and the stator 6
．． 7 is magnetized, the rotor 5 rotates clockwise and reaches another stable stationary position (first position).
If a second stopper 9 is provided at which the protrusion 17c provided on a part of the rotor 5 comes into contact (corresponding to point C in figure O),
When the stator 6.7 is not magnetized, the protrusion 17b of the rotor 5 comes into contact with the first stopper 8 with a slight rotational force and is stopped (this position is called the first stop position). When magnetized, the protrusion 17c of the rotor 5 similarly contacts the second stopper 9 with a slight rotational force and becomes stopped (this position is referred to as a second stop position).

At the first stop position, the first optical fiber 1 and the second optical fiber 2 are optically coupled via the right angle prism 4, so that the optical path is from the first optical fiber 1 to the second optical fiber. Can be switched to 2.

On the other hand, at the second stop position, the first optical fiber 1 and the third optical fiber 3 are optically coupled via the right angle prism 4, so that the optical path is changed from the first optical fiber 1 to the third optical fiber 3.
Switched to optical fiber.

(Problem to be solved by the invention) By the way, in the optical switch having the structure described above, in order to switch the optical path from the first optical fiber 1 to the third optical fiber 3 and continue that state, the rotor 5 must be moved to the second optical fiber. The stator 6.7 must be maintained at the stopped position, and for this purpose, it is necessary to constantly supply an excitation current to the excitation coil of the stator 6.7 to continue magnetizing the stator 6.7. This problem becomes a major problem in practical use because as the number of optical switches increases, power consumption increases and heat is generated.

(Means for Solving the Problems) In order to solve the above problems, the present invention focuses on the detent torque characteristics of an electromagnetic conversion actuator, and connects the output terminal of the first optical fiber to the second and third optical fibers. An optical path changing means for changing the optical path by reflection or refraction of light is provided in the optical path to the input terminal of the input terminal so as to be swingable on an arc, and the optical path changing means swings in one direction on the arc and then stops. At a stop position, the first optical fiber and the second optical fiber are optically coupled, and at a second stop position, the optical path changing means swings on an arc in opposite directions and stops. an optical switch that can switch an optical path between the first optical fiber and the second optical fiber or the third optical fiber by optically coupling an optical fiber with the third optical fiber. As a driving source for the optical path changing means, a pair of stators are arranged facing each other on the same plane, and a rotatable member is provided between the two stators so that the gap between the stators and the stators gradually changes along the circumference. Using an electromagnetic transducer actuator having an odd number of pole pairs or an odd number of rotors arranged, the first stop position is viewed from a stable stationary position of the rotor with respect to the stator in a non-energized state in the direction of rotation of the rotor in one direction. The second stop position is set at a position below an angle corresponding to 1/4 of one cycle of the detent torque curve of the actuator, and the second stop position is set at a position where the rotor rotates in the same direction from a stable rest position with respect to the stator in a non-excited state. It is set at a position that is at least an angle corresponding to 3/4 of one period of the curve when viewed in the direction.

(Operation) If the first and second stop positions are determined in this way, the first
Since the rotor is held in that position only by the detent torque at both the stop position and the second stop position, no excitation current is required for holding.

(Example) The present invention will be explained below based on the drawings.

1 and 2 show the structure of an optical switch according to the invention.

In the figure, lO is a rotating shaft, and the upper and lower sides of this rotating shaft lO are attached to the upper plate 13 and lower plate 14 via bearings 11 and 12, respectively, and the upper bearing 11 and the abutting surface 10a of the rotating shaft A slight gap S is provided between them. This rotation axis IO is located near the top and bottom of the rotation axis 15 and 16, respectively.
The center of rotation is biased by the bearing play so that it does not move, and a stable operating condition is maintained.

A support bracket 17 for attaching a right angle prism 4 for changing the optical path using reflection is fixed to the rotation axis IO, and a rotor 5 is fixed to the lower surface of the support bracket 17. An aluminum plate is used as the support base 17, and a support part 17a on which the right angle prism 4 is placed on the front part, and protrusions 17 on both sides of the support part 17a that abut the first and second stoppers 8.9.
b.

17c, and further a protrusion 17d for maintaining balance is formed at the rear thereof. Thus, the rotor 5 is assembled with the lower surface of the support base 17 as a reference, and its attachment can be carried out easily and with high precision. Also, since the center of gravity of the entire rotating body can be placed almost on the rotation axis,
The magnitude of the inertial force acting at the stop position is constant, and the position error is minimized.

A stator 6 arranged to sandwich the rotor 5 from both sides.
7 has a step slightly below the rotor 5, and constantly urges the rotating shaft lO downward to eliminate axial play of the bearing.
This makes the rotational movement stable. These stators 6.7 are magnetized by passing a current through the excitation coil 18, and together with the yokes 19 and 20 inserted into the excitation coil 18, form a magnetic loop.

The stopper 8.9 is constituted by a screw inserted through the - section of the upper plate 13, and by adjusting this screw, the restriction position of the support base 17 can be easily adjusted.

Figure 3 is a transport route diagram schematically representing an electromagnetic actuator used in an optical switch having the structure described above, and the same components as in Figures 1 and 2 are designated with the same reference numerals. Ta. Moreover, FIG. 4(a) and FIG. 4(b) are drive circuits of this electromagnetic conversion type actuator.

In Fig. 3, the rotor 5 is made of a permanent magnet, and its outer circumferential surface is magnetized with multiple poles, and the number of poles is 2 p = 2.
(2m −1) (P is the number of pole pairs, m = 1.

2.3...), and in this embodiment there are 14 poles. Therefore, one step angle θ5 of the rotor 5 is θ=360
°/14=25.7]6.

In FIG. 4(a), 20 is a changeover switch that is turned on when switching the optical switch, 21 is a flip-flop,
22 is an exclusive OR circuit, 23°24 is a NOR circuit, 25
．． 26 is an inverter, and 18 is an exciting coil for the Stella Pink motor.

Next, the operation of this drive circuit will be explained with reference to FIG. 4(b).

Now, if you are trying to change the optical switch and turn on the changeover switch 20 for a moment at time t1, the potential at point M or L.
Therefore, the output terminal Q of the flip-flop 21
And Q outputs a signal as shown in FIG. 4 (b). The output signal from output terminal Q is input to one input terminal of exclusive OR circuit 22 and NOR circuit 23, and the output signal from output terminal Q is input to one input terminal of NOR circuit 24.

The output signal from the output terminal Q of the flip-flop 21 is input to the other input terminal of the exclusive OR circuit 22 via an integrating circuit constituted by a resistor R and a capacitor C. A pulse N having a width of time constant τ determined by the resistor R and the capacitor C is output. This pulse N is input to the other input terminals of NOR circuits 23 and 24, so that signals P and S as shown are obtained. These signals P and S are inverted by inverters 25 and 26, respectively, and flow into the excitation coil 18 of the actuator as drive signals P and S. As a result, the stators 6 and 7 are magnetized by the drive signal P,
The rotor 5 rotates from its first stop position to the second position.
It comes into contact with the stopper 9 and stably stops at the second stop position.

Then, when the selector switch 20 is momentarily turned on at time t2,
From now on, drive signals P and S as shown in FIG. 4(b) will be obtained, which will flow from terminals a and b to the excitation coil 18, causing the rotor 5 to reverse from its previous second stop position. 1st
It comes into contact with the stopper 8 and stably stops at the first stop position.

Next, referring to FIG. 5, the switching operation of the optical switch according to the present invention will be explained in relation to the torque generated in the electromagnetic conversion type actuator.

In FIG. 5, Tb is a drive torque curve, and Ta is a detent torque curve. Driving torque is generated when an exciting current flows through the exciting coil 18 of the electromagnetic conversion actuator, and detent torque is generated even when no exciting current flows through the exciting coil 18. One period θ3 of the detent torque curve Ta is 25.71', and the driving torque curve MTb
The period is 1/2 of the period of .

The point where the detent torque is 0 is 0. Of I and F, 0 and F are stable points, ■ is unstable points, and the maximum value of detent torque is 25.71°x 1/4 = 6.42° and 25.7]°x 3/4 = 19. Appears at a point of 26°. If the rotation angle θ8 = 20° when the right-angle prism 4 is mounted on the rotor 5, then the position (
A first stopper 8 is provided at a point (corresponding to point A in the figure) to prevent the rotor 5 from moving further from point A due to detent torque. That is, the rotor 5 is held at the point A where it comes into contact with the first stopper 8 by the detent 1 herc. θ that determines point A, which is this first stopping position
1 is θ1≦θS/4=5.42°. Next, the second stopping position (corresponding to point C in the figure) is set at a point θ2 back from the nearest stable point F, and 02≦θS/4=6.42.
°. Further, point E of the drive torque curve Tb is a stable point, and point J is an unstable point. The angular difference between the stable point E of the driving torque and the stable point F of the detent torque is θ3. Also, θ2>θ3 is required.

In this way, when no excitation current flows through the excitation coil 18, the rotor 5 is held at the first stop position, point A, by the first stopper 8, and the excitation current is input from the optical fiber 1 through the fiber collimator la. The information light is reflected by the reflecting surfaces 4c and 4b of the right angle prism 4 constituting a part of the optical path changing means, has its optical path changed, and enters the fiber 2 via the fiber collimator 2a. Now, when an excitation current flows through the excitation coil 18, a driving torque is generated, and since this driving torque is much larger than the detent torque, if we focus on the driving torque alone, the driving point moves from point A to point B. However, since point B is unstable, the driving torque moves toward point E according to the curve Tb, and the rotor 5 rotates accordingly. However, since the second stopper 9 is provided,
The rotor 5 actually hits this second striker 9 and is O5.
' It rotates for a long time and stops, and is held at the 0 point. If the excitation current is cut off here, only the detent torque remains, and as a result, it is held at point D by the torque heading toward the next nearest stable point F. This is the second stop position. In this state, an optical path from the first optical fiber l to the third optical fiber 3 is formed via the right angle prism 4.

In this way, the rotor 5 is stably held at the first and second stop positions even if the excitation current is cut off, and no power is consumed at all.

Next, when you want to return to the first stop position in order to switch the optical path of the first optical fiber 1 from the third optical fiber 3 to the second optical fiber 2, apply the excitation current to the excitation coil 18 in the opposite direction. If it flows, the driving torque will be generated with the sign reversed as shown by the broken line in Figure 5, and point D will move to point G, and since point G is unstable, it will return to point H along the broken line. . If the excitation current is cut off here, the rotor 5 reaches the point A from point H and is held at the first stop position.

In summary, in order for the rotor 5 to be reliably held at the first stop position and the second stop position, θ1≦0, /
4, θ2≦OS/4,02〉θ3゜DKI>IcK
I, IGKI>IGK is required, and in this example, θ,=2'<θs/4 =25.71°/4=6.
42°θ2=3.71°≦OS/4=6.426θ,'
=20°θ, = 25.71°−01+02+05, 1D
Kl = IGKI> Old IC is driving torque (reverse torque)
This is a design problem, and the number of turns of the excitation coil 18 and the drive current may be selected appropriately.

In the above embodiment, the number of poles of the rotor 5 of the electromagnetic conversion actuator was set to 14, but the present invention is not limited to this number of poles, and may be any number of poles.

Furthermore, the present invention is not limited to switching the optical path from the first optical fiber to the second or third optical fiber using the reflection of the prism as shown in the embodiment, and the prism 4 as shown in FIG. is rotated in the direction of the arrow and using its refraction, the optical path of optical fiber F1 is changed from optical fiber F3 to F4.
Of course, it can also be applied to optical switches that switch to

(Effects of the Invention) As explained above, in the present invention, the electromagnetic conversion actuator for driving the optical path changing means that moves on a circular arc is controlled by the tetent torque of the motor at both the first stop position and the second stop position. I tried to hold it with
Electric power is consumed only for changing the position of the optical path switching means, and no electric power is consumed for holding the optical path switching means. Therefore, electric power consumption can be reduced, and heat generation is hardly a problem. Therefore, there is no practical problem even if the number of optical switches increases, and since only one excitation coil is required, miniaturization is possible, and there is also the effect that a simple drive circuit is required.

[Brief explanation of the drawing]

FIG. 1 is a plan sectional view showing the internal structure of an embodiment of the optical switch according to the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1, and FIG. 3 is an electromagnetic conversion used in the optical switch according to the present invention. Figure 4 (a) is an example of the optical switch drive circuit according to the present invention, and Figure 4 (b) is a timing chart of each part of the drive circuit shown in Figure 4 (a). Figure 5 shows a crank diagram illustrating the driving principle of an electromagnetic conversion actuator used in an optical switch according to the present invention.
FIG. 6 is a schematic diagram showing another application example of the optical switch according to the present invention, FIGS. 7 and 8 are schematic diagrams showing the optical path switching mechanism of a conventional optical switch, and FIG. FIG. 10, which is a diagram explaining the rotation principle of a stepping motor used for switching, is a torque characteristic curve of an electromagnetic conversion type actuator used in a conventional optical switch. 1.2.3...Optical fiber, 4...Right angle prism,
5 - Rotor, 6, 7 - Stator, 18 - Excitation coil = 173 Fig. 10

Claims (1)

[Claims] An optical path changing means for changing the optical path by reflection or refraction of light is provided in the optical path from the output terminal of the first optical fiber to the input terminals of the second and third optical fibers, and the optical path changing means is swingable on an arc. The first optical fiber and the second optical fiber are optically coupled at a first stop position where the changing means swings in one direction on an arc and stops, and the optical path changing means swings on the arc in one direction and optically couples the second optical fiber. The first optical fiber and the second optical fiber are optically coupled by optically coupling the first optical fiber and the third optical fiber at a second stop position where they swing in opposite directions and stop. Or, in an optical switch that switches the optical path between a third optical fiber and a third optical fiber,
As a driving source for the optical path changing means, a pair of stators are arranged facing each other on the same plane, and a set of stators is rotatably arranged between the two stators so that a gap between the stators and the stators gradually changes along the circumference. The electromagnetic conversion is performed by using an electromagnetic conversion actuator having a rotor having an odd number of pole pairs, and viewing the first stop position from a stable stationary position of the rotor with respect to the stator in a non-excited state in one direction of rotation of the rotor. 1/1 period of the detent torque curve of the type actuator
4, and the second stop position is set at a position equal to or less than an angle corresponding to An optical switch characterized in that the optical switch is set at a position greater than or equal to an angle corresponding to 3/4.