JP2003329941A - Variable shielding mechanism and optical variable attenuator using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized mechanical variable shielding mechanism in which a structurally accompanied play of a movable part does not influence the repetitive reproducibility of variable shielding operation. <P>SOLUTION: This variable shielding mechanism uses an ultrasonic wave motor which is adaptable to downsizing for a driving part, the motor being equipped with a disklike shielding member driven by the driving part to rotate. To absorb play of the bearing part of the disklike shielding member, the mechanism is equipped with a means which always energizes the shaft of the shielding member in a direction matching the displacing direction of the shielding member, or a shield part end of the disklike shield member is shaped into a plane matching the play direction of the bearing part of the shield member to eliminate the influence of the play on variable shielding operation, thus preventing the play of the bearing part from influencing the shielding area. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable asymmetric disk rotor driven by an ultrasonic motor, which is suitable for application to an optical attenuator used for adjusting an optical signal to a predetermined optical intensity in optical communication. Regarding the shielding mechanism.

[0002]

2. Description of the Related Art In the field of optical communication, technological development for increasing the transmission capacity is being advanced in order to cope with an increase in the amount of information, and one of the attempts to expand the transmission capacity is a technology for speeding up the optical communication. WDM (Wavelength Division Mult
iplexing: Wavelength division multiplexing) transmission system is about to be introduced. In the optical communication network using this WDM system, combining or demultiplexing optical signals of different wavelengths, path switching,
An optical function module that performs attenuation and the like is required, and further improvement in performance is desired. Such a demand for miniaturization and higher performance also exists for the variable optical attenuator, and it is desired that the light quantity of the optical signal be adjusted more precisely and quickly. As the adjustment method, there are an optical waveguide method, a magneto-optical effect method, and a mechanical method. Among them, the mechanical method has characteristics that it is superior to other methods in that it does not affect optical characteristics and is inexpensive. ing.

However, on the other hand, there is a problem that variations occur in repetitive operation during control due to play (backlash) and backlash of the movable portion. A mechanical variable optical attenuator adjusts the amount of light received by interposing a shielding member in the optical path where the light source and the light receiving section face each other, and changes the effective area of the optical path by displacing the shielding member in the direction intersecting the optical path. This is a device that adjusts the amount of light attenuation. The one shown in FIG. 8 is a conventional optical variable attenuator.
Is a plate-like shield that connects lenses 204 and 207 to the ends of the optical cable for input light 201 and the optical cable for output 205, respectively, and the light beam 117 of the optical signal traveling from the input side to the output side is driven and displaced by the drive device 209. The member 208 variably shields and attenuates. An electromagnetic step motor is used for the drive unit 209, and the plate-shaped shield member 20 is used.
8 is variably linearly displaced in the X or Y direction.

Conventionally, an electromagnetic step motor has been used as the motor because the position control is easy. However, the positioning resolution is rough with respect to the motor volume, and it is not possible to control the shielding amount with high accuracy,
Congestion of devices to cope with the recent huge amount of information,
There is a problem that it cannot fully cope with miniaturization. In addition, there is a problem in terms of energy saving because it is necessary to always energize in order to maintain the position.

Under such circumstances, the present applicant has previously provided a disk-shaped disc having a groove portion or a notch portion whose area continuously changes in the peripheral portion and rotating to change the amount of incident light. An optical variable attenuator including a shield member, an ultrasonic motor that rotates the shield member, and a control unit that detects and controls the rotation angle of the shield member and the ultrasonic motor is presented.
The application was filed as No. 1-148848. This precedent example uses an ultrasonic motor that can obtain a large driving force even if it is small as a drive source to achieve miniaturization and also has energy saving by having a self-holding function, and a groove part whose area continuously changes at the peripheral part. Alternatively, it is possible to variably and accurately variably adjust the shielding area by adopting a method of changing the light amount of incident light by rotating a disc-shaped shielding member having a cutout portion. .

A cross-sectional view of this variable optical attenuator is shown in FIG.
The variable optical attenuator 100-1 includes a holding base 116, a piezoelectric element 106,
A drive unit including the vibrating body 107 and the pressure bonding member 118, an encoder including an encoder / scale 111, a light emitting element 113, a light receiving element 114, and a rotation angle calculation unit 123, a control unit 109, and a shielding member.
It consists of 103. The shielding member 103 has a disk shape, and is provided with a V-shaped groove portion 119 on its peripheral portion, and is rotated by a driving unit to shield the light flux 117 and change the amount of incident light. An ultrasonic motor is used for the driving unit, and the ultrasonic motor is provided with a piezoelectric element 106 provided with an equally-divided electrode pattern, and is bonded onto the piezoelectric element 106 to form a protrusion.
The vibrating body 107 includes a vibrating body 107 and a rotor positioned on the vibrating body 107.
This is a drive device that vibrates 07, converts this vibration into a rotational movement of the rotor by the protrusion 108, and rotates the rotor.
The rotor is a driven member, and in this case serves as the shielding member 103. The shielding degree of the groove portion 119 with respect to the light flux 117 is accurately processed so as to continuously change corresponding to the rotation angle of the shielding member 103. The rotation angle of the shielding member 103 is detected by an encoder, and the control unit 109 drives the ultrasonic motor to control the rotation angle so as to achieve a desired degree of shielding.

Since the shielding member 103 of the variable optical attenuator is rotated and guided by the central shaft 115 and is in close contact with the driving portion by the crimping member 118, no movement or play other than rotational movement occurs. This makes it possible to stabilize the shielding area corresponding to the rotation angle of the shielding member 103. However, even in this variable optical attenuator, there is a backlash of 1/10 μm order in the rotary bearing portion, and the backlash has a problem that the shielding degree varies.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to realize miniaturization of a mechanical type variable shield mechanism, and structural play in its movable part affects repeatability of variable shield operation. To provide such a mechanism.

[0009]

A variable shield mechanism of the present invention uses an ultrasonic motor capable of miniaturization as a drive unit,
It is assumed that a disk-shaped shielding member that is rotationally driven by the drive unit is used, and the shaft of the shielding member is displaced so as to absorb backlash in the bearing portion of the disk-shaped shielding member. A means for constantly urging in a direction coinciding with the direction is provided, or the shape of the end of the shield portion of the disk-shaped shield member is adjusted so that the backlash does not affect the variable shield operation. By forming the surface so as to match the direction, the play of the bearing portion does not affect the shielding area.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to an optical attenuator used for adjusting an optical signal in optical communication to a predetermined optical intensity, so as to consolidate a device for coping with the recent huge amount of information. , Adopting an ultrasonic motor as a drive source considering that it can be downsized and that it is an energy-saving type, and also as an attenuation rate adjustment mechanism that variably and accurately adjusts the shielded area. An asymmetric disk was used for the shield plate, and the problem started with this method was to solve the variation in the adjustment function due to backlash caused by the inevitable clearance of the moving parts.
As a method for solving this problem, firstly, a means for constantly urging the shaft of the shielding member in a direction coinciding with the displacement direction of the shielding member is provided to mechanically absorb the backlash so that the influence of the shielding disc The present invention is conceived of as a method of preventing shake and secondly as a method of providing a mechanism that does not affect the degree of shielding by the disc even if there is backlash.

First, a first embodiment of the present invention is shown in FIG. Lens systems 204 and 207 are respectively connected to the ends of the optical cable for input light 201 and the optical cable for output 205, and a light flux 117 of an optical signal traveling from the input side to the output side is eccentric disk-shaped to be rotationally driven and displaced by a driving device. The shielding member 103 variably shields and attenuates the shielding. An optical attenuator that variably shields and attenuates an ultrasonic motor as a drive source by a shield member that is an eccentric disk has been present before. In this optical attenuator for rotating and driving the eccentric disk, a clearance is inevitably present in the rotary bearing portion in the direction of the rotation surface, and rattling occurs in the rotary driving. According to one embodiment of the present invention, the piezoelectric actuator 32 is provided on the outer peripheral surface of the shield member 103 having an eccentric disk shape.
It is driven to rotate by applying a frictional force due to, and is provided with means for constantly urging the shaft of the shielding member in a direction coinciding with the displacement direction of the shielding member.

If any biasing means is provided in the backlash direction in order to reduce the backlash of the bearing portion of the conventional electromagnetic motor, it will be added to the motor, resulting in negative operation stability. However, in the case of the ultrasonic motor, the pressurizing means for constantly applying a pressure to the moving body is an essential configuration, and even if the pressurizing means is also used as the means for constantly energizing the moving body, it is not added to the motor drive at all. There is no such inconvenience. That is, the piezoelectric actuator 32 is adapted to be pressed in the rotation axis direction by the spring 18 via the U-shaped crimping member 17 in which the support member 16 in the central portion is guided by the guide member 19. In the bearing part, the shaft is always pressed to one side, and the clearance exists on the other side. In the example of FIG. 1, the eccentric disk-shaped shielding member 103 is constantly pushed upward,
The bearing clearance does not cause looseness during rotation, and a stable shielding state is maintained.

FIG. 2 is a block diagram showing a rectangular plate piezoelectric vibrator 32 used as a piezoelectric actuator in the first embodiment of the present invention shown in FIG. This rectangular plate piezoelectric vibrator
A resonance type actuator 32 is composed of two piezoelectric elements. An electrode 322 is formed on the entire one surface of the piezoelectric element 321 of the first layer ((a) in the figure), and the piezoelectric element 324 of the second layer is formed.
Has four electrodes substantially equally divided into crosses, and diagonal electrodes are short-circuited to form two electrode groups 325, 326.
(Fig. 3 (c)). Further, on the surface where the two piezoelectric elements 321 and 324 are bonded, both electrodes 323 on the entire surface are bonded.
(GND electrode) is formed and bonded with an adhesive (Fig.
(b)). Further, in the present embodiment, these electrodes are formed by the vacuum vapor deposition method, but a sputtering method or a printing method may be used.

The rectangular plate piezoelectric vibrator 32 is used as an actuator by applying an alternating voltage to the electrodes of the piezoelectric element to simultaneously generate longitudinal vibration and bending vibration. The shape of the rectangular plate piezoelectric vibrator 32 is determined so that the resonance frequency of the longitudinal vibration and the resonance frequency of the bending vibration are close to each other, and by applying an alternating voltage having a frequency near the resonance point, the longitudinal vibration and the bending vibration are A phase difference is created in the displacement between the longitudinal vibration and the bending vibration based on the shift of the resonance point of the vibration, and the same figure is displayed on the side surface of the rectangular plate piezoelectric vibrator 32.
The displacement of the elliptical locus as shown in (d) is obtained. And
When the rectangular plate piezoelectric vibrator 32 that generates such vibration is brought into pressure contact with the driven member at a predetermined pressure, the driving force of the driven member is obtained through friction.

The piezoelectric element 321 is for exciting longitudinal vibration, and the piezoelectric element 324 is for exciting bending vibration. One of the two electrode groups 325 and 326 provided in the piezoelectric element 324 is used, and bending vibration excited by using the electrode group 325 and bending vibration excited by using the electrode group 326 are mutually generated. The direction of vibration displacement is reversed. That is, the two electrode groups 325 and 326 of the piezoelectric element 324 are
By selecting, the displacement direction of the elliptical locus generated on the side surface of the rectangular plate piezoelectric vibrator 32 is reversed. The rotation direction of the driven member is determined by switching the electrode groups 325 and 326.
As is clear from the above description, in the embodiment of the first system, the clearance that is inevitably present in the rotating portion is constantly biased in one direction to be stabilized in the eccentric position, and the backlash is prevented during the rotational driving. It is designed to be absorbed to ensure the stability of the shielding operation.

Next, a second embodiment of the present invention will be described with reference to FIG. This optical attenuator is of the same type as the optical attenuator shown in FIG. 9 introduced as prior art as a type. The variable optical attenuator shown here has a holding base 116.
And a driving unit including a piezoelectric element 106, a vibrating body 107, and a pressure-bonding member 118, an encoder including a scale encoder 111, a light-emitting element 113, and a light-receiving element 114, and a shielding member 103. It has a disc shape, and a groove 119 is provided on the peripheral portion thereof.
17 is shielded to change the amount of incident light. An ultrasonic motor is used for the driving unit, and the ultrasonic motor includes a piezoelectric element 106 having electrode patterns equally divided as shown in FIG. 4, and a piezoelectric element 106 on the piezoelectric element 106 as can be seen from (1) of FIG. And a vibrating body 107 that is bonded to the
The vibrating body 107 is vibrated by the piezoelectric element 106, and this vibration is generated by the protrusion 1
It is a drive device that converts the rotational movement of the rotor by 08 and rotates the rotor.

The rotor is a member to be operated, and in this case the shield member 103. A groove 1 having a rectangular cross section is formed on the outer peripheral surface of the shielding member.
As shown in (2) of FIG. 3, the degree of shielding of the groove portion 119 from the light flux 117 is accurate so that the bottom dimension continuously changes according to the rotation angle of the shielding member 103, as shown in FIG. Well processed. The rotation angle of the shield member 103 is detected by an encoder, and the rotation angle is controlled by driving an ultrasonic motor so that a desired shield degree is obtained by a control unit (not shown).

FIG. 4 is a plan view of the piezoelectric element 106, which has electrode patterns divided into twelve quarter wavelengths in the circumferential direction. For each electrode pattern, +, +,-, in order
Polarization processing is performed by changing the polarization direction every other one, such as −, +, +. Six protrusions 108 on the upper surface of the vibrating body 107
Are provided so as to be located on the boundary between two adjacent patterns of the same polarization in the piezoelectric element 106. FIG. 5 is a diagram showing a positional relationship between the piezoelectric element 106 and the vibrating body 107. The piezoelectric element 106 has two electrodes by short-circuiting every other 12 electrode patterns. A pattern group is formed. The symbol in the drawing indicates that the electrode pattern belongs to the first electrode pattern group, and the symbol indicates that it belongs to the second electrode pattern group.

The vibrating body 107 having such a configuration
As shown in FIGS. 6A and 6B, when an AC voltage near the resonance frequency of the vibrating body 107 is applied to the first electrode pattern group, the vibrating body 107 bends due to the piezoelectric effect of the piezoelectric element 106. Standing wave vibration occurs. The bending standing wave generated here has a node at the position of the broken line A as shown in (a) of FIG.
The vibration amplitude in the radial direction is as shown in FIG. Conversely, when an AC voltage is applied to the second electrode pattern group, the position of the bending standing wave shifts, and the node position becomes the broken line B. This situation will be described with reference to FIG. 7. As shown in FIG. 7A, when a voltage is applied to the first electrode pattern group, the vibrating body 107 vibrates, and peaks and troughs are formed. As a result, the six protrusions 10
Of the eight, the protrusion that leans to the right rises and the protrusion that leans to the left 108
The department descends.

The projections tilting to the right and the projections tilting to the left each have opposite elliptical motions, but the projections in contact with the rotor are only the three rising rightward projections 108. Therefore, the shield member 103 corresponding to the rotor comes into contact with the protrusion 108 inclined to the right and is rotated about the rotation shaft 115 in the direction of arrow V. At the next timing, the protrusion 108 inclined to the right descends while inclining to the left, and the protrusion 108 inclined to the left ascends while inclining to the right to come into contact with the shielding member 103 and move the shielding member 103 in the V direction. Rotate to. Conversely, FIG.
As shown in (b) of No. 2, when a voltage is applied to the second electrode pattern group, the positional relationship between the peaks and the valleys is opposite to the above example,
Since the protruding portion 108 tilted to the left rises, the elliptic movement in the opposite direction is performed, and the shielding member 103 is rotated in the direction of the arrow W opposite to the arrow V described above.

In the above operation as an optical attenuator, there is essentially no difference between the second embodiment of the present invention and the prior art shown in FIG. The same applies to a phenomenon in which the shaft portion of the disk-shaped shield member 103 having a movable portion has a structural clearance and looseness occurs due to rotational driving. The structure of the groove 119 that determines the shielding rate is different from the preceding example of this embodiment, and this is a feature of the present invention. In the prior art example, the V-shaped groove was formed on the outer peripheral surface of the disk by continuously changing the depth, but in the present invention, the groove cross section is rectangular and the bottom dimension, that is, the dimension in the thickness direction of the disk of the groove is continuously changed. It was formed. Groove 119 as shown in cross section in FIG.
Has a rectangular cross section and partially blocks the light flux 117 of the optical signal traveling from the input side to the output side. The degree of shielding is formed so as to continuously change according to the rotational position, as can be seen from (2) of FIG. 3 which is an exploded view of the outer peripheral surface of the disk-shaped shielding member 103.

Incidentally, in FIG. 1A, the height dimension of the groove 119 that partially shields the light flux 117 is a, and the height dimension of the groove 119 at a position different from this by 180 degrees is b. Has become. This difference in height dimension corresponds to the degree of light shielding, but what is important here is that the shaking of the shielding member 103 due to looseness around the axis is the rotation plane, and the shielding member 103 shakes in this direction. However, it does not affect the shielding degree of the light flux 117. That is, in the prior art, since the groove has a V-shaped cross section, the deflection in the direction of the rotation plane affects the degree of shielding, but in the present invention, the shape of the bottom surface of the groove in the disk-shaped shielding member is the direction of the play. It is formed so that the shake does not affect the degree of shielding by matching with. As the rotor of the ultrasonic motor is constantly pressed against the moving body by the pressing means, the position of the bottom of the groove 119 that determines the degree of shielding is stable.

As is apparent from the above description, the second aspect of the present invention
In the embodiment of the method of (1), the backlash at the time of rotational driving due to the clearance that is inevitably present in the rotating part is allowed, and the shielding structure is devised so that the backlash does not affect the shielding degree of the shielding member. It was done like this. In the above description, the variable shield mechanism of the present invention has been described for an optical attenuator used in the field of optical communication, but the mechanism is not limited to this, and for example, a regulating valve in a fluid path or the like. It can be widely applied as a general variable shielding mechanism.

[0024]

The disk-shaped variable shield mechanism of the present invention can be made smaller than that of the conventional electromagnetic motor by using the ultrasonic motor as the drive unit, and is rotated and driven by the drive unit as the shield member. The use of a disk-shaped one that not only ensures the fineness and stability of the shielding adjustment but also provides a mechanism that constantly urges the shaft in one direction, resulting in a mechanical structural defect. It was possible to absorb the play in the bearing portion of the shielding member, which was eliminated, and the operation stability and reproducibility could be improved. In addition, in the ultrasonic motor which originally has a means for pressurizing the moving body, the stability of the operation is maintained without absorption of the backlash of the bearing portion to the motor.

Further, an ultrasonic motor capable of miniaturization is used as a driving unit, and a disc-shaped shielding member that is rotationally driven by the driving unit is provided. By forming the shape to be a surface that matches the backlash direction of the bearing portion of the shielding member,
In the disk-shaped variable shield mechanism of the present invention, which is characterized in that the backlash of the bearing portion does not affect the shield area, the disk-shaped variable shield mechanism can be made smaller than that of the conventional electromagnetic motor, and the drive portion can be used as the shield member. By using a disk-shaped one that is driven to rotate by the above, not only can the fineness and stability of the shielding adjustment be ensured, but the shape of the end of the shielding portion can be the same as the backlash direction of the bearing portion of the shielding member. Since the shielding member does not change even if the shielding member swings in the clearance direction of the bearing portion during movement, the shielding degree does not change.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an embodiment of an optical attenuator adopting a first method of the present invention.

2A and 2B are views for explaining the structure and operation of the piezoelectric actuator used in the embodiment example shown in FIG.

3A and 3B are diagrams showing an embodiment of an optical attenuator adopting the second method of the present invention, FIG. 1A is a sectional view thereof, and FIG. 2B is a development view of an outer peripheral surface of a disk-shaped shielding member.

FIG. 4 is a diagram illustrating a structure of a piezoelectric element used in the embodiment example shown in FIG.

5 is a diagram showing a positional relationship between a piezoelectric element and a vibrating body used in the embodiment example shown in FIG.

6A and 6B are diagrams showing a state of a standing wave of the vibrating body in the embodiment example shown in FIG. 3, in which FIG. 6A is a plan view and FIG.

FIG. 7 is an operation explanatory diagram of rotational drive in the embodiment example shown in FIG.

FIG. 8 is a diagram showing a conventional optical attenuator.

FIG. 9 is a diagram showing the prior art previously proposed by the applicant.

[Explanation of symbols]

16 Support member 17,118 Crimping member 18 spring 19 Guide member 32 Piezoelectric actuator 103 Shielding member 106, 321, 322 Piezoelectric element 107 Vibrating body 108 Protrusion 111, 112, 113 encoder constituent members 115 central axis 117 luminous flux 119 groove 201 Output side optical cable 204 Output lens 205 Input side optical cable 207 Input lens 325, 326 electrodes

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yukio Akiyama             1-8 Nakase, Nakase, Mihama-ku, Chiba City, Chiba Prefecture             Ico Instruments Co., Ltd. (72) Inventor Tomohiro Shimada             1-8 Nakase, Nakase, Mihama-ku, Chiba City, Chiba Prefecture             Ico Instruments Co., Ltd. F-term (reference) 2H041 AA02 AB02 AC08 AZ03 AZ05                 5H680 AA00 BB03 BB16 BC00 CC02                       DD02 DD15 DD23 DD35 DD65                       DD66 DD73 DD84 DD97 EE20                       EE22 FF08 FF32

Claims (4)

[Claims] 1. An ultrasonic motor capable of miniaturization is used as a drive unit, and a disc-shaped shield member rotationally driven by the drive unit is provided, in which the axis of the shield member is displaced in the direction of displacement of the shield member. A disk-shaped variable shielding mechanism characterized by absorbing backlash of a bearing portion by providing means for always urging in a direction coinciding with. 2. An eccentric disk is used as the disk-shaped shielding member, and the ultrasonic motor comprises a rotor which is the eccentric disk and an ultrasonic actuator for frictionally driving the outer peripheral surface thereof.
2. The disk-shaped variable shield mechanism according to claim 1, wherein the pressing means for the rotor also serves as means for constantly urging the shaft of the shield member in a direction coinciding with the displacement direction of the shield member. 3. An ultrasonic motor capable of miniaturization is used for a drive unit, and a disc-shaped shield member is rotatably driven by the drive unit, wherein an end portion of the shield portion of the disc-shaped shield member is provided. A disk-shaped variable shield mechanism, characterized in that the shield member is formed so as to have a surface that coincides with the play direction of the bearing portion so that the play of the bearing portion does not affect the shield area. 4. An ultrasonic motor comprises a rotor that is the eccentric disc and an ultrasonic actuator that frictionally drives the bottom surface of the rotor, and the end of the shield portion has a rectangular cross section provided on the outer peripheral end face of the disc-shaped shield member. The disk-shaped variable shielding mechanism according to claim 3, wherein