JPH0659200A - Motor-driven tunable filter module - Google Patents

Abstract

PURPOSE:To provide a motor-driven tunable filter module capable of being set to a prescribed center wavelength corresponding to a prescribed inclination angle according to the rotation angle of an ultrasonic motor by positioning and fixing accurately a filter hold base holding a filter having narrow band dividing characteristics to an ultrasonic output shaft. CONSTITUTION:This motor-driven tunable filter module is constituted so that a base member 14 holding the narrow band filter 20 is fixed to the output shaft 32 of the ultrasonic motor 30 attachably/detachably, and at this time, the filter hold base member 14 is fixed in the axial center direction of the output shaft 32 attachably/detachably, and rotation prevention fixing means 17, 18, 36 preventing relative rotating deviation around the axial center are provided on the output shaft 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric tunable filter module having a narrow band filter attached thereto, and in particular, the narrow band filter is stably attached to an output shaft of an ultrasonic motor through its holding base. The present invention relates to a mounting structure for positioning.

[0002]

2. Description of the Related Art A narrow band filter is an important element in the field of optical communication and measurement, and in particular, a dielectric multilayer interference filter has a characteristic that the band characteristic does not change with temperature and humidity changes. Has the characteristics that it does not change over time and that the center wavelength can be changed by tilting it. Electric tunable modules that use such narrow band filters are Since a large demand is expected for the realization of a subscriber optical communication system by division multiplexing transmission, it is in the stage of earnest research, development.

The wavelength division multiplex transmission system uses a low loss characteristic of an optical fiber over a wide wavelength range to transmit a large number of optical signals through a single optical fiber, which will be briefly described with reference to FIG. In FIG. 9, different optical signals are
The light emission wavelengths are respectively applied to different light emitting elements A1, A2, ... Then, the lights from the light emitting elements A1, ... An are incident on the star coupler (combiner) S and are combined in the coupler S. Then, the plurality of optical signals branched from the coupler S are transmitted to the receiving side by one optical fiber. That is, these optical signals are tuned on the receiving side by the wavelength tunable filters F1, F2 ,. ． ． The necessary wavelengths are selectively separated by Fn, and then the light receiving elements R1 and R
2 ,. ． ． Light enters Rn.

The light receiving elements R1, R2 ,. ． ． R
A predetermined signal for communication is obtained by being converted into an electric signal by n. As described above, in the wavelength division multiplexing transmission system, the optical multiplexer and the optical demultiplexer are extremely important elements because they are coupled and separated in order to transmit a plurality of optical signals through one fiber.

A narrow band filter is attached to the above optical demultiplexer,
If you use an electric tunable module that has an ultrasonic motor as a drive system, it is possible to perform high precision optical demultiplexing.
Also, high-speed switching of channels is possible. And
It has various advantages such as excellent environmental resistance and cost reduction.

Now, referring to FIG. 10, considering the relationship between the center wavelength of the narrow band filter and the tilt angle, that is, the tilt angle from the plane perpendicular to the filter surface of the optical signal in the direction of incident light, the same graph diagram is shown. Represents the transmittance (dB) of the filter on the vertical axis and the transmission wavelength (μm) on the horizontal axis. The tilt angles of the single filter with respect to the incident direction of the optical signal are 0 ° and 2 respectively. The center wavelength when variously changed, such as .5 °, ... 23 °, is shown. As shown in the characteristic diagram, in order to change the center wavelength of a filter having a half-value width of 1 nm with an accuracy of 0.1 nm, indexing accuracy with an angle accuracy of 0.03 degrees is required. Considering that the filter is also applicable, it is necessary to have indexing accuracy with which an angle can be set with an accuracy of 0.01 degree.

When the tilt angle of the filter with respect to the optical signal increases, the amount of change in the center wavelength increases, and the proportional relationship between the two disappears.

Referring to FIG. 7, there is shown a general structure of an electric tunable module having a structure in which a filter having a predetermined narrow band filtering characteristic is attached to an output shaft of an ultrasonic motor. In this module, an ultrasonic motor 2 is provided inside a housing 1, one end side of an output shaft 3 thereof projects from the upper surface of the housing 1, and a holding base member 4 is provided on the protruding shaft portion.
The narrow band filter 5 is fixed via the.

An encoder 7 having a rotating disk 6 is provided on the lower shaft 3a side of the output shaft 3 of the ultrasonic motor 2 so that the rotation angle of the output shaft 3 of the ultrasonic motor 2 can be detected precisely. It is configured. With this configuration, the ultrasonic motor 2 itself can control the rotation angle of the output shaft 3 with an accuracy of 0.01 degree, so that the input / output relationship of the motor 2 can be accurately measured. If it is stored in the control system, the center of the filter is controlled by controlling the rotation angle of the ultrasonic motor for turning the filter by outputting a command pulse from the control device having a computer based on the stored data. The wavelength can be controlled.

However, with the configuration shown in FIG. 7, when tuning the wavelength of the filter over a wide bandwidth, the shift amount of the center wavelength of the narrow band filter is limited. It is necessary to replace the filter attached to the output shaft of the sonic motor with a filter suitable for the bandwidth.

That is, a filter in which the relationship between the center wavelength and the tilt angle is measured is prepared and stored in advance, and the filter mounted on the output shaft of the ultrasonic motor is selected from the stored filters and replaced. . Then, the relationship between the central wavelength and the tilt angle is input to and stored in the control system, and the central wavelength is controlled by the command pulse from the control device.

[0012]

However, as shown in FIG. 8, the output shaft 3 of the ultrasonic motor 2 and the filter holding base member 4 are set screws 9 penetrating the filter holding base member 4 from the side surface. To simply form the flat portion 3b on the outer surface of the cylindrical motor output shaft 3,
Since it has a structure that is fixed at the tip of the set screw 9,
Relatively low mounting accuracy, fixing with 0.01 degree accuracy,
It is impossible to position. Therefore, when the filter is replaced, there is a disadvantage that the center wavelength of the filter cannot be set according to the input data.

That is, in the fastening structure using the set screw 9, the contact point between the motor output shaft 3 and the tip 9a of the set screw 9 penetrating the filter holding base member 4 is at the shaft flat portion 3.
Although it becomes a point position where one point in the plane of b and the tip 9a of the set screw come into contact with each other, the fastening method at such one point position is unstable, and the filter holding base material 4 cannot be securely fastened. This is due to a defect that cannot be done.

Therefore, an object of the present invention is to eliminate the above-mentioned structural defect in the conventional electric tunable module in which a narrow band filter is fixed to the output shaft of the ultrasonic motor.

[0015]

In view of the above object, the present invention relates to an electric tunable module in which various narrow band filters are attached to an output shaft of an ultrasonic motor via a holding base member thereof. On the output shaft of the ultrasonic module, the base member holding the narrow band filter can be removably fixed in the axial direction of the output shaft, and the base member is fixed to the output shaft. The electric tunable module is provided with anti-rotation fixing means capable of preventing relative rotation deviation around the axis.

According to a preferred embodiment of the present invention, the above-mentioned detent fixing means is provided with a V groove axially extended and cut on the output shaft of the ultrasonic motor, and from the side surface of the filter base. It is composed of a rotation fixing screw having a screw head which is screwed into a screw hole penetrating the inner peripheral surface of a fitting hole with the output shaft and which projects and abuts against the V groove.

According to another embodiment of the present invention, the detent fixing means includes a star-shaped outer peripheral surface formed on an outer periphery of an output shaft of the ultrasonic motor and an output shaft of the filter base. The star-shaped outer peripheral surface of the output shaft and the star-shaped fitting hole of the complementary shape are formed on the inner peripheral surface of the dowel hole.

According to still another preferred embodiment of the present invention, the detent fixing means is provided at the fitting portion between the cylindrical outer peripheral surface of the output shaft of the ultrasonic motor and the circular hole of the filter base. It is configured by a tapered hole penetrating from the side surface of the base and a taper pin attached to the tapered hole.

[0019]

According to the above-mentioned structure, the filter base to which the narrow band filter is attached can be freely inserted into and attached to the output shaft of the ultrasonic motor, and can be removed at the time of replacement, and the anti-rotation effect can be prevented. Therefore, once the filter base is attached and fixed to the motor output shaft, there is no deviation around the motor output shaft, and therefore the rotation angle of the output shaft of the ultrasonic motor is controlled by the control device. As a result, it becomes possible to perform positioning with respect to the optical signal input direction with an accuracy of 0.01 degree.

The present invention will be described below in more detail based on the embodiments shown in the accompanying drawings.

[0021]

1 is an exploded perspective view showing a mounting structure of an ultrasonic motor and a filter base in an electric tunable filter module according to an embodiment of the present invention, and FIG. 2 is a sectional view of the mounting structure. FIG. 3 is an exploded perspective view showing a mounting structure of an ultrasonic motor and a filter base in an electric tunable filter module according to another embodiment of the present invention. FIG. 4 is a sectional view of the mounting structure. FIG. 6 is an exploded perspective view showing a mounting structure of an ultrasonic motor and a filter base in an electric tunable filter module according to still another embodiment of the present invention. FIG. 6 is a sectional view of the mounting structure. FIG. 8 is a schematic view showing the overall configuration of an electric tunable filter module, and FIG. 8 is an ultrasonic motor and a filter base in an electric tunable filter module according to a conventional technique. Sectional view showing a mounting structure of FIG. 9,
FIG. 1 is a schematic mechanism diagram illustrating a wavelength division multiplexing transmission system.
0 is a graph illustrating the relationship between the center wavelength of the bandpass filter and the tilt angle.

Referring now to FIG. 1, the electric tunable module according to the present embodiment has a filter holding base 1
4, the filter holding base 14 has a configuration including a barrel portion 15 having a cylindrical shape and a holding frame portion 16 of the filter 20 formed at a predetermined position on the top of the barrel portion 15. There is. The body portion 15 of the filter holding base 14
A shaft support hole 17 is formed in the shaft support hole 17 from the bottom side, and a screw hole 18 is formed in the shaft support hole 17 from the side surface of the body portion 15.

The filter holding base 14 holding the filter 20 is formed so that it can be inserted into and removed from the output shaft 32 of the ultrasonic motor 30 through the shaft support hole 17, and at the time of insertion, the side surface of the output shaft 32. V-groove 34 extending in the axial direction
And the screw hole 18 are aligned and fitted. That is, by matching the V groove 34 and the screw hole 18, the filter 20
It is possible to uniquely determine the mounting positional relationship between the filter holding base 14 having the above and the output shaft 32 of the ultrasonic motor 30.

After the filter holding base 14 is attached, the set screw 36 is screwed into the screw hole 18 of the filter holding base 14, and the spherical head 36 formed at the tip of the set screw 36.
The filter holding base 14 is fixed and fixed to the output shaft 32 by engaging a with the opposite surfaces of the V groove 34 of the output shaft 32 while giving a rotation preventing effect to the output shaft 32. FIG. 2 is a cross-sectional view showing a mounting state of the filter holding base 14 fixed in this way and the output shaft 32 of the ultrasonic motor 30.

Here, the included angle of the V groove 34 formed on the output shaft 32 of the ultrasonic motor 30 is approximately 90 °.
And the surface accuracy of the facing surface is such that the ten-point average roughness (Rz) is about 0.05z in terms of positioning when the filter holding base 14 is attached or detached. Is effective in obtaining the reproducibility of.

Further, the screw hole 1 of the filter holding base 14
8 is preferably formed in a precision female screw hole of about M2 in the metric system, and the head portion 36a of the set screw 36 has a radius of 2
It is preferable to form a spherical portion of 0 mm in order to obtain stable fastening property.

The filter holding base 14 may have a filter 20 having a required demultiplexing bandwidth in a narrow band width and may be attached, for example, a demultiplexer having a center wavelength of 1560 nm. If an electronic tunable filter module is required, the center wavelength 156
The filter base 14 holding the 0 nm filter 20 is inserted into the output shaft 32 of the ultrasonic motor 30, and the set screw 3
Fasten at 6.

According to this structure, an electric tunable filter module having a required band can be formed by replacing and attaching the filter holding base 14 having a filter element having another center wavelength as required. Needless to say.

3 and 4 show an electric tunable filter module having a mounting structure according to another embodiment of the present invention. As is apparent from FIG. 3, in the present embodiment, the filter holding base 14 holding the filter 20 in the holding frame portion 16 has a polygonal shaft support hole 17a which is axially recessed from the bottom surface of the body portion 15. On the other hand, the outer peripheral surface of the output shaft of the ultrasonic motor 30 is formed as a polygonal shaft 32a whose cross section perpendicular to the axis is completely complementary to the cross section of the polygonal shaft support hole 17a of the body portion 15 described above. There is. In particular,
In the illustrated example, the star-shaped complementary fitting structure formed by electric discharge machining enables highly accurate fitting coupling and positioning, and in particular, according to the present embodiment, fastening by a set screw is omitted. Even with this, it is possible to obtain the anti-rotation effect, and it is possible to simplify the attachment / detachment when the filter holding base 14 is replaced.

In the case of the complementary fitting structure of the polygonal shaft support hole and the polygonal shaft according to this embodiment, the polygonal shaft support hole 17a is formed in the body portion 15 of the filter holding base 14. , The positional relationship with the holding frame portion 16 of the filter 20 is uniquely determined in advance by using an appropriate jig or the like, and the filter holding base 14 is connected to the output shaft 3 of the ultrasonic motor 30.
It is preferable that a fixed positioning setting be obtained when it is inserted into 2a. Also in the case of this embodiment, the filter holding base 14 provided with various filters 20 having the demultiplexing characteristic of the required bandwidth can be detachably attached to the output shaft 32a of the ultrasonic motor 30 easily. Yes, and
Due to the anti-rotation effect, the filter 20 and the output shaft 32 are always
It is possible to uniquely set the positional relationship with a. Therefore, the central wavelength can be precisely set based on the relationship between the central wavelength and the tilt angle in which the rotation angle of the ultrasonic motor 30 is stored in advance. Is possible.

FIGS. 5 and 6 show an example of an electric tunable filter module having still another mounting structure according to the present invention. In this embodiment, a shaft support hole 17 is provided axially recessed from the bottom surface of the body portion 15 of the filter holding base 14, and a tapered hole 19a is formed from one side surface through the coaxial support hole 17 and the other side surface side. The taper pin 37 is formed so that it can be inserted into the taper hole 19a.

On the other hand, when the output shaft 32 of the ultrasonic motor 30 is also formed with a taper hole 19b having the same taper angle and the filter holding base 14 is inserted and mounted on the output shaft 32, the taper hole on the body portion 15 side is just formed. 19a and the taper hole 1 on the output shaft 32 side
9b and 9b are formed so as to match and match. Therefore,
If the taper pin 37 is inserted and attached at the time of fitting the both, a unique positioning connection state having a rotation preventing effect can be obtained between the filter holding base 14 holding the filter 20 and the output shaft 32 of the ultrasonic motor 30. Therefore, it is possible to mount the filter holding base 14 with high accuracy without any misalignment, so that the central wavelength of the filter 20 can be accurately obtained according to the rotation of the ultrasonic motor 30. It is possible to form a bull filter module.

[0033]

As can be understood from the above description of the embodiments, according to the present invention, various narrow band filters are attached to the output shaft of the ultrasonic motor through the holding base member thereof. In the tunable filter module, the holding base member holding the narrow band filter can be removably fixed to the output shaft of the ultrasonic motor in the axial direction of the output shaft, and the holding base member is fixed. Since the rotation stop fixing means capable of preventing relative rotation deviation around the output shaft with respect to the output shaft is provided, the positional relationship between the narrow band filter and the output shaft of the ultrasonic motor is always unique. Therefore, if the relationship between the center wavelength and the tilt angle is set in advance in the control system, the rotation angle of the ultrasonic motor is controlled by the command pulse according to the relationship, and the filter Set to a predetermined inclination angle with respect to the input optical signal, obtained electric tunable filter module to obtain a demultiplexing capability of the desired center wavelength.

Further, by using such an electric tunable filter module as a demultiplexer of an optical communication system, it is possible to construct and use a demultiplexer having highly accurate transmission characteristics.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a mounting structure of an ultrasonic motor and a filter base in an electric tunable filter module according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the mounting structure.

FIG. 3 is an exploded perspective view showing a mounting structure of an ultrasonic motor and a filter base in an electric tunable filter module according to another embodiment of the present invention.

FIG. 4 is a sectional view of the mounting structure.

FIG. 5 is an exploded perspective view showing a mounting structure of an ultrasonic motor and a filter base in an electric tunable filter module according to still another embodiment of the present invention.

FIG. 6 is a cross-sectional view of the mounting structure.

FIG. 7 is a schematic diagram showing the overall configuration of an electric tunable filter module.

FIG. 8 is a sectional view showing a mounting structure of an ultrasonic motor and a filter base in an electric tunable filter module according to a conventional technique.

FIG. 9 is a schematic mechanism diagram illustrating a configuration of a wavelength division multiplexing transmission system.

FIG. 10 is a graph illustrating the relationship between the center wavelength of the bandpass filter and the tilt angle.

[Explanation of symbols]

 14 ... Filter holding base 15 ... Body part 16 ... Holding frame part 17 ... Shaft support hole 17a ... Polygonal shaft support hole 18 ... Screw hole 19a ... Tapered hole 19b ... Tapered hole 20 ... Filter 30 ... Ultrasonic motor 32 ... Output shaft 32a ... Output shaft 34 ... V groove 37 ... Taper pin

Claims (1)

[Claims] 1. An electric tunable module in which various narrow band filters are detachably fixed to an output shaft of an ultrasonic motor through a holding base member thereof, wherein the output shaft of the ultrasonic motor is The holding base member holding the narrow band filter can be fixed in the axial direction of the output shaft so that the holding base member can be freely inserted and removed, and the holding base member is
An electric tunable filter module, characterized in that rotation stop fixing means capable of preventing relative rotation deviation about the output shaft with respect to the output shaft is provided.