JPH04130681A - Piezoelectric actuator an optical switch device using same - Google Patents

Abstract

PURPOSE:To suppress vibration of a piezoelectric plate, to operate in a high accuracy at a high speed and to obtain an optical switch applied by an actuator by specifying positional relationship between the plate and a stopper. CONSTITUTION:A certain time is required until a voltage is applied to the electrode 5 of a piezoelectric plate to cause a bending deviation, a free vibration is generated at the plate 1 and the plate 1 is stopped, but the plate 1 collides with a stopper 2 provided at a position opposed to both sides of the plate 1 to suppress the free vibration. Here, when the length of the plate 1 is l, a distance from the tip of the plate 1 to the position provided with the stopper 3 is x, and the diameter of the stopper is a, the mounting position of the stopper 2 is set from the tip of the plate 1 a/2 or more and x/l<0.2, thereby greatly shortening a vibration suppressing time. Accordingly, an operation can be performed in a high accuracy at a high speed, thereby obtaining an optical switch which can switch at a high speed.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a piezoelectric actuator capable of high-speed and high-precision displacement, and an optical switch device using the actuator, which suppresses vibration of the piezoelectric plate and can operate at high speed and high precision. The purpose of the present invention is to obtain an actuator that can actuate the actuator as well as to realize an optical switch that applies this actuator. When the diameter of the stopper is a, the stopper is 872 or more from the tip of the piezoelectric plate with the center as a reference, and x/l<0.2
The feature is that it can be installed in a position where

[Industrial Application Field] The present invention relates to a piezoelectric actuator capable of high-speed and highly accurate displacement, and an optical switch device using the actuator.

In recent years, there has been a demand for actuators that can provide high-speed and highly accurate displacement, particularly for application to optical switch devices in optical transmission systems such as optical LANs.

In particular, in order to apply it to an optical switch, it is necessary to
There is a need for an actuator that has a speed of about 100 µm and an accuracy of about ±1 μm.

[Conventional technology]

Conventionally, piezoelectric actuators have been used that utilize bending displacement of a piezoelectric plate that changes depending on applied voltage.

There is a piezoelectric actuator that is provided with stoppers on both sides of the piezoelectric plate in order to suppress free vibrations that occur during operation of the piezoelectric plate.

In the optical switch using the actuator, a primary optical fiber is installed on the piezoelectric plate, and a plurality of secondary optical fibers are installed on the main body of the optical switch device. This optical switch applies a voltage to the piezoelectric plate to cause bending displacement, thereby moving the primary optical fiber. A switching operation is performed by aligning the tip axis with one of the secondary optical fibers.

[Problems to be Solved by the Invention] However, when attempting to operate a piezoelectric actuator provided with the stopper at high speed, although the free vibration can be suppressed, secondary vibration occurs when the piezoelectric plate collides with the stopper. Chattering vibrations such as resonance were occurring. The stopper cannot suppress this chattering vibration, and therefore the actuator has to be operated at a low speed.

In order to achieve high speed and high precision, a speed within 20 m5, preferably within LOMS, and operation with an accuracy of approximately ±1 μm are required, and for this purpose, vibration suppression is absolutely necessary.

Therefore, an object of the present invention is to obtain an actuator that can suppress the vibration of a piezoelectric plate and operate at high speed and with high precision, and to realize an optical switch using this actuator.

[Means to solve the problem]

FIG. 1 shows an explanatory diagram of the principle of the present invention.

A voltage is applied to the electrodes 5 installed on both sides of the piezoelectric plate 1, and bending displacement occurs in the piezoelectric plate 1.

In the present invention, stoppers 2 are provided on both sides of a piezoelectric plate 1, the length of the piezoelectric plate 1 is l, the distance from the tip of the piezoelectric plate 1 to the position where the stopper 2 is provided is x, and the diameter of the stopper is a.
When the piezoelectric plate 1 is
A/2 or more from the tip, and x/i! , <0.2.

[Effect]

A voltage is applied to the electrode 5 provided on the piezoelectric plate 1, causing the piezoelectric plate 1 to undergo bending displacement. At this time, free vibration occurs in the piezoelectric plate 1, and it takes a certain amount of time for the piezoelectric It1i1 to stop, but the piezoelectric It1i1 collides with the stoppers 2 provided at opposite positions on both sides of the piezoelectric plate 1. By causing this, the free vibration can be suppressed. Here, set the stopper installation position a/2 from the tip of piezoelectric plate 1.
With the above and by setting x/1<0.2, it becomes possible to significantly shorten the vibration suppression time.

〔Example〕

FIG. 2 shows an embodiment according to the invention.

In FIG. 2, 1 is a bimorph, 2 is a stopper, 3 is a load mass, 4 is a fixing base, 5 is an electrode, and 6 is a terminal. The explanation will be given below using FIG. 2.

What is shown in FIG. 2 is a piezoelectric actuator using a piezoelectric bimorph made of lead zirconate titanate (PZT) as a piezoelectric plate. One end of the bimorph 1 is fixed by a fixing base 4.

Gold is deposited on the surface of the bimorph 1, and this gold is used as the electrode 5. When a voltage is applied to this electrode 5, a bending displacement occurs in the bimorph 1 in response.

Stoppers 2 are located at positions facing both sides of the bimorph 1.
is provided. This stopper has the function of determining the position of the bimorph 1 and suppressing the vibration of the bimorph 1.

The tip of the stopper 2 is coated with epoxy resin. This is to provide insulation from the electrode 5 on the surface of the bimorph 1.

Further, the stopper 2 applies a load to the bimorph 1. The stopper 2 is attached 20 to 30 μm inside the position where the bimorph 1 should originally be. That is, the bimorph 1 is not just in contact with the stopper 2, but is in the same state as being pressed inward by 20 to 30 μm. When converted into force, this corresponds to approximately 100 mg. By applying this load, the influence of external vibrations applied to the bimorph 1 can be eliminated.

A load mass 3 is provided on the top of the bimorph 1. This load mass 3 is desirably made of an insulating material since the electrode 5 is provided on the surface of the bimorph 1.

The relationship between the time after voltage application and the vibration of bimorph 1 will be investigated. FIG. 3 is a graph showing the relationship between the time after voltage application and the vibration of the bimorph 1. 3A shows the graph when the stopper 2 and the load mass 3 are not present, FIG. 3B shows the graph when only the stopper 2 is present, and FIG. 3C shows the graph when both the stopper 2 and the load mass 3 are present. The bimorph length at this time is 29n+m, and the stopper position is provided 3III11 from the tip of the bimorph. If the length of bimorph 1 is l, and the distance from the tip of bimorph 1 to the stopper attachment position is x, then x/
1 is approximately 0.1. Here, the mounting position of the stopper 2 is determined based on the center of the stopper 2. The same applies below.

Comparing FIG. 3A and FIG. 3B, it can be seen that the time required for vibration damping is shorter in FIG. 3B, that is, in which the stopper 2 is provided. This is because the free vibration of the bimorph 1 is suppressed by the stopper 2. The load that the stopper 2 applies to the bimorph 1 also contributes to suppressing vibrations. However, since there is chattering vibration caused by the collision between the bimorph 1 and the stopper 2, it still takes a long time to stop.

Next, let's compare FIG. 3C with the aforementioned FIGS. 3A and 3B. In this case, it can be seen that in the case according to FIG. 3C, in which the stopper 2 and the load mass 3 are provided, the vibrations of the bimorph 1 are damped much faster than in the other two cases. In other words, this shows that the load mass 3 has the effect of absorbing chattering vibrations. At this time, the stopper 2 applies a preliminary load to the piezoelectric plate 1, and this load has the effect of suppressing vibration even more effectively.

Next, we investigated the relationship between x/l, that is, the stopper attachment position, and the vibration damping time, where the length of Bimorph I is 11 and the distance from the tip of Bimorph I to the attachment position of Stopper 2 is X. .

FIG. 4 is a graph showing the measurement results. In FIG. 4, the horizontal axis is x/1. , the vertical axis represents the vibration damping time. Furthermore, the broken line indicates the measurement results when the load mass 3 is not provided, and the solid line indicates the measurement results when the load mass 3 is 20 mg. The length ρ of the bimorph 1 is 301, the width t is 0.2 mm, and the width is 51.

When the shape of the bimorph l is as described above, the smaller χ/l is, the closer the stopper 2 is to the tip of the bimorph piezoelectric plate 1, both with and without the load mass 3 as shown in FIG. The vibration damping time becomes exponentially shorter as the distance increases.

Comparing those with x/l of 0.2 or more and those with less than 0.2, it can be seen that the vibration damping time is shorter in those with x/l less than 0.2. Therefore, by setting the mounting position of the stopper 2 in the range of x/f<0.2, it is possible to obtain the effect of reducing the vibration damping time.

At this time, the stopper 2 may be located just at the tip of the bimorph 1, that is, x/l=0.

Although it is conceivable that the tip of the bimorph 1 may be damaged by the collision with the stopper 2, this problem can be solved by providing the tip of the bimorph 1 with a protective cover made of, for example, a piece of metal.

However, there may be a case where an error in dimensions or the like occurs and the stopper 2 does not collide completely and the vibrations are not suppressed. Therefore, it is desirable that the stopper diface completely collide with the bimorph 1.

Therefore, if the diameter of stopper 2 is a, the lower limit of the stopper attachment position is a / from the tip of bimorph 1.
Setting it to 2 will give a good effect. Using specific numerical values, if the diameter of the stopper 2 is 1rr1m, the lower limit of the stopper attachment position is 0.5 from the tip of the bimorph 1.
The position is mm.

Further, when comparing the case where the load mass is provided and the case where the load mass is not provided, even in this case, the vibration of the bimorph 1 can be damped more effectively when the load mass is provided on the bimorph 1.

The relationship between the mounting position of the stopper 2 and the vibration damping time when the length, thickness, etc. of the bimorph 1 is changed is as shown in the fourth example, although there are slight differences in the specific numbers.
It shows almost the same trend as shown in the figure. - For example l = 25 mm, t = 0.2 + am, width 5 mm,
When the load mass is 20 mg, x/I! , = 0.3, the damping vibration time is 13 m5, and when x/ff1 = 0.5, the vibration damping time is 40 m5, and the curve of the vibration damping time shows changes similar to those shown in FIG. The graph is shown in FIG.

Otherwise, l = 2On+m, t = 0.2mm,
When the width is 5mm and the load quality is ffi2omg, x/I! ,=
0.2, a curve similar to that shown in FIG. 4 is drawn passing through the position where the vibration damping time is 5 ms.

Similarly, 1 = 20mm, t = 0.3mm, width 5m
m, when the load mass is 20 mg, the vibration damping time is 4 ms at x/(2-0,2, (1 = 40 mm, t = 0.2
mm, width 5II 1m, load mass 20mg, x/j
2=0.2, vibration damping time is 22m5, f=40mm,
t = 0.3mm, width 51III 111 load mass 20
mg, the vibration damping time is 19m5 at x/l=0.2
, and draw curves similar to those in Figure 4. These curves are also shown in the graph of FIG.

Therefore, the mounting position of the stopper 2 is at least a/2 and x/l from the tip of the bimorph 1 with the center as a reference.
It can be seen that the vibration damping time of the bimorph 1 can be most effectively reduced by setting the value within the range of <0.2.

Regarding the size of bimorph 1, its length l is 20~
A range of 40 mm is desirable. This is because if l is 20 mm or less, the voltage for operating the bimorph 1 must be increased, and if l is 40 mm or more, it is too large. Moreover, its thickness t is 0.2 to 0
．． A range of 31 is desirable. This is because if it is more than 0.3 ml11, a large operating voltage is required, and if it is less than 0.2 mm, it becomes unstable and becomes weak against external vibrations.

FIG. 6 shows an optical switch device to which a piezoelectric actuator according to the present invention is applied. FIG. 7 is a three-sided view of the optical switch device according to this embodiment.

Moreover, FIG. 8 is an enlarged view of the attachment part of the optical fiber 7.8.9. In Figures 6 to 8, 1 is a paimojirefu, 2 and 2 are stoppers, 3 is a load mass, 4 is a fixed base,
5 is an electrode, 6 is a terminal, 7 is a first optical fiber, 8 is a second optical fiber.
9 is the third optical fiber, 10.11 is the optical switch device main body cover 12 is the optical switch main body, 13
is a first fiber guide, and 14 is a second fiber guide. Note that in FIG. 6, one cover 11 is omitted for ease of viewing. The explanation will be given below using FIGS. 6 to 8.

One end of the bimorph 1 is fixed by a fixing base 4.

Further, on the upper part of the bimorph 1, a load mass 3 made of silicon and a first fiber guide 1 having a figure-7 groove 15 are provided.
3 is installed. The first optical fiber 7 is installed in the groove 15 of the first fiber guide 13 . Stoppers 2.2° are installed on covers 10° and 11, respectively.

By applying a voltage to the electrode 5 and operating the bimorph 1, the first optical fiber 7 is directly moved. The optical switch body 11 also has a second fiber guide 14 having a 7-shaped groove 16,17.
Second and third optical fibers 8.9 are installed in the grooves 16.17, respectively.

Normally, the first optical fiber 7 and the second optical fiber 8 are arranged so that their optical axes coincide with each other. When a voltage is applied to the electrode 5 and the bimorph 1 operates, the first optical fiber 7 installed on the bimorph 1 moves, thereby causing light to flow between the first optical fiber 7 and the third optical fiber 9. Arranged so that the axes match. In this way, by moving the first optical fiber 7 by the bending displacement of the bimorph I, the optical path is changed and switching is performed.

Stoppers 2, 2゛ are the covers 10゜11 of the switch body.
It is set in. The stopper attachment position is a/2 or more from the tip of bimorph 1, and x/e <0.
Needless to say, it is 2. The tip of this stopper 2°2° is coated with epoxy resin. This is to obtain electrical insulation from the bimorph 1. The distance between the stoppers 2 and 2' is 170 to 200 μm.

In this optical switch device as well, the stoppers 2, 2' are attached about 20 to 3 oIIm inside the stop position of the bimorph 1, and a load is applied to the bimorph 1. Thanks to this load, even if external vibrations are applied to the switch body, it is possible to eliminate the effect on the device.

By adopting such a configuration, high-speed operation of about 10 m5 is possible, and since there is little vibration, fiber positioning can be performed with high accuracy of about ±1 μm. Furthermore, bimorph 1 is removed by stoppers 2 and 2.
Since the load is applied to the oscillator, the influence of external vibration can also be eliminated.

(Other Examples) (1) FIG. 9 shows an optical switch device having a plurality of optical fibers on a bimorph 1. In Figure 9,
18, 19, 20, 21, 22 are optical fibers, 23 is a first fiber guide, and 24 is a second fiber guide. The same parts as in other figures are given the same reference numerals. Further, FIG. 10 shows the arrangement of optical fibers and the optical path of the optical switch device according to FIG. 9.

The first fiber guide 23 is provided on the top of the bimorph 1. The fiber guide 24 of the second option is provided in the optical switch device main body 12. The first fiber guide 23 is provided with three V-shaped grooves 25, 26, 27, and the second fiber guide 24 is likewise provided with three V-shaped grooves 28, 29, 30. There is.

Further, a load mass 3 for absorbing chattering vibrations is provided above the bimorph 1. Further, a stopper 2 is provided on the switch body cover 10. This stopper 2 is according to the present invention, and its mounting position is a
/2 or more, x/l<0.2. In FIG. 10, the main body cover 11 is omitted for easy viewing, but the main body cover 11 also has a stopper 2, similar to the optical switch device shown in FIG. 7, which has the same basic configuration.゛ is provided.

The primary side optical fiber 1 is inserted into the V-shaped grooves 25, 26, and 27 in order.
8, one end of an optical fiber 19 and an optical fiber 20 are installed, respectively. Further, the other end of the secondary side optical fiber 20, an optical fiber 21, and an optical fiber 22 are installed in the V-shaped grooves 28, 29, and 30, respectively. The optical fiber 21 and the optical fiber 22 input optical signals to the optical switch device,
Optical fiber 18 and optical fiber 19 output optical signals from this optical switch device.

The cross sections of each optical fiber are arranged to face each other. The installation condition of the optical fiber is the first
0 is shown in Figures A and B. Figure 10A shows the arrangement of optical fibers and the state of the optical path when voltage is applied to bimorph 1, and Fig. 10B shows the arrangement of the optical fibers and the state of the optical path when no voltage is applied to bimorph 1. ing. In each figure, (a) shows the arrangement of optical fibers, and (b) shows the optical path.

The symbols attached to (b) represent the respective numbered optical fibers.

To explain the arrangement of the optical fibers shown in Figure 1A and B, the direction where the primary side optical fiber is installed is 31, and the side where the secondary side optical fiber is installed is 32. In this case, the optical fibers 19 and 21 are from the 31 side, and the optical fibers 18 and 22 are from the 32 side.
It is extending from the side. The optical fiber 20 has one end connected to the first
The other end is connected to the second fiber guide 23, and the other end is connected to the second fiber guide 24, serving as a bypass.

When voltage is applied to bimorph 1, optical fiber 1
The optical axes of the optical fiber 8 and the optical fiber 21 and the optical fiber 19 and the optical fiber 22 are made to coincide with each other.

When no voltage is applied to the bimorph 1, the second fiber guide 2 of the optical fiber 18 and the optical fiber 20
The optical axes of the optical fibers 19 and 21, and one end of the optical fiber 20 on the first fiber guide 23 side coincide with the optical axes of the optical fibers 22.

By such an operation, the optical path changes as shown in FIGS. 10A and 10B. When voltage is applied, light input from the 31 side through the optical fiber 21 is output to the 32 side through the optical fiber I8, and light input from the 32 side through the optical fiber 22 is output to the 31 side through the optical fiber 19.

When the bimorph 1 does not operate, the light input from the 31 side through the optical fiber 21 is outputted again through the optical fiber 19 to the 31 side. On the other hand, the light input from the optical fiber 22 side through the optical fiber 22 enters one end of the first fiber guide 23 example of the optical fiber 20, and enters the optical fiber 18 from one end of the optical fiber 20 on the second fiber guide 24 side.
The signal enters the signal and is output to the 32 side again.

If the piezoelectric actuator according to the present invention is used for optical switch devices that perform such operations, bimorph l
It is possible to suppress the vibrations generated during the operation of the bimorph 1 and the chattering vibrations generated when the bimorph 1 collides with the stoppers 2 and 2 degrees.

Therefore, it is possible to change a plurality of optical paths simultaneously at high speed and with high precision.

Note that the number of optical fibers and the arrangement method are not limited to those described in this embodiment.

(2) When using a piezoelectric bimorph in which the metal plate 33 shown in FIG. 11A is sandwiched between a plurality of ceramics 34 and 35, the occurrence of hysteresis shown in FIG. 11B becomes a problem. This hysteresis makes highly accurate positioning difficult.

The piezoelectric plate using poled lithium niobate (LiNb0+) 36 shown in FIG. 12A has no hysteresis. Therefore, it is very convenient for actuators used in things that require high precision, such as optical switches. By using this LiNb0+, the actuator of the present invention can position the fiber with even higher accuracy.

〔Effect of the invention〕

As described above, by using the present invention, it is possible to suppress the vibration of the piezoelectric plate and realize a piezoelectric actuator that can operate at higher speed and higher precision than before, as well as an optical switch that can perform high-speed switching. becomes possible.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the principle of the present invention, Fig. 2 is an embodiment according to the present invention, Fig. 3A is the vibration of the piezoelectric plate when there is no stopper or load mass, and Fig. 3B is when only the stopper is provided. Figure 3C shows the vibration of the piezoelectric plate when both the stopper and the load mass are installed, and Figure 4 shows the change in the vibration damping time of the piezoelectric plate in this example when the stopper mounting position is changed. , FIG. 5 shows the change in vibration damping time of piezoelectric plates of different dimensions when the stopper attachment position is changed, FIG. 6 is a perspective view of an optical switch device using a piezoelectric actuator according to an embodiment, and FIG. The figure is a three-sided view of an optical switch device using a piezoelectric actuator according to one embodiment, FIG. 8 is an optical fiber attachment part in the optical switch device, FIG. 9 is an optical switch device according to another embodiment, and FIG. 10A is a Figure 10B shows the arrangement of optical fibers and the optical path when a voltage is applied to the bimorph. Figure 11A shows the arrangement of the optical fibers and the optical path when no voltage is applied to the bimorph. Figure 11B is the voltage-displacement characteristic of the ceramic piezoelectric plate, Figure 12A is the lithium niobate piezoelectric plate,
FIG. 12B shows the voltage-displacement characteristics of the lithium niobate piezoelectric plate. In all the figures, the same parts are given the same reference numerals. In the figure, 1 is a piezoelectric plate, 2 is a stopper, 3 is a load mass, 5 is an electrode, and 7.8.9 is an optical fiber. X-force Nutoga \°M Nuri attached to the slave who made J1 bond /) Piezoelectric 4
Anti-driving force A praise of my friend's reward 1st ruri 1st map 5 fibers of light + 5 fibers of light that climbs to 1st /) 3rd direction is the sound p th υ river] Child /) Others f) Ability color classification Switch device No. 1 Ceramic 2 piezoelectric plate A (f) Lamiraph piezoelectric a (f) Electric L-Tomo et al. 11 Fig. B Fig. B

Claims (5)

[Claims] 1. A piezoelectric plate (
1), and stoppers provided at positions facing both side surfaces of the piezoelectric plate (1), which position the piezoelectric plate (1) and suppress free vibrations generated when the piezoelectric plate (1) operates. (2) In the piezoelectric actuator having the following, the length of the piezoelectric plate (1) is l, the distance from the tip of the piezoelectric plate (1) to the mounting position of the stopper (2) is x,
When the diameter of the stopper is a, the stopper (
2) A piezoelectric actuator, characterized in that it is attached at a position a/2 or more from the tip of the piezoelectric plate (1) with the center as a reference, and x/l<0.2. 2. 2. The load mass (3) according to claim 1, further comprising a load mass (3) installed on the piezoelectric plate (1) to suppress chattering vibrations generated when the piezoelectric plate (1) collides with the stopper (2). piezoelectric actuator. 3. The piezoelectric actuator according to claim 1 or 2, characterized in that the piezoelectric plate (1) is made of polarization-inverted lithium niobate. 4. A first fiber guide (13) provided on the top of the piezoelectric plate (1), a first optical fiber (7) installed in the first fiber guide (13), and an optical switch device main body (12). ) on the second fiber guide (14), and on the second fiber guide (14), facing the first optical fiber (6), the first optical fiber (6) is provided on the second fiber guide (14).
) and a plurality of optical fibers (8, 9) provided so as to have the same optical axis.
An optical switch device using the piezoelectric actuator according to 2 or 3. 5. The first fiber guide (13) has a plurality of primary optical fibers (18, 19, 20), and the primary optical fibers (18, 19, 20) are connected to the second fiber guide (14). Multiple installed secondary optical fibers (20
, 21, 22), the secondary optical fiber (2
0, 21, 22), and the piezoelectric plate (1) is arranged to have the same optical axis as each of the primary optical fibers (18, 19).
, 20), switching of a plurality of optical paths is performed simultaneously.