JP4209622B2 - Piezoelectric actuator having displacement expansion function and electronic device having the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric actuator as a high-accuracy positioning actuator, and more particularly to an actuator having an optical path switching and adjustment function suitable for use in the field of optical communication or information recording devices.
[0002]
[Prior art]
Piezoelectric actuators are used as high-precision positioning actuators that are compact and have strong driving force. A typical form of a piezoelectric element used as a drive source of this piezoelectric actuator is shown in FIG. In the piezoelectric element shown in A, a plurality of plate-like piezoelectric bodies whose polarization direction is the thickness direction are stacked so that the polarization directions are alternately opposite to each other, and the contact surface is back-to-back with the contact surface electrode facing the polarization direction. By applying a voltage between the electrodes, the piezoelectric element expands and contracts in the stacking direction by the piezoelectric longitudinal effect.
[0003]
The piezoelectric element of B is a form in which two plate-like piezoelectric bodies whose polarization direction is the thickness direction are overlapped as shown in 1) with the polarization directions different by 180 degrees, and a voltage is applied between the electrodes. Then, since the polarization directions are opposite, one piezoelectric body expands and the other piezoelectric body contracts. 2) When the upper plate is contracted and the lower plate is extended with one end of the plate-like piezoelectric member fixed as shown in 2), the other end of the plate-like piezoelectric member warps upward as shown in 4). On the contrary, when the upper plate is extended and the lower plate is contracted, the other end of the plate-like piezoelectric body warps downward as shown in 3).
[0004]
A piezoelectric actuator using such a piezoelectric element as a drive source has been limited in use because the generally obtained displacement is extremely small. There are also some piezoelectric actuators that have been conceived to obtain a large displacement, and examples thereof include (A) Mooney actuator and (B) cymbal actuator as shown in FIG. This is a structure in which brass end caps are attached to both sides of a piezoelectric element that contracts when voltage is applied, and the distance between the ends of the end cap, which is an elastic body, is narrowed and the central part is expanded by contraction of the piezoelectric element. do. As the piezoelectric element serving as a drive source of this piezoelectric actuator, the rod-shaped piezoelectric element shown in FIG. 7A can be used, or a disk-shaped piezoelectric element in which layers are concentrically stacked can also be used. Since this piezoelectric actuator has an end cap on both sides and can obtain two displacements in opposite directions at the same time, it is an actuator with good displacement conversion efficiency, but it has a difficulty that a support structure is difficult.
[0005]
In addition, there are also known piezoelectric actuators with an enlargement mechanism as shown in FIGS. 9A to 9F. (A) is a parallel plate type translation mechanism obtained by enlarging the lateral displacement of the piezoelectric element at the free end tip using a parallel plate, and (b) is a radiation plate that includes a radiation plate and causes rotational displacement at the top. (C) is a lever-type displacement enlarging mechanism in which a cut portion is provided in an elastic body and the displacement is enlarged by this principle, (d) is one end fixed to both ends of a rod-like piezoelectric element via elastic hinges, and the other Is an elastic hinge mechanism that transmits the displacement while allowing lateral displacement, (e) is a symmetrical type with piezoelectric elements that extend and contract in the same direction on both sides of the elastic member. A parallel plate type translation mechanism, and (f) is a symmetric type radiation plate type rotation mechanism that has the radial plate type rotation mechanism of (b) on both sides and obtains a large rotational force. However, these are accompanied by a problem that they increase in size because they are provided with a displacement enlarging mechanism.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a piezoelectric actuator having a displacement enlarging function that can be easily supported without increasing the size of the mechanism with a simple structure.
[0007]
[Means for Solving the Problems]
The piezoelectric actuator having a displacement expansion function according to the present invention includes two piezoelectric elements each having one end fixed, a bend in which both ends are fixed to the other end of the two piezoelectric elements, and a member to be displaced is attached to a central position. It is composed of a mold flexible member, and a large displacement is obtained at the central portion by extending and contracting the distance between both ends of the flexible member by driving the piezoelectric element.
The two piezoelectric elements having one end fixed are piezoelectric elements having a stretching function in the longitudinal direction, and bending the bending member by the stretching operation, or a piezoelectric element having a bending function in the longitudinal direction, The flexible member is bent by a bending operation.
[0008]
In addition, the piezoelectric actuator having the displacement expansion function of the present invention includes an elastic member having one side fixed at the center, and both ends fixed to both ends on the other side of the elastic member and displaced at the position of the center. A bending-type flexible member to which the member is attached, and a piezoelectric element fixed to both ends on one side of the elastic member, wherein the elastic member is deformed into a mountain shape or a valley shape by driving the piezoelectric element. A large displacement is obtained at the center of the flexible member by bending and stretching the flexible member. In this case, in order to enhance the displacement magnifying function, the elastic member and the flexible member may be formed in a disc shape instead of a rectangle, and the piezoelectric element may take an annular or disc shape.
[0009]
Further, the piezoelectric actuator having a displacement expanding function according to the present invention includes two piezoelectric elements each having one end fixed, and both ends fixed to both ends of the piezoelectric element and displaced at the center position. A bending-type flexible member to which the member is attached, wherein the distance between both ends of the piezoelectric element is reduced by the shear drive of the piezoelectric element, and the center of the flexible member is bent by narrowing the distance between both ends of the flexible element. A large displacement is obtained in the part.
[0010]
Further, in the present invention, the both end portions of the flexible member are fixed to the side surface portion on the other end side of the piezoelectric element having the longitudinal shape with one end fixed, and the displacement is obtained in a direction perpendicular to the longitudinal direction. It is an advantageous form under conditions where the height cannot be taken. Furthermore, in order to enhance the displacement magnifying function, the present invention cuts the flexible member to form an easily bent portion.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The piezoelectric actuator having the displacement expansion function of the present invention is used for driving a mirror, fiber, or lens of an optical path switching switch used in the field of optical communication, or for a read head of an information recording apparatus such as a CD-ROM. It was developed as an actuator for positioning. As shown in FIG. 6A, this optical switch switches and transmits an optical signal propagated to two optical cables. In this simplest 2 × 2 switch, as shown in the upper part of the figure, two sets of emitting ends 1 and 2 and light receiving ends 1 and 2 face each other, and a mirror 5 is arranged in a space where the optical paths cross, As shown in the lower part, the mirror 5 is displaced to take two positions. When the mirror 5 is in the retracted position, the light emitted from the emitting end 1 is directed to the light receiving end 1, and the light emitted from the emitting end 2 is directed to the light receiving end 2. When light is received and the mirror 5 is in the position where it protrudes, the light emitted from the emitting end 1 is reflected by the mirror and received by the light receiving end 2, and the light emitted from the emitting end 2 is received by the light receiving end 1. It has become. That is, the two optical signal paths are switched depending on the position of the mirror 5. A piezoelectric actuator is used to drive the position of the mirror in this optical switch. By using the piezoelectric actuator in this way, high-speed and precise positioning becomes possible.
[0012]
The optical path switching switch used in the field of optical communication is not simple as described above, and an n × n switch as shown in FIG. 6B is used for switching between a large number of cables. There are many cases. In this n × n switch, n output end groups are arranged in parallel, and n light receiving end groups are arranged in parallel in a different (generally orthogonal) direction, and the optical axes of both end groups intersect. The mirror group is arranged at a position, that is, in a matrix. Each mirror of this mirror group is displaced in the same manner as the previous mirror 5 to take two positions. When it is at the retracted position, the light emitted from the exit end is allowed to pass, and when the mirror is at the position where it is projected. The light emitted from the emitting end is reflected by the mirror and received by the light receiving end.
[0013]
Assuming that the mirror at the position of i row and j column in the mirror group arranged in a matrix is in a state of protruding, the light emitted from the emission end i is received by the light receiving end j. In this way, when it is desired to send the signal of the i-th emission side optical fiber to the j-th light-receiving side optical cable, the mirrors at the intersections of the optical axes may be made to protrude. In this way, by using an n × n switch, n communication lines can be freely switched and connected. In this case, a piezoelectric actuator is used to drive the position of the mirror group in this optical switch. However, since n × n mirrors are arranged and driven, it is necessary to arrange the same number of actuators for driving the mirrors. There is. In order to prevent the device from becoming large, the actuator used here must have a simple structure and a displacement enlargement function that can be supported easily and stably without securing the mechanism to be large and can secure the required displacement. Desired.
In addition, high-density information can be detected by driving a read head such as a CD-ROM.
[0014]
FIG. 1 shows the simplest form of the present invention. Two plate-like piezoelectric elements that expand and contract in the longitudinal direction are used, one end in the longitudinal direction is fixed to a fixing member, and a U-shaped bent flexible member 2 is formed on the other end of the two piezoelectric elements A and A ′. The mirror 5 which is a member to be displaced is attached to the central portion of the bent type bending member 2. The mechanism is placed in a stable support state by adopting a configuration in which one end of each of the two piezoelectric elements is fixedly supported by a fixing member. The position of the other end portion of the piezoelectric elements A and A ′ is displaced by driving the piezoelectric elements A and A ′, but both ends of the U-shaped bending member 2 are fixed to the other end portion. Both ends of the flexible member 2 are also displaced together.
[0015]
Now, assuming that the piezoelectric elements A and A ′ extend from the state shown in the figure, the distance between both ends of the U-shaped flexure member 2 is narrowed, and the central portion to which the mirror 5 is attached is bent into a mountain shape. Then, the mirror 5 is pushed upward. On the other hand, if the piezoelectric elements A and A ′ are contracted from the state shown in the figure, the distance between both ends of the U-shaped flexible member 2 is widened, and the central portion to which the mirror 5 is attached is bent into a valley shape. Then, the mirror 5 is pushed down. That is, a piezoelectric actuator capable of obtaining a large displacement at the center by extending and bending the distance between both ends of the U-shaped bending member 2 was realized.
[0016]
The example shown in FIG. 2 uses three plate-like piezoelectric elements that expand and contract in the longitudinal direction, one end in the longitudinal direction is fixed to a fixing member, and the other end of the three piezoelectric elements A, A ′, and B is connected to the other end side. The both ends of the U-shaped bending-type flexible member 2 are fixed, and a mirror 5 as a displaced member is attached to the central portion of the bent-type bending member 2. The difference from the previous example is that the flexible member 2 is bent and displaced by the expansion and contraction of the pair of two piezoelectric elements A and A ′ and one piezoelectric element B. As can be seen from FIG. 2B, the end of the flexible member 2 fixed to the free end of the piezoelectric element is not the end close to the fixed end of the piezoelectric element, but the far end painted black in the drawing. By doing in this way, there exists an advantage which can enlarge the longitudinal dimension of a piezoelectric element and can obtain a big displacement.
[0017]
However, since the piezoelectric elements fixed on both sides overlap at the center portion in this way, the piezoelectric element fixed on one side is divided into two parts A and A ′ and the piezoelectric element B fixed on the other side. The end portion of the flexible member 2 is fixed so as to sandwich the gap. The position of the other end of the piezoelectric element is displaced by driving the piezoelectric elements A and A ′ and the piezoelectric element B, but both ends of the U-shaped flexible member 2 are fixed to the other end. Both ends of the flexible member 2 are also displaced together.
[0018]
Now, assuming that the piezoelectric element is contracted from the state shown in FIG. 2A, the distance between both ends of the U-shaped flexible member 2 is narrowed, and the central portion to which the mirror 5 is attached is bent into a mountain shape. Push 5 upwards. On the other hand, if the piezoelectric elements A and A ′ are extended from the state shown in the figure, the distance between both ends of the U-shaped flexible member 2 is widened, and the central portion to which the mirror 5 is attached is bent into a valley shape. The mirror 5 is pushed downward. That is, this example is also a piezoelectric actuator that can obtain a large displacement at the center by expanding and contracting the distance between both ends of the U-shaped flexible member 2 as in the previous example. Although this example can obtain a large displacement by using a long piezoelectric element, it does not become structurally large.
[0019]
In the example shown in FIG. 3, both ends of a U-shaped bending member 2 are fixed to the other ends of two bimorph piezoelectric elements 1 each having one end fixed to a fixed portion, and the center of the bending member 2 is fixed. The mirror 5 which is a member to be displaced is attached to the position of the part. This example is different from that shown in FIG. 1 in that the piezoelectric element is a bimorph type. As described with reference to FIG. 7B, the bimorph type piezoelectric element performs a bending operation when one of two stacked piezoelectric members extends and the other contracts. The position of the other end of the piezoelectric element is displaced to the left and right by driving the left and right piezoelectric elements 1, but both ends of the U-shaped bending member 2 are fixed to the other end. The two ends of the two are also displaced together.
[0020]
Assuming that the distance between the other ends of the left and right piezoelectric elements 1 is narrower than the state shown in the figure, the distance between both ends of the U-shaped flexure member 2 is narrowed, and the central portion where the mirror 5 is attached is The mirror 5 is bent and pushes the mirror 5 upward. On the contrary, if the distance between the other end portions of the left and right piezoelectric elements 1 is larger than the state shown in the figure, the distance between both ends of the U-shaped flexure member 2 is also widened, and the central portion where the mirror 5 is attached is It is bent into a valley shape and pushes the mirror 5 downward. That is, with this configuration, a piezoelectric actuator capable of obtaining a large displacement in the central portion by expanding and contracting the distance between both ends of the U-shaped flexible member 2 was realized.
Since the bimorph type can obtain a large displacement among piezoelectric actuators, the actuator of the present invention can also obtain a larger displacement.
[0021]
In the example shown in FIG. 4, both ends of a U-shaped bent flexible member 2 are fixed to the other end of two bimorph piezoelectric elements 1 having one end fixed to a fixed portion, and the center of the bent flexible member 2 is also fixed. 3 is a structure in which a mirror 5 as a member to be displaced is attached to the position of this portion, but this example is different from that shown in FIG. 3 in that the position where both ends of the flexible member 2 are fixed is the bimorph type piezoelectric element. This is not the end face but the side face of the end. This positional relationship is well understood with reference to the top view and side view of the figure. In addition, the shape of the flexible member 2 is not the U-shape of the previous example, but a shape in which the central part is a high flat part and both flat parts are low flat parts and is connected by an inclined part. The same U-shape may be used.
[0022]
The position of the other end portion of the piezoelectric element is displaced left and right in the end view by driving the two piezoelectric elements 1 and 1, but both ends of the bending member 2 are fixed to the other end side portion. Both ends of the member 2 are also displaced together. Now, assuming that the distance between the other end portions of the two piezoelectric elements 1 and 1 is narrower than the state shown in the figure, the distance between both ends of the flexible member 2 is narrowed, and a central flat portion to which a mirror (not shown) is attached. Is curved into a chevron and pushes the mirror upwards. On the contrary, if the distance between the other end portions of the two piezoelectric elements 1 and 1 is larger than the state shown in the drawing, the distance between both ends of the flexible member 2 is also widened, and the inclination of the inclined portion is extended and reduced. Along with this, the position of the central flat portion is lowered, and the mirror attached thereto is pushed downward. That is, a piezoelectric actuator capable of obtaining a large displacement in the central portion by expanding and contracting the distance between both ends of the flexible member 2 by this configuration is realized. In this example, a displacement magnifying mechanism is attached to the side surface portion of the bimorph type piezoelectric element, so that the output displacement direction is orthogonal to the longitudinal direction of the piezoelectric element and is an advantageous form under the condition that the height dimension cannot be taken. .
[0023]
In the example shown in FIG. 5A, the elastic member 4 is fixed at one side by a column in the center, and both ends are fixed at both ends at the other side of the elastic member 4, and the center member is displaced. It consists of a curved flexible member 2 to which a member is attached and a piezoelectric element 1 fixed to both end portions on one side of the elastic member 4. The curved flexible member 2 and the elastic member 4 are rectangular or disc-shaped. In the former case, the piezoelectric element 1 is rectangular, and in the latter case, an annular or disk-shaped element is used. The latter has the advantage that the displacement can be increased as compared with the former rectangular shape.
[0024]
When the elastic member 4 is expanded in the left-right direction in FIG. 4A by driving the piezoelectric element 1, the elastic member 4 is deformed into a valley shape as shown in FIG. The distance between both ends of the flexible member 2 fixed to the upper end portion of the elastic member 4 is narrowed, and the flexible member 2 is bent in a mountain shape so that the central portion of the flexible member 2 is displaced to a higher position. Be made. On the other hand, when the elastic member 4 is narrowed leftward and rightward in FIG. 4A, the elastic member 4 is deformed into a mountain shape as shown in FIG. The distance between both ends of the flexible member 2 fixed to the upper end portion of the elastic member 4 is widened, and the flexible member 2 is stretched left and right so that the central portion of the flexible member 2 is displaced to a lower position. It is done.
[0025]
The example shown in FIG. 5D is a U-shaped piezoelectric element 1 with a fixed central part, and both ends are fixed to both ends of the piezoelectric element 1 and a mirror or the like is positioned at the central part. And a bent type bending member 2 to which the displaced member is attached. The bent type bending member 2 may be rectangular or disc-shaped. In the former case, two piezoelectric elements may be used on the left and right without using a U-shaped cross section, and in the latter case, the whole may be cylindrical. However, the U-shaped cross section has the advantage that the piezoelectric elements can be formed integrally and that a plurality of piezoelectric elements can be formed integrally. In this example, the bending type bending member 2 is provided with a cut groove so as to be easily bent. When the distance between the tip portions on both sides of the piezoelectric element 1 is reduced by shear drive as shown in FIG. 5E, the distance between both ends of the flexible member 2 is reduced accordingly, and the central portion of the flexible member 2 is reduced. Is bent into a mountain shape, a large displacement can be obtained.
[0026]
In an example in which the bent type bending member 2 has a rectangular shape and the piezoelectric element 1 has a U-shaped member, the mounting position of the bending member 2 is attached to the side surface of the front end of the piezoelectric element, not as illustrated. There are also variations. Similar to the example shown in FIG. 4, this form is advantageous in the condition that the output displacement direction is perpendicular to the longitudinal direction of the piezoelectric element and the height dimension cannot be taken.
In the above description, the piezoelectric actuator according to the present invention has been described with the displacement actuator for the optical switch used in the optical communication field shown in FIG. 6 in mind. As described above, it can be employed in various electronic devices such as a recording device such as a CD-ROM.
[0027]
【The invention's effect】
The piezoelectric actuator having a displacement expansion function according to the present invention includes two piezoelectric elements each having one end fixed, a bend in which both ends are fixed to the other end of the two piezoelectric elements, and a member to be displaced is attached to a central position. Since it consists of a mold flexible member, a large displacement can be obtained in the central part by bending the distance between both ends of the flexible member by driving the piezoelectric element, while having a simple configuration.
Further, the piezoelectric element in the piezoelectric actuator having the displacement enlarging function of the present invention is a bimorph type piezoelectric element having a bending function such as a piezoelectric element having a stretching function in the longitudinal direction or a bimorph type piezoelectric element. By adopting the configuration in which one end of the support is fixed to the fixing member, the support structure is extremely stable and the displacement operation is also stable.
[0028]
An elastic member having one side fixed at the central portion, a bending-type flexible member that fixes both ends to both ends of the other side of the elastic member and attaches a displaced member to the position of the central portion, and one side of the elastic member The piezoelectric actuator having the displacement expanding function of the present invention, which is composed of piezoelectric elements fixed to both ends of the present invention, has not only a support structure that is fixed by fixing with a support column, but also the elastic member formed into a mountain shape by driving the piezoelectric element. Alternatively, a large displacement can be obtained in the central portion of the flexible member by a simple mechanism in which the flexible member is bent and stretched by being deformed into a valley shape. A more effective displacement enlarging mechanism can be realized by adopting a configuration in which the elastic member and the flexible member are disk-shaped and the piezoelectric element is annular or disk-shaped.
[0029]
Further, the displacement expansion of the present invention comprising two piezoelectric elements having one end fixed, and a bending type flexure member in which both ends are fixed to both other end portions of the piezoelectric element and a displaced member is attached to the center portion. The piezoelectric actuator having a function not only has a firm support structure by a structure in which both ends of the flexible member are fixed to both ends of the piezoelectric element, but also has both ends of the piezoelectric element driven by shear drive of the piezoelectric element. A large displacement can be obtained in the central part of the flexible member by a simple mechanism in which the distance between the parts is narrowed and the distance between both ends of the flexible member is reduced and bent.
[0030]
Further, in the present invention, the both end portions of the flexible member are fixed to the side surface portion on the other end side of the piezoelectric element having the longitudinal shape with one end fixed, and the displacement is obtained in a direction perpendicular to the longitudinal direction. An advantageous form was realized under conditions where the height dimension could not be taken. Furthermore, this invention implement | achieved improving the displacement expansion function by notching a flexible member and forming an easily bending part.
[Brief description of the drawings]
FIG. 1 is a diagram showing a first embodiment of the present invention.
2A and 2B are diagrams showing a second embodiment of the present invention, in which A is a side view and B is a rear view.
FIG. 3 is a diagram showing a third embodiment of the present invention.
FIG. 4 is a top view, a side view, and an end view showing a fourth embodiment of the present invention.
FIGS. 5A and 5B are side views showing a fifth embodiment of the present invention, and FIGS. 5B and 5C are views showing the operation modes thereof. FIGS. (D) is a side view which shows the 6th Embodiment of this invention, (E) is a figure which shows the operation | movement aspect.
FIG. 6 is a diagram for explaining a basic configuration of an optical switch used in the optical communication field to which the present invention is applied.
FIG. 7 is a diagram showing a typical example of a piezoelectric element used in the present invention.
FIG. 8 is a diagram illustrating an example of a conventional piezoelectric actuator.
FIG. 9 is a view showing a conventional piezoelectric actuator with an enlargement function.
[Explanation of symbols]
1, A, A ′, B Piezoelectric element 2 Deflection member 4 Elastic member 5 Mirror

Claims (9)

The piezoelectric element includes two piezoelectric elements having one end fixed, and a bending type flexible member that fixes both ends to the other end side of the two piezoelectric elements and attaches a displaced member to a central position. A piezoelectric actuator having a displacement enlarging function, wherein a large displacement is obtained at a central portion by extending and bending the distance between both ends of the flexible member by driving an element. 2. The two piezoelectric elements having one end fixed are piezoelectric elements having a stretching function in a longitudinal direction, and the distance between both ends of the flexible member is changed by the expansion and contraction operation to bend the flexible member. Piezoelectric actuator with a displacement expansion function. 2. The displacement expansion according to claim 1, wherein the two piezoelectric elements having one end fixed are piezoelectric elements having a bending function, wherein the two ends of the flexible member are changed by the bending operation to bend the flexible member. A piezoelectric actuator with a function. An elastic member having one side fixed at the central portion, a bending-type flexible member that fixes both ends to both ends of the other side of the elastic member and attaches a displaced member to the position of the central portion, and one side of the elastic member The piezoelectric element is fixed to both ends of the elastic member, and the elastic member is deformed into a mountain shape or a valley shape by driving the piezoelectric element, so that the flexible member is bent and stretched, whereby a central portion of the flexible member is formed. A piezoelectric actuator having a displacement expansion function characterized by obtaining a large displacement. 5. The piezoelectric actuator having a displacement enlarging function according to claim 4, wherein the elastic member and the flexible member are disk-shaped, and the piezoelectric element is annular or disk-shaped. The piezoelectric element includes two piezoelectric elements each having one end fixed, and a bending-type flexible member having both ends fixed to the other end portions of the piezoelectric element and a displacement member attached to a central portion. A piezoelectric actuator having a displacement enlarging function, wherein the distance between both ends of the piezoelectric element is narrowed by shear driving of the element, and a large displacement is obtained at the center by bending the distance between both ends of the flexible member. . The displacement is obtained in a direction perpendicular to the longitudinal direction by fixing both end portions of the flexible member to a side surface portion on the other end side of the piezoelectric element having a longitudinal shape with one end fixed. Piezoelectric actuator with a displacement expansion function. The piezoelectric actuator having a displacement enlarging function according to any one of claims 1 to 7, wherein the flexible member is cut to form an easily bendable portion. An electronic apparatus comprising the piezoelectric actuator according to claim 1.

Images