JP2003527046A - Packaged strain actuator - Google Patents

Abstract

SUMMARY A modular actuator assembly includes one or more plates or elements of an electroactive material bonded to an electrode sheet, preferably by a structural polymer, thereby forming a single card. The card is sealed and may itself constitute a practical device (e.g., a vane, shaker, stirrer, lever, pusher, or sonicator) for direct contact with solids or immersion in liquids. Alternatively, it may be bonded with a solid adhesive, thereby providing a face-to-face mechanical connection with a solid workpiece, device, substrate equipment or sample. The structural polymer provides folding stiffness, whereby the thin plate does not deform to its point of failure, and the structural polymer also provides mechanical stiffness, whereby the shear forces From the workpiece.

Description

Detailed Description of the Invention

(Related Application)
No. 08/94 filed on October 3, 1997, which is a continuation application of No. 5
It is a partial continuation application of application number 09 / 261,475 which is a partial continuation application of 3,645.

BACKGROUND OF THE INVENTION The present invention is directed to, for example, active vibration reduction, structural control, dynamic test methods (d).
dynamic testing), precise positioning, motion control, Stirling,
It relates to an actuator element that can be used for shaking and passive damping or active damping. More particularly, the present invention relates to electrically controllable packaging actuator assemblies. The actuator assembly may be used separately, or may be adapted to actively dampen vibrations, or may be adapted to actuate a structure,
It may also be adapted to weaken the mechanical condition of the attached device.
As described in subsequent sections, the assembly may be coupled or attached to a structure or system, thereby integrating the assembly with the system to be actuated, controlled or dumped.

Smart materials (eg, piezoelectric, electrostrictive, or magnetostrictive materials) can also be used for high bandwidth tasks (eg, actuation or damping of structural or acoustic noise) and precision positioning applications. . Such applications often require smart materials to be bonded or attached to the structure for control. However, general-purpose actuators of these materials are not generally available, and those who desire to implement such control tasks will typically have unprocessed raw, along with any required electrodes, adhesives and insulating structures. Electrodes are not attached as much as possible (non-
The electroded smart material stock must be obtained and either fixed on the target pedestal or developed for incorporation into the prospective pedestal.

For such applications, mechanical or electrical connections to the smart material are robust and can create strain within the smart member or replace or force the system. It is necessary to connect and attach these materials in various ways, and to combine this strain, movement and force on the controlled object. Often, smart materials are required to be able to be used in poor environments, greatly increasing their mechanical or electrical failure.

As an example, one of the applications of vibration suppression and actuation of structures requires the attachment of piezoelectric elements (or elements) to the structure. The elements are then actuated and the piezoelectric effect transforms the electrical energy applied to the element into mechanical energy distributed throughout the element. By selectively producing mechanical shocks or by selectively changing strain in the piezoelectric material,
A particular shape control of the lower structure is achieved. Rapid actuation can be used to suppress natural vibrations, or controlled vibrations or displacements.
placement). This application of piezoelectric materials and examples of other intelligent materials have become increasingly popular in recent years.

In typical vibration suppression and actuation applications, piezoelectric elements are bonded to structures in a complex series of steps. The surface of the structure is first machined so that one or more channels are created, thereby connecting the electrical leads needed to connect the piezoelectric elements. Alternatively, instead of a machined channel, two different epoxies may be used to make both mechanical and electrical contacts. In this alternative approach, a conductive epoxy is spotted (ie, locally applied to form a conductor) and structural epoxy is applied to the rest of the structure to bond the piezoelectric element to the structure. Subsequently, everything is covered with a protective coating.

This assembly procedure is labor intensive and often requires a lot of rework due to the problems of working with epoxies. Mechanical homogeneity between different piezoelectric elements is difficult to obtain due to process variability (particularly piezoelectric element placement and bonding). The electrical and mechanical connections made in this way are often uncertain. It is common for the conductive epoxy to flow in a way that is not preferred, causing shorts across the ends of the piezoelectric element. Moreover, piezoelectric elements are very fragile and, if unsupported, can break during bonding or handling.

Another drawback of conventional manufacturing processes is that if a crack occurs after the piezoelectric element is bonded to the structure, some of the piezoelectric elements that are not in contact with the conductor will fail. Therefore, the complete actuation of the device is reduced. Shielding can also be a problem. Because other circuit components, as well as the personnel, generally must be shielded from the electrodes of these devices (which carry the high voltage).

One approach to incorporate piezoelectric elements (eg, thin piezoelectric plates, cylinders, discs or stacks of annulets) into a controllable structure is Javier.
de Luis and Edward F. Crawley US Pat. No. 4,849,
No. 668. This technique involves precision hand-assembly of various elements into an integrated structure that is contained within the structure of the laminated composite body in which the piezoelectric elements act as insulation and strong support. This support reduces the problem of electrode cracking and can be implemented in a computational manner to optimize structural strength along with mechanical actuation efficiency, at least as described in that patent. Moreover, for cylinders or stack annulets, the natural piezo-type natural in-passage simplifies the task of another different installed wiring to some extent. Nevertheless, the design is not simple, manufacturing still requires a great deal of time, and suffers from numerous failure modes during assembly and operation.

The field of a dynamic test requires a versatile actuator to shake or perturb the structure, so the response of the actuator can be measured or controlled. However, herein, the accepted methodologies for shaking test devices are linear disturbances.
Using an electromechanical motor to generate The motor is typically applied via a Stinger design to decouple the motor from the desired signal. Such external motors still have the drawback that dynamic connections often face when using the motor to excite structures. Moreover, for this actuator type, the structure is such that inertia is added to the structure, resulting in undesirable power.
Excitons may be installed if there is no integral part of the structure. These factors make device operation and modeling or analysis of states of interest very difficult.
The use of piezoelectric actuators overcomes many of these drawbacks, but, as noted above, introduces complex structures, variations in actuation characteristics, and self-problems of durability. Similar problems occur when piezoelectric and electrostrictive elements are used as sensing.

Accordingly, the desired improvements are made in the manner in which the device is coupled to the structure in a controlled or actuated manner, whereby the device may have high bandwidth actuation performance and is easy to assemble. In addition, it can be mechanically and electrically robust and does not significantly alter the mechanical properties of the structure as a whole. It is also desirable to achieve a high strain transformation from the piezoelectric element to the structure of interest.

SUMMARY OF THE INVENTION An actuator assembly according to the present invention includes a housing forming one or more strain components (piezoelectric plates or shells, or electrostrictive plates or electrostrictive shells, etc.) and a protective body around the strain components. , And electrical contacts mounted in the housing and connected to the strained components, these parts together forming a flexible card. At least one aspect of the assembly includes a thin sheet attached to a major surface of the strained component, the exterior of which is adhered to the object such that a tight, shear-free bond between the object within the housing and the strained component. Obtained in between.

In a preferred embodiment, the strained component is a piezoelectric ceramic plate. The piezoceramic plate is extremely thin (preferably slightly less than 1/8 mm to a few mm thick), has a relatively large surface area, and has one of the width and length dimensions of the piezoceramic plate. And both are tens of times the thickness dimension or tens
It is 0 times. The metallized film contacts the electrodes, while the adhesive and insulating materials hermetically seal the device to avoid delamination, cracking, and environmental exposure. The adhesive used can be epoxy (B-stage or C-stage epoxy), thermoplastics, or piezoelectric ceramic plates, metallization films, and any other material useful in adhering with insulating materials. The particular adhesive used depends on the intended use of the device. In a preferred embodiment, both the metallized film and the insulating material are provided in a flexible circuit of a tough polymeric material. Thus, it provides a robust mechanical and electrical connection with the closed components. Alternatively, the metallized film may be placed directly on the piezoelectric ceramic plate and the insulating material may have electrical contact.

By way of illustration, one example is a rectangle having a thickness of 1/4 millimeter and a length and width dimension of 1 to 3 centimeters each, thus each component having an active strain producing surface of 1 to 10 square centimeters area. An example of the configuration using the PZT plate will be described below. PZT plates are mounted on or between sheets of rigid, tough polymer (eg, 0.5, 1, or 2 mil polyimide), which polymer has copper clad on one or both sides. And has a compatible conductive electrode pattern formed in the copper layer to contact the PZT plate. Various spacers surround the PZT plate, and the entire structure is bonded with structural polymer into a waterproof, insulated, closed package with approximately the same thickness as the PZT plate (eg, 30-50 mm). To do. The encapsulation allows the package to be bent, stretched and deflected and subjected to sharp impacts without breaking the fragile PZT components contained therein. In addition, the conductor pattern is firmly attached to the polyimide sheet so that cracking of the PZT component will not cut the electrode or prevent actuation over the entire area of the component, or otherwise significantly reduce performance. Lower.

The thin package forms a complete modular unit in the form of a complete small “card” with electrodes. The package may then be conveniently attached by adhering one side to the structure, thereby coupling the strain between the encapsulated strain component and the structure. This may establish a thin, high shear strength PZT plate bond, for example by simply attaching the adhesive to the package, adding minimal weight to the overall system. The PZT plate can be an actuator that couples energy to the attached structure, or it can be a sensor that responds to coupled strain from the attached structure.

In different embodiments, specific electrode patterns are selectively formed on the sheet, either in the plane of the electrodes of the PZT plate, or in the plane of the intersecting planes,
Multiple layers of T components are configured to be arranged or stacked in a single card, which can result in bending or shear, as well as specialized strains.

According to a further aspect of the invention, circuit components are formed within or with the module package that filters, shorts, or processes the signals generated by the PZT components, thereby sensing the mechanical environment. , Locally performing switching or power amplification to further drive the actuation elements. The actuator package forms a modular surface mount shell that is adaptable for mounting around a pipe, rod, or shaft with preformed PZT components such as a semi-cylindrical shape.

These and other desirable features of the invention will be understood from the detailed description of the exemplary embodiments.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1A shows a schematic diagram of the process and overall configuration of a prior art surface mount piezoelectric actuator assembly 10. The structure 20 can be a structural or mechanical element, a plate, an airfoil or other interactive sheet, or a device or part thereof, which is bonded to itself by some combination of conductive polymer 14 or structural polymer 16. The high-performance material sheet 12 is provided. Insulator 18 may be formed wholly or partially of structural polymer 16,
The highly functional material is housed and protected and conductive leads or surface electrodes are formed or attached to the conductive polymer. The external control system 30 includes a line 32a,
A drive signal may be provided along 32b to provide the high performance material and a measurement signal may be received from a surface mounted instrument (eg, strain gauge 35) from which the appropriate drive signal may be derived. Various forms of control are possible. For example, the strain gauges may be arranged to sense the excitation of natural resonances, and the control system 30 may actuate the PZT element only in response to the sensor output, thereby reinforcing the structure and providing self-confidence. The resonance frequency can be changed. Alternatively, the vibration sensed by the sensor may be fed back as a processed phase delayed drive signal to null out the dynamic state that occurs or the actuator may be driven for motion control. In well-known mechanical systems, the controller recognizes experimental conditions (ie, aerodynamic conditions or events) and selects special control rules that specify the gain and phase of the drive signal to each actuator 12. Can be programmed to achieve the desired changes.

In all such applications, is it necessary to carry out a large amount of work to attach the bare PZT plate to its control circuit and the work piece, and many such assembly processes can fail? , Or where quantitative control is desired to establish control parameters for useful mode of operation appropriate for the particular thickness and mechanical stiffness achieved in the manufacturing process,
Extensive modeling of the device after assembly may be required.

FIG. 1B shows an actuator according to one embodiment of the invention. As shown, this embodiment is modular in other configurations that are only attached to structure 20 with quick-setting adhesive (eg, epoxy 13 that cures in 5 minutes) or that is attached in dots or lines. A pack or card 40. Thus, sensing and control operations benefit from a more easily mounted and uniformly modeled actuator structure. In particular, the modular pack 40 is a rigid and foldable plate in the form of a card, preferably one or more electrical connectors, preferably in the form of a pad, for plugging into a multi-pin socket. For the end (not shown) of the control system 50, thereby simplifying the control system 50.
Can be connected to. As described in more detail below in connection with FIG. 2C, the modular package 40 includes a signal processing element (eg, weighting).
Or planar or thin circuit elements, which may include shunt resistors, impedance matchers, filters and signal processing preamplifiers), and may also include switching transistors and other elements operating directly under digital control. This ensures that the only external electrical connections needed are for the microprocessor or logic controller and the power supply.

In a further embodiment particularly applicable to certain low power control situations, the modular package 60 illustrated in FIG. 1C may include its own power source (eg, battery or power cell), controller (eg, microprocessor). Chip or programmable logic array) to operate the implemented drivers and shunts, thus performing a perfect combination of sensing and control operations without requiring any connection to external circuitry. .

The present invention particularly relates to piezoelectric polymers, and to materials that are hard and occasionally extremely brittle, such as sintered metal zirconates, niobate crystals or similar piezoelectric materials. The present invention also relates to electrostrictive materials. As used in the claims herein, both piezoelectric and electrostrictive elements have electromechanical properties in the element material, and these elements are referred to as electroactive elements.
In order to effectively transfer strain to the external structure or work piece, which is often composed of metal or a hard structural polymer, through the element surface, high rigidity is essential, and in this actuator aspect, the invention Do not generally contemplate flexible polymeric piezoelectric materials. The terms "hardness" and "softness" are relative, but in this context, hardness, when applied to an actuator, has a Young's modulus of 0.1 x 10 ⁶ (preferably 0.2 x 10 ⁶⁾ large metal than, cured epoxy, it will be appreciated substantially equal to advanced composite material or other rigid material. When constructing a sensor rather than an actuator, the present invention also allows the use of a low hardness piezoelectric material (eg, polyvinylidene difluoride (PVDF) film, and the replacement of lower cure temperature bonding or adhesive materials. However, major challenges in construction have occurred with the first type piezoelectric material described above, and these challenges are discussed below.

The present invention generally includes novel modes of actuators and methods of making such actuators. In the present invention, “actuator” is understood as meaning a complete and mechanically useful device which, when energized, couples forces, movements or the like to an object or structure. In this broader aspect, the fabrication process of an actuator involves "packaging" a raw electro-active device to make the electro-active device mechanically useful. For illustrative purposes, the raw electroactive piezoelectric material or "element" is generally available in the form of various semi-machined bulk materials, including the raw piezoelectric material in its basic shape. Examples of such material "elements" include, for example, sheets, rings,
There are washers, cylinders and plates, or more complex or compound forms (eg stacks, or hybrid forms including bulk materials with mechanical elements (eg levers). Piezoelectric materials are described for exemplary purposes in the following description, which may have metal coatings on one or more surfaces to function as electrical contacts or may not be metallized. All materials are referred to as “elements,” “materials,” or “electrically active elements.” As noted above, the present invention produces strains, vibrations, positions, or other physical properties. Further comprising a structure or device that acts as a sensing rather than a sensing element, whereby:
The term "actuator" may include a sensing transducer, if applicable.

In embodiments of the present invention, these rigid, electrically actuated materials are in the form of thin films (eg, less than a few millimeters thick, illustratively 1/5 to 5 mm thick).
1/4 mm discs, rings, plates and cylinders or shells)
To use. Advantageously, this thin dimension makes it possible to achieve a high field strength over a distance comparable to the thickness dimension in a plate with a relatively low overall potential difference, whereby a drive of 50 volts or less is achieved. It is possible to obtain full piezoelectric actuation with voltage. Such thin dimensions also allow the device to be attached to an object without significantly altering the structure or physical response characteristics of the object. However, in the prior art, such thin elements are fragile and can break due to irregular stresses during handling, assembly or curing. Even a few centimeters drop can cause cracks in the piezoceramic plate, and the degree of bending deformation that can be withstood before failure occurs is negligible.

According to the invention, this thin electrically actuated element is enclosed by a layer of hard insulating material. At least one of the layers of hard insulating material is a reinforced film that has a patterned conductor on one of its surfaces and is thinner than the device itself. When assembling a package from a piezoelectric element, an insulating layer, and various spacers or structural fill materials, the electrodes, piezoelectric element (s), and encapsulating film or layers, together make them more substantially than bare actuated elements. Assemble to form a sealed card that is not too thick. As will be discussed below, when the device is placed in multiple layers, the package thickness is not appreciably greater than the total thickness of the stacked actuated devices.

FIG. 2A shows a basic embodiment 100 of the present invention. A thin film 110 of a highly insulating material, such as a polyimide material, is metallized on at least one side, typically with a copper coating, to occupy the same extent as the completed actuator package, or
Or form a rectangle slightly larger than the completed actuator package. Suitable materials available for use in manufacturing multilayer circuit boards are Ariz.
Fl by ona's Chander Rogers Corporation
ex-I-Mid3000 Sold as a non-adhesive circuit material and composed of polyimide formed on a rolled copper foil. A range of sizes is commercially available where the metal foil is 18-70 micrometers thick and is integrally coated with a 13-50 micrometer thick polyimide film. Other thicknesses may be manufactured. In this commercial material, the foil and polymer film are directly attached without the use of adhesive.
As such, the metal layer can be patterned by conventional masking and etching, and the plurality of patterned layers can cause residual adhesive to break the assembly or cause delamination in the manner described in more detail below. Can be formed into a multilayer substrate without using. Rolled copper foil provides high in-plane tensile strength, while polyimide film exhibits a strong, stiff, and defect-free electrical insulation barrier.

In the structure described below, the membrane constitutes not only the insulator on the electrodes, but also the outer surface of the device. Therefore, it is necessary to have high dielectric strength, high shear strength, water resistance, and the ability to bond to other surfaces. High heat resistance is required in view of the temperature cure used in the preferred manufacturing process and for some application environments. In general, polyamide / polyimides have been found to be effective, but other materials such as polyesters or thermoplastics with similar properties can also be used.

In this configuration, the foil layer has conventional masking and etching techniques (eg,
Photoresist masking, patterning followed by etching with iron chloride) to form electrodes that contact the surface of the piezoelectric plate element. Alternatively, a more ductile conductive thin layer may be used. For example, a conductive thin layer may be printed with a silver conductive ink directly on the polymer film or on the piezoelectric element. Figure 2A
In, the electrode 111 extends over one or more sub-regions inside the rectangle,
It connects to a stiffening pad 111a or stiffening land 111b extending at the end of the device. The electrodes are arranged in a pattern that contacts the piezoelectric elements along a wide turning path. This wide turning path intersects the entire length and width of the element, thus ensuring that the element remains connected even if a small amount of cracking or local breakage occurs in the electrode or piezoelectric element. To do. The frame member 120 is positioned around the perimeter of the sheet 110 and the at least one piezoelectric plate element 112 is
It is located in the central region so as to be contacted by the electrode 111. The frame member is
The thin laminate acts as an edge joint so that it does not spread to the edges, and their frame members also serve as thickness spacers for hot press assembly operations, which are described further below, and in the early stages of building a laminate package. It functions as a position maker that defines the position of the piezoelectric plate to be inserted.

FIG. 2A is a schematic diagram as it does not show the layer structure of the device. FIG. 2A includes an additional translucent top layer 116 (FIG. 2B) to enclose the layer structure of the device together. The translucent top layer 116 actually extends across the plate 112 and, together with the spacer 120 and the sheet 110, seals the assembly. A similar layer 114 is placed under the piezoelectric element with appropriate cutouts so that the electrode 111 contacts the element. The layers 114, 116 are preferably formed from a cured epoxy sheet material, which has a cured thickness equal to the thickness of the metal electrode layer, to join together the material that contacts it on each side. Works as an adhesive layer. When the epoxy cures, it forms the structural body of the device and cures an assembly that extends over a substantial portion of the surface of the piezoelectric element to strengthen the element and prevent crack growth. This prolongs the life. Moreover, the epoxy from this layer is actually a very thin but highly discontinuous film (about 0.
(0025 mm thickness) and spread on the electrode. The epoxy firmly bonds the electrodes to the piezoelectric plate, but has a sufficient number of voids and pinholes so that direct electrical contact between the electrodes and the piezoelectric element results in a fairly distributed contact area. Still occurs above.

FIG. 2B shows a cross-sectional view of the embodiment of FIG. 2A. However, note that it is not drawn to scale. As a rough ratio, in the case of the piezoelectric plate 112 having a thickness of 0.2 to 0.25 mm, the insulating film 110 is much thinner and is 1/10 of the plate.
Only ~ 1/5 thick. The conductive copper electrode layer 111 may typically have a thickness of 10 to 15 microns, although the latter range is not a hard and fast limit. However, such a range represents an effective range of electrically usable electrode thickness, which is convenient for manufacturing and is not so thick that it impairs strain transfer efficiency or causes delamination problems. Will be either. Structural epoxy 114
It fills the space between the electrodes 111 in each layer and has approximately the same thickness as these electrodes, so that the entire assembly forms a solid block. Spacer 120 is formed of a relatively compressible material having a low modulus of elasticity, such as a relatively uncrosslinked polymer, and preferably is piezoelectric when used with a pressure cured epoxy as described below. It is roughly as thick as a plate or stack of elements. Thereby, these spacers form edge bonds around other components between the upper and lower layers of film 110.

The preferred method of manufacture includes applying pressure to the entire package as layer 116 cures. The spacers 120 function to align any circuit elements with the piezoceramic plates described below with reference to FIGS. 3-5, the spacers being a frame that is slightly pressurized during assembly during the curing process. To form. At this time, the frame can be deformed to seal the edges without leaving any stress or irregularities. The compression eliminates voids and provides a dense and crack-free solid medium, while thermosetting achieves a high degree of cross-linking to provide high strength and hardness.

The assembly process of the embodiment of FIGS. 2A and 2B is as follows. One or more copper strips over the polyimide film, each with a total thickness of about 0.025 to 0.050 millimeters, are cut to a size slightly larger than the dimensions of the finished actuator package. The copper size of the film is masked and patterned to form the desired shape of the electrodes. This brings the piezoelectric element into contact with the conductive leads and any desired lands or access terminals. 7 shows a pitchfork electrode pattern with three teeth. These three teeth are one of the piezoelectric elements
It is positioned so that the center of one side is in contact with both sides, but in other embodiments an H-shape or a comb-shape is used. Patterning can be done by masking, etching, and then cleaning, similar to circuit board or semiconductor processing techniques. Masking is accomplished by photoresist patterning, screening, tape masking, or other suitable process. Each of these electrode pieces made of a polyimide film, such as in conventional printed circuit boards, defines the position of the circuit element or actuator sheet and is hereinafter simply referred to as the "bend circuit". However, the methods and devices of the present invention also contemplate using electrode piezoelectric elements, insulators, and electrical contacts rather than "bending circuits."

Next, an uncured sheet epoxy material about the same thickness as or slightly thicker than the electrode foil layer is optionally trimmed so that the through apertures match the electrode pattern. This allows for improved electrical contact when built through the aperture and is placed on each flex circuit. Therefore, the epoxy material adheres to the flex circuit to form a planarization layer between and around the electrode portions. The backing is then removed from the epoxy layer attached to the flex circuit and precut spacers 120 are positioned at the corners and ends of the flex circuit. The spacer extends over the electrode surface and outlines a frame that defines one or more recesses. In the next assembly process, the piezoelectric element is fitted in the recess. The piezoelectric element (s) are then placed in the recesses defined by the spacers, and the second electrode films 111, 112 along with their own planarization / bonding layer 114 are placed in predetermined locations on the element. An electrode contact is formed on top of the. If the device has several layers of piezoelectric elements, as is the case with some bending actuator configurations, these assembly steps are repeated for each additional electrode film and piezoelectric plate, and the intermediate sheet It should be noted that a polyimide film, which is covered and patterned on both sides, can be used when forming an intermediate electrode layer that contacts the actuator element both above and below.

Once all the elements are in place, the complete sandwich assembly of patterned flex circuits, piezoelectric sheets, spacers and curable patterned epoxy layers is pressed between the hot platens. Placed and cured under high temperature pressure to harden the assembly into a hard, crack-free actuator card. In an exemplary embodiment, a 30 minute cure cycle at 350 ° F and 50-100 psi pressure is used. The epoxy has a curing temperature below the depolarization temperature of the piezoelectric element, but is selected to achieve high hardness.

The above configuration shows a simple actuator card with one piezoelectric plate sandwiched between two electrode films. Thus, the plate effectively transfers shear strain through the membrane to the surface of the actuator card. The transfer efficiency criterion (referred to as gamma (Γ)), defined as the shear coefficient divided by the square of the layer thickness, is the coefficient and thickness of the epoxy 114, the rolled foil electrode 111, and the polyimide film 110. Depends on. In an exemplary embodiment, the epoxy and copper electrode layers are 1.4
Being mil thick, the epoxy has a modulus of 0.5 × 10 ⁶ and a gamma of about 9 × 10 ¹⁰ pounds / inch ⁴ is achieved. A substantially higher Γ is achieved by using a thinner epoxy layer and a 0.8 mil foil film. Generally, the electrode / epoxy layer gamma is greater than 5 × 10 ¹⁰ pounds / inch ⁴ , while the membrane gamma is greater than 2 × 10 ¹⁰ pounds / inch ⁴ .

When using a 10 mil thick PZT actuator plate, three flex circuit electrode membrane layers, with the middle layer double-coated to contact both plates, are placed on top of each other. The card with two PZT plates stacked together has a total thickness of 28 mils and is 40% larger than with only one plate. In terms of mass loading, the weight of the actuator element represents 90% of the total mass of this assembly. In other configurations, the plate typically comprises 50-70% of the package thickness,
It constitutes 70-90% of its mass. Thus, the actuator itself allows modeling of near theoretical performance. This configuration offers a similarly high degree of versatility to implement the vendor and stack (discussed above) or an array of one sheet.

Another useful figure of merit for an actuator constructed in accordance with the present invention is a high ratio of actuator strain ε to piezoelectric element free strain Λ, which is a two-layer implementation described herein. In the case of the form, it is about (0.8), and generally (0
． 5) Greater than Similarly, the ratio of package to free element curvature (ie, K) is
For the configuration described, it is about 0.85 to 0.90 and is generally greater than 0.7.

Thus, overall, the packaging involved in constructing a piezoelectric element incorporated into a flex circuit impairs its weight and electromechanical operating characteristics well below 50% and as small as 10%. However, another important point is that it greatly enhances its durability and mechanical operating range. For example, adding a sheet packaging structure to the base element reduces the achievable K, but in actual use the flex card configuration becomes a piezoelectric bender configuration, which can lead to cracking defects and other mechanical failure modes. Larger plate structures can be produced without occurring and high curvatures can be repeatedly actuated so that a much larger total deflection can be achieved. Some drawings show variations of configurations that provide such improved physical properties.

First, the structure of electro-active elements embedded between flex circuits not only provides a low mass integrated mechanical structure with predictable response characteristics, but also within the actuator card or Allows the incorporation of circuit elements on the actuator card. FIG. 2C shows a top view of one device 70 of this type. Here, each of the regions 71, 73 comprises a substrate electrically active sheet, while the central region 72 comprises a battery 75, a planar power amplifier or set of amplifiers 77, a microprocessor 7
9 and a circuit or output element including a plurality of strain gauges 78. The other circuit elements 82a, 82b may be arranged in the periphery somewhere along the path 81 of the circuit conductor. In other embodiments, the spacers 120 define the placement and seal the edges of the device, while the electrodes 111 attach the electro-active elements to the processing or control circuitry to be subsequently incorporated. The circuit elements 82a, 82b may include weighting registers, or shunt resistors if the device acts as a sensor, to provide passive damping control. Alternatively, these circuit elements may be filtering, amplification, impedance matching, or storage elements such as capacitors, amplifiers and the like. In any case, these elements are also located away from the electro-active plate 84. The components may collectively sense strain and perform various actuation patterns in response to sensed situations or perform other sensing or control tasks.

Returning now to the actuator aspect of the present invention, FIG. 3 shows a top view of an actuator package 200 that has dimensions of about 1.25 × 9.00 × 0.030 inches. , Assembled with two layers of piezoelectric plates, each with four plates. The rectangular polyimide sheet 210 with the termination tabs 210a is in the form of an H-shaped thin copper wire grid interconnected with each other and with one runner 211a extending to the tab.
1 to provide a low impedance connection directly to each of the four rectangular areas carrying the piezoelectric plate.

The H-shaped spacer elements 220 a and 220 b or the L-shaped spacer elements 220 c mark off and represent a rectangular space where the piezoelectric plate 216 is placed. In this embodiment, a plurality of gaps 230, described further below, are between adjacent locations of the H-shaped spacers or L-shaped spacers.
As will be apparent from the description below, the utilization of these small, discrete spacer elements (I-shaped, T-shaped or O-shaped spacers may also be convenient) is improved.
This is because these spacers can be easily placed on the adhesive bonding epoxy layer 114 in the assembling, thereby indicating the assembling position and forming a recess for receiving the piezoelectric element. Because it is possible. However, the spacer structure is not limited to such a set of discrete elements and can also be a single or pair of frame parts formed as punched extruded sheets or molded frames, whereby Orientation and / or sealing ends or all or one or more recesses that hold the actuation of the circuit components may be provided.

FIG. 5 shows a top view of each of the three sheets (ie, the electrode layer and the piezoelectric plate layer, respectively), and FIG. 5A shows a generalized layering film layer, conductor layer and spacer / piezoelectric layer. Indicates the order. As shown, the spacer 220 and the piezoelectric plate 216 form a single layer between each pair of electrode layers.

FIGS. 4A and 4B (not shown to scale) show the layered structure of the assembled actuator with longitudinal cross-sections taken at the locations indicated as “A” and “B” in FIG. 3. As shown more clearly in FIG. 4A, the patterned bonding layer of the epoxy sheet 214 is coplanar with each electrode layer 211 and fills the space between the electrodes, while the spacer 220c is the same as the piezoelectric plate 216. It lies on a plane and has substantially the same thickness as the piezoelectric plate 216 or slightly thicker than it. By way of example, the piezoelectric plate 216 is a PZT-5A ceramic plate, which is commercially available in thicknesses of 5-20 mils, and which has a continuous conductive layer covering each adhesive surface with the electrode 211. 216a. The spacer 220 is formed of a plastic having a softening temperature of about 250 ° C. and having a slight compressibility. This makes it possible to obtain a considerable degree of conformability at the curing temperature, so that the spacer material will have a small gap 21 during the assembly process.
4a (FIG. 4A) may be filled. As shown in FIG. 4B, the gap 23 between the spacers
0 (although, if present, causes an opening 214b that drains excess epoxy from the curable bonding layer 214 and fills with epoxy during the curing process. As shown in the figure, a certain amount of epoxy can also be bleed into the patch of film 215 between electrode 211 and piezoelectric plate 216. Since the electrode 211 is large and continuous, such leakage of epoxy from the gap does not impair the electrical contact with the piezoelectric element, and the additional connection structure provided by such a gap is It is useful for preventing peeling.

The illustrated electrode configuration may be used to actuate a pair of vertically layered piezoelectric plates in opposition to each other to induce bending or to provide more individual electrodes. It is understood that it is also possible to actuate different pairs of plates in different ways. In general, as noted above, the present invention provides all sensing, control, and power or attenuation elements in more highly complex systems involving the actuation of many discrete elements in different ways. , Intended to be mounted on the same card. In this respect, the flexibility of this system further provides a great deal of flexibility in adapting the card to the actual task. This system is generally more pliable in flexibility as compared to a 30 mil thick epoxy strip so that it can undergo bending, striking, or vibration without damage. Also, the system is capable of significant bending or bending in the region of the centerline CL (FIG. 3) where no piezoelectric element is housed, which results in good conformability to the mounting surface or corner. These elements can be polled, which allows for in-plane or cross-plane dimension changes. Therefore, any of the control actions described above may be performed, or a particular waveform or type of acoustic energy (eg, bending waveform,
The actuators can be mounted to deliver strain to the abutment surface in a manner effective to fire a shear or compression waveform to the abutment surface.

FIG. 6 illustrates another actuator embodiment 300. In this embodiment, the epoxy bonding layers, film elements and spacer elements are not shown as schematically shown, but only the electrode sheet and the piezoelectric sheet are shown to show the effective mechanism. Both the first set of electrodes 340 and the second set of electrodes 342 are provided in the same layer, each set having a comb shape with two interdigitated combs, whereby An electrical actuation electric field is set between the teeth of one comb and the adjacent teeth of the remaining comb. Figure 11
As shown in A and 11B, the linear electrode 408 (that is, the "tooth portion" of the comb structure)
) Connects to the common bus 402. Bus 402 may be disposed on piezoceramic surface 404 (as shown in FIG. 11A) or piezoceramic surface 404.
Can be placed off (illustrated in FIG. 11B). FIG. 12 also shows one embodiment 400 of the present invention, in which the bus 402 is located remote from the piezoceramic surface 404. Alternatively, the bus may be placed on the side of the polymer film opposite the flex circuit. These linear electrodes are in electrical contact with the bath through the polymer film. For example, the polymer film may include through-hole plating properly placed, or it may be simply polished away to obtain electrical contact. The interlocking “comb” configuration of electrodes is referred to herein as, for example, an interdigital electrode (IDE), as shown in FIGS. 11A, 11B and 12. In FIG. 6, a pair of parallel combs 340a and 342a are provided on opposite sides of the piezoelectric sheet to connect the comb electrode 340 to 340a and the comb electrode 342 to 342a, which results in equipotential lines " The electric field is set with "e" extending into the piezoelectric sheet and having an in-plane potential gradient between each pair of teeth from different combs. In the illustrated embodiment, the piezoceramic plate is not metallized, so there is a direct electrical contact between each comb and the plate. These plates are poled in-plane by first applying a high voltage on the comb to generate a field strength of over 12000 volts / inch along the planar direction. This then orients the piezoelectric structure such that in-plane (shear) actuation occurs upon application of a potential difference across the two comb electrodes. Therefore, by directly contacting the interdigital electrodes, it is possible to provide the electric field generated in parallel to the actuation direction to the piezoelectric element.

10A, 10B and 10C illustrate various configurations of the present invention. FIG. 10A shows
IDE pattern (eg, linear electrode 408 printed directly on PZT element 404)
And common bus 402). FIG. 10B shows linear electrodes 408 printed on PZT element 404 and a common bus printed on both top film 412 and bottom film 414. FIG. 10C shows an IDE pattern (eg, top film 4).
12 and lower film 414 on both linear electrodes 408 and common bus 402
) Is shown.

With the method or device of the present invention, in addition to shear actuation,
Directional actuation and damping can be provided. For example, as shown in FIG. 7, it is also possible to intersect two such actuators 300 to provide torsional actuation. Alternatively, FIGS. 13, 14A and 14B
An angled IDE patterning actuator 406 can be placed on the structure along the major strain axis of the structure, as shown in, to couple shear torsional energy. Bonding a piezoelectric device having an angleless IDE pattern onto a structure such that the IDE pattern effectively makes an angle with the principal strain axis of the piezoelectric element (ie, the device is angled bonded), The same effect can be achieved.

In describing the above embodiments, the transfer of strain energy directly through the electrode / polyimide layer to any adjacent structure was identified as a clear and novel advantage. Such operations may be useful in actuation task applications and are versatile in airfoil shaped control actuation and noise or vibration cancellation or control. 8A and 8B are typical views of a flat actuator embodiment 60 (FIG. 8A) and a semi-cylindrical actuator embodiment 60 (FIG. 8B) applied to a flat or slightly curved surface and shaft, respectively. Shows the static attachment.

However, even though the electromechanical material of these actuators operates by strain energy conversion, the application of the present invention exists beyond strain coupling through the actuator surface to globally translate the motion, torque or force imparted by the actuator. Including many professional mechanical structures used for. In each of these embodiments, a basic strip or shell sealed actuator is pinned or connected at one or more points along its length to provide a robust, elastic machine. Used as an element. As shown in FIG. 9, the strip, when electrically actuated, acts as an automatic lever, flap, leaf spring, stack or bellows, either alone or with other elements. In the views of Figures 9A-9Q, the elements A, A ', A "... are strip actuators or sheet actuators as indicated above, and small triangles are, for example, fixed support points or connection points to structures. Indicates the fixed or pinned position corresponding to the arrow, the arrow indicates the direction of movement or actuation or the contact point of such actuation, while L indicates the lever attached to the actuator and S indicates Indicates a stack element or actuator.

The configurations of FIGS. 9A-9C (eg, stack, bender or pinned bender configurations) can replace many conventional actuators. For example, a cantilever can carry a stylus, which can be used to displace one axis with good control to form a highly linear and large displacement positioning mechanism for a pen-based plotter. It is possible. In particular, interesting mechanical and actuation properties are expected from multi-element configuration 9 (d) (see below). This multi-element configuration 9 (d) uses a mechanically robust actuator that has a seat area. Thus, as shown in FIGS. 9D and 9E, the pin-pin bellows configuration provides extended and accurate uniaxial Z translational positioning by simple surface contact movement.
It may be useful in applications such as camera focusing, or it may be useful in implementing a peristaltic type pump by using the full displacement of the bearing relative to the fluid. As described in connection with FIG. 3, since this bending circuit is extremely compliant, it is possible to bend or fold the end like a hinge by simply bending the position such as the center line in FIG. This allows the closed bellows assembly to be made with a small number of large multi-element actuator units. This flex circuit configuration consists of placing strips of actuator elements or checkerboards at the fold lines between each pair of adjacent elements, and during the curing phase, these fold lines were contoured (multipurpose waffle baking). ) It is possible to press thinly using a press platen. With such a construction, a completely seamless bellows or other folding actuator can be made from one bending circuit assembly.

FIG. 16 shows one embodiment of an S-shaped device having four piezoelectric regions 430, 432, 434 and 436. In such an embodiment, the device has a generally S-shaped configuration. In the embodiment shown in FIG. 16, the device has two sections with bends in opposite directions. For example, some of the devices may display positive bends (430 and 432) with respect to the fiducial, while a second part of the device has negative bends (434 and 436) with respect to the fiducial. Can be displayed. Although these two portions of the S-shaped device have substantially the same length, size, and degree of curvature, useful devices include two or more different lengths, sizes, and / or degrees of curvature. It also includes a part. As shown in FIG. 17, for an S-shaped device, the end of device (452) is displaced a specific distance (454) with respect to the end of the second device (450). This type of displacement is
By driving the piezo elements in 32 and 434 in one direction to its poling field (positive or negative) and the piezo elements in regions 430 and 436 in the opposite direction to its poling field, To be achieved. Arbitrary configurations in the poling direction and the electric field direction are possible as long as the configuration can obtain a device having a generally S-shape. Referring to FIG. 16, a poling electric field can be driven from the outer electrodes of the four-section sections 430 and 434 to the outer electrodes of the four-section sections 432 and 436 without contact with the central section. Alternatively, the poling field can be driven from the outer electrode of each quadrant to the inner electrode of each quadrant, thereby allowing independent access to each piezoelectric element. The latter configuration allows the device to be S-shaped or conventional bimorph depending on the driving conditions.
Embodiments of the invention include devices that make separate piezoelectric elements or separately poled regions of the device in electrical contact with separate electrodes, and two or more devices in electrical contact with electrodes in electrical communication with each other. A device having a region.

Although FIG. 16 shows a bimorph S-shaped device, the S-shaped device is
Unimorph, bimorph or multimol
ph) may be designed. These areas (430, 432, 434 and 43
6) is a separate piezoelectric element or a separately polled piezoelectric element area,
Alternatively, it may represent a combination of separate piezoelectric elements and separately polled piezoelectric element regions. For example, in the unimorph device embodiment, the quadrants 430 and 434 may be two separate piezoelectric elements, one of which has a positive bend and the other of which has a positive curvature. It is driven so that it has a negative bend and regions 432 and 436 are inactive. The inactive region is a metal (eg,
Brass or stainless alloy), plastic, polyimide, polyester, other specific polymers, wood, or composite materials such as glass fiber, graphite or GRFP. Alternatively, the inactive region may be a component of a larger system, that is, a device through physical bonding or other compounding (comp.
onent). For example, the inactive region may be a beam or panel plate used for acoustic emission metals, or (eg, where it is desired to translate or replace the temporary stop head and to minimize rotation of the temporary stop head). It may include a temporary stop structure in the disk drive temporary stop.

In another embodiment, the S-shaped device may include two piezoelectric elements. Each piezoelectric element may include two electrode regions that are poled in opposite directions and driven with an electric field in the same direction relative to the thickness of the device. Alternatively, these electrode regions can be poled in the same direction and driven by an electric field in the opposite direction to the thickness of the device.

Embodiments of the invention include both packaged S-shaped devices and S-shaped actuators that are not packaged as cards.

The actuator of the present invention can be used to perform simple mechanical movements (eg bending, twisting or rocking) imparted to a mask or a part of a doll used in a play, and also the actuator of the present invention. In addition, it has excellent actuation characteristics,
It has been shown to have mounting versatility for this type of small load, moderate displacement actuation task.

In general, the flex circuit actuator card of the present invention can be used as a separate mechanical element to address the task of enabling pneumatic actuators with low or moderate displacement. Is. Also, if the task involves structures such as sheets, flaps or walls, the flex circuit itself may constitute its structural component. Accordingly, the present invention is directed to an automatic stirring vane, bellows or pump wall,
Suitable for functions such as mirrors. In addition, as mentioned above, tasks involving small displacement surface coupling in the acoustic or ultrasonic frequency bands can also be readily implemented with low mass, high coupling flex circuit actuators.

As described above, the piezoelectric element does not have to be a rigid ceramic element, and when the bending circuit is used only as a sensor, either a ceramic element or a soft material such as PVDF can be used. In the case of polymers, the thinner the wall, the more flexible low temperature adhesive is used for device bonding, rather than the harder curable epoxy bonding layer.

[0059]   Embodiments of the present invention will be exemplified below.

(Example) A device including an interdigital electrode (IDE) function of a fine wire using a surface acoustic wave (SAW) propagation principle in a solid state may be called an interdigital converter (IDT). Most of the IDTs currently used operate using low electric field and high frequency propagating waves instead of high electric field and low frequency. The latter condition is necessary for actuation and damping applications. The principle behind IDE is that the device is more commonly used for in-plane actuation or damping, the d ₃₁ characteristic (ie, as before, charge is collected on the same surface). However, the force is not applied at right angles to the polarization axis, but rather the d ₃₃ characteristic (ie, the force is exerted in three directions along the polarization axis and presses on the same surface where the charge is collected). Can be used more efficiently. This is accomplished by arranging the electrodes so that the poling and excitation fields operate almost parallel to the actuation plane. FIG. 15A shows the field lines 422 of the d ₃₁ device 424 with the solid electrodes 420 disposed on the top and bottom surfaces of the piezoceramic plate 404. FIG. 15B shows the force lines 422 of the d ₃₃ IDE device 426 with the connecting linear electrodes 408. These electromechanical properties in the d ₃₃ direction are generally more than twice as great as those in the d ₃₁ direction.

Linear IDE devices have been successful at some low field applications, but internal cracks or shorts can occur when applying large fields during poling or excitation.
These defects are due to internal stress caused by the non-uniform electric field in the material near the electrode ends. It is also clear that the stress is further concentrated by the electrode wires connecting the interdigital wires on the surface of the piezoelectric ceramic. The linear IDE pattern is also used in the construction of piezoelectric fiber composite material devices without stress concentration.

An interdigital electrode monolithic thin plate piezoelectric device (hereinafter simply referred to as "IDE device") was developed using the method described herein. The results, a piezoelectric device using the d ₃₁ piezoelectric ceramic plate with a solid electrode on the plate both surfaces (hereinafter, referred to as "solid electrode device") is compared with. The electromechanical coupling rate and damping capacity of these devices were quantified and compared using the calculated electrical and mechanical energies and the experimental results of resonance measurements.

Both solid-state electrodes and IDE devices were made using PZT-5A type materials with dimensions of 46.05 mm × 20.65 mm × 0.254 mm. The dimensional ratio between the thickness of the piezoceramic and the electrodes of the IDE device is important, but the determination of the optimum value depends on the application-specific requirements (eg displacement, generated strain, force, and available drive voltage). As a typical design, 0 with a pitch of 1.52 mm
． The IDE device electrode pattern consisting of 38 mm lines was selected. The piezoceramic material and electrodes were packet caged with a protective polyimide coating pre-installed with electrical leads.

1. Vibration Damping Experiments Damping experiments were constructed using IDE devices and solid electrode devices bonded to aluminum beams. These beams are 229.0 mm x 31.8 m
m × 2.3 mm, and the free clamp length was 133.0 mm. The devices were bonded to one surface of an aluminum beam 6.35 mm from the clamp end. The movement of the tip due to the initial displacement was measured using a laser displacement sensor. The decay from the tip displacement ring down was calculated using the log reduction method. Attenuation measurements are performed on bare beams and RC shunted
) Type IDE devices and solid electrode devices and beams with non-shunt IDE devices and solid electrode devices. A second method of measuring system attenuation was used to confirm log reduction results. In this method, an electromechanical shaker attached to the beam is used to provide the beam with a swept sinusoidal excitation through a load cell, which is then attenuated from a transfer function measured from the load on the tip displacement. Was calculated.

Due to the difficulties associated with consistently exciting the beams in their first resonant mode, the response of these beams as a function of the average strain on the surface of the device bonded to the aluminum beam. A large variability was observed in the percentage of critical damping measured in. Compared to the beam-bonded unshunted IDE device and the unshunted solid state device, the shunted IDE device showed more than twice the damping achieved by the shunted solid electrode device.

2. Generated Strain and Elasticity Experiments The free-free strain produced by IDE devices and solid state electrode devices was measured with strain gauges bonded to both sides of these devices. In addition to the ability to generate high strains, piezoceramic devices also have the ability to generate high forces due to the inherently high material elasticity. Elasticity measurements are very difficult (especially when the excitation field is high). Low field measurements are useful as a general measure of elasticity, but caution should be exercised when applying these measurements to predict high field AC performance. The elasticity of the device can be determined by measuring the strain under known mechanical stress. In this way, generate a stress-strain curve,
It is possible to quantify elasticity as a function of applied electric field.

In this experiment, an aluminum bonding sheet was used to apply known mechanical stress to both sides of the device. Due to the symmetrical structure, the in-plane strain was uniform over the thickness of the device, excluding the edges. If the measurement results of the strain and the elasticity of aluminum (68.8 GPa) are known, the stress in aluminum can be determined from Hooke's law. Neglecting the presence of the thin, low-elasticity bonding layer, the stress-thickness product in the piezoceramic layer is equal in opposite direction to the same product in the aluminum layer. Therefore, strain measurements on the aluminum surface can be used to discover stress in the device. Taking measurements of multiple aluminum sheets of different thickness in this way allows the device elasticity to be calculated under different electric field levels and different mechanical strain levels.

The free strain of the device was measured by averaging the signals from strain gauges applied to both sides of the device at room temperature. The drive signal given is 1
Was a sine wave of Hz; the maximum voltage was +/- 600 volts (1200 V _pp ) for IDE devices and +/- 100 volts s for solid electrode devices.
(200 V _pp ). The applied electric field is set such that the spacing between the electrode surfaces is 0.254 mm in the case of the solid electrode device, and the spacing between the electrode lines is 1.5 in the case of the IDE device.
It was calculated as 24 mm. Since the electric field in an IDE device is non-uniform, the values calculated in this manner should be considered as mean or nominal values. For comparable field strengths, the strain output of the IDE device is about 70% higher than that of the solid electrode device.

For comparison purposes, Table 1 shows the measured low field piezoelectric strain constants (d ₃₁ and d ₃₃ ) of the unpackaged PZT 5A material and the high field of IDE and solid state electrode devices (8 kV / cm) strain constant. The piezoelectric constant value is
Although it is actually non-linear as a function of the electric field and highly dependent on the type of excitation signal (eg, waveform, drive frequency, DC offset, etc.), this comparison is still useful. The high electric field d ₃₁ constant of the solid electrode device actuator was higher than the low electric field constant of the unpackaged material. The strain constant of the IDE device actuator was approximately 10% lower than the d ₃₃ constant of the unpackaged material. This is because the electric field in the IDE device is not exactly equivalent to the electric field in the d ₃₃ device.

[0070]

[Table 1] 0.0375 mm, 0.07 mm thickness bonded to both sides of unpackaged piezoceramic plate and solid electrode and IDE device
Strain constraint and elastic modulus were measured using 50 mm and 0.1250 mm aluminum layers. Data points showing the relationship between the calculated stress and the strain of the unpackaged piezoceramic plate for aluminum constrained layers of different thickness were taken at four different electric field levels (2 kV / cm, 4 kV / c).
m, 6 kV / cm and 8 kV / cm). The elastic modulus was obtained from the slope of the line connecting the data points obtained at a particular electric field level. I
Similar measurements were made for DE devices and solid electrode devices.

(3. Electromechanical Coupling Factor) The electromechanical coupling rate is useful in quantifying the performance of the piezoelectric device. It is a dimensionless parameter calculated from the electrical and mechanical energy of the system. The electromechanical coupling rate can be found from the following.

[0072]

[Equation 1] Here, the mechanical energy output of the device is represented by W _M and the electrical energy input to the system is represented by W _E. Alternatively, the electromechanical coupling rate is
It can also be found from the following.

[0073]

[Equation 2] Here, f _a and f _r are the anti-resonance frequency and the resonance frequency measured by the impedance analyzer. However, Equation 2 shows that the sample is rod-shaped and (length / width) ²
It is completely accurate only if the condition> 10 is met. If this condition is not met, the result of Equation 2 can only be used to compare similarly shaped devices.

Table 2 contains the calculated electromechanical coupling rates determined using both of the above methods. Approximately based on Equation 1, when the applied electric field is 8 kV / cm, the coupling rate is 0.71 for the IDE device and 0.32 for the solid electrode device.
Is. Impedance plots measured using an HP impedance analyzer (Model 4194A) are used to find the resonant and anti-resonant frequencies used in Equation 2. The device value (length / width) was approximately equal to 5. 5
Since is less than 10, the value obtained from Equation 2 should be used for comparison purposes only. Approximation based on Equation 2 shows that the IDE device coupling rate is about 65% higher than the solid state electrode device coupling rate.

[0075]

[Table 2] Therefore, summarizing the results, the electromechanical coupling ratio calculated using two different methods is 0.45-0 for IDE devices compared to 0.29-0.35 for d ₃₁ devices. Indicates that a value of 0.71 has been achieved. In addition, experimental results comparing the damping and actuation performance of the d ₃₁ device with that of the IDE device are also provided. The resistance shunt IDE damper device has achieved more than a twofold improvement in damping compared to conventional PZT dampers. Further, the high electric field generated strain of the IDE actuator was 70% higher than the high electric field generated strain generated by the d ₃₁ actuator.

The above description of the manufacturing method and the exemplary embodiments are presented to illustrate the range of structures to which the invention applies. The present invention overcomes many of the deficiencies in fragility, circuitry and general utility of strain actuators, strain activated assemblies and sensors. Other variations of the physical construction and practical application of the modular flex circuit actuators and sensors of the present invention will be envisioned by those of ordinary skill in the art, and such variations are set forth in the claims appended hereto. It is believed that it is within the scope of the present invention to claim such patents.

[Brief description of drawings]

FIG. 1A   FIG. 1A is a system diagram of a typical prior art actuator.

FIG. 1B   FIG. 1B is a diagram of one of the two systems according to the present invention.

[FIG. 1C]   FIG. 1C is a diagram of one of the two systems according to the present invention.

2A is a top view of a basic actuator or sensor card according to an embodiment of the present invention. FIG.

FIG. 2B is a cross-sectional view of a basic actuator or sensor card according to an embodiment of the present invention.

FIG. 2C is a diagram of an actuator or sensor card having circuit components.

[Figure 3]   FIG. 3 is a diagram of another card.

FIG. 4A   4A is a cross-sectional view of the card of FIG.

FIG. 4B   4B is a cross-sectional view of the card of FIG.

[Figure 5]   FIG. 5 shows details of the layer structure of the card of FIG.

FIG. 5A   FIG. 5A shows details of the layer structure of the card of FIG.

FIG. 6 shows actuator package comb electrodes for in-plane actuation.

[Figure 7]   FIG. 7 shows a torsion actuator package using the card of FIG.

FIG. 8A shows an actuator mounted as a surface mount actuator on a surface.

FIG. 8B shows an actuator mounted as a surface mount actuator on a rod.

FIG. 9A   FIG. 9A shows the actuator mounted as a mechanical component.

FIG. 9B   FIG. 9B shows the actuator mounted as a mechanical component.

FIG. 9C   FIG. 9C shows the actuator mounted as a mechanical component.

FIG. 9D   FIG. 9D shows the actuator mounted as a mechanical component.

[FIG. 9E]   FIG. 9E shows the actuator mounted as a mechanical component.

[FIG. 9F]   FIG. 9F shows the actuator mounted as a mechanical component.

[FIG. 9G]   FIG. 9G shows the actuator mounted as a mechanical component.

[FIG. 9H]   FIG. 9H shows the actuator mounted as a mechanical component.

[FIG. 9I]   FIG. 9I shows the actuator mounted as a mechanical component.

[Fig. 9J]   FIG. 9J shows the actuator mounted as a mechanical component.

[Fig. 9K]   FIG. 9K shows the actuator mounted as a mechanical component.

[FIG. 9L]   FIG. 9L shows the actuator mounted as a mechanical component.

[FIG. 9M]   FIG. 9M shows the actuator mounted as a mechanical component.

[FIG. 9N]   FIG. 9N shows the actuator mounted as a mechanical component.

[Figure 9O]   FIG. 9O shows the actuator mounted as a mechanical component.

[Figure 9P]   FIG. 9P shows the actuator mounted as a mechanical component.

[Figure 9Q]   FIG. 9Q shows the actuator mounted as a mechanical component.

FIG. 10A shows different configurations of linear interdigital electroded electro-active devices.

FIG. 10B shows different configurations of linear interdigital electroded electro-active devices.

FIG. 10C shows different configurations of linear interdigital electroded electro-active devices.

FIG. 11A shows a linear interdigital electroded electro-active device with a common bus disposed on a piezoelectric component.

FIG. 11B shows a linear interdigital electroded electro-active device with a common bus located across the piezoelectric components.

FIG. 12 shows a linear interdigital electroded electro-active device with multiple piezoelectric components.

FIG. 13 shows an angled linear interdigitally electroded electro-active device with multiple piezoelectric components.

FIG. 14A shows an angled rectilinear interdigitally electroded electro-active device connected to a beam structure.

FIG. 14B shows an angled linear interdigital electroded electroactive device connected to a tube or rod structure.

FIG. 15A shows the electric field lines of a piezoelectric device having a piezoelectric ceramic plate with solid electrodes on both surfaces of the piezoelectric ceramic.

FIG. 15B shows the electric field lines for one embodiment of a piezoelectric device with interdigital electrodes.

FIG. 16   FIG. 16 shows an S-type device with an electro-active quadrant.

FIG. 17   FIG. 17 shows the relative displacement of the S-shaped device.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE), BR, CA, J P, KR, MX (72) Inventor Landstrom, Mark E.             United States Washington 98104,             Seattle, Floor 6, First             Avenue 616 (72) Inventor Moore, Jeffrey W ..             United States Massachusetts             02174, Arlington, Summerst             REIT 158 (72) Inventor Crawley, Edward             United States Massachusetts             02138, Cambridge, Danastri             Toe 49 Bee (72) Inventor Russo, Farla             United States Massachusetts             02445, Brookline, Willist             Download 29 (72) Inventor Yoshikawa, Shoko             United States Massachusetts             02128, Cambridge, Apartmentmen             To 703, Concord Avenue 655 (72) Inventor Fitch, Eric             United States Massachusetts             02155, Medford, Spring               Street 111

Claims (33)

[Claims] 1. An actuator device, comprising an electro-active element, a conductor having a pair of interdigital electrodes, an insulator, and an electrical contact portion, wherein in-plane strain in the electro-active element is the electrical device. Bonding the electrically active element, the conductor and the insulator together such that a shear bond is formed between the active element and the insulator,
An actuator device in which the pair of interdigital electrodes are in direct electrical contact with the electrical contact of the electrically active element and the insulator. 2. The electro-active element has a first surface and a second surface,
The pair of interdigital electrodes are a first pair of interdigital electrodes that are in direct electrical contact with the first surface of the electrically active element and are in direct electrical contact with the second surface of the electrically active element. Two pairs of interdigital electrodes, wherein the second pair of interdigital electrodes are connected to the first pair of interdigital electrodes through equipotential lines extending through the electro-active element. Item 2. The actuator device according to Item 1. 3. The actuator device according to claim 1, wherein each of the pair of interdigital electrodes comprises a plurality of linear electrodes and a common bus arranged away from the electro-active element. 4. The actuator device of claim 1, wherein each of the pair of interdigital electrodes comprises silver conductive ink. 5. The actuator device of claim 1, wherein the electrically active element is not metallized. 6. The electro-active device, the conductor and the insulator are bonded together with a bonding agent selected from the group consisting of B-stage epoxy, C-stage epoxy and thermoplastics. Actuator device. 7. The actuator device of claim 1, wherein each of the pair of interdigital electrodes comprises a plurality of angled linear electrodes and a common bus. 8. The insulator comprises a first surface bonded to the electro-active element and the conductor and a second surface, each of the pair of interdigital electrodes comprising a plurality of linear electrodes. The actuator device according to claim 1, further comprising a common bus disposed on the second surface of the insulator, wherein the linear electrode is electrically connected to the common bus through the insulator. 9. An actuator device, comprising: an electro-active element; and a bending circuit including an insulator and a pair of interdigital electrodes, wherein in-plane strain in the electro-active element is different from that of the electro-active element. An actuator device, wherein the electro-active element is bonded to the flex circuit such that it is shear coupled to the flex circuit and the pair of interdigital electrodes are in direct electrical contact with the electro-active element. 10. An actuator device comprising: at least one electrically active element; and at least one flex circuit comprising an insulator and at least a first pair of interdigital electrodes, the at least one electrically active element. Each have at least one surface bonded to one of the at least one flex circuit such that one of the at least first pair of interdigital electrodes is coupled to the at least one electrically active element. An actuator device in direct electrical contact with the in-plane strain of the at least one electrically active element is shear coupled between the at least one electrically active element and the at least one flex circuit. 11. The actuator of claim 10, wherein one of the at least one flex circuit comprises a first and second pair of interdigital electrodes disposed on opposite surfaces of the insulator. device. 12. A method of dampening vibrations in an object, comprising: (a) said actuator device being shear coupled to said object and said electrical signal being applied to said pair of interdigital electrodes. Bonding the actuator device according to claim 1 so that the in-plane strain of the active element mechanically acts on the object through the insulator, and (b) an electrical signal to the pair of interdigital electrodes. And a method of including. 13. An actuator device comprising at least first and second electrically active elements, and at least first and second conductors, the first conductors being the first electrically active elements. In direct electrical contact with the second conductor in direct electrical contact with the second electrically active element, the device being generally S-shaped when the first and second electrically active elements are activated. An actuator device that configures the first and second electrically active elements and the conductor to form a shape. 14. An actuator device further comprising at least a third conductor, said first electro-active element comprising at least first and second regions, said first conductor comprising said first conductor. The actuator device of claim 13, wherein the actuator is in direct electrical contact with the first region of the electrically active element and the third conductor is in direct electrical contact with the second region of the first electrically active element. 15. The actuator device of claim 13, further comprising an inactive element. 16. The actuator device of claim 14, wherein at least two of the at least three conductors are in electrical communication with each other. 17. The immobilizing element is a component of a disk drive,
The actuator device of claim 14. 18. At least one of the electro-active elements is driven positively with respect to its poling field and at least one of the electro-active elements is driven negative with respect to its poling field. The actuator device of claim 13, wherein 19. The actuator device of claim 13, wherein the device further comprises an encapsulation layer containing the electrically active element and the conductor, the actuator device forming a card. 20. The actuator device of claim 13, wherein the at least first and second conductors make direct electrical contact with the at least first and second electrically active elements at a plurality of points. 21. The actuator device of claim 13, wherein the actuator device is shear bonded to an object. 22. The actuator device of claim 13, wherein the actuator device is configured as a stack, bend, shell, plate or bender. 23. An actuator device further comprising an insulator,
The first and second electrical so that in-plane strains in the first and second electrically active elements are shear coupled between the first and second electrically active elements and the insulator. 14. The actuator device of claim 13, wherein the active element and the insulator are bonded together. 24. An actuator device comprising at least a third conductor, said third conductor making direct electrical contact with said first conductor or said second conductor. . 25. An actuator device comprising at least one electrically active element having at least a first region and a second region; and at least one first and second conductor, said first conductor. Is in direct electrical contact with the first region of the electrically active element, the second conductor is in direct electrical contact with the second region of the electrically active element, and An actuator device that configures the electrically active element and the conductor such that the device forms a generally S-shape when the second region is activated. 26. The actuator device of claim 25, wherein the first and second regions of the electrically active element are polled in opposite directions. 27. The actuator device of claim 25, wherein the first and second regions of the electro-active element are polled in the same direction. 28. The actuator device of claim 25, wherein the actuator device is shear bonded to an object. 29. The actuator device of claim 25, wherein the actuator device is configured as a stack, bend, shell, plate or bender. 30. An actuator device further comprising an insulator,
Bonding the electrically active element and the insulator together such that in-plane strain in the electrically active element is shear coupled between the electrically active element and the flex circuit.
The actuator device according to claim 25. 31. The actuator device of claim 30, further comprising at least a third conductor, the third conductor making direct electrical contact with the first conductor or the second conductor. 32. A method of damping vibrations of an object, comprising: (a) applying at least one of said at least first and second conductors to said at least first and second electrical conductors. Bonding the actuator device according to claim 13 to an object such that the in-plane strain of the active element mechanically acts on the object, and (b) applying an electrical signal to one of the conductors. And including. 33. A method of forming an actuator device, the method comprising: (a) creating a flex circuit comprising an insulator and at least first and second conductors; and (b) in-plane in an electrically active device. The electroactive element is coupled to the flex circuit such that strain is shear coupled between the electroactive element and the flex circuit and the electroactive element is in direct electrical contact with the at least first and second conductors. Bonding to the substrate, and a method including.