WO2014093741A1

WO2014093741A1 - Electroactive polymer actuated surface with flexible sealing membrane

Info

Publication number: WO2014093741A1
Application number: PCT/US2013/074863
Authority: WO
Inventors: Silmon James Biggs; Arthur Hughes MUIR; Alireza Zarrabi
Original assignee: Bayer Materialscience Ag
Priority date: 2012-12-13
Filing date: 2013-12-13
Publication date: 2014-06-19
Also published as: TW201439816A

Abstract

An apparatus is disclosed. The apparatus includes a housing (102), an element (104) comprising a surface, and a pre-formed membrane (106) positioned between the surface and the housing to form a seal between the surface and the housing. The apparatus may include at least one electroactive polymer actuator (200) positioned proximate to and in contact with the surface to provide haptic feedback in response to a user's stimulus.

Description

ELECTROACTIVE POLYMER ACTUATED SURFACE WITH FLEXIBLE SEALING MEMBRANE

RELATED APPLICATIONS

[0001] This application claims the benefit, under 35 USC § 1 19(e), of U.S.

Provisional Application No.: 61/748,785 filed January 4, 2013 entitled

"MOVING TOUCH PANEL SEAL" and U.S. Provisional Application No. :

61 /736,601 filed December 13, 2012 entitled "VIVITOUCH HAPTIC

KE YBOARD," the entirety of each of which is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention is directed in general to electroactive polymer based input / output devices. More particularly, the present invention is directed to electroactive polymer based keyboards and touchscreen displays. More particularly, the present invention is directed to seals for electroactive polymer based input / output systems. More particularly, the present invention is directed to seals for electroactive polymer based keyboards and touch screen displays.

BACKGROUND OF THE INVENTIO

[0003] A tremendous variety of devices used today rely on actuators of one sort or another to convert electrical energy to mechanical energy. Conversely, many power generation applications operate by converting mechanical action into electrical energy. Employed to harvest mechanical energy in this fashion, the same type of device may be referred to as a generator. Likewise, when the structure is employed to convert physical stimulus such as vibration or pressure into an electrical signal for measurement purposes, it may be characterized as a sensor. Yet, the term "transducer" may be used to genetically refer to any electroactive devices described herein.

[0004] A number of design considerations favor the selection and use of advanced dielectric elastomer materials, also referred to as "electroactive polymers", for the fabrication of transducers. These considerations include potential force, power density, power conversion/consumption, size, weight, cost, response time, duty cycle, service requirements, environmental impact, etc. As such, in many applications, electroactive polymer technology offers an ideal replacement for piezoelectric, shape-memory alloy and electromagnetic devices such as motors and solenoids.

[0005] An electroactive polymer transducer comprises two electrodes having deformable characteristics and separated by a thin elastomeric dielectric material. When a voltage difference is applied to the electrodes, the oppositely charged electrodes attract each other thereby compressing the polymer dielectric layer therebetween. As the electrodes are pulled closer together, the dielectric polymer film becomes thinner (the Z-axis component contracts) as it expands in the planar directions (along the X- and Y-axes), i.e., the displacement of the film is in-plane. The electroactive polymer film may also be configured to produce movement in a direction orthogonal to the film structure (along the Z-axis), i.e., the displacement of the film is out-of-plane. U.S. Pat. No. 7,567,681 discloses electroactive polymer film constructs which provide such out-of-plane displacement— also referred to as surface deformation or as thickness mode deflection.

[0006] The material and physical properties of the electroactive polymer film may be varied and controlled to customize the deformation undergone by the transducer. More specifically, factors such as the relative elasticity between the polymer film and the electrode material, the relative thickness between the polymer film and electrode material and/or the varying thickness of the polymer film and/or electrode material, the physical pattern of the polymer film and/or electrode material (to provide localized active and inactive areas), the tension or pre-stram placed on the electroactive polymer film as a whole, and the amount of voltage applied to or capacitance induced upon the film may be controlled and varied to customize the features of the film when in an active mode.

[0007[ Numerous applications exist that benefit from the advantages provided by such electroactive polymer films whether using the film alone or using it in an electroactive polymer actuator. One of the many applications involves the use of electroactive polymer transducers as actuators to produce haptic feedback (the communication of information to a user through forces applied to the user's body) in user interface devices, There are many known user interface devices which employ haptic feedback, typically in response to a force initiated by the user. Examples of user interface devices that may employ haptic feedback include keyboards, keypads, game controller, remote control, touchsereens, computer mice, trackballs, stylus sticks, joysticks, etc. The user interface surface can comprise any surface that a user manipulates, engages, and/or observes regarding feedback or information from the device. Examples of such interface surfaces include, but are not limited to, a key (e.g., keys on a keyboard), a game pad or buttons, a display screen, etc.

[0008] The haptic feedback provided by these types of interface devices is in the form of physical sensations, such as vibrations, pulses, spring forces, etc., which a user senses either directly (e.g., via touching of the screen), indirectly (e.g.. via a vibrational effect such as when a cell phone vibrates in a purse or bag) or otherwise sensed (e.g., via an action of a moving body that creates a pressure disturbance sensed by the user). The proliferation of consumer electronic media devices such as smart phones, personal media players, portable computing devices, portable gaming systems, electronic readers, etc., can create a situation where a sub-segment of customers would benefit or desire an improved haptic effect in the electronic media device. However, increasing haptic capabilities in every model of an electronic media device may not be justified due to increased cost or increased profile of the device. Moreover, customers of certain electronic media devices may desire to temporarily improve the haptic capabilities of the electronic media device for certain activities.

[0009] Use of electroactive polymer materials in consumer electronic media devices as well as the numerous other commercial and consumer applications highlights the need to increase production volume while maintaining precision and consistency of the films.

[0010] Electroactive polymer actuated electronic media often include movable parts, which are difficult to seal when they are in motion. Sealing the interior of a movable haptic touchscreen display surface or a movable haptic electronic keyboard element should resist the effects of the operating environment for the life of the device, without restricting the motion of the device and adding only negligible damping force to the system.

[0011] Conventional sealing solutions typically employ foam gaskets, labyrinth seals, or membrane seals. Such conventional sealing techniques, however, have the following drawbacks. Foam gaskets are compressed against the surface and add too much friction to the system. Labyrinth seals are complex to make, necessitate high tolerances, are not as effective as desired, and can add friction. Membrane seals add too much stiffness in the direction of shear in the membrane.

SUMMARY OF THE INVENTION

[0012] Electroactive polymer actuators include, but are not limited to planar, diaphragm, thickness mode, roll, and passive coupled devices (hybrids) as w^rell as any type of electroactive polymer device described in the commonly assigned patents and applications cited herein,

[0013] in one embodiment, the present invention provides an element comprising a surface and at least one electroactive polymer actuator positioned proximate to and in contact with the surface of the element to provide haptic feedback in response to a user's stimulus input.

[0014] In one embodiment, the present invention provides an element comprising a surface and pre-formed membrane positioned between the surface and a housing to form a seal between the surface and the housing, in one embodiment, the preformed membrane comprises a thin flexible elastoraeric film, in one embodiment, the pre-formed membrane is loosely positioned to create slack.

[0015] In one embodiment, the element is an electronic element such as a keypad and / or a touchscreen display.

[0016] These and other features, objects and advantages of the invention will become apparent to those persons skilled in the art upon reading the details of the invention as more fully described below. In addition, variations of the processes and devices described herein include combinations of the embodiments or of aspects of the embodiments where possible are within the scope of this disclosure even if those combinations are not explicitly shown or discussed,

BRIEF DESCRIPTION OF THIS DRAWINGS

[0017] The invention is best understood from the following detailed description when read in conjunction with the accompanying drawings. To facilitate understanding, the same reference numerals have been used (where practical) to designate similar elements are common to the drawings. Included in the drawings are the following:

[0018] Figs. 1 A and IB illustrate a top perspective view of an electroactive device before and after application of a voltage to electrodes in accordance with one embodiment of the present invention;

[0019] Fig. 2A illustrates an exemplary electroactive polymer cartridge in accordance with one embodiment of the present invention;

[0020] Fig, 2B illustrates an exploded view of an electroactive polymer actuator, inertial mass and actuator housing in accordance with one embodiment of the present, invention;

[0021] FIG. 3 A illustrates a section view of a movable panel system comprising a movable panel contained within a housing in accordance with one embodiment of the present invention;

[0022] FIG. 3B illustrates a section view of the movable panel system shown in FIG. 3 A contained within a housing with an electroactive polymer actuator assembly coupled to the movable panel in accordance with one embodiment of the present invention;

[0023] FIG, 4 illustrates a top view of an electroactive polymer actuator arrangement in accordance with one embodiment of the present invention.

[0024] FIG. 5 illustrates an exploded view of a system assembly comprising the electroactive polymer actuator assembly shown in FIG. 4 positioned between a movable el ement and a housing in accordance with one embodiment of the present invention; [0025] FIG. 6 illustrates an electronic keyboard assembly comprising the system assembly shown in FIG. 5 and a slot connector to receive a tablet computer in accordance with one embodiment of the present invention;

[0026] FIG. 7 illustrates a system assembly comprising the electronic keyboard assembly shown in FIG. 6 connected to a tablet, computer in accordance with one embodiment of the present invention;

[0027] FIG. 8 illustrates a deflection model of a beam under the influence of a bending force F acting on the beam in the x direction; and

[0028] FIG. 9 illustrates a deflection model of a beam under the influence of a shear force F acting on the beam in the x direction.

[0029] Variation of the invention from that shown in the figures is contemplated,

DETAILED DESCRIPTION OF THE INVENTION

[0030] Examples of e!eetroactive polymer devices and their applications are described, for example, in U.S. Pat. Nos. 7,394,282; 7,378,783; 7,368,862;

7,362,032; 7,320,457; 7,259,503; 7,233,097; 7,224,106; 7,21 1 ,937; 7,199,501 ; 7,166,953; 7,064,472; 7,062,055; 7,052,594; 7,049,732; 7,034,432; 6,940,221; 6,911,764; 6,891 ,317; 6,882,086; 6,876,135; 6,812,624; 6,809,462; 6,806,621 ; 6,781,284; 6,768,246; 6,707,236; 6,664,718; 6,628,040; 6,586,859; 6,583,533; 6,545,384; 6,543,1 10; 6,376,971 ; 6,343,129; 7,952,261; 7,91 1 ,761 ; 7,492,076; 7,761,981; 7,521,847; 7,608,989; 7,626,319; 7,915,789; 7,750,532; 7,436,099; 7,199,501; 7,521 ,840; 7,595,580; 7,567,681 ; 7,595,580; 7,608,989; 7,626,319; 7,750,532; 7,761,981 ; 7,91 1,761; 7,915,789; 7,952,261 ; 8,183,739; 8,222,799: 8,248,750, and in U.S. Patent Application Publication Nos. 2007/0200457;

2007/0230222; 2011/0128239; and 2012/0126959, the entireties of which are incorporated herein by reference.

[0031] In various embodiments, the present invention provides an electronic element comprising a surface and at least one eiectroactive polymer actuator positioned proximate to and in contact with the surface of the electronic element to provide haptic feedback in response to a user's input. In one example, electroactive polymer actuators are positioned proximate and in contact with a surface of a keyboard to provide hapiic feedback in response to a user's input. In another example, electroactive polymer actuators are positioned proximate and in contact with a surface of a display, such as for example an electronic touchscreen display, to provide haptic feedback in response to a user's input. In various embodiments, the electroactive polymer actuators may be implemented with a low profile thin shape to minimize total assembly height when the electroactive polymer actuators are positioned beneath a surface of a keyboard or display, for example. In other implementations, electroactive polymer actuators may be located on lateral portions of the assembly to minimize total assembly height.

[0032] In another embodiment, the present invention provides an electronic element comprising a surface and an elastomeric film or membrane to form a flexible seal with slack and loosely positioned between a movable surface and a support surface of the electronic element. The various embodiments of the present invention provide a pre-formed membrane to seal the interior of the surface while only adding negligible damping force to the system. The seal formed by the pre-formed membrane resists the effects of the operating environment for the life of the device without restricting the motion of the screen. In one example, the pre-formed membrane is positioned between a surface and a housing of a movable haptic touchscreen display. In another example, the preformed membrane is positioned between a surface and a housing of a keyboard, such as for example, flat membrane type keyboards known under the trade name of MICROSOFT SURFACE keyboards.

[0033] In various embodiments, the pre-formed membrane comprises a thin, elastomeric film or membrane, formed in such a way as to be loosely positionable with slack between a surface of a display or keyboard element and support surfaces. In one embodiment, the pre-formed membrane is thin and with a curvature of slack in it to promote low force movement. Embodiments of the preformed membrane provide advantages over typical foam gaskets, labyrinth seals, or conventional membrane seals. For example, a pre-formed membrane in accordance with the present invention does not compress against the surface of the device and does not add excessive friction to the system as with conventional foam gasket seals. Furthermore, the pre-formed membrane seals in accordance with the present invention are simple to make and do not require hi gh tolerances, in contrast to conventional labyrinth seals, which are complex to make, need high tolerances, are not as effective a seal as desired and can add friction.

Additionally, pre-formed membrane seals in accordance with the present invention are flexible in the shear direction of the membrane as opposed to conventional membrane seals, which can be stiff in the shear direction of the membrane,

[0034] Vaiious embodiments of the pre-formed membrane in accordance with the present invention are thin and flexible and can be cast, molded, or thermoformed such that it bridges the gap between an external housing and a surface of a device. The surface may be a movable surface, such as a display or touchscreen of the de vice. By providing sufficient slack in the portion of the pre-formed membrane that is required to flex (i.e., the bridging portion) the pre-formed membrane seals in accordance with the present invention avoids adding significant damping forces into the movable portions of the system.

[0035] Advantages of the pre-formed membrane seals in accordance with the present invention include, without limitation, a better way to seal the interior space of a display or keyboard system, or any suitable electronic assembly with movable components. In various embodiments, the pre-formed membrane in accordance with the present invention may provide a dust- and/or moisture-tight seal, which may improve the longevity of an equipped device used in an environment where dust, moisture or spills are prevalent. The pre-formed membrane in accordance with the present invention provides a sealing function without employing a friction inducing compression gasket (such as PORO urethane foam, for example) in contact with movable parts of the system. The pre-formed membrane in accordance with the present invention also does not offer significant resistance to movement, thereby allowing the haptic motion to occur while using existing low power actuators. [0036] It is noted that the figures discussed herein schematically illustrate exemplary configurations of devices and processes that employ electroactive polymer films or transducers having such electroactive polymer films. Many variations are within the scope of this di sclosure, for example, in variations of the device, the electroactive polymer transducers can be implemented to control the size of apertures having varying geometries.

[0037] In any application, the displacement created by the electroactive polymer transducer can be exclusively in-plane which is sensed as lateral movement, or can be out-of-plane (which is sensed as vertical displacement). Alternatively, the electroactive polymer transducer material may be segmented to provide independently addressable/movable sections so as to provide angular displacement of the housing or electronic media device or combinations of other types of displacement, in addition, any number of electroactive polymer transducers or films (as disclosed i the applications and patent listed herein) can be incorporated in the user interface devices described herein.

[0038] The electroactive polymer transducer may be configured to displace upon the application of an electric voltage potential, which facilitates programming the size of an aperture for use with a control system with feedback devices.

Electroactive polymer transducers are ideal for many such applications for a number of reasons. For example, because of their light weight and minimal components, electroactive polymer transducers oiler a very low profile and, as such, are ideal for use in sensory haptic/optical feedback applications.

[0039] Embodiments of the present invention may be manufactured using various processes.

[0040] Various embodiments of electroactive polymer transducers or devices for actuator positioned proximate to and in contact with the surface of electronic elements to provide haptic feedback in response to a user's input and pre-formed membrane seals are described in detail hereinbelow. Prior to describing such embodiments, however. FIGS. I A- IB illustrate a top perspective view of an electroactive device before and after application of an electric voltage potential to electrodes in accordance with one embodiment of the present invention and provide a brief description of general electroactive polymer structures and processes for producing such structures.

[0041] Accordingly, the description now turns to FIGS. 1 A and IB, which illustrate an example of an electroactive polymer film or membrane 10 structure, A thin elastomeric dielectric film or layer 12 is sandwiched between compliant or stretchabie electrode plates or layers 14 and 16, thereby forming a eapacitive structure or film. The length "F and width "w" of the dielectric layer, as well as that of the composite structure, are much greater than its thickness "t". Preferably, the dielectric layer has a thickness in the range from about 10 μηι to about 100 μπι, with the total thickness of the structure in the range from about 15 μπι to about 10 cm. Additionally, it is desirable to select the elastic modulus, thickness, and/or the geometry of electrodes 14, 16 such that the additional stiffness they contribute to the actuator is generally less than the stiffness of the dielectric layer 12, which has a relatively low modulus of elasticity, i.e., less than about 100 MPa and more preferabl y less than about 10 MPa, but is likely thicker than each of the electrodes. Electrodes suitable for use with these compliant eapacitive structures are those capable of withstanding cyclic strains greater than about 1 % without failure due to mechanical fatigue.

[0042 j As seen in FIG. IB, when a voltage is applied across the electrodes, the unlike charges in the two electrodes 14, 16 are attracted to each other and these electrostatic attractive forces compress the dielectric film 12 (along the Z-axis). The dielectric film 12 is thereby caused to deflect with a change in electric field. As electrodes 14, 16 are compliant, they change shape with dielectric layer 12. In the context of the present disclosure, "deflection" refers to any displacement, expansion, contraction, torsion, linear or area strain, or any other deformation of a portion of dielectric film 12. Depending on the architect ure, e.g., a frame, in which eapacitive structure 10 is employed (collectively referred to as a

"transducer"), this deflection may be used to produce mechanical work. Various different transducer architectures are disclosed and described in the above- identified patent references. [0043] With a voltage applied, the transducer film 10 continues to deflect until mechanical forces balance the electrostatic forces driving the deflection. The mechanical forces include elastic restoring forces of the dielectric layer 12, the compliance or stretching of the electrodes 14, 16 and any external resistance provided by a device and/or load coupled to transducer 10. The resultant deflection of the transducer 10 as a result of the applied voltage may also depend on a number of other factors such as the dielectric constant of the elasiomeric material and its size and stiffness. Removal of the voltage difference and the induced charge causes the reverse effects.

[0044] In some cases, the electrodes 14 and 16 may cover a limited portion of dielectric film 12 relative to the total area of the film. This may be done to prevent electrical breakdown around the edge of the dielectric or achieve customized deflections in certain portions thereof. Dielectric material outside an active area (the latter being a portion of the dielectric material having sufficient electrostatic force to enable deflection of that portion) may be caused to act as an external spring force on the active area during deflection. More specifically, material outside the active area may resist or enhance active area deflection by its contraction or expansion.

[0045] The dielectric film 12 may be pre-strained. The pre-strain improves conversion between electrical and mechanical energy, i.e., the pre-strain allows the dielectric film 12 to deflect more and provide greater mechanical work. Pre- strain of a film may be described as the change in dimension in a direction after pre-straining relative to the dimension in that direction before pre-straining. The pre-strain may incl ude elastic deformation of the dielectric film and be form ed, for example, by stretching the film in tension and fixing one or more of the edges while stretched. The pre-strain may be imposed at the boundaries of the film or for only a portion of the film and may be implemented by using a rigid frame or by stiffening a portion of the film. [0046] The transducer structure of FIGS, 1A and I B and other similar compliant structures and the details of their constructs are more fully described in many of the referenced patents and publications disclosed herein.

[0047] FIG, 2A illustrates an exemplary electroactive polymer cartridge 12 having an electroactive polymer transducer film 26 placed between rigid frame 8 where the electroactive polymer film 26 is exposed in openings of the frame 8. T he exposed portion of the film 26 includes two working pairs of thin elastic electrodes 32 on either side of the cartridge 12 where the electrodes 32 sandwich or surround the exposed portion of the film 26. The electroactive polymer film 26 can have any number of configurations. However, in one example, the electroactive polymer film 26 comprises a thin layer of elastomeric dielectric polymer (e.g., made of acrylate, silicone, urethane, thermoplastic elastomer, hydrocarbon rubber, fluoroelastomer, copolymer elastomer, or the like). When a voltage difference is applied across the oppositely-charged electrodes 32 of each working pair (i.e., across paired electrodes that arc on either side of the film 26), the opposed electrodes attract each other thereby compressing the dielectric polymer layer 26 therebetween. The area between opposed electrodes is considered the active area. As the electrodes are pulled closer together, the dielectric polymer 26 becomes thinner (i.e., the Z-axis component contracts) as it expands in the planar directions (i.e., the X- and Y-axes components expand) (See FIG. 1 B for axis references).

[0048] Furthermore, in variations where the electrodes contain conductive particles, like charges distributed across each electrode may cause conductive particles embedded within that electrode to repel one another, thereby contributing to the expansion of the elastic electrodes and dielectric films. In alternate variations, electrodes do not contain conductive particles (e.g.. textured sputtered metal films). The dielectric layer 26 is thereby caused to deflect with a change in electric field. As the electrode material is also compliant, the electrode layers change shape along with dielectric layer 26. As stated hereinabove, deflection refers to any displacement, expansion, contraction, torsion, linear or area strain, or any other deformation of a portion of dielectric layer 26. This deflection may be used to produce mechanical work. As shown, the dielectric layer 26 can also include one or more mechanical output bars 34. The bars 34 can optionally provide attachment points for either an inertial mass (as described below) or for direct coupling to a substrate in the electronic media device.

[0049] In fabricating a transducer, an elastic film 26 can be stretched and held in a pre-strained condition usually by a rigid frame 8. In those variations employing a four-sided frame, the film can be stretched bi-axially. It has been observed that pre-strain improves the dielectric strength of the polymer layer 26. thereby enabling the use of higher electric fields and improving conversion between electrical and mechanical energy, i.e., the pre-strain allows the film to deflect more and provide greater mechanical work. Preferably, the electrode material is applied after pre-straining the polymer layer, but may be applied beforehand. The two electrodes provided on the same side of layer 26, referred to herein as same- side electrode pairs, i.e., electrodes on the top side of dielectric layer 26 and electrodes on a bottom side of dielectric layer 26, can be electrically isolated from each other. The opposed electrodes on the opposite sides of the polymer layer form two sets of working electrode pairs, i.e., electrodes spaced by the

electroactive polymer film 26 form one working electrode pair and electrodes surrounding the adjacent exposed electroactive polymer film 26 form another working electrode pair. Each same-side electrode pair can have the same polarity, whereas the polarity of the electrodes of each working electrode pair is opposite each other. Each electrode has an electrical contact portion configured for electrical connection to a voltage source.

[0050] In this variation, the electrodes 32 are connected to a voltage source via a ilex connector 30 having leads 22, 24 that can be connected to the opposing poles of the voltage source. The cartridge 12 also includes conductive vias 18, 20. The conductive vias 18, 20 can provide a means to electrically couple the electrodes 8 with a respective lead 22 or 24 depending upon the polarity of the electrodes.

[0051] The cartridge 12 illustrated in FIG. 2A shows a three-bar actuator configuration. However, the devices and processes described herein are not limited to any particular configuration, unless specifically claimed. Preferably, the number of the bars 34 depends on the active area desired for the intended application. The total amount of active area, e.g., the total amount of area between electrodes, can be varied depending on the mass that the actuator is trying to move and the desired frequency of movement. In one example, selection of the number of bars is determined by first assessing the size of the object to be moved, and then the mass of the object is determined. The actuator design is then obtained by configuring a design that will move that object at the desired frequency range. Clearly, any number of actuator designs is within the scope of the disclosure.

[0052] An electroactive polymer actuator for use in the processes and devices described herein can then be formed in a number of different ways. For example, the electroactive polymer can be formed by stacking a number of cartridges 12 together, having a single cartridge with multiple layers, or having multiple cartridges with multiple layers. Manufacturing and yield considerations may favor stacking single cartridges together to form the electroactive polymer actuator, in doing so, electrical connectivity between cartridges can be maintained by electrically coupling the vias 18, 20 together so thai adjacent cartridges are coupled to the same voltage source or power supply.

[0053] The cartridge 12 shown in FIG. 2A includes three pairs of electrodes 32 separated by a single dielectric layer 26. In one variation, as shown in FIG. 2B, two or more cartridges 12 are stacked together to form an electroactive actuator 14 that is coupled to an inertia! mass SO. Alternatively, the electroactive actuator 14 can be coupled directly to the electronic media device through a transitional attachment plate or frame. As discussed below, the electroactive actuator 14 cars be placed within a cavity 52 that allows for movement of the actuator as desired. The pocket 52 can be directly formed in a housing of a haptic case. Alternatively, pocket 52 can be formed in a separate case 56 positioned within the housing of the device. If the latter, the material properties of the separate case 56 can be selected based upon the needs of the actuator 14. For example, if the main body of the haptic housing assembly is flexible, the separate case 56 can be made rigid to provide protection to the electroactive actuator and/or the mass 50, In any event, variations of the device and processes described herein include size of the cavi ty 52 with sufficient clearance to allow movement of the actuator 14 and/or mass 50 but a close enough tolerance so that the cavity 52 barrier (e.g., the haptic housing or separate case 56) serves as a limit to prevent excessive movement of the electroactive actuator 14. Such a feature prevents the active areas of the actuator 14 from excessive displacement that can shorten the life of the actuator or otherwise damage the actuator.

[ 0054] Additional examples of electroactive polymer films can be found in the commonly assigned patents and patent applications disclosed and incorporated by reference herein.

[0055] FIG. 3 A il lustrates a section view of a movable panel system 100 comprising a movable panel 104 contained within a housing 102 in accordance with one embodiment of the present invention. The movable panel 104 of the movable panel system 1 0 is contained within the housing 102, mounted on bearings 108 to allow travel normal to the section plane. A pre-fornied membrane 106 that spans a gap 110 between the panel 104 surface and the housing 102 provides a seal between an interior portion 112 and an exterior portion 114 of the movable panel system 100. The movable panel 104 of the movable panel system 100 can also be moimted onto flexures to allow travel normal to the section plane.

[0056] In one embodiment, the panel 104 of the movable panel system 100 is an electronic element comprising a surface, which is movable. The pre-fornied membrane 106 comprises an elastomeric film formed to have slack and is positioned between the movable surface of the panel 104 and a support surface of the housing 102 of the electronic element. The pre-formed membrane 106 in accordance with various embodiments of the present invention seals the Interior portion 112 of the panel 1.04 from the exterior portion 114 while adding only negligible damping force to the movable panel system 100. The pre-formed membrane 1 6 resists the effects of the operating environment for the life of the movable panel system 100 without restricting the motion of the panel 104. In one example, the pre-fornied membrane 106 is positioned between a surface and a housing 102 of a movable haptic touchscreen display panel 104. In another example, the pre-formed membrane 1 6 is positioned between a surface and a housing 102 of a keyboard, such as for example, flat membrane type keyboards known under the trade name of MICROSOFT SURFACE keyboards.

[0057J In various embodiments, the pre-formed membrane Ϊ06 comprises a thin, elastomeric film or membrane, formed in such a way as to have slack between a surface of the panel 104, e.g., a display or keyboard element, and support surfaces of the housing 102. In one embodiment, the pre-formed membrane 106 is thin and with a curvature of slack in it to promote low force movement. Embodiments of the pre-formed membrane 106 provide advantages over typical foam gaskets, labyrinth seals, or membrane seals. For example, the pre-formed membrane 106 in accordance with the present invention does not compress against the surface of the device to add excessive friction to the system as with conventional foam gasket seals. Furthermore, the pre-formed membrane 106 in accordance with the present invention is simple to make and does not require high tolerances, in contrast to conventional labyrinth seals, which are complex to make, need high tolerances, are not as effective as desired and can add friction. Additionally, the pre-formed membrane 106 in accordance with the present invention is flexible in the shear direction of the membrane 106 as opposed to conventional membrane seals, which can be stiff in the shear direction of the membrane. Models approximating the stiffness characteristics of the pre-formed-membrane 106 in bending and shear modes are described in connection with FIGS, 8 and 9 hereinbelow.

[0058] Returning now to FIG. 3 A, in various embodiments, the pre-formed membrane 106 in accordance with the present invention is thin and flexible and can be cast, molded, or thermoformed such that it bridges the gap 110 between the external housing 102 and the panel 1Θ4. The panel 104 may comprise a movable surface, such as a display, touchscreen, or keyboard of the movable panel system 100. By providing sufficient slack in the portion of the pre-formed membrane 1 6 that is required to flex (i.e., the bridging portion) the pre-formed membrane 106 in accordance with the present invention avoids adding significant damping forces into the movable portions of the movable panel system 100.

[0059] Advantages of the pre-formed membrane 106 in accordance with the present invention include, without limitation, a better way to seal the interior space 112 of a display or keyboard system, or any suitable electronic assembly with movable components such as the movable panel system 100. In various embodiments, the pre-formed membrane 106 in accordance with the present invention provides a dust- and/or moisture-tight seal, which may improve the longevity of the movable panel system 100 used in an environment where dust, moisture or spills are prevalent. The pre-formed membrane 106 in accordance with the present invention provides a sealing function without employing a friction inducing compression gasket (such as PORON urethane foam, for example) in contact with movable parts of the system. The pre-formed membrane 106 in accordance with the present invention also does not offer significant resistance to movement, thereby allowing the haptic motion to occur- while using existing low power electroactive polymer actuators.

[0060] FIG. 3B illustrates a section vie of a movable panel system 150 shown in FIG. 3 A contained within a housing 102 with an electroactive polymer actuator assembly ISO coupled to the movable panel 104 in accordance with one embodiment of the present invention. The electroactive polymer actuator assembly 150 comprises electroactive polymer actuators to move the movable panel 104 when energized by an electric voltage potential difference as described in connection with FIGS. 1 A, IB, 2A, 2B, for example. One embodiment of the electroactive polymer actuator assembly 150 is described hereinbelow in connection with FIG. 4.

[0061] FIG. 4 illustrates a top view of an electroactive polymer actuator assembly 200 in accordance with one embodiment of the present invention. The electroactive polymer actuator assembly 200 comprises at least one or a plurality of individual electroactive polymer actuators 202 as described in connection with FIGS. 1 A, I B, 2A, and 2B. The electroactive polymer actuators 202 comprise a flex connector 204 to electrically connect the electrodes of the electroactive polymer actuators 202 to an electric voltage potential source, In one embodiment, the flex connector 204 has leads that can be connected to the opposing poles of the electric voltage potential source. As illustrated in FIG. 4, the electroactive polymer actuator assembly 200 the electroactive polymer actuators 202 are arranged in a matrix configuration over a mounting plate 206. The mounting plate 206 includes grooves 208 formed in the mounting plate 206 to receive the electroactive polymer actuators 202 including the flex connectors 204.

[0062] It will be appreciated that additional or fewer electroactive polymer actuators 202 may be provided in the electroactive polymer actuator assembly 200. In one embodiment, the electroactive polymer actuators 202 may be configured to operate independently. In another embodiment, two or more of the electroactive polymer actuators 202 may be configured to operate simultaneously to amplify force, for example. In other embodiments, the electroactive polymer actuators 202 may be configured to provide localized feedback, Furthermore, in other embodiments, two more electroactive polymer actuator assemblies 200 may be located on different sides of an object and configured to operate In a two-phase configuration. For example, one or more electroactive polymer actuators 202 may be positioned on opposite surfaces of an object and the electroactive polymer actuators 202 driven to subject the object to different forces, such as torsion, for example. In another example, one or more electroactive polymer actuators 202 may be positioned on adjacent surfaces of an object and driven to subject the object to different forces. These forces include shear, bending, torsion, among other forces.

[0063] The electroactive polymer actuator assembly 200 is configured to be mounted proximate to and in contact with a movable element, such as the panel 104 shown in FIG. 3A, a touchscreen display panel, a keyboard, such as for example, flat membrane type keyboards known under the trade name of

MICROSOFT SURFACE keyboards, among other movable panels. In one embodiment, the electroactive polymer actuator assembly 200 can be placed between a touchscreen and a chassis or can be placed between a keyboard assembly and a chassis, In one embodiment, the electroactive polymer actuator assembly 200 comprises at least one electroactive polymer actuator 202 per keyboard key. in other embodiments, at least one electroactive polymer actuator 202 may be shared between several keyboard keys. The electroactive polymer actuators 202 may arranged in any suitable pattern.

[0064] FIG. 5 illustrates an exploded view of a system assembly 300 comprising the electroactive polymer actuator assembly 200 shown in FIG. 4 positioned between a movable element 302 and a housing 304 in accordance with one embodiment of the present invention. In one embodiment, the electroactive polymer actuator assembly 200 may be molded and sealed between the movable element 302 (e.g.. keyboard assembly and / touchscreen display) and the housing 304, which may be made of thermoplastic, for example. In one embodiment, the movable element 302 comprises a keyboard assembly comprising keys, sensor, and onboard electronics. The electroactive polymer actuator assembly 200, or any of the variations thereof previously described, is positioned between the keyboard assembly (e.g., movable element 302) and the chassis (e.g., housing 304). The electroactive polymer actuator assembly 200 are positioned such that they contact the underneath portion of the keyboard assembly to provide haptic feedback in response to a force initiated by the user such as pressing one of the key elements of the keyboard assembly, in other embodiments, the movable element 302 of the system assembly 300 comprises a movable haptic touchscreen display in place of / or in addition to the keyboard assembly, The electroactive polymer actuator assembly 200 is electrically coupled to an electric voltage potential source to actuate the individual actuators 202 via the flex connectors 204 as described in connection with FIGS. 1 A, IB, 2A, 2B, and 3.

[0065] In the embodiment shown in FIG. 5, the electroactive polymer actuator assembly 200, or any variation thereof previously described, is placed under a MICROSOFT SURFACE type keyboard to provide haptic feedback in response to a user's input. In this implementation, the electroactive polymer actuator assembly 200 placed underneath the keyboard will increase the total height of the system assembly 300 but in other implementations, it is possible to minimize any increase in height of the system assembly 300 by positioning the electroactive polymer actuator assembly 2Θ0 on the side of (e.g., lateral portion) the system assembly 300.

[0066] The system assembly 300 also may comprise the preformed membrane 106 seal discussed in connection with FIG. 3 A. The preformed membrane 106 provides a tight flexible seal to resist the effects of the operating environment for the life of the system assembly 300 without restricting the motion of the movable element 302 (e.g., keyboard assembly and / or touchscreen display).

[0067] FIG. 6 illustrates an electronic keyboard assembly 400 comprising the system assembly 300 shown in FIG. 5 and a slot connector 402 to receive a tablet computer in accordance with one embodiment of the present invention. The system assembly 300 comprises an electroactive polymer actuator assembly 200 as described in connection with FIG. 4, and any variations thereof, located between the keypad assembly 302 and the housing 304. The keypad assembly 302 comprises a plurality of buttons or keys 404, or at least one button or key 404. The slot connector 402 is configured to receive a tablet computer, for example. As previously discussed, the electroactive polymer actuator assembly 200 comprises electroacti ve polymer actuators 202 electrically connected to an electric voltage potential source through flex connectors 204. At least one electroactive polymer actuator 202 is positioned proximate to, adjacent or beneath, a key 404 to provide haptic feedback in response to a force initiated by the user such as pressing one of the keys 404 of the keypad assembly 302.

[0068] FIG. 7 illustrates a system assembly 500 comprising the electronic keyboard assembly 400 shown in FIG. 6 connected to a tablet computer 502 in accordance with one embodiment of the present invention. As described in connection with FIG. 5, the system assembly 300 comprises an electroactive polymer actuator assembly 200 as discussed in connection with FIG. 4 located between the keypad assembly 302 and the housing 304, The keypad assembly 302 comprises a plurality of buttons or keys 404, or at least one button or key 404. The slot connector 402 is configured to receive the tablet, computer 502, for exarnple. The system assembly 300 comprises an electroactive polymer actuator assembly 200 as described in connection with FIG. 4, and any variations thereof, located between the keypad assembly 302 and the housing 304, The keypad assembly comprises a plurality of buttons or keys 404, or at least one button or key 404. The slot connector 402 is configured to receive a tablet computer, for example. As previously discussed with reference to FIG. 4, the electroactive polymer actuator assembly 200 comprises electroactive polymer actuators 202 electrically connected to an electric voltage potential source through flex connectors 204. At least one electroactive polymer actuator 202 is positioned proximate to, adjacent or beneath, a key 404 to provide haptic feedback in response to a force Initiated by the user such as pressing one of the keys 404 of the keypad assembly 3Θ2. The tablet computer 502 also may include electroactive polymer actuator assembly 200 which comprises electroactive polymer actuators 202 electrically connected to an electric voltage potential source through flex connectors 204 to provide a haptic feedback in response to a force initiated by the user such as pressing one of the keys 404 of the keypad assembly 302.

[0069] FIG. 8 illustrates a deflection model of a beam 602 under the influence of a bending force F acting on the beam 602 in the x direction. The beam 602 has a height "h", length "y", and width "w" and Is under the influence of a bending force F acting on the beam 602 in the x direction.

[0070] The elastic deflection kt coefficient of the beam 602 under a bending force F in the x direction, modulus of elasticity E, and area moment of inertia Ϊ is given by:

0071] Ax where /

3E! 12

4Fhh

0073] άχ

Eyw^:

F Eyw

00741 k b 4fl³ [0075] FIG. 9 illustrates a deflection model of a beam 604 under the influence of a shear force F acting on the beam 604 in the x direction. The beam model 602 is defined as a beam having a height "h", length "x", and width "w" and the shearing force F is applied in the x direction.

[0076! The elastic deflection k_s coefficient of the beam 604 under a shear force F in the x direction, modulus of elasticity E, and area moment of inertia 1 is given hv:

[0078] k_s

Ax k

Gxw

h

[0080] For incompressible materials E = 3G

)82] With reference now to both FIGS. 8 and 9 the total elastic deflection coefficient fa is the sum of the bending elastic defection coefficient fa and the shear elastic deflection coefficient fa as follows:

[0083] k_t = k_b + k_s

h

[0084] Simplifying in terms of aspect ratio a

w

[0086] The equation makes clear the primacy of aspect ratio in determining the shear stiffness of a gasket. For il lustration, consider a gasket one meter square (x = 1 , and _y = 1) made from a material with Young's modulus typical of a soft polymer (£ = IxlO⁶ Pascal). Now compare two gaskets. The first gasket is typical of the art, and is ten times wider than it is tall, so that (a ^:::: 0.1).

Substituting values into the equation, its stiffness is k_pri₀r ^:zzz 2.5xl0⁸ N/m. The second is the gasket of the present invention, comprised of the same volume of the same material as the last gasket, but this time formed into a membrane ten times taller than it is thick (a = 10). Substituting, the stiffness of this new gasket is found to be k_inVerttwn 3.4 xlO' N/m. Comparing the exponents of these two spring rates (1()⁸ versus 10⁴) one may note that the thin gasket of the present invention is easier to move than the gasket of prior art by a factor of almost 10,000-fold. Thus it is advantageous that the wall thickness of the gasket in the present invention is less than about 10% of the height of the gasket.

[0087] Although this simplified analysis neglects the complexities of shear buckling in thin plates, it deals with very large (orders-of-raagnitude effects), and so it is sufficient to point the way toward design of gaskets that are easy to move in shear. Providing the gasket with slack so that the gasket is loosely positionable, (note curvature in Figure 3B, 106), ensures that no portion of the membrane is drawn into pure tension. It is ad vantageous that the gasket of the present invention deflects to permit relative motion of the elements to which it is attached with a spring rate less than 1E5 N/m.

[0088] As for other details of the present invention, materials and alternate related configurations may be employed as within the level of those with skill in the relevant art. The same may hold true with respect to process-based aspects of the invention in terms of additional acts as commonly or logically employed. In addition, though the invention has been described in reference to several examples, optionally incorporating various features, the invention is not to be limited to that which is described or indicated as contemplated with respect, to each variation of the invention. Various changes may be made to the invention described and equivalents (whether recited herein or not included for the sake of some brevity) may be substituted without departing from the true spirit and scope of the invention. Any number of the individual parts or subassemblies shown may^¬ be integrated in their design. Such changes or others may be undertaken or guided by the principles of design for assembly.

[0089] Also, it is contemplated that any optional feature of the inventive variations described may be set forth and claimed independentl , or in

combination with any one or more of the features described herein. Reference to a singular item, includes the possibility that there are plural of the same items present. More specifically, as used herein and in the appended claims, the singular forms "a," "an," "said," and "the" include plural referents unless the specifically stated otherwise. In other words, use of the articles allo w for "at l east one" of the subject item in the description above as well as the claims below, it is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as "solely," "only" . and the like in connection with the recitation of claim elements, or use of a "negative" limitation. Without the use of such exclusive terminology, the term "comprising" in the claims shall allow for the inclusion of any additional element - irrespective of whether a given number of elements are enumerated in the claim, or the addition of a feature could be regarded as transforming the nature of an element set forth in the claims. Stated otherwise, unless specifically defined herein, all technical and scientific terms used herein are to be given as broad a commonly understood meaning as possible while maintaining claim validity.

[0090] Various aspects of the subject matter described herein are set out in the following numbered clauses:

[0091] 1. An apparatus, comprising a housing, an element, comprising a surface; and a pre-formed membrane positioned between the surface and the housing and forming a seal between the surface and the housing.

[0092] 2. The apparatus according to clause 1, wherein the pre-formed membrane has a wail thickness less than one tenth of the membrane height and comprises a curvature of slack to promote low force movement.

[0093] 3. The apparatus according to clause 1, wherem the pre-formed membrane deflects to permit relative motion between surface and housing with a spring rate less than 1E5 N/m.

[0094] 4. The apparatus according to clause 1 , wherein the pre-formed membrane comprises an elastomeric film. [0095] 5. The apparatus according to clause 1 , wherein the pre-formed membrane is less than 1 millimeter thick, and flexible, and is configured to bridge a gap between the housing and the element.

[0096] 6. The apparatus according to clause 1, wherein the pre-formed membrane is formed by a process selected from the group consisting essentially of casting, molding, or thermoforming, and any combination thereof.

[0097] 7. The apparatus according to clause 1 , further comprising at least one flexure or bearing, wherein the element is contained within the housing and mounted on the at least one flexure or bearing to allow the element to move.

[0098] 8. The apparatus according to clause 1 further including at least one electroactive polymer actuator positioned proximate to and in contact with the element comprising the surface to provide haptic feedback in response to a user's stimulus.

[0099] 9. The apparatus according to clause 8, wherein the at least one electroactive polymer actuator is positioned between the surface of the element and the housing.

[0100] 10, The apparatus according to clause 8, wherein the at least one electroactive polymer actuator is positioned laterally of the surface of the element and the housing.

[0101] 11. The apparatus according to clause 8, further comprising at least two electroactive polymer actuators positioned on opposite si des of the surfaces of the element.

[0102] 12. The apparatus according to clause 8, further comprising at least two electroactive polymer actuators wherein at least one electroactive polymer actuator is positioned on one side of the surface of the element and at least one electroactive polymer actuator is positioned on a lateral side of the element.

[0103] 13. The apparatus according to clause 8, wherein the element is a key board or keypad. [0104] 14. The apparatus according to clause 8, wherein the element is a touchscreen or display.

Claims

WHAT IS CLAIMED IS:

1. An apparatus, comprising:

a housing;

an element comprising a surface; and

a pre-formed membrane positioned between the surface and the housing and forming a seal between the surface and the housing.

2. The apparatus according to Claim 1, wherein the pre-formed membrane has a wail thickness less than one tenth of the membrane height and comprises a curvature of slack to promote low force movement.

3. The apparatus according to Claim 1 , wherein the pre-formed membrane deflects to permit relative motion between surface and housing with a spring rate less than 1E5 N/m,

4. The apparatus according to Claim 1, wherein the pre-formed membrane comprises an elastomeric film,

5. The apparatus according to Claim 1, wherein the pre-formed membrane is less than 1 millimeter thick, and flexible, and is configured to bridge a gap between the housing and the element,

6. The apparatus according to Claim 1, wherein the pre-formed membrane is formed by a process selected from the group consisting essentially of casting, molding, or thermoforming, and any combination thereof,

7. The apparatus according to Claim 1, further comprising at least one flexure or bearing, wherein the element is contained within the housing and mounted on the at least one flexure or bearing to allow the element to move.

8. The apparatus according to Claim 1 further including at least one electroactive polymer actuator positioned proximate to and in contact with the element comprising the surface to provide haptic feedback in response to a user's stimulus.

9. The apparatus according to Claim 8, wherein the at least one electroactive polymer actuator is positioned between the surface of the element and the housing.

10. The apparatus according to Claim 8, wherein the at least one electroactive polymer actuator is positioned laterally of the surface of the element and the housing.

1 1. The apparatus according to Claim 8, further comprising at least two electroactive polymer actuators positioned on opposite sides of the surfaces of the element.

12. The apparatus according to Claim 8, further comprising at least two electroactive polymer actuators wherein at least one electroactive polymer actuator is positioned on one side of the surface of the element and at least one electroactive polymer actuator is positioned on a lateral side of the element.

13. The apparatus according to Claim 8, wherein the element is a keyboard or keypad.

14. The apparatus according to Claim 8, wherein the element is a touchscreen or display.