WO2013148641A1 - Rotational inertial drive system and bearing systems for electroactive polymer devices - Google Patents

Abstract

An apparatus is disclosed, which includes a movable surface haying a first end and a second end. The first and second ends are arranged on opposite ends of the movable surface. At least a first actuator is coupled to the first end of the movable surface. At least a second actuator is coupled to the second end of the movable surface. The at least first and second actuators are operably out-of-phase relative to each other and are in a rotational inertial configuration about a moment of inertia defined by the movable surface. Also disclosed is a magnetic bearing configured to suspend the movable surface. In addition, a magnetic bearing retention system is disclosed.

Description

ROTATIONAL INERTIAL DRIVE SYSTEM AND BEARING SYSTEMS FOR ELECTROACTIVE POLYMER DEVICES

RELATED APPLICATIONS

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

Provisional Application No,: 61/666,127 filed June 29, 2012 entitled

"MAGNETIC SURFACE BEARING", U.S. Provisional Application No.:

61/615,915 filed March 27, 2012 entitled "ROTATIONAL INERTI AL DRIVE SYSTEM TO MINIMIZE ACTUATOR POWER REQUIREMENTS FOR TABLET AND SIMILAR HANDHELD DEVICES" arid U.S. Provisional

Application No.: 61/740,609 filed December 21, 2012 entitled "MAGNETIC

SURFACE BEARING MECHANISM" the entirety of which is incorporated herein by reference. i-;iEL] } ( }iL;! L[[;j_.xvj ri )

The present invention is directed in general to rotational inertia! drive systems for devices comprising actuators. More particularly, the present invention is directed to a rotational inertia! drive system to minimize actuator power requirements for devices comprising electroactive polymer cartridges and

actuators. The present invention also is directed to magnetic bearings for devices comprising actuators, in particular embodiments, an actuator may comprise an electroactive polymer cartridge.

BACKGROUND OF THE INVENTION

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 puiposes, it may be characterized as a sensor. Yet, the term "transducer^'" may be used to genetically refer to any of the devices. 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, electroacti e polymer technology offers an ideal replacement for piezoelectric, shape-memory alloy and electromagnetic devices such as motors and solenoids.

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.

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 relati e thickness between the polymer film and electrode material and/or the varying thickness of the polymer film and/or electrode materia), the physical pattern of the polymer film and/or electrode material (to provide localized active and inactive areas), the tension or pre-strain placed on the electroactive polymer film as a whole, and the amoun 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. 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 inany 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, touch screens, 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.

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 a when a cell phone vibrates in a pocket) 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 smait 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 medi device for certain activities.

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

Tablet computers and similar handheld devices (e.g., iPads and such) have a significant amount of mass (500 grains to 1500 grams). When trying to use inertial drive actuators to produce tactile feedback to a user holding the device a significant amount of actuator power is required to produce compelling acceleration levels. This increases the size of the actuator, increases the electrical power drive requirements, and increases the cost. Attempts have been, made to solve this problem by employing very high haptic frequencies to help reduce actuator power, size, and cost requirements. One example is the use of piezoelectric actuators that employ haptic frequencies in the range of 175-225 Hz, Higher haptic frequencies, however, fail short of providing realistic feedback in haptic devices and are not. as compelling for gaming and can be quite annoying at times.

Accordingly, embodiments of the present invention provide actuators operating mechanically out-of-phase thereby changing the haptic signal into a rotational inertial configuration instead of a translational inertial configuration. This configuration significantly reduces the effective mass that the actuator must drive while still producing the same tactile sensation to the hands of the users. This also allows lower frequencies and larger inertial masses to be used which benefits system level design.

Furthermore, conventional, handheld devices do not have low friction, bearing surfaces that allow a moving surface to support loads and move easily with very little friction relative to a reference surface while also constraining the moving surface from moving beyond preset limits of motion (linear or rotational) without causing significant friction during rest or operation.

Accordingly, embodiments of the present invention provide means for supporting a surface such that it has very little friction relative to a reference surface while constraining the moving surface from moving beyond preset, limits of linear or rotational motion without causing significant friction during rest or operation. Additional shortcomings exist in devices that include bearings between the housing and a movable surface to minimize friction. Because such bearings are extremely small, they often fall out and thus are not retained in the factory installed position.

Various embodiments of the present invention provide a bearings retention system to retain the bearings in their factory installed positions.

An apparatus comprises a movable surface, having a first side and a second end. The first and second ends are arranged on opposite ends of the movable surface. At least a first actuator coupled to the first end of the movable surface. At least a second actuator eoupled to the second end of the movable surface. The at least first and second actuators are operably out-of-phase relative to each other and are in a rotational inertial configuration about a moment of inertia defined by the movable surface.

These and other features 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.

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 eommon to the drawings. Included in the drawings are the following:

Figs. 1 A and IB illustrate a top perspective view of a transducer before and after application of a voltage in accordance with one embodiment of the present invention:

Fig. 2A illustrates an exemplary el.eetroact.ive polymer cartridge in accordance with one em bodiment of the present invention; Fig. 2.R illustrates an exploded view of an electroactive polymer actuator, inertial mass and actuator housing in accordance with one embodiment of the present invention;

Fig. 3 illustrates a device with a conventional single inertial mass inertia! drive system;

Fig. 4 illustrates a device with at least two inertial masses coupled to corresponding actuators operating mechanically out-of-phase;

Fig. 5 illustrates the principle of kinetic energy of a solid disk;

F ig. 6 is a schematic diagram of a circuit for driving actuators out-of-phase and consequently driving the inertial masses out-of-phase;

Fig. 7 is a schematic diagram of a circuit for driving actuators out-of-phase and consequently driving the inertial masses out-of-phase;

Fig. 8 illustrates a device with multiple actuators located along opposite ends of a device, where the multiple actuators are coupled to corresponding inertial masses operating mechanically out-of-phase;

Fig. 9 il lustrates a device with multiple actuators located along all sides of a device, where the multiple actuators are coupled to corresponding inertial masses operating mechanically out-of-phase:

Fig. 10 illustrates a movable surface of a device capable of moving in three dimensions;

Fig. 1 1 illustrates a sectional view of a device comprising a movable surface and magnetic bearing, where the movable surface is capable of moving within preset limits in three dimensions;

Fig. 12 illustrates a detail view of the device comprising a movable surface illustrated in Fig. 1 1 ;

Fig. 13 illustrates a sectional view of a device comprising a movable surface on a magnetic bearing capable of moving within preset limits in three dimensions and two inertial masses coupled to corresponding actuators operating mechani cal 1 y o u t-o t -p base ; Fig. 14 illustrates a sectional view of a device comprising a movable surface on a bearings retention system, where the movable surface is capable of moving within preset limits; and

Fig, 1 5 illustrates a detail view of the bearings portion of the device and movable surface illustrated in Fig. 14.

V ariation of the invention from that shown in the figures is contemplated .

DETAJLED ΠΚ^^

Examples of eiectroactive polymer devices and their applications arc 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 ; 6,91 1 ,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; 6,543,110; 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; and 7,567,681 , and in U.S. Patent Application Publication Nos. 2009/0154053; 2008/01 16764; 2007/0230222; 2007/0200457; 2010/0109486; and 2011/128239, and PCT Publication No. WO2010/054 14, the entireties of which are incorporated herein by reference.

In various embodiments, the present invention provides an apparatus, comprising a movable component having a first end and a second end, wherein the first and second ends are arranged opposite each other on the movable component, at least a first actuator coupled to the first end of the movable component, and at least a second actuator coupled to the second end of the movable component, wherein the at least first and second actuators are operablv out-of-phase relative to each other and are in a rotational inertial configuration about a moment of inertia defined by the movable component.

These and other embodiments of the present in vention are described in detail hereinbelow. Prior to describing such processes, however, Figs. 1 -2 provide a brief description of general eiectroactive polymer structures. Accordingly, the description now turns to Figs. 1A and I B, which illustrate an example of an e!ectroactive polymer film or membrane 10 structure. A thin e!astomerie dielectric film or layer 12 is sandwiched between compliant or stretchable electrode plates or layers 14 and 16, thereby forming a capacitive structure or film. The length "1" and width "w" of the dielectric layer, as well as that of the composite structure, are much greater than its thickness "f". Preferably, the dielectric layer has a thickness in the range from about 10 μτη to about 100 μτη, with the total thickness of the structure in the range from about 15 μιη 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 preferably less than about 10 MPa, but is likel thicker than each of the electrodes. Electrodes suitable for use with these compliant capacitive structures are those capable of withstanding cyclic strains greater than about 1% without failure due to mechanical fatigue.

As seen in Fig. 1 B, 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 fi lm 12. Depending on the. architecture, e.g., a frame, in which capacitive structure 10 is employed (collectively referred to as a

"transducer"), this deflection may he used to produce mechanical work. Various different transducer architectures are disclosed and described in the above- identified patent references.

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 .1.0. 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 elastomeric material and its size and stiffness. Removal of the voltage difference and the induced charge causes the reverse effects.

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. Dieiectric 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.

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 include elastic deformation of the dieleciric film and be formed, 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.

The transducer structure of Figs. 1 A and 1 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.

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. ^'The 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 are 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 Figs. 1 B for axis references). 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.

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. If the opening of the frame is circular, the film can be stretched radially. 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 f lm 26 form another working electrode pair. Each same-side electrode pair can have the same polarity, whereas the polari ty 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, in some variations, the same-side electrodes may be electrical ly connected together with a bus bar.

In one variation as shown in Fig. 2A, 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 electrical !y couple the electrodes 8 with a respective lead 22 or 24 depending upon the polarity of the electrodes.

The cartridge J 2 illustrated in Fig. 2A shows a 3 -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, i n 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 desi gn 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.

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 connecti ity between cartridges can be maintained by electrically coupling the vias 18, 20 together so that adjacent cartridges are coupled to the same voltage source or power supply.

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 2 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 an attachment plate or frame (this plate or frame may be permanent or temporary). As discussed below, the electroactive actuator 14 can 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 an event, variations of the device and processes described herein include size of the cavity 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 ease 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.

Fig. 3 illustrates a device 300 with a conventional single inertial mass inertial drive actuator 302 system. The device 300 includes a body 303, a screen 306, and optionally handles 308a, 308b. The inertial drive actuator 302 is generally mounted below the screen 306 and offset from the center of mass 310. Thus, when the inertia! drive actuator 302 is activated it moves laterally as indicated by arrows A and B to give the user holding the handles 308a, 308b a haptic feedback (e.g., acceleration, vibration, and the like). The lateral movement of the inertia! drive actuator 302 in the direction of arrows A and B is referred to as translational (or linear) inertia.

Such devices 300, e.g., tablet computers and similar handheld devices

(e.g.. IP ADS and such), have a significant amount of mass (500 g to 1500 g) relative to the inertia! actuator. When trying to use inertial drive actuators 304 to produce tactile feedback to a user holding the device 300 a significant amount of actuator power is required to produce compelling acceleration levels. This increases the size of the actuator 304, increases the electrical power drive requirements, and increases the cost. Attempts have been made to solve this problem by employing very high haptic frequencies to help reduce actuator power, size, and cost requirements. One example is the use of piezoelectric actuators that employ haptic frequencies in the range of 175-225 Hz. Higher haptic frequencies, however, fall short of providing realistic feedback in haptic devices and are not as compel ling for gaming and can be quite annoying at times.

Accordingly, embodiments of the present invention provide inertia! actuators which provide the haptic signal, with a rotational inertial configuration instead of a translational inertial configuration. This configuration significantly reduces the effective mass that the actuator must drive while still producing the same tactile sensation to the hands of the users. This also allows lower frequencies and larger inertia! masses to be used which benefits system level design. In one embodiment, the present invention provides rotational inertiai actuators. In another embodiment, the present invention provides rotational inertiai actuators comprising electroactive polymer cartridges mounted to inertiai masses. These and other embodiments are described herembelow.

In one embodiment of this invention, a single inertiai mass inertia! drive actuator can be situated on one of the handles 308a or 308b with motion parallel to the length of the handle when activated to create a rotational torque.

Fig, 4 illustrates another embodiment wherein a device 400 comprises at least two actuators 402a, 402b coupled to corresponding handles 404a, 404b of the device. The two actuators 402a, 402b operate mechanically out-of-phase to provide a rotational drive force 408 in the same direction. The device 400 includes a body 403, a screen 406, and optionally handles 404a, 404b. The rotational inertiai drive system minimizes actuator power requirements for devices having a mass that Is significantly larger than the mass of the act uator. Although the arrangement in FIG. 4 shows a rotational drive force in a clockwise direction, it will be appreciated that the orientation of the two actuators 402a, 402b may be reversed such that the rotational drive force is induced in the opposite direction shown in Flg.4, e.g., counterclockwise, it will further be appreciated that only one of the two actuators 402a, 402b creates the momentum in the forward or the reverse direction.

The rotational inertiai drive system configuration depicted in Fig. 4 employs rotational dynamics to minimize actuator requirements and enables lower haptic frequencies to be used. The two actuators 402a, 402b operate mechanically out-of-phase to thereby change the haptic signal into a rotational inertiai configuration about a moment, of inertia 410 rather than the translational inertiai configuration as shown in Fig. 3. This significantly reduces the effective mass that, the actuators 402a, 402b must drive but sti ll produces the same tactile sensation to the hands of the user.

Therefore, the rotational inertia! drive system depicted in Fig. 4 enables lower haptic frequencies and larger inertiai masses to be used which benefits system level design. Generally speaking, to produce lower haptic frequencies with conventional transiational inertial drive systems requires more actuator power (which is undesirable) hut are far more desirable for user experience.

Larger inertia! masses in general reduce actuator power requirements, which is an advantage. Less actuator, e.g., eleclroactive actuator, mass is used because the moment of inertia 410 determines the effective mass and not the whole body mass. Accordingly, the rotational inertia! drive system can be configured around a lower effective mass, which is an advantage

A comparison of rotational versus linear (transiational) inertia in regards to moving the edge of a solid disk will be described in connection with Fig. 5, illustrates the principle of kinetic energy of a solid disk 500.

With reference to the solid disk 500 shown in Fig. 5, the disk 500 has a radius r, mass m. lies in the x-y plane, and rotates about axis z. The rotational inertia of the disk 500 is given by:

] r_ - - ¹-mr ^{^"} ( l i

?

Linear inertia in simply given by:

ί,, ^■■■■ m (2)

The rotational kinetic energy of the solid disk 500 is given by: U,_rl, :^::: --- kit = - [ - Mr' ^ "~ «Μ' (3

The linear kinetic energy of the solid disk 500 is given by:

1

Vlmem- = - «V^" (4)

Consider an incremental displacement at the perimeter of the disk 500 of linear distance x or arc length s in a time t. The displacement has some velocity:

v_{! !}≡ro}, for small angular rotations Θ (5)

The ratio of rotational kinetic energy to linear kinetic energy is given by:

£/,.,. 0.25mvi . Energy ratio is the same as the Power ratio:

All

P (7)

Therefore, the rotational mode always takes half the instantaneous power of the linear mode. Taking the integral to arrive at average po wer does not change that ratio. Accordingly, this factor of 0.5 will hold for any arbitrary waveform, .sinusoidal or otherwise.

Fig, 6 is a schematic diagram of a circuit 600 for driving actuators 602a, 602b coupled to inertia! masses 604a, 604b out-of-phase and consequently driving the inertia! masses 604a, 604b out-of-phase. An energy source produces a drive voltage V to drive the actuators 602a, 602b coupled to inertial masses 604», 604b. The drive voltage V used to drive the actuators 602a, 602b is in phase, therefore, the actuators 602a, 602b are physically oriented in opposite directions relative to each other such that they can be driven mechanically out-of-phase relative to each other. The circuit 600 provides an economical solution to driving the inertial masses 604a, 604b out-of-phase and thereby changing the hap tic signal into a rotational inertial configuration instead of a transnational inertial configuration. This configuration significantly also reduces the effective mass of the inertial masses 604a, 604b that the corresponding actuators 602a, 602b must drive while still producing the same tactile sensation to the hands of the users. This also allows lower frequencies and larger inertial masses to be used which benefits system level design. It will be appreciated that in one embodiment, the actuators 602a, 602b may be electroactive polymer actuaiors as disclosed herein in connection with Figs. 1 and 2. in other embodiments, the actuators 602a, 602b may be selected from a variety of other actuators including, but not limited to, piezoelectric, solenoid, voicecoil and other mechanical motors.

Fig. 7 is a schematic diagram of a circuit 700 for driving actuators 702a, 702b coupled to inertial masses 704a. 704b out-of-phase and consequently driving the inertia! masses 704a, 704b out-of-phase. The drive voltage source V is inverted by inverter 706 to produce a second drive voltage -V that is out-of- phase relative to drive voltage V. The actuators 702a, 702b are coupled to inertial masses 704a, 704b. Beeause two drive voltages V, -V are out-of-phase relative to each other, the actuators 702a, 702b are physically oriented in the same direction relative to each other such that they can be driven mechanically out-of-phase relative to each other. The circuit. 700 provides a more flexible solution to driving the inertial masses 704a, 704b out-of-phase and thereby changing the haptic signal into a rotational inertial configuration instead of a translational inertial configuration. This configuration significantly also reduces the effective mass of the inertia! masses 704a, 704b that the corresponding actuators 702a, 702b must drive while still producing the same tactile sensation to the hands of the users. This also allows lower frequencies and larger inertial masses to be used which benefits system level design. It will be appreciated that in one embodiment, the actuators 702a, 702b may be electroactive polymer actuators as disclosed herein in connection with Figs. 1 and 2. hi other embodiments, the actuators 702a, 702b may be selected from other actuators including, but not limited to, piezoelectric, solenoid, voicecoil and other mechanical motors.

Fig. 8 illustrates a device 800 with multiple actuators 802a/ to 802a« and 802b to 802b« located along opposite ends of a device 800, where the multiple actuators 802a/-802a« are coupled to corresponding inertial masses 804a to 804a« operating mechanically out-of-phase to form a rotational drive force about the moment of inertia 810. A first set of up to n actuators 802a/-802a„ are disposed along one side 808a of the device 800 in the same (in-phase) physical orientation relative to each other. A second set of n actuators 802b/~802b« are disposed along the opposite end 808b of the device 800 in the same (in-phase) physical orientation relative to each other but. in opposite physical orientation, and hence out-of-phase, relative to the first set of n actuators 802b/-802b«.

Beeause the first and second set of actuators are physically oriented out-of- phase, a single voltage source can be used to drive the first and second set of actuators 802a/-802a_fJ and 802b/-802I½ as described in connection with the 48- circuit 600 in Fig. 6. If the physical orientation of the first or second set of actuators 802a/-802a„ and 802b/-802b« is reversed such that the first and second set of actuators 802a/-802¾ and 802b/-802b« are physically oriented in the same direction, then the inertia) masses 804si/~804¾ and 804b/-804b« can be driven mechanically out-of-phase with the circuit 700 described in connection with Fig. 7. Accordingly, the first set of actuators 802a/~8O2¾_> is driven by the voltage source V and the second set of actuators of actuators 802b/-802b_ra is driven by -V.

Fig. 9 illustrates a device 900 with multiple actuators 902a/ to 902a«, 902b/ to 902b„, 902c; to 902e„, and 902d/ to 902d„ located along all sides of a device 900, where the multiple actuators 902a/-902a«, 902b/-902b«, 902c/-902c«, and 902d/-902d_n are coupled to corresponding inertial masses 9υ4ίΐ/-"υ48ιι,

904b/-904b?j, 904c/-904c_ra, and 904d/-904d_ra operating mechanically out-of-phase to form a rotational drive force about the moment of inertia 9 J O. A first set of up to n actuators 902¾/-902a_¾ are disposed along one first end 908a of the device 900 in the same (in-phase) physical orientation relative to each other. A second set of n actuators 902b/-902b_n are disposed along a second end 908b of the device 900 in the same (in-phase) rotational physical orientation relative to each other and to the first set of actuators 902ai-902a_fi. A third set of n actuators 902c/-902c„ are disposed along a third side 908c of the device 900 in the same (in-phase) physical orientation relative to each other but in opposite physical orientation than the first set of actuators 902a/-902a«. A fourth set of n actuators 902d/-902d_¾ are disposed along a fourth side 908d of the device 900 in the same (in-phase) physical orientation relative to each other but in opposite physical orientation than the second set of actuators 902b/-902b».

Because the actuators are physically oriented out-of-phase, a single voltage source can be used to drive all the actuators 902a/-902a_n, 902b/-902i½, 902c/~ 902c«, and 902d/-902d» as described in connection with the circuit 600 in Fig. 6. If the physical orientation of the third set of actuators 902c/-902e« and the fourth set of actuators 902d/-902d« is reversed such that the first and third set of actuators 902a/-902a« and 902c/-902c„ are physically oriented in the same direction and the second and fourth set of actuators 902b/-902b« and 902d -902d« are physically oriented in the same direction, then the inertia! masses 904a; to 904a», 904b/ to 904b«, 904c/ to 904c«, and 904d/ to 904d„ can be driven mechanically out-of-phase using the are driven by the same voltage source V and the can be driven mechanically out-of-phase with the circuit 700 described in connection with Fig. 7, Accordingly, the first and second set of actuators 902a/- 902¾« and 902b/-902b_H are driven by the voltage source V and the third and fourth set of actuators 902c/-902c» and 902d/~902d_w arc driven by -V,

As used herein, actuators said to be physically or mechanically oriented out-of-phase relative to each other generally refers to the actuators being oriented in opposite directions relative to each other or simply about 180 degrees out-of- phase. Likewise, voltage sources, or other energy sources, said to be out-of-phase relative to each other generally refers to the energy sources about 180 degrees out- of-phase relative to each other.

Fig. 10 illustrates a mo vable component 1000 of a device capable of moving in three dimensions. The movable component 1000 can move in plane 1002 or in directions orthogonal 1004 to the plane 1002.

Fig. 1 1 illustrates a sectional view of a device 1 00 comprising a movable component 1102 on a magnetic bearing 1104, where the movable component 1102 is capable of moving within preset limits in three dimensions. The device 100 includes a housing or frame 1106 comprising a slot 1108 sized to receive a ridge 1.110 portion projecting outwardly from the perimeter edges of the movable component 1102, The movement of the movable component 1102 is restricted within the slot 1108 by at least one of the inside walls of the slot. A plurality of magnets 1112 are positioned along the slot 1108 and ridge 1110 to produce a magnetic bearing 1104 that supports the component 1102 while the component 1102 is in motion. An actuator 1114 is coupled to the movable surface ϊ 1 4 on one side and to the reference frame 1106 on the other side. Thus, when the actuator 114 is activated, the movable surface 1 02 inoves relative to the fraine 1106,

The magnetic bearing 1 104 provides a means to support the component

1.102 such that it has very little friction relative to the frame 1106 reference surface. in one embodiment, the component 1102 is a touch panel or screen that provides haptic motion by the actuator 1 1 .14 in response to user input via the panel/screen. To move the screen such that the user feels the haptic motion, it is desirable to have the screen suspended via a very low friction bearing surface so that the screen is free to move within a range of motion in a given plane (using Cartesian coordinates let us choose the XY plane as an example). The screen should be free to move within the XY plane, constrained in the Z axis, and constrained within preset limits in the X and Y axes.

Fig. 12 illustrates a detail view of the magnetic bearing 1104 of the device 1100 and movable component 1102 illustrated in Fig. 1 1. The magnets 1112 are arranged with opposing North poles (N) facing each other to produce a magnetic bearing 1104 that supports the weight of the movable component 1102. It will be appreciated that opposing South poles (S) facing each other may be used to implement the magnetic bearing 1104. The magnetic bearing 1104 uses magnetic forces to suspend and/or constrain the surface within the prescribe range of motion, bearing loads in the Z axis. By arraying magnets 1112 at various locations around the screen, a very low friction bearing, that uses little or no power can be created. Similarly, magnets 1 1 12 can be arrayed to provide non contacting motion guides or stops to constrain the surface into the desired plane of motion, within the desired range of mo tion within that plane.

Employing magnetic repulsion to create low friction bearing surfaces ί 104 enables the moving component 1102 to support loads and move easily and also constrains the moving component 1102 from moving beyond the preset limits of motion (liner or rotational) without causing significant friction during rest or operation. Minor mechanical compliance may be provided when subjected to forces normal to the bearing component 1102 as well as a non-linear restoring force. Magnetic suspension by the magnetic bearing surface 11 4 has very low static and dynamic friction, which is important in making a moving haptic touch component 1102 as the forces used and range of motion are small.

Furthermore, in one embodiment, the magnetic bearing 1 04 can be implemented using permanent magnets 1112. in embodiments utilizing permanent magnets 1112, the magnetic bearing 1104 requires no additional electrical power. Additionally, as force is applied normal to the magnetic hearing surface 1112, the airgap g between opposing magnets 1112 decreases (mechanical compliance), however, as the airgap g decreases, the magnetic repulsion increases with a non-linear relationship. In practice, it will be difficult to load the magnetic bearing 1112 to the point that the airgap g is eliminated and the moving plate touches the reference surface, which would result in additional friction.

in various embodiments, the magnets 1112 may be discrete permanent, magnets, a plurality of sintered permanent magnets, or a plurality of resin bonded permanent magnets. In other embodiments, where electrical power is not an issue, electromagnets may be employed to implement the magnetic bearing 1104.

Furthermore, in some embodiments the actuator 1114 coupled to the movable component 1102 may be pre-biased by a combined magnetic force and a force other than a magnetic force. Such actuators 1114 are configured to be selectively biased to obtain specifically desired performance characteristics. The selection of biasing follows a negative bias spring model in which the spring force increases as the actuator 1114 moves from a preloaded position to its most highly activated position, The model may exclusively employ a negative bias spring, or may further incorporate constant force spring bias and/or a positive or "standard" spring-bias is combined with fiat-rate or negative rate biasing. The biasing devices may additionally include biasing components, for example a coil spring, leaf spring, bellows spring, elastomer spring, foam support., air or fluid pressure biasing, etc. or a combination of any of these means or the l ike, are also contemplated.

Fig, 13 illustrates a sectional view of a device 1300 comprising a movable component 1302 on a magnetic bearing 1304 capable of moving within preset limits in three dimensions and two or more inertia! masses coupled to two or more corresponding actuators 1308a, 1308b operating mechanically out-of-phase.

Thus, the device 1300 combines the benefits of the rotational inertia! drive system configuration described in connection with Figs. 4-9 that employs rotational dynamics to minimize actuator requirements and enables lower haptic frequencies to be used with the magnetic bearing 1304 described in connection with Figs. 10- 12. It will be appreciated that the device 1300 shown in Fig, 13 may employ any of the various embodiments of rotational inertiai dri ve systems described in connection with Figs. 4-9. Optionally, an actuator 1314 may be provided. The actuator 1314 is coupled to the movable component 1304 on one side and to the reference frame 1306 on the other side,

Fig. 14 illustrates a sectional view of a device 1400 comprising a movable component 1402 on a bearings retention system 1404, where the movable component 1402 is capable of moving within preset limits. Fig. 15 illustrates a detail view of the bearing retention system 1404 portion of the de vice 1400 and movable component 1402 illustrated in Fig. 14. The device 1400 includes a housi g or frame 1406 comprising a slot 1408 sized to receive a ridge 1410 portion projecting outwardly from the perimeter edges of the movable component 1402. The movement of the component 1402 is restricted within the slot 1408. Bearings 1418 made of ferrous materials are interposed between the ridge 14.10 portion of the movable component 1402 and interior walls of the slot 1408 to enable the moving component .1402 to move freely within the slot 1408. Because the bearings 1418 can be quite small and tend to displaced or lost, a plurality of magnets 1412 are positioned along the slot 1408 to retain the bearings 1418 in place, provided the bearings are made from a ferrous material. The bearings 1418 are located in predefined cup-like fixtures 1414. Magnets 1416 are located within the slot 1408 formed within the frame body 1406 of the device 1400. Thus, the magnets 1416 will retain the ferrous bearings 1418. in various embodiments, the magnet 1416 is selected from the group consisting of a permanent magnet, sintered permanent magnet, resin bonded permanent magnet, an electromagnet and combinations thereof.

In other embodiments, the device 1400 can be combined with the two or more inertiai masses coupled to two or more corresponding actuators operating mechanically out-of-phase. Thus, the device 1400 combines the benefits of the rotational inertiai drive system configuration described in connection with Figs. 4- 9 that employs rotational dynamics to minimize actuator requirements and enables lower haptic frequencies to be used with the bearings 1404 described in connection with Figs. 13-15. It will be appreciated that the device 1400 shown in Fig. 14 may employ any of the various embodiments of rotational inertial dri ve systems described in connection with Figs. 4-9.

Any of the devices 400, 800, 900, 1100, 1300, and 1400 may be combined with any of the features discussed herein including the rotational inertia! drive system, magnetic bearing system, magnetic bearing retention system, and/or the pre-biased actuator systems, without limitations.

In some embodiments, the magnetic bearing system may be used to suspend and position an inertial mass rather than a display or touch screen surface. This mass may be driven by a planar actuator such as a 3 -bar actuator, or, by other actuator architectures such as rolls, stacks, surface morphing, bimorphs, etc.

These embodiments simplify the task of suspending and supporting an inertia! mass in that it is very low friction, have graceful travel stops, and may be made in a very robust fashion within multiple form factors. This system has a number of advantages when compared to other more traditional methods of support - e.g. flexure based systems, bearing based systems, etc. - which may require precise bearing systems or complex and often fragile flexures.

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 inventio 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. V arious 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. Also, it s contemplated that any optional feature of the inventive variations described may be set forth and claimed independently, 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 allow for "at least one" of the subject item in the description above as well as the claims below, ft 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.

Claims

WHAT IS CLAIMED IS;

1. An apparatus, comprising:

a movable component having a first end and a second end, wherein the first and second ends are arranged opposite eac other on the movable component; at least a first actuator coupled to the first end of the movable component; and at least a second actuator coupled to the second end of the movable component; wherein the at least first and second actuators are operabiy out-of-phase relative to each other and are in a rotational, inertia! configuration about, a moment of inertia defined by the movable component.

2. The apparatus according to Claim 1 , wherein the at least first and second actuators are physically oriented in opposite directions relative to each other and are operabiy responsive to a single drive voltage.

3. The apparatus according to Claim 1, wherein the at least first and second actuators are physically oriented in the same direction relative to each other and wherein the at least first actuator is operabiy responsive to a first drive voltage and the at least second actuator is operabiy responsive to a second drive voltage that is out-of phase with the first drive voltage.

4. The apparatus according to Claim 3, further comprising an inverter to receive the first drive voltage and provide the second drive voltage.

5. The apparatus according to Claim 1 , further comprising a magnetic bearing configured to suspend the movable component.

6. The apparatus according to Claim I , further comprising a bearing retention system coupled to the movable component, wherein the bearing retention system comprises at least one magnet.

7. The apparatus according to Claim 1 , wherein the at least first and second actuators comprise electroactive polymer cartridges.

8. An apparatus, comprising:

a housing;

a movable component moveably coupled to the housing; and

a magnetic bearing configured to suspend the movable component relative to the bousing. 9. The apparatus according to Claim 8, wherein the housing comprises a slot and the movable component comprises a ridge projecting outwardly from

perimeter edges of the movable component, wherein the ridge is configured to be received within the slot. 10. The apparatus according to Claim 9, further comprising a first magnet located in the slot portion of the housing and a second magnet located in the ridge portion of the movable component, wherein the first and second magnets are arranged with opposing poles facing each other to produce a magnetic bearing and suspend the ridge portion of the movable component within the slot portion of the housing.

1 1. The apparatus according to Claim 9 or 10, wherein movement of the movable component is restricted within the slot by at least one inside wall of the slot,

12, The apparatus of Claim 8, further comprising an actuator coupled to the movable component on one side and to the housing on the other side, wherein when the actuator is activated, the movable component moves relative to the housing.

33. The apparatus of Claim 8, further comprising; at least a first actuator coupled to a first end of the movable component; and at least a second actuator coupled to a second end of the movable component; wherein the at least first and second actuators are operably out-of-phase relative to each other and are in a rotational inertia! configuration about a moment of inertia defined by the movable component.

14. The apparatus according to Claims 12 or 13, wherein the actuator comprises an eieetroactive polymer cartridge, 15. The apparatus according to Claim 8, wherein the magnet is selected from the group consisting of a permanent magnet, sintered permanent magnet, resin bonded permanent magnet, an electromagnet and combinations thereof.

16. An apparatus, comprising:

a housing;

a movable surface moveab!y coupled to the housing; and

a bearing retention system.

17. The apparatus according to Claim 16, wherein the bearing retention system comprises a ferrous bearing disposed between the housing and the movable surface and a magnet located in the housing to magnetically retain the ferrous bearing.

18. The apparatus according to Claim 16, wherein the magnet is selected from the group consisting of a permanent magnet, sintered permanent magnet, resin bonded permanent magnet, an electromagnet and combinations thereof.

19. The apparatus of Claim 16, further comprising an actuator coupled to the movable surface on one end and to the housing on the other end, wherein when the actuator is activated, the movable surface moves relative to the housing. -2.8-

20. The apparatus according to any one of Claims 1 to 17 wherein the movable component or surface is selected from the group consisting of a touch screen, a sensor panel, and a display panel.