ELECTROACTIVE POLYMER ACTUATOR HAPTIC GRIP ASSEMBLY

The present invention provides a housing to allow for removable coupling of electroactive polymer transducer with an electronic media device, where the housing produces an improved haptic effect in the electronic media device.

DETAILED DESCRIPTION OF THE INVENTION

The devices, systems and methods of the present invention are now described in detail with reference to the accompanying figures.

It is noted that the figures discussed herein schematically illustrate exemplary configurations of devices that employ electroactive polymer (“EAP”) films or transducers having such EAP films. Many variations arc within the scope of this disclosure, for example, in variations of the device, the EAP transducers can be implemented to move a mass to produce an inertial haptic sensation. Alternatively, the EAP transducer can produce movement in the electronic media device when coupled to the assembly described herein.

In any application, the feedback displacement created by the EAP 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 EAP 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 EAP transducers or films (as disclosed in the applications and patent listed herein) can be incorporated in the user interface devices described herein.

The EAP transducer may be configured to displace to an applied voltage, which facilitates programming of a control system used with the subject tactile feedback devices. EAP transducers are ideal for such applications for a number of reasons. For example, because of their light weight and minimal components, EAP transducers offer a very low profile and, as such, are ideal for use in sensory/haptic feedback applications.

FIGS. 1A and 1Billustrate an example of an EAP film or membrane10structure. A thin elastomeric dielectric film or layer12is sandwiched between compliant or stretchable electrode plates or layers14and16, thereby forming a capacitive structure or film. The length “l” and width “w” of the dielectric layer, as well as that of the composite structure, are much greater than its thickness “t”. Typically, the dielectric layer has a thickness in range from about 10 μm to about 100 μm, with the total thickness of the structure in the range from about 15 μm to about 10 cm. Additionally, it is desirable to select the elastic modulus, thickness, and/or the geometry of electrodes14,16such that the additional stiffness they contribute to the actuator is generally less than the stiffness of the dielectric layer12, which has a relatively low modulus of elasticity, i.e., less than about 100 MPa and more typically less than about 10 MPa, but is likely 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 inFIG. 1B, when a voltage is applied across the electrodes, the unlike charges in the two electrodes14,16are attracted to each other and these electrostatic attractive forces compress the dielectric film12(along the Z-axis). The dielectric film12is thereby caused to deflect with a change in electric field. As electrodes14,16are compliant, they change shape with dielectric layer12. Generally speaking, deflection refers to any displacement, expansion, contraction, torsion, linear or area strain, or any other deformation of a portion of dielectric film12. Depending on the architecture, e.g., a frame, in which capacitive structure10is employed (collectively referred to as a “transducer”), this deflection may be used to produce mechanical work. Various different transducer architectures arc disclosed and described in the above-identified patent references.

With a voltage applied, the transducer film10continues to deflect until mechanical forces balance the electrostatic forces driving the deflection. The mechanical forces include elastic restoring forces of the dielectric layer12, the compliance or stretching of the electrodes14,16and any external resistance provided by a device and/or load coupled to transducer10. The resultant deflection of the transducer10as 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 electrodes14and16may cover a limited portion of dielectric film12relative 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.

The dielectric film12may be pre-strained. The pre-strain improves conversion between electrical and mechanical energy, i.e., the pre-strain allows the dielectric film12to 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 comprise elastic deformation of the dielectric 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 ofFIGS. 1A and 1Band 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. 2Aillustrates an exemplary EAP polymer cartridge12having an EAP transducer film26placed between rigid frame8where the EAP film26is exposed in openings of the frame8. The exposed portion of the film26includes two working pairs of thin elastic electrodes32on either side of the cartridge12where the electrodes32sandwich or surround the exposed portion of the film26. The EAP film26can have any number of configurations. However, in one example, the EAP film26comprises a thin layer of elastomeric dielectric polymer (e.g., made of acrylate, silicone, urethane, thermoplastic elastomer, hydrocarbon rubber, fluororelastomer, copolymer elastomer, or the like). When a voltage difference is applied across the oppositely-charged electrodes32of each working pair (i.e., across paired electrodes that are on either side of the film26), the opposed electrodes attract each other thereby compressing the dielectric polymer layer26therebetween. The area between opposed electrodes is considered the active area. As the electrodes are pulled closer together, the dielectric polymer26becomes thinner (i.e., the z-axis component contracts) as it expands in the planar directions (i.e., the x- and y-axes components expand) (seeFIG. 1Bfor 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 layer26is 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 layer26. Generally speaking, deflection refers to any displacement, expansion, contraction, torsion, linear or area strain, or any other deformation of a portion of dielectric layer26. This deflection may be used to produce mechanical work. As shown, the dielectric layer26can also include one or more mechanical output bars34. The bars34can optionally provide attachment points for either an inertial mass (as described below) or for direct coupling to the electronic media device.

In fabricating a transducer, an elastic film26can be stretched and held in a pre-strained condition by a rigid frame8. In those variations employing a4-sided frame, the film can be stretched bi-axially. It has been observed that the pre-strain improves the dielectric strength of the polymer layer26, thereby improving conversion between electrical and mechanical energy, i.e., the pre-strain allows the film to deflect more and provide greater mechanical work. Typically, 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 layer26, referred to herein as same-side electrode pairs, i.e., electrodes on the top side of dielectric layer26and electrodes on a bottom side of dielectric layer26, 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 EAP film26form one working electrode pair and electrodes surrounding the adjacent exposed EAP film26form another working electrode pair. Each same-side electrode pair can have the same polarity, while the polarity of the electrodes of each working electrode pair are opposite each other. Each electrode has an electrical contact portion configured for electrical connection to a voltage source.

In this variation, the electrodes32are connected to a voltage source via a flex connector30having leads22,24that can be connected to the opposing poles of the voltage source. The cartridge12also includes conductive vias18,20. The conductive vias18,20can provide a means to electrically couple the electrodes8with a respective lead22or24depending upon the polarity of the electrodes.

The cartridge12illustrated inFIG. 2Ashows a three-bar actuator configuration. However, the devices and methods described herein are not limited to any particular configuration, unless specifically claimed. Typically, the number of the bars34depends 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, 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.

An electroactive polymer actuator for use in the methods 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 cartridges12together, having a single cartridge with multiple layers, or having multiple cartridges with multiple layers. Typically, manufacturing and yield considerations 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 vias18,20together so that adjacent cartridges are coupled to the same voltage source or power supply.

The cartridge12shown inFIG. 2Aincludes three pairs of electrodes32separated by a single dielectric layer26. In one variation, as shown inFIG. 2B, two or more cartridges12are stacked together to form an electroactive actuator14that is coupled to an inertial mass50. Alternatively, the electroactive actuator14can be coupled directly to the electronic media device through a temporary attachment plate or frame. As discussed below, the electroactive actuator14can be placed within a cavity52that allows for movement of the actuator as desired. The pocket52can be directly formed in a housing of a haptic case. Alternatively, pocket52can he formed in a separate case56that is positioned within the housing of the device. If the latter, the material properties of the separate case56can be selected based upon the needs of the actuator14. For example, if the main body of the haptic housing assembly is flexible, the separate case56can be made rigid to provide protection to the electroactive actuator and/or the mass50. In any event, variations of the device and methods described herein include size of the cavity52with sufficient clearance to allow movement of the actuator14and/or mass50but a close enough tolerance so that the cavity52barrier (e.g., the haptic housing or separate case56) serves as a limit to prevent excessive movement of the electroactive actuator14. Such a feature prevents the active areas of the actuator14from excessive displacement that can shorten the life of the actuator or otherwise damage the actuator.

FIG. 2Cillustrates a partial cross sectional view of an actuator component housing16comprising an electroactive actuator14located within a cavity52. In this example, the electroactive actuator14comprises two stacked cartridges12. The actuator14can include one or more actuator spacers58and one or more mass spacers54. The spacers54and58can have recesses or raised surfaces that are aimed to facilitate unhindered movement of the active area of the actuators14within the device or case56. For example, the inertial mass50can be coupled to the actuator bars34of the transducer14while being separated from the remaining non-moving portion of the actuator14. Furthermore,FIG. 2Cillustrates the clearance C between the inertial mass50and a wall of the separate case56, which allows a perimeter of the interior cavity52to serve as a barrier or hard stop or bumper for the actuator and/or mass.

FIG. 2D, illustrates a planar view of an actuator spacer58. In this variation, the actuator spacer58includes a series of recesses or cutouts60. These cutouts60align with the movable portions of the actuator (i.e., the dielectric surrounded by the output bars34) so as to allow unimpeded movement of the active portion of the actuator.

FIGS. 2E and 2Fillustrate a bottom view and side view of an inertial mass50. As shown, the inertial mass50can include a number of spacers54. The spacers54can be coupled to the output bars34of the actuator so that the moving surface of the mass50does not engage the non-moving surface of the actuator14. Furthermore, the mass spacer54can couple the inertial mass50to the output bars34of the actuator14.

FIGS. 3A to 3Cillustrate another variation of a two-phase electroactive polymer transducer. In this variation, the transducer10comprises a first pair of electrodes90about the dielectric film96and a second pair of electrodes92about the dielectric film96where the two pairs of electrodes90and92are on opposite sides of a bar or mechanical member34that facilitates coupling to another structure to transfer movement. As shown inFIG. 3A, both electrodes90and92are at the same voltage (e.g., both being at a zero voltage). In the first phase, as illustrated inFIG. 3B, one pair of electrodes92is energized to expand the film and move the bar34by a distance D. The second pair of electrodes90is compressed by nature of being connected to the film but is at a zero voltage.FIG. 3Cshows a second phase in which the voltage of the first pair of electrodes92is reduced or turned off while voltage is applied to the second pair of electrodes90is energized. This second phase is synchronized with the first phase so that the displacement is greater than D (as much as 2 times D).FIG. 3Dillustrates the displacement of the transducer10ofFIGS. 3A to 3Cover time. As shown, Phase 1 occurs as the bar34is displaced by amount D when the first electrode92is energized for Phase 1. At time T1the beginning of Phase 2 occurs and the opposite electrode90is energized in synchronization with the reduction of the voltage of the first electrode92. The net displacement of the bar34over the two phases is 2×D.

Depending upon the electrode configurations, the electroactive actuators14can be capable of functioning in either a single or a dual-phase mode (also known as a two-phase mode). When operating as a single mode actuator only one set of working pairs of electrodes of actuator14would be activated at any one time. In a configuration that includes multiple areas of active electrodes (like those shown inFIG. 2A) each set of electrodes is activated at the same time to cause movement of the output bars in the same direction. The single-phase operation of actuator14may be controlled using a single high voltage power supply. As the voltage applied to the single set of working electrode pairs is increased, the activated portion (one half) of the transducer film will expand, thereby moving the output member34in-plane in the direction of the inactive portion of the transducer film.FIG. 4Aillustrates the force-stroke relationship of the sensory feedback signal (i.e., output member displacement) of actuator30relative to neutral position when alternatingly activating the two working electrode pairs in dual-phase mode. As illustrated, the respective forces and displacements of the output bars are equal to each other but in opposite directions (e.g., one pair of electrodes expands the polymer film while the other pair contracts the film).

FIG. 4Billustrates the resulting non-linear relationship of the applied voltage to the output displacement of the actuator when operated in this dual-phase mode. The “mechanical” coupling of the two electrode pairs by way of the shared dielectric film may be such as to move the output disc in opposite directions. Thus, when both electrode pairs are operated, albeit independently of each other, application of a voltage to the first working electrode pair (phase 1) will move the output disc20in one direction, and application of a voltage to the second working electrode pair (phase 2) will move the output disc20in the opposite direction. As the various plots ofFIG. 4Creflect, as the voltage is varied linearly, the displacement of the actuator is non-linear. The acceleration of the output disk during displacement can also be controlled through the synchronized operation of the two phases to enhance the haptic feedback effect. The actuator can also be partitioned into more than two phases that can be independently activated to enable more complex motion of the output disk. Two-phase mode allows for a greater displacement and faster acceleration of the output bar34, and thus provide a greater sensory feedback signal to the user. A two-phase mode allows activating both portions of the actuator simultaneously.FIG. 4Cillustrates the force-stroke relationship of the sensory feedback signal of the output disc when the actuator is operated in two-phase mode. As illustrated, both the force and stroke of the two portions90,92of the actuator in this mode produce movement of the output bar34in the same direction and have double the magnitude than the force and stroke of the actuator when operated in single-phase mode.FIG. 4Dillustrates the resulting linear relationship of the applied voltage to the output displacement of the actuator when operated in this two-phase mode.

By connecting the mechanically coupled portions90,92of the actuator electrically in series and controlling their common node155, such as in the manner illustrated in the block diagram140ofFIG. 5, the relationship between the voltage of the common node155and the displacement (or blocked force) of the output member (in whatever configuration) approach a linear correlation. In this mode of operation, the non-linear voltage responses of the two portions90,92of actuator effectively cancel each other out to produce a linear voltage response. With the use of control circuitry144and switching assemblies146,148, one for each portion of the actuator, this linear relationship allows the performance of the actuator to be fine-tuned and modulated by the use of varying types of waveforms supplied to the switch assemblies by the control circuitry. Another advantage of using circuit140is the ability to reduce the number of switching circuits and power supplies needed to operate the sensory feedback device. Without the use of circuit140, two independent power supplies and four switching assemblies would be required. Thus, the complexity and cost of the circuitry are reduced while the relationship between the control voltage and the actuator displacement are improved, i.e., made more linear. Another advantage is that during two-phase operation, the actuator obtains synchronicity, which eliminates delays that could reduce performance.

FIG. 6Aillustrates one example of a housing assembly100for removably coupling with an electronic media device that is configured to deliver an output signal to an output port. The housing assembly produces a haptic effect in response to the output signal of the electronic media device. Clearly, the housing assembly100can be used with any electronic media devices such as smart phones, personal media players, portable computing devices, portable gaming systems, electronic readers, etc. Moreover, the term electronic media devices can include such components as remote controls, GPS units, scanners, personal digital assistants, diagnostic equipment, electronic peripherals (e.g., mice, gaming controllers, etc.) or any such electronic equipment that can benefit from an improved haptic response given an output signal from the device. Often such devices are hand-held, though the application is not limited to such hand-held devices unless specifically claimed. In certain variations, the assemblies described herein, along with the methods and systems, can be coupled to devices200that are fully functional in a stand-alone mode. In such a case, the housing assembly100only serves to improve or augment haptic or other output from the device200.

In the illustrated variation, the housing assembly100includes a housing or case102adapted to nest at least a portion of electronic media device (200as shown inFIG. 6C). The housing can include one or more one media device connectors104adapted to detachably couple to an output port or speaker jack of the electronic media device200. In most cases, the output port of the media device200comprises a USB port, dock port, or other connector that allows both input to and output from the media device200. In certain cases, the assembly100is coupled via a speaker output that only provides output from the media device200. In any case, the term output port is meant to include ports that allow for input and output, or output alone.

The housing case102can comprise a flexible or textured sleeve to provide improved handing grip and ruggedness to the media device. Alternatively, the housing case102can comprise a rigid material to provide added protection to the device. The media device200nests within a pocket or cavity106. To accommodate placement, the media device connector104can swivel or articulate to allow for ease of coupling the media device200to the case102.FIG. 6Aalso illustrates optional components for the housing assembly100. For example, the housing assembly can include one or more handles108to aid in maneuvering the device200without covering a screen or other portion of the device200. Furthermore, the housing assembly100can include one or more speakers110. In such a case, the output signal of the device200can be split between drive circuitry that controls the electroactive polymer actuator and the speakers110of the housing assembly100. Although not shown, the electroactive polymer actuator can reside beneath a surface of the cavity106.

FIG. 6Billustrates a bottom perspective view of the housing assembly100ofFIG. 6A. As shown, the handles108can include flat surfaces or other features to aid in handling or placement of the assembly100and device200. The housing also can optionally include one or more input/output jacks112. For example, such input/output jacks can accommodate any variation of a USB connector to allow for charging of a power supply coupled to the actuator. Alternatively, or in combination, the jack112can provide a pass-through to the media device200so that the media device200can be charged or allow for data transfer without the need to remove it from the housing assembly100.FIG. 6Balso illustrates that the housing assembly100can include any number of controls114,116so that the operator can adjust audio, haptics, or other features of the device200and/or assembly100.FIG. 6Aalso illustrates that the housing case102can include features118so that controls on the media device200can be adjusted without necessarily removing the device200from the case102. In this example, the feature118comprises a recess so that a power toggle can be manipulated on the media device200. In most cases, the shape of the case102as well as the cavity106will be customized for the particular make and model of the media device200. Accordingly, any number of such features118that permit control of the media device200while coupled to the case102are considered to be within the scope of this disclosure

FIG. 6Cillustrates an electronic media device200(in this example, an IPOD TOUCH) removably coupled with a housing assembly100that can convert an output signal from the iPod into an increased haptic effect that can be felt by the user either at the body case102, the handles110and/or the device200.

FIG. 6Dshows a representation of a view as taken along the line6D-6D inFIG. 6C. As discussed above, the housing assembly100includes at least one electroactive polymer actuator14having an active portion configured to produce movement in response to a triggering signal from the electronic media device200. Movement of the active portion creates the haptic effect discernable on or at the housing assembly100(optionally including at the device200itself). The triggering signal can be the ordinary output of the media device200or can comprise custom software that is incorporated into the media device. The device200can optionally power the electroactive polymer actuator14. Alternatively, the housing assembly100can include a separate power supply that powers the electroactive actuator14. Optionally, the housing assembly100includes an inertial mass50that is driven by the actuator14to produce the haptic effect. In some variations, the separate power supply can be used as the inertial mass50. In alternate variations, the housing assembly100includes both a separate power supply and a discrete inertial mass.

FIG. 6Dalso illustrates the housing100including at least one drive electronics assembly118configured to electronically couple the electroactive polymer actuator14(typically via a connector30) to the media device connector104, such that the drive electronics is capable of generating the triggering signal in response to the output signal of the electronic media device200. As discussed above,FIG. 6Dalso illustrates the actuator14and inertial mass50as being contained within an actuator case56. Again, the actuator case56can designed provide as a protective housing for the actuator14. In one embodiment, the two piece assembly allows the same actuator case56to be inserted into different housings100to accommodate different device form factors. Thus, the bulk of the assembly (all parts contained in56) can remain the same while the outside grip is changed to fit many device models/form factors. Alternatively, use of the housing56can allow a user to remove the actuator housing56containing the actuator14and inertial mass50and replace it with an alternate actuator housing56. The alternate actuator housing can provide the device with an electroactive polymer actuator having different characteristics or can provide the device with an entirely different functionality.

FIGS. 7A to 7Crepresent top, side, and right views of another variation of a housing assembly100capable of removably coupling with an electronic media device. In this variation, the case102of the housing assembly100includes a pair of symmetric handles108that converts the shape of the electronic media device200into a more conventional gaming device. The handles108form grips to permit use of the device200in a portrait mode and permit manipulation of the assembly100and device200without the need to obscure a viewing area of the device200.

FIG. 7Dshows a sectional view taken along the lines7C-7C inFIG. 7A. In this variation, the actuator14and inertial mass50are directly coupled to a mounting plate58in the case102rather than using an actuator housing. It is noted that alternate variations of the device include omitting the inertial mass50to allow the actuator14to directly drive the media device200. While the drive electronics are not illustrated inFIG. 7C, the circuitry can be positioned within the handles108.

FIG. 8Ashows another variation of a housing assembly100or haptic grip assembly for use with a media device200.FIG. 8Bshows a partial cut-away section of the assembly100. In this variation, the assembly100includes a battery60that is separate from an inertial mass50. As discussed above, the inertial mass50is coupled to an electroactive polymer actuator14located within the case102. As with the variations shown above, the housing100can optionally isolate the battery60or power supply from the media device200so that the power supply60only powers the haptic transducer assembly14as well as any drive electronics118that converts an output signal from the media device200into a triggering signal that controls movement of the actuator14and the resulting haptic effect.

Filtered Sound Drive Waveform for Electroactive Polymer Haptics

The methods and devices described herein can generate the haptic effect by a sound signal provided by the media device. Such a configuration eliminates the need for a separate processor to generate waveforms to produce different types of haptic sensations. Instead, haptic devices can employ one or more circuits to modify an existing audio signal into a modified haptic signal, e.g. filtering or amplifying different portions of the frequency spectrum. Therefore, the modified haptic signal then drives the actuator. In one example, the modified haptic signal drives the power supply to trigger the actuator to achieve different sensory effects. This approach has the advantages of being automatically correlated with and synchronized to any audio signal which can reinforce the feedback from the music or sound effects in a haptic device such as a gaming controller or handheld gaming console.

FIG. 9Aillustrates one example of a circuit to tune an audio signal to work within optimal haptic frequencies for electroactive polymer actuators. The illustrated circuit modifies the audio signal by amplitude cutoff, DC offset adjustment, and AC waveform peak-to-peak magnitude adjustment to produce a signal similar to that shown inFIG. 9B. In certain variations, the electroactive polymer actuator comprises a two phase electroactive polymer actuator and altering the audio signal comprises filtering a positive portion of an audio waveform of the audio signal to drive a first phase of the electroactive polymer transducer and inverting a negative portion of the audio waveform of the audio signal to drive a second phase of the electroactive polymer transducer to improve performance of the electroactive polymer transducer. In another variation, a source audio signal in the form of a sine wave can be converted to a square wave (e.g., via clipping), so that the haptic signal is a square wave that produces maximum actuator force output.

In another example, the circuit can include one or more rectifiers to filter the frequency of an audio signal to use all or a portion of an audio waveform of the audio signal to drive the haptic effect.FIG. 9Cillustrates one variation of a circuit designed to filter a positive portion of an audio waveform of an audio signal. This circuit can be combined, in another variation, with the circuit shown inFIG. 9Dfor actuators having two phases. As shown, the circuit ofFIG. 9Ccan filter positive portions of an audio waveform to drive one phase of the actuator while the circuit shown inFIG. 9Dcan invert a negative portion of an audio waveform to drive the other phase of the two-phase haptic actuator. The result is that the two phase actuator will have a greater actuator performance.

In another implementation, a threshold in the audio signal can be used to trigger the operation of a secondary circuit which drives the actuator. The threshold can be defined by the amplitude, the frequency, or a particular pattern in the audio signal. The secondary circuit can have a fixed response such as an oscillator circuit set to output a particular frequency or can have multiple responses based on multiple defined triggers. In some variations, the responses can be pre-determined based upon a particular trigger. In such a case, stored response signals can he provided in upon a particular trigger. In this manner, instead of modifying the source signal, the circuit triggers a pre-determined response depending upon one or more characteristics of the source signal. The secondary circuit can also include a timer to output a response of limited duration.

Many systems could benefit from the implementation of haptics with capabilities for sound, (e.g. computers, smart phones, PDA's, electronic games). In this variation, filtered sound serves as the driving waveform for electroactive polymer haptics. The sound files normally used in these systems can be filtered to include only the optimal frequency ranges for the haptic feedback actuator designs.

Current systems operate at optimal frequencies of <200 Hz. A sound waveform, such as the sound of a shotgun blast, or the sound of a door closing, can be low pass filtered to allow only the frequencies from these sounds that are <200 Hz to be used. This filtered waveform is then supplied as the input waveform to the EPAM power supply that drives the haptic feedback actuator. If these examples were used in a gaming controller, the sound of the shotgun blast and the closing door would be simultaneous to the haptic feedback actuator, supplying an enriched experience to the game player.

In one variation use of an existing sound signal can allow for a method of producing a haptic effect in a user interface device simultaneously with the sound generated by the separately generated audio signal. For example, the method can include routing the audio signal to a filtering circuit; altering the audio signal to produce a haptic drive signal by filtering a range of frequencies below a predetermined frequency; and providing the haptic drive signal to a power supply coupled to an electroactive polymer transducer such that the power supply actuates the electroactive polymer transducer to drive the haptic effect simultaneously to the sound generated by the audio signal.

Another variation for driving an electroactive polymer transducer includes the use of stored wave forms given a threshold input signal. The input signal can include an audio or other triggering signal. For example, the circuit shown inFIG. 10illustrates an audio signal serving as a trigger for a stored waveform. Again, the system can use a triggering or other signal in place of the audio signal. This method drives the electroactive polymer transducer with one or more pre-determined waveforms rather than using simply driving the actuator directly from the audio signal. One benefit of this mode of driving the actuator is that the use of stored waveforms enables the generation of complex waveforms and actuator performance with minimal memory and complexity. Actuator performance can be enhanced by using a drive pulse optimized for the actuator (e.g. running at a preferred voltage or pulse width or at resonance) rather than using the analog audio signal. The actuator response can be synchronous with the input signal or can he delayed. In one example, a 0.25 v trigger threshold can be used as the trigger. This low-level signal can then generate one or more pulse waveforms. In another variation, this driving technique can potentially allow the use of the same input or triggering signal to have different output signals based on any number of conditions (e.g., such as the position of the user interface device, the state of the user interface device, a program being run on the device, etc.).

FIGS. 11A and 11Billustrate yet another variation for driving an electroactive polymer transducer by providing two-phase activation with a single drive circuit. As shown, of the three power leads in a two-phase transducer, one lead on one of the phases is held constant at high voltage, one lead on the other phase is grounded, and the third lead common to both phases is driven to vary in voltage from ground to high voltage. This enables the activation of one phase to occur simultaneously with the deactivation of the second phase to enhance the snap-through performance of a two-phase actuator.

The electroactive polymer actuator used in the present disclosure can be controlled to operate between a pulse mode and a subwoofer mode depending upon the frequency of the signal output by the media device. Such a feature is useful to distinguish between repeatable effects (such as the typing on a keyboard) and effects produced during games or other by various other media.FIG. 12Aillustrates one variation of a flow chart used to determine the actuator mode based on the input signal.FIG. 12Billustrates on possible example of a trigger circuit.FIG. 12Cprovides one example of the control architecture used for a variation of the electroactive polymer actuator and housing assembly as described above.

Drive Schemes

In many cases, the system can limit power consumption using a circuit that cuts off or reduces voltage when the current draw is too high, e.g. at higher frequencies. In a first example, the second stage cannot run unless the input stage of the converter is above a given voltage. When the second stage initializes, the circuit causes the voltage on the first stage to drop and then drops out of the second stage if the input power is limited. At low frequencies, the haptic response follows the input signal. However, because high frequencies require more power, the response becomes clipped depending on the input power. Power consumption is one of the metrics needed to optimize the sub-assembly and drive design. Clipping the response in this manner conserves power.

In another variation, the drive scheme can employ amplitude modulation. For example, the actuator voltage can be driven at resonant frequency where the signal amplitude is scaled based on the input signal amplitude. This level is determined by the input signal, and the frequency is determined by the actuator design.

In another variation, the haptic response or effect can be tailored by the choice of the drive scheme, e.g. analog (as with the audio signal) or digital bursts or combinations of Filters or amplifiers can be used to enhance the frequencies in the input drive signal that leads to the highest performance of the actuators. This permits an increased sensitivity in the haptic response by the user and/or to accentuate the effect desired by the user. For example, the sub-assembly/system frequency response can be designed to match/overlap fast a fast Fourier transform taken of sound effects that are used as the drive input signal.

Another variation for producing a haptic effect involves the use of a roll-off filter. Such a filter allows attenuation of high frequencies that require a high power draw. To compensate for this attenuation, the sub-assembly can be designed to have its resonance at higher frequencies. The resonant frequency of the sub-assembly can be adjusted for example by changing the stiffness of the actuators (e.g. by changing the dielectric material, varying the thickness of the dielectric film, changing the type or thickness of the electrode material, changing the dimensions of the actuators), changing the number of cartridges in the actuator stack, changing the load or inertial mass on the actuators. Moving to thinner films or softer materials can move the cut-off frequency needed to meet a current/power limitation to higher frequencies. Clearly, adjustment of the resonance frequency can occur in any number of ways. The frequency response can also be tailored by using a mixture of actuator types.

Rather than using a simple follower circuit, a threshold can be used in the input drive signal to trigger a burst with an arbitrary waveform that requires less power. This waveform could be at a lower frequency and/or can be optimized with respect to the resonant frequency of the system—sub-assembly & housing—to enhance the response. In addition, the use of a delay time between triggers can also be used to control the power load.

Zero-Crossing Power Control

In another variation, a control circuit can monitor input audio waveforms and provide control for a high voltage circuit. In such a case, as shown inFIG. 13A, an audio waveform510is monitored for each transition through zero voltage value512. With these zero crossings512, a control circuit can indicate the crossing time value, and the voltage condition.

This control circuit changes high voltage based on zero crossing time and voltage swing direction. As shown inFIG. 13B, for zero crossing: positive swing, high voltage drive changes from zero volts to 1 kV (High Voltage Rail Value) at514. For zero crossing: negative swing, high voltage drive changes from 1 kV to zero volts (Low Voltage Rail Value) at516.

Such a control circuit allows actuation events to coincide with frequency of the audio signal510. In addition, the control circuit can allow for filtering to eliminate higher frequency actuator events to maintain 40-200 Hz actuator response range. The square wave provides the highest actuation response for inertial drive designs and can be set by the limit of the power supply components. The charge up time can be adjusted to limit power supply requirements. To normalize actuation forces, the mechanical resonance frequency can be charged by a Triangle wave, while off resonant frequency actuations can be energized by a square wave.

The circuit technology used to drive haptic electronics can be selected to optimize the footprint of the circuit (i.e. reduce the size of the circuit), increase the efficiency of the haptic actuator, and potentially reduce costs. The following Figures identify examples of such circuit diagrams.FIG. 14Aillustrates one example comprising a power supply for a photoflash controller.FIG. 14Billustrates a second example circuit comprising a push-pull metal-oxide-semiconductor field-effect transistor (MOSFET) array with closed loop feedback. In addition,FIG. 14Cillustrates one example of schematics for a circuit design to drive the haptic assembly coupled to an electronic media device.

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 method-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.

Also, it is 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. 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.