Haptic devices having multiple operational modes including at least one resonant mode

An apparatus comprises a signal source, a driver and an electro-mechanical transducer. The signal source is configured to output a haptic feedback signal. The driver is configured to receive the haptic feedback signal and output a drive signal. The electro-mechanical transducer is configured to receive the drive signal. The electro-mechanical transducer is configured to have a set of operational modes. Each operational mode from the set of operational modes has at least one resonant mode from a set of resonant modes.

FIELD OF THE INVENTION

The invention relates generally to the application of vibrotactile feedback. More particularly, the invention relates to a haptic feedback device having multiple operational modes including multiple resonant modes.

BACKGROUND OF THE INVENTION

Generally, electro-mechanical transducers exhibit a level of power consumption that may be higher than desired. Furthermore, such electro-mechanical transducers may not be able to produce haptic feedback of a desired magnitude or bandwidth due to space constraints.

What is needed is an electro-mechanical transducer that is configured to produce vibrotactile feedback having a relatively high magnitude and/or an adjustable bandwidth. Additionally, it would be desirable to have an electro-mechanical transducer that can generate haptic feedback having relatively low energy consumption.

SUMMARY OF THE INVENTION

An apparatus comprises a signal source, a driver and an electro-mechanical transducer. The signal source is configured to output a haptic feedback signal. The driver is configured to receive the haptic feedback signal and output a drive signal. The electro-mechanical transducer is configured to receive the drive signal. The electro-mechanical transducer is configured to have a set of operational modes. Each operational mode from the set of operational modes has at least one resonant mode from a set of resonant modes.

DETAILED DESCRIPTION

An apparatus comprises a signal source, a driver and an electro-mechanical transducer having a cantilever. The signal source is configured to output a haptic feedback signal. The driver is configured to receive the haptic feedback signal and output a drive signal. The electro-mechanical transducer has a cantilever and is configured to receive the drive signal. The electro-mechanical transducer is configured to have a set of operational modes. Each operational mode from the set of operational modes has at least one resonant mode from a set of resonant modes.

In one embodiment, electro-mechanical devices are used in an electro-mechanical transducer that is configured to output haptic feedback in an operational mode having one or more resonant modes. The electro-mechanical transducer is also configured to have multiple operational modes. Such a device can produce diverse and robust haptic feedback that can exhibit relatively low power consumption in a space-efficient manner. Although many embodiments described herein relate to using cantilevers as resonant structures, analogous devices are also possible. For example, such resonant structures can use acoustic cavities, membranes, mass-springs, wheel-torsional springs, and/or other structures capable of exhibiting mechanical resonance. Some embodiment, for example, can have a combination of different types of structure capable of exhibiting mechanical resonance.

As used herein, the term “operational mode” means a method or manner of functioning in a particular condition at a given time. For example, if a first electro-mechanical device is operating in a first resonant mode and a second electro-mechanical device is operating in a second resonant mode, the electro-mechanical transducer is operating collectively in, for example, a first operational mode. Alternatively, for example, if the first electro-mechanical device is operating in a third resonant mode, and the second electro-mechanical device is operating in a fourth resonant mode, the electro-mechanical transducer is operating collectively in a second operational mode. In another example, if the first electro-mechanical device is operating in a first resonant mode, and the second electro-mechanical device is not operating, the electro-mechanical transducer is operating collectively in a third operational mode. In other words, a given operation mode can be based on one electro-mechanical device operating in a resonant mode and another electro-mechanical device not being activated.

The term “resonant mode” means any mode of an electro-mechanical device operating in a frequency band centered around a resonant frequency. When an electro-mechanical device operates at or near a resonant frequency, several consequences occur. For example, when a transducer operates at or near a resonant frequency, the inertial term and the elastic terms substantially cancel. The power consumed by the actuator is then dedicated to balance dissipation (e.g. damping). If the dissipation is low, for example, in a cantilevered piezo-electric beam (i.e. a resonator with a high Q factor), the displacement is relatively large and limited by dissipative forces. In addition, if the mass that resonates is comparable to the mass of the structure to which the transducer is attached (e.g. case of a telephone), then the structure vibrates with a relatively large magnitude. Power lost during activation is in the dissipation. The remaining power is transmitted to the anatomy of the person with which the device is in contact.

The term “electro-mechanical device” as used herein, means an individual active component configured to provide haptic feedback. The term “active component” refers to a single component that provides a mechanical response to the application of an electrical signal. For example, for the embodiment illustrated inFIG. 5and discussed below, a single length of, for example, piezoelectric material (for example, piezoelectric bar410) and the associated mass (for example, mass412) is referred to herein as the electro-mechanical device. In the example illustrated inFIG. 8and discussed below, the electro-mechanical transducer includes only one electro-mechanical device.

The term “electro-mechanical transducer” means an apparatus having one or more electro-mechanical devices coupled to a mechanical ground. For example, in the embodiment of the invention illustrated inFIG. 5, the electro-mechanical transducer includes all three lengths of piezoelectric material, each having a mass coupled thereto. In the embodiment illustrated inFIG. 8, the electro-mechanical transducer includes piezoelectric bar610and the masses620,630, and640.

An embodiment of an electro-mechanical transducer is illustrated inFIG. 1. An electro-mechanical transducer according to this embodiment of the invention includes a drive circuit110having an amplifier and includes an electro-mechanical transducer120. The electro-mechanical transducer120includes one or more electro-mechanical (E-M) devices121.

Drive110receives a haptic feedback signal and outputs a drive signal to electro-mechanical transducer120. The haptic feedback signal may be based on a command from a microprocessor within, for example, a computer or a portable communications device (not shown). The electro-mechanical transducer120is configured to selectively operate in one of multiple possible operational modes at a given time. The operational mode of the electro-mechanical transducer120at a given time will depend, for example, on the characteristics of the drive signal received from driver10. For a given operational mode, an electro-mechanical transducer can operate in multiple resonant modes as will be described in greater detail below. The one or more electro-mechanical devices121of electro-mechanical transducer120collectively output haptic feedback based on the drive signal, as illustrated inFIG. 7.

FIG. 2illustrates a piezoelectric bar in accordance with one embodiment of the invention. As described below in more detail, such a piezoelectric bar can be used as an electromechanical device within an electro-mechanical transducer.

The piezoelectric bar200is a bimorph piezoelectric device that is a two-layer bending motor having a length (L)220substantially larger than a width (W)210. In one embodiment, the piezoelectric bar200has a width (W)210of approximately 0.6 mm, a length (L)220of approximately 25 mm and a height (H)230of approximately 5 mm. Alternatively, the piezoelectric bar can have any suitable dimensions depending on the desired use.

When a voltage240from, for example, a drive source (not shown), is applied across the piezoelectric bar200, the piezoelectric bar200will flex. An appropriate level of voltage240to be applied to the piezoelectric bar200can be selected, based at least in part, on the material and the thickness of the material used to construct the piezoelectric bar200.

The piezoelectric bar200can be driven near a resonant frequency. When the piezoelectric bar200is driven near a resonant frequency, impedance transformation may be obtained. Impedance transformation results in large mechanical displacements as described above.

An electro-mechanical device300that can be used in combination with other electro-mechanical devices to construct an electro-mechanical transducer is illustrated asFIG. 3. Multiple electro-mechanical devices300can be configured to operate in a selected operational mode from a set of possible operational modes, each operational mode having one or more resonant modes, as will be described in further detail with respect toFIG. 5.

The electro-mechanical device300illustrated inFIG. 3includes a piezoelectric bar310having mass320coupled to an end portion325of the piezoelectric bar310. A second end portion335of the piezoelectric bar310is coupled to a base member330. Base member330acts as a mechanical ground and is configured to remain stationary relative to the movement of the piezoelectric bar310.

The electro-mechanical device illustrated inFIG. 3can operate as follows. A voltage340from a voltage source (not shown) can be applied to piezoelectric bar310. The piezoelectric bar can be, for example, a bimorph piezoelectric device as described above in connection withFIG. 2. Voltage340causes piezoelectric bar310to flex in a first direction D1. Voltage340can be modulated at a frequency, fd, which is referred to herein as the drive frequency of the electro-mechanical device300. As described above, the frequency fdcan be selected such that the electro-mechanical device300operates near a resonant frequency the electro-mechanical device300. Frequency fdis a function of the type of electro-mechanical device used in the electro-mechanical transducer, the dimensions of the electro-mechanical device (e.g., the length, width, height or thickness), and the position and weight of the masses in the electro-mechanical device.

When the drive frequency fdof the voltage340is such that the electro-mechanical device300operates near its resonant frequency, the electro-mechanical device300can produce a large vibration sensation relative to the voltage340applied to the electro-mechanical device300.

Both the weight of mass320and the length of the piezoelectric bar310affect the amplitude of the displacement. Furthermore, the weight of mass320and the length of the piezoelectric bar310affect the resonant frequencies of the electro-mechanical device300. Therefore, the particular resonant frequencies may be tailored by selecting the appropriate length of the piezoelectric bar and/or weight of the mass320for a desired resonant frequency. When voltage340is applied to the piezoelectric bar310, the electro-mechanical device300will move in a plane oriented as vertical for the depiction inFIG. 3.

The embodiment illustrated inFIG. 4is similar to that illustrated inFIG. 3.FIG. 4shows an electro-mechanical device350including a piezoelectric bar360having mass370coupled to an end portion375of piezoelectric bar360. The piezoelectric bar360has its second end portion385coupled to a base member380, which acts as a ground and is configured to remain stationary with respect to movement of the piezoelectric bar360.

The operation of the electro-mechanical device350is similar to the embodiment described with reference toFIG. 3except that when voltage390is applied to piezoelectric bar360, the electro-mechanical device350will vibrate in direction D2(i.e., relative to the perspective shown inFIG. 4) due to the orientation of the bimorph piezoelectric bar360relative to base member380.

FIG. 5illustrates an electro-mechanical transducer400, according to another embodiment of the invention. The electro-mechanical transducer400includes three electro-mechanical devices410,420, and430. In the illustrated embodiment, each of the electro-mechanical devices410,420and430includes a piezoelectric bar411,421, and431, respectively. A mass412,422, and432can be coupled to an end portion413,423, or433, of each piezoelectric bar411,421and431, respectively. The second end portion414,424, and434, of each piezoelectric bar411,421, and431, respectively, is coupled to a base member440. Base member440can be configured to remain stationary with respect to movement of the piezoelectric bars411,421and431. More specifically, base member440is stationary relative to any movement of piezoelectric bars411,421and431, but can move in the context of the overall product or device (e.g., mobile phone, game controller, etc.) with which the electro-mechanical device400is disposed. In fact, base member440can relay the vibrations produced by the movement of piezoelectric bars411,421and431to the product or device. Base member440may be a single contiguous mechanical ground, as illustrated inFIG. 5. Alternatively, each piezoelectric bar411,421, and431may be coupled to a different mechanical ground.

Piezoelectric bars411,421, and431have lengths L1, L2, and L3, respectively. In one embodiment, these lengths may be the same. Alternatively, lengths L1, L2, and L3can be different. Additionally, the weights of masses412,422, and432, can be equal to one another. Alternatively, weights of the masses412,422, and432can be different from one another. The particular configuration of the masses412,422and432and the lengths of the piezoelectric bars411,421, and431can be based on the desired frequency response from the electro-mechanical transducer400.

The operation of the electro-mechanical transducer inFIG. 5will be described with reference toFIGS. 4 and 5. Voltage450can be applied to the electro-mechanical devices through contacts451. The voltage may by modulated at approximately the resonant frequency of the electro-mechanical devices410,420, and/or430. The voltage may be applied by a single voltage source via contacts451, or alternatively, each electro-mechanical device410,420,430, may have an independent voltage source (not shown) that is modulated approximately at the resonant frequency of the respective electro-mechanical device, or a resonant mode of the respective electro-mechanical device. Alternatively, voltage450may be modulated at a higher order resonant frequency of the electro-mechanical devices410,420, and/or430.

In an alternative arrangement, the electro-mechanical transducer400can include electro-mechanical devices410,420, and430that have different lengths L1, L2, L3. In this arrangement, each of the electro-mechanical devices410,420, and430has a different resonant frequency f1, f2, and f3, respectively. These different resonant frequencies can be driven at different drive frequencies fd1, fd2, and fd3. An example of the frequency response for an electro-mechanical transducer400is illustrated inFIG. 7. As depicted in the plot inFIG. 7, an electro-mechanical transducer with three electro-mechanical devices each operating at a different resonant frequency (or resonants thereof) has a frequency response with a greater bandwidth than the frequency response for an electro-mechanical transducer having a single electro-mechanical device, which is illustrated inFIG. 7. Note that the gain values shown on the y-axes inFIGS. 6and7relate to the magnitude of the device position divided by the magnitude of the input voltage to the device.

In another arrangement, masses412,422, and432and lengths L1, L2, and L3of electro-mechanical devices411,421, and431can be configured such that a single drive frequency, fd, may be used to drive, for example, the resonant mode in electro-mechanical device411, the first resonant mode in electro-mechanical device422, and the second resonant mode in electro-mechanical device432.

In yet another arrangement, the bandwidth of the electro-mechanical transducer400may be adjusted by selectively operating one or more of the electro-mechanical devices410,420,430in different resonant modes. Each one of these combinations of resonant frequencies collectively superpose into a different operational mode of the electro-mechanical transducer400.

In a first operational mode, for example, the electro-mechanical transducer400can be operated such that electro-mechanical devices410and430may be operating at frequencies f1and f3, respectively, with f1and f3being resonant modes of the electro-mechanical devices410and430, respectively. A voltage need not be applied to electro-mechanical device420in this operational mode. In this operational mode, the output of the electro-mechanical transducer400would include peaks510and530illustrated inFIG. 7.

In a second operational mode, for example, the electro-mechanical transducer400can be operated such that electro-mechanical devices410and420are operating at frequencies f1and f2, respectively, where f1and f2are resonant modes of the electro-mechanical devices410and420. In this operational mode, the electro-mechanical transducer400can produce an output having only two peaks, as illustrated, for example, inFIG. 7as510and520. This operational mode can have two frequencies that are different from the two frequencies of the first operational mode described above. Therefore, by changing the operational mode of the electro-mechanical transducer400, the resultant frequencies of the tactile feedback can be changed.

In a third operational mode, for example, the electro-mechanical transducer400can be operated such that electro-mechanical devices420and430may be operating at frequencies f2and f3, respectively, where f2and f3are resonant modes of each of the electro-mechanical devices420and430. In this operational mode, the electro-mechanical transducer400can produce an output having only two peaks, as illustrated, for example, inFIG. 7as520and530. This operational mode can have two frequencies that are different from the two frequencies for first operational mode described above. Additionally, the third operational mode can have two frequencies that are different from the two frequencies of the second operational mode. Therefore, by changing the operational mode of the electro-mechanical transducer400, the resultant frequencies of the haptic feedback can be changed.

In other operational modes, the electro-mechanical transducer400can be operated such that one of electro-mechanical devices410,420and430is operating at frequencies f1, f2and f3, respectively, where f1, f2and f3are resonant modes of each of the electro-mechanical devices410,420and430. In these operational modes, the electro-mechanical transducer400can produce an output having only one peak at a time. In other words, operational modes are possible where only a single electro-mechanical device is actuated at a given time.

The voltage can be modulated at a number of different drive frequencies, fd. For example, the drive frequency fdcan approximate a resonant mode of the electro-mechanical devices. Alternatively, fdcan include any other frequency that is an integral multiple of the electro-mechanical device's resonant frequency.

While certain operational modes have been described with reference toFIG. 5, it will be apparent from this discussion that many other operational modes are possible. For example, by providing additional electro-mechanical devices, the number of possible operational modes increases. Additionally, while only three piezoelectric bars were illustrated inFIG. 5, any number of piezoelectric bars may be employed.

Additionally, while the embodiments were described above with reference to electro-mechanical devices that included piezoelectric bars, any electro-active material or device can be used. For example, the electro-mechanical devices can include electro-active polymers (EAP), voice coil transducers or other electromagnetic device, an inertial resonant device, or a resonant eccentric rotating mass (HERM) device. An example of an inertial resonant device is described in co-pending U.S. Pat. No. 6,088,019, which is hereby incorporated by reference in its entirety. An example of a HERM device is described in co-pending patent application Ser. No. 10/301,809, which is hereby incorporated by reference in its entirety.

FIG. 8illustrates an alternative embodiment of an electro-mechanical transducer600having multiple masses620,630, and640disposed on the same piezoelectric bar610.

In this embodiment, electro-mechanical transducer600comprises one electro-mechanical device, the structure of which corresponds to the structure of electro-mechanical transducer600. The piezoelectric bar610is secured to a base member650, which acts as a mechanical ground and remains substantially fixed with respect to the movement of the electro-mechanical device600. Masses620,630, and640can have equal weights or can have different weights. Alternatively, the weights of the two masses can be equal to one another, while the weight of the third mass can be different. Additionally, the masses620,630, and640can be equally spaced along the length of the piezoelectric bar610or can be spaced at any desired location along the length of the piezoelectric bar610. The weight of and spacing between masses620,630, and640allow the electro-mechanical device to be designed to have a predetermined number of resonant frequencies.

Next, the operation of the embodiment illustrated inFIG. 8will be described with reference toFIGS. 6-10.FIGS. 7-10illustrate an example of the different operational modes that can be obtained with an electro-mechanical transducer600bearing three masses. The bends in the piezoelectric bar610are exaggerated in this figure to illustrate the bending of the piezoelectric bar610more clearly.

Frequency modulated voltage can be applied to the piezoelectric bar610. As illustrated inFIG. 9, the electro-mechanical device is initially in a resting position.FIG. 10illustrates a first resonant mode of the electro-mechanical device.FIG. 11illustrates a second resonant mode of the electro-mechanical device.FIG. 12illustrates a third resonant mode of the electro-mechanical device. The modes illustrated inFIGS. 7-10will produce a resultant output having frequencies that are similar to the frequencies illustrated inFIG. 7due to the superposition of the three resonant modes produced by the electro-mechanical device.

FIG. 13illustrates a method for producing an operational mode of an electro-mechanical transducer, according to an embodiment of the invention. At step1110, a haptic feedback signal is generated. At step1120, the haptic feedback signal is supplied to a driver. At step1130, the drive signal is then applied to a first electro-mechanical device. At step1140, a drive signal is also applied to the second electro-mechanical device. At step1150, the electro-mechanical devices output haptic feedback that includes haptic feedback at a first resonant mode (step1151) and haptic feedback at a second resonant mode (step1152). The output of haptic feedback at a first resonant mode by a first electro-mechanical device and/or at a second resonant mode by a second electro-mechanical device correspond to an operational mode of the electro-mechanical transducer having the first electro-mechanical device and/or the second electro-mechanical device, respectively.

Additional electro-mechanical devices can be added and can have the drive signal selectively applied thereto to collectively yield a variety of different operational modes of the electro-mechanical transducer. Alternatively, the electro-mechanical transducer may include multiple masses, as illustrated inFIG. 8. By altering the frequency of the drive signal such that it substantially corresponds to the resonant frequencies of the electro-mechanical device, the electro-mechanical transducer can output haptic feedback having multiple frequencies for a given operational mode.

In another embodiment, a number of electro-mechanical devices in a serial configuration, as illustrated inFIG. 8, can be arranged in parallel as illustrated inFIG. 5.

The devices described above are capable of being used in small, portable devices where energy consumption needs to be low. For example, electro-mechanical transducers can be used in cellular phones, electronic pagers, laptop touch pads, a cordless mouse or other computer peripherals whether cordless or otherwise, a personal digital assistant (PDA), along with a variety of other portable and non-portable devices.

While the particular embodiments of the invention were described above with respect to piezoelectric bars, the invention is not limited to the use of piezoelectric bars and piezoelectric devices having various structures can be used depending on the desired application of the electro-mechanical transducer. For example, the piezoelectric device can have a planar shape where the width is approximately the same as the length.

While particular embodiments of the invention have been described with reference to piezoelectric ceramics, numerous other electro-mechanical devices may be used to implement the invention. For example, the electro-mechanical devices according to the invention may include electro-active polymers (EAP), voice coil transducers or other electromagnetic device, or resonant eccentric rotating mass (HERM) devices.

The previous description of the embodiments is provided to enable any person skilled in the art to make or use the invention. While various electro-mechanical transducers have been described including at least one electro-mechanical device including a piezoelectric substance, various other electro-mechanical devices may be utilized that can be configured to operate in multiple operational modes, each one of the multiple operational modes including a number of resonant modes. Other modifications to the overall structure of the electro-mechanical devices and arrangement of the selector-mechanical transducers can be made without departing from the spirit and scope of the invention.