Patent Description:
Linear resonant actuators (LRAs) and other vibrational actuators (e.g., rotational actuators, vibrating motors, etc.) are increasingly being used in mobile devices (e.g., mobile phones, personal digital assistants, video game controllers, etc.) to generate vibrational feedback for user interaction with such devices. Typically, a force/pressure sensor detects user interaction with the device (e.g., a finger press on a virtual button of the device) and in response thereto, the linear resonant actuator vibrates to provide feedback to the user. For example, a linear resonant actuator may vibrate in response to force to mimic to the user the feel of a mechanical button click.

<CIT> discloses an integrated haptic system comprising a digital signal processor and an amplifier. The processor determines a vibration waveform pattern on the basis of force detection data.

One disadvantage of existing haptic systems is that existing approaches to processing of signals of a force sensor and generating of a haptic response thereto often have longer than desired latency, such that the haptic response may be significantly delayed from the user's interaction with the force sensor. Thus, in applications in which a haptic system is used for mechanical button replacement, capacitive sensor feedback, or other application, and the haptic response may not effectively mimic the feel of a mechanical button click. Accordingly, systems and methods that minimize latency between a user's interaction with a force sensor and a haptic response to the interaction are desired.

In addition, to create appropriate and pleasant haptic feelings for a user, a signal driving a linear resonant actuator may need to be carefully designed and generated. In mechanical button replacement application, a desirable haptic response may be one in which the vibrational impulse generated by the linear resonant actuator should be strong enough to give a user prominent notification as a response to his/her finger pressing and/or releasing, and the vibrational impulse should be short, fast, and clean from resonance tails to provide a user a "sharp" and "crisp" feeling. Optionally, different control algorithms and stimulus may be applied to a linear resonant actuator, to alter the performance to provide alternate tactile feedback - possibly denoting certain user modes in the device - giving more "soft" and "resonant" tactile responses.

In accordance with the teachings of the present disclosure, the disadvantages and problems associated with haptic feedback in a mobile device may be reduced or eliminated.

In accordance with embodiments of the present disclosure, an integrated haptic system includes a digital signal processor and an amplifier communicatively coupled to the digital signal processor and integrated with the digital signal processor into the integrated haptic system. The digital signal processor is configured to receive an input signal indicative of a force applied to a force sensor and generate a haptic playback signal responsive to the input signal. The amplifier is configured to amplify the haptic playback signal and drive a vibrational actuator communicatively coupled to the amplifier with the haptic playback signal as amplified by the amplifier. The digital signal processor is further configured to, responsive to a condition for changing a polarity of the haptic playback signal, change the polarity of the haptic playback signal. The condition for changing the polarity of the haptic playback signal comprises one of: the passage of a time equal to an inverse of a frequency at which a maximum clipping-free acceleration level of the vibrational actuator is obtainable; or an estimated velocity of the vibrational actuator reaching a threshold velocity level or velocity peak, wherein the digital signal processor is further configured to calculate the estimated velocity based on one or more measured electrical parameters of the vibrational actuator.

In accordance with these and other embodiments of the present disclosure, a method includes receiving, by a digital signal processor, an input signal indicative of a force applied to a force sensor. The method also includes generating, by the digital signal processor, a haptic playback signal responsive to the input signal. The method further includes driving, with an amplifier communicatively coupled to the digital signal processor and integrated with the digital signal processor into an integrated haptic system, a vibrational actuator with the haptic playback signal as amplified by the amplifier. The method further comprises changing, by the digital signal processor, a polarity of the haptic playback signal responsive to a condition for changing the polarity of the haptic playback signal. The condition for changing the polarity of the haptic playback signal comprises one of: the passage of a time equal to an inverse of a frequency at which a maximum clipping-free acceleration level of the vibrational actuator is obtainable; or an estimated velocity of the vibrational actuator reaching a threshold velocity level or velocity peak, and the method comprises calculating the estimated velocity based on one or more measured electrical parameters of the vibrational actuator.

In accordance with these and other examples of the present disclosure, an article of manufacture may include a non-transitory computer-readable medium computer-executable instructions carried on the computer-readable medium, the instructions readable by a processor, the instructions, when read and executed, for causing the processor to receive an input signal indicative of a force applied to a force sensor and generate a haptic playback signal responsive to the input signal, such that an amplifier communicatively coupled to the processor and integrated with the digital signal processor into an integrated haptic system, amplifies and drives the haptic playback signal.

Technical advantages of the present disclosure may be readily apparent to one having ordinary skill in the art from the figures, description and claims included herein. The objects and advantages of the embodiments will be realized and achieved at least by the elements, features, and combinations particularly pointed out in the claims.

It is to be understood that both the foregoing general description and the following detailed description are examples and explanatory and are not restrictive of the claims set forth in this disclosure.

A more complete understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein:.

<FIG> illustrates a block diagram of selected components of an example mobile device <NUM>, in accordance with embodiments of the present disclosure. As shown in <FIG>, mobile device <NUM> may comprise an enclosure <NUM>, a controller <NUM>, a memory <NUM>, a force sensor <NUM>, a microphone <NUM>, a linear resonant actuator <NUM>, a radio transmitter/receiver <NUM>, a speaker <NUM>, and an integrated haptic system <NUM>.

Enclosure <NUM> may comprise any suitable housing, casing, or other enclosure for housing the various components of mobile device <NUM>. Enclosure <NUM> may be constructed from plastic, metal, and/or any other suitable materials. In addition, enclosure <NUM> may be adapted (e.g., sized and shaped) such that mobile device <NUM> is readily transported on a person of a user of mobile device <NUM>. Accordingly, mobile device <NUM> may include but is not limited to a smart phone, a tablet computing device, a handheld computing device, a personal digital assistant, a notebook computer, a video game controller, or any other device that may be readily transported on a person of a user of mobile device <NUM>.

Controller <NUM> may be housed within enclosure <NUM> and may include any system, device, or apparatus configured to interpret and/or execute program instructions and/or process data, and may include, without limitation a microprocessor, microcontroller, digital signal processor (DSP), application specific integrated circuit (ASIC), or any other digital or analog circuitry configured to interpret and/or execute program instructions and/or process data. In some embodiments, controller <NUM> interprets and/or executes program instructions and/or processes data stored in memory <NUM> and/or other computer-readable media accessible to controller <NUM>.

Memory <NUM> may be housed within enclosure <NUM>, may be communicatively coupled to controller <NUM>, and may include any system, device, or apparatus configured to retain program instructions and/or data for a period of time (e.g., computer-readable media). Memory <NUM> may include random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), a Personal Computer Memory Card International Association (PCMCIA) card, flash memory, magnetic storage, opto-magnetic storage, or any suitable selection and/or array of volatile or non-volatile memory that retains data after power to mobile device <NUM> is turned off.

Microphone <NUM> may be housed at least partially within enclosure <NUM>, may be communicatively coupled to controller <NUM>, and may comprise any system, device, or apparatus configured to convert sound incident at microphone <NUM> to an electrical signal that may be processed by controller <NUM>, wherein such sound is converted to an electrical signal using a diaphragm or membrane having an electrical capacitance that varies as based on sonic vibrations received at the diaphragm or membrane. Microphone <NUM> may include an electrostatic microphone, a condenser microphone, an electret microphone, a microelectromechanical systems (MEMs) microphone, or any other suitable capacitive microphone.

Radio transmitter/receiver <NUM> may be housed within enclosure <NUM>, may be communicatively coupled to controller <NUM>, and may include any system, device, or apparatus configured to, with the aid of an antenna, generate and transmit radio-frequency signals as well as receive radio-frequency signals and convert the information carried by such received signals into a form usable by controller <NUM>. Radio transmitter/receiver <NUM> may be configured to transmit and/or receive various types of radio-frequency signals, including without limitation, cellular communications (e.g., <NUM>, <NUM>, <NUM>, LTE, etc.), short-range wireless communications (e.g., BLUETOOTH), commercial radio signals, television signals, satellite radio signals (e.g., GPS), Wireless Fidelity, etc..

A speaker <NUM> may be housed at least partially within enclosure <NUM> or may be external to enclosure <NUM>, may be communicatively coupled to controller <NUM>, and may comprise any system, device, or apparatus configured to produce sound in response to electrical audio signal input. In some embodiments, a speaker may comprise a dynamic loudspeaker, which employs a lightweight diaphragm mechanically coupled to a rigid frame via a flexible suspension that constrains a voice coil to move axially through a cylindrical magnetic gap. When an electrical signal is applied to the voice coil, a magnetic field is created by the electric current in the voice coil, making it a variable electromagnet. The coil and the driver's magnetic system interact, generating a mechanical force that causes the coil (and thus, the attached cone) to move back and forth, thereby reproducing sound under the control of the applied electrical signal coming from the amplifier.

Force sensor <NUM> may be housed within enclosure <NUM>, and may include any suitable system, device, or apparatus for sensing a force, a pressure, or a touch (e.g., an interaction with a human finger) and generating an electrical or electronic signal in response to such force, pressure, or touch. In some embodiments, such electrical or electronic signal may be a function of a magnitude of the force, pressure, or touch applied to the force sensor. In these and other embodiments, such electronic or electrical signal may comprise a general purpose input/output signal (GPIO) associated with an input signal to which haptic feedback is given (e.g., a capacitive touch screen sensor or other capacitive sensor to which haptic feedback is provided). For purposes of clarity and exposition in this disclosure, the term "force" as used herein may refer not only to force, but to physical quantities indicative of force or analogous to force, such as, but not limited to, pressure and touch.

Linear resonant actuator <NUM> may be housed within enclosure <NUM>, and may include any suitable system, device, or apparatus for producing an oscillating mechanical force across a single axis. For example, in some embodiments, linear resonant actuator <NUM> may rely on an alternating current voltage to drive a voice coil pressed against a moving mass connected to a spring. When the voice coil is driven at the resonant frequency of the spring, linear resonant actuator <NUM> may vibrate with a perceptible force. Thus, linear resonant actuator <NUM> may be useful in haptic applications within a specific frequency range. While, for the purposes of clarity and exposition, this disclosure is described in relation to the use of linear resonant actuator <NUM>, it is understood that any other type or types of vibrational actuators (e.g., eccentric rotating mass actuators) may be used in lieu of or in addition to linear resonant actuator <NUM>. In addition, it is also understood that actuators arranged to produce an oscillating mechanical force across multiple axes may be used in lieu of or in addition to linear resonant actuator <NUM>. As described elsewhere in this disclosure, a linear resonant actuator <NUM>, based on a signal received from integrated haptic system <NUM>, may render haptic feedback to a user of mobile device <NUM> for at least one of mechanical button replacement and capacitive sensor feedback.

Integrated haptic system <NUM> may be housed within enclosure <NUM>, may be communicatively coupled to force sensor <NUM> and linear resonant actuator <NUM>, and may include any system, device, or apparatus configured to receive a signal from force sensor <NUM> indicative of a force applied to mobile device <NUM> (e.g., a force applied by a human finger to a virtual button of mobile device <NUM>) and generate an electronic signal for driving linear resonant actuator <NUM> in response to the force applied to mobile device <NUM>. Detail of an example integrated haptic system is depicted in <FIG>.

Although specific example components are depicted above in <FIG> as being integral to mobile device <NUM> (e.g., controller <NUM>, memory <NUM>, user interface <NUM>, microphone <NUM>, radio transmitter/receiver <NUM>, speakers(s) <NUM>), a mobile device <NUM> in accordance with this disclosure may comprise one or more components not specifically enumerated above. For example, although <FIG> depicts certain user interface components, mobile device <NUM> may include one or more other user interface components in addition to those depicted in <FIG>, (including but not limited to a keypad, a touch screen, and a display), thus allowing a user to interact with and/or otherwise manipulate mobile device <NUM> and its associated components.

<FIG> illustrates a block diagram of selected components of an example integrated haptic system 112A. In some examples, integrated haptic system 112A may be used to implement integrated haptic system <NUM> of <FIG>. As shown in <FIG>, integrated haptic system 112A may include a digital signal processor (DSP) <NUM>, a memory <NUM>, and an amplifier <NUM>.

DSP <NUM> may include any system, device, or apparatus configured to interpret and/or execute program instructions and/or process data. In some examples, DSP <NUM> may interpret and/or execute program instructions and/or process data stored in memory <NUM> and/or other computer-readable media accessible to DSP <NUM>.

Memory <NUM> may be communicatively coupled to DSP <NUM>, and may include any system, device, or apparatus configured to retain program instructions and/or data for a period of time (e.g., computer-readable media). Memory <NUM> may include random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), a Personal Computer Memory Card International Association (PCMCIA) card, flash memory, magnetic storage, opto-magnetic storage, or any suitable selection and/or array of volatile or non-volatile memory that retains data after power to mobile device <NUM> is turned off.

Amplifier <NUM> may be electrically coupled to DSP <NUM> and may comprise any suitable electronic system, device, or apparatus configured to increase the power of an input signal VIN (e.g., a time-varying voltage or current) to generate an output signal VOUT. For example, amplifier <NUM> may use electric power from a power supply (not explicitly shown) to increase the amplitude of a signal. Amplifier <NUM> may include any suitable amplifier class, including without limitation, a Class-D amplifier.

In operation, memory <NUM> may store one or more haptic playback waveforms. In some examples, each of the one or more haptic playback waveforms may define a haptic response a(t) as a desired acceleration of a linear resonant actuator (e.g., linear resonant actuator <NUM>) as a function of time. DSP <NUM> may be configured to receive a force signal VSENSE from force sensor <NUM> indicative of force applied to force sensor <NUM>. Either in response to receipt of force signal VSENSE indicating a sensed force or independently of such receipt, DSP <NUM> may retrieve a haptic playback waveform from memory <NUM> and process such haptic playback waveform to determine a processed haptic playback signal VIN. In examples in which amplifier <NUM> is a Class D amplifier, processed haptic playback signal VIN may comprise a pulse-width modulated signal. In response to receipt of force signal VSENSE indicating a sensed force, DSP <NUM> may cause processed haptic playback signal VIN to be output to amplifier <NUM>, and amplifier <NUM> may amplify processed haptic playback signal VIN to generate a haptic output signal VOUT for driving linear resonant actuator <NUM>. Detail of an example processing system implemented by DSP <NUM> is depicted in <FIG>.

In some examples, integrated haptic system 112A may be formed on a single integrated circuit, thus enabling lower latency than existing approaches to haptic feedback control. By providing integrated haptic system 112A as part of a single monolithic integrated circuit, latencies between various interfaces and system components of integrated haptic system 112A may be reduced or eliminated.

As shown in <FIG>, DSP <NUM> may receive diagnostic inputs from which processing system <NUM> may monitor and adjust operation of amplifier <NUM> in response thereto. For example, as discussed below with respect to <FIG>, DSP <NUM> may receive measurements from linear resonant actuator <NUM> to estimate the vibrational transfer function of linear resonant actuator <NUM>. However, in some examples, DSP <NUM> may receive and monitor one or more other diagnostic inputs, and DSP <NUM> may control operation of amplifier <NUM> in response thereto. For example, in some examples, DSP <NUM> may monitor a current level associated with linear resonant actuator <NUM> and/or a voltage level associated with linear resonant actuator <NUM>. From such measurements, DSP <NUM> may be able to infer or calculate a status (e.g., status of motion) of linear resonant actuator <NUM>. For example, from a monitored voltage and current, DSP <NUM> may be able to employ a mathematical model of linear resonant actuator <NUM> to estimate a displacement, velocity, and/or acceleration of linear resonant actuator <NUM>. As another example, DSP <NUM> may inject a high-frequency signal into linear resonant actuator <NUM> and infer an inductance of linear resonant actuator <NUM> based on the current and/or voltage responses of linear resonant actuator <NUM> to the injected signal. From the inductance, DSP <NUM> may be able to estimate a displacement of linear resonant actuator <NUM>. Based on determined status information (e.g., displacement, velocity, and/or acceleration), DSP <NUM> may control processed haptic playback signal VIN for any suitable purpose, including protecting linear resonant actuator <NUM> from over-excursion that could lead to damage to linear resonant actuator <NUM> or other components of mobile device <NUM>. As yet another example, one or more diagnostic inputs may be monitored to determine an operational drift of linear resonant actuator <NUM>, and DSP <NUM> may control amplifier <NUM> and/or processed haptic playback signal VIN in order to account for the operational drift. As a further example, one or more diagnostic inputs may be monitored to determine temperature effects of linear resonant actuator <NUM> (e.g., thermally induced changes in the performance of linear resonant actuator <NUM>), and DSP <NUM> may control amplifier <NUM> and/or processed haptic playback signal VIN in order to account for the temperature effects.

<FIG> illustrates a block diagram of selected components of an example processing system <NUM> implemented by DSP <NUM>. As shown in <FIG>, processing system <NUM> may include vibrational pulse processing <NUM>, regulated inversion <NUM>, click-driving pulse processing <NUM>, a comparator <NUM>, and vibrational transfer function estimation <NUM>. In operation, vibrational pulse processing <NUM> may receive a haptic playback waveform a(t) (or relevant parameters of such a waveform such as frequency and duration) and process such waveform to generate an intermediate signal a<NUM>(t). Processing performed by vibrational pulse processing <NUM> may include, without limitation, filtering (e.g., band-pass filtering) for frequency bands of interest, equalization of haptic playback waveform a(t) to obtain a desired spectral shape, and/or temporal truncation or extrapolation of haptic playback waveform a(t). By adjusting or tuning the temporal duration and frequency envelope of haptic playback waveform a(t), various haptic feelings as perceived by a user and/or audibility of the haptic response may be achieved.

Regulated inversion <NUM> may apply an inverse transfer function ITF to intermediate signal a<NUM>(t), either in the frequency domain or equivalently in the time domain through inverse filtering. Such inverse transfer function ITF may be generated from vibrational transfer function estimation <NUM> based on actual vibrational measurements of linear resonant actuator <NUM> and/or model parameters of linear resonant actuator <NUM>. Inverse transfer function ITF may be the inverse of a transfer function that correlates output voltage signal VOUT to actual acceleration of linear resonant actuator <NUM>. By applying inverse transfer function ITF to intermediate signal a<NUM>(t), regulated inversion <NUM> may generate an inverted vibration signal VINT in order to apply inversion to specific target vibrational click pulses to obtain an approximation of certain desired haptic click signals to drive the vibrational actuators for the generation of haptic clicks. In examples in which inverse transfer function ITF is calculated based on measurements of linear resonant actuator <NUM>, processing system <NUM> may implement a closed-loop feedback system for generating output signal VOUT, such that processing system <NUM> may track vibrational characteristics of linear resonant actuator <NUM> over the lifetime of linear resonant actuator <NUM> to enable more accurate control of the haptic response generated by integrated haptic system 112A.

In some examples, processing system <NUM> may not employ an adaptive inverse transfer function ITF, and instead apply a fixed inverse transfer function ITF. In yet other examples, the haptic playback waveforms a(t) stored in memory <NUM> may already include waveforms already adjusted by a fixed inverse transfer function ITF, in which case processing system <NUM> may not include blocks <NUM> and <NUM>, and haptic playback waveforms a(t) may be fed directly to click-driving pulse processing block <NUM>.

Click-driving pulse processing <NUM> may receive inverted vibration signal VINT and control resonant tail suppression of inverted vibration signal VINT in order to generate processed haptic playback signal VIN. Processing performed by click-driving pulse processing <NUM> may include, without limitation, truncation of inverted vibration signal VINT, minimum phase component extraction for inverted vibration signal VINT, and/or filtering to control audibility of haptic playback signal VIN.

Comparator <NUM> may compare a digitized version of force signal VSENSE to a signal threshold VTH related to a threshold force, and responsive to force signal VSENSE exceeding signal threshold VTH, may enable haptic playback signal VIN to be communicated to amplifier <NUM>, such that amplifier <NUM> may amplify haptic playback signal VIN to generate output signal VOUT.

Although <FIG> depicts comparator <NUM> as a simple analog comparator, in some examples, comparator <NUM> may include more detailed logic and/or comparison than shown in <FIG>, with the enable signal ENABLE output by comparator <NUM> depending on one or more factors, parameters, and/or measurements in addition to or in lieu of comparison to a threshold force level.

In addition, although <FIG> depicts enable signal ENABLE being communicated to click-driving pulse processing <NUM> and selectively enabling/disabling haptic playback signal VIN, in other examples, ENABLE signal ENABLE may be communicated to another component of processing system <NUM> (e.g., vibrational pulse processing <NUM>) in order to enable, disable, or otherwise condition an output of such other component.

<FIG> illustrates a block diagram of selected components of an example integrated haptic system 112B, in accordance with embodiments of the present disclosure. In some embodiments, integrated haptic system 112B may be used to implement integrated haptic system <NUM> of <FIG>. As shown in <FIG>, integrated haptic system 112B may include a digital signal processor (DSP) <NUM>, an amplifier <NUM>, an analog-to-digital converter (ADC) <NUM>, and an ADC <NUM>.

DSP <NUM> may include any system, device, or apparatus configured to interpret and/or execute program instructions and/or process data. In some embodiments, DSP <NUM> may interpret and/or execute program instructions and/or process data stored in a memory and/or other computer-readable media accessible to DSP <NUM>. As shown in <FIG>, DSP <NUM> may implement a prototype tonal signal generator <NUM>, nonlinear shaping block <NUM>, a smoothing block <NUM>, and a velocity estimator <NUM>.

Prototype tonal signal generator <NUM> may be configured to generate a tonal driving signal a(t) at or near a resonance frequency f<NUM> of linear resonant actuator <NUM>, and monitors an estimated velocity signal VEL generated by velocity estimator <NUM> to determine an occurrence of a predefined threshold level for estimated velocity signal VEL or for an occurrence of a peak of estimated velocity signal VEL. At the occurrence of the predefined threshold level or peak, prototype tonal signal generator <NUM> may then cause a change of polarity of driving signal a(t), which in turn may cause a moving mass of linear resonant actuator <NUM> to experience a sudden change in velocity, creating a large acceleration in linear resonant actuator <NUM>, resulting in a sharp haptic feeling. Driving signal a(t) generated by prototype tonal signal generator <NUM> may be followed by nonlinear shaping block <NUM> that shapes the waveform driving signal a(t) for a more efficient utilization of a driving voltage, and may be further smoothed by smoothing block <NUM> to generate input voltage VIN.

Velocity estimator <NUM> may be configured to, based on a measured voltage VMON of linear resonant actuator <NUM>, a measured current IMON of linear resonant actuator <NUM>, and known characteristics of linear resonant actuator <NUM> (e.g., modeling of a velocity of linear resonant actuator <NUM> as a function of voltage and current of linear resonant actuator <NUM>), calculate an estimated velocity VEL of linear resonant actuator <NUM>. In some embodiments, one or more other measurements or characteristics associated with linear resonant actuator <NUM> (e.g., inductance) may be used in addition to or in lieu of a measured voltage and measured current in order to calculate estimated velocity VEL.

Amplifier <NUM> may be electrically coupled to DSP <NUM> and may comprise any suitable electronic system, device, or apparatus configured to increase the power of an input signal VIN (e.g., a time-varying voltage or current) to generate an output signal VOUT. For example, amplifier <NUM> may use electric power from a power supply (e.g., a boost power supply, not explicitly shown) to increase the amplitude of a signal. Amplifier <NUM> may include any suitable amplifier class, including without limitation, a Class-D amplifier.

ADC <NUM> may comprise any suitable system, device, or apparatus configured to convert an analog voltage associated with linear resonant actuator <NUM> into a digitally equivalent measured voltage signal VMON. Similarly, ADC <NUM> may comprise any suitable system, device, or apparatus configured to convert an analog voltage across sense resistor <NUM> (having a voltage indicative of an analog current associated with linear resonant actuator <NUM>) into a digitally equivalent measured voltage signal IMON.

In some embodiments, integrated haptic system 112B may be formed on a single integrated circuit, thus enabling lower latency than existing approaches to haptic feedback control.

<FIG> illustrates a graph depicting example waveforms of haptic driving signals that may be generated, in accordance with embodiments of the present disclosure. For example, as shown in <FIG>, prototype tonal signal generator <NUM> may generate a tonal acceleration signal a(t) which begins at resonant frequency f<NUM> and ends at a higher frequency with an average frequency f<NUM> shown in <FIG>. Such average frequency f<NUM> may be chosen to be a frequency of tone that achieved a maximum acceleration level that avoids clipping of output voltage VOUT. To illustrate, the maximum achievable vibration of linear resonant actuator <NUM>, in terms of acceleration, may be restricted. As an example, linear resonant actuator <NUM> may be subject to an excursion limit, which defines a maximum displacement (e.g., in both a positive and negative direction) that a moving mass of linear resonant actuator <NUM> may displace without contacting non-moving parts of a device including linear resonant actuator <NUM> or otherwise causing audible buzzing and/or rattling distortions.

<FIG> illustrates a graph depicting an example transfer function of displacement of linear resonant actuator <NUM> as a function of frequency (x(f)) at a voltage level equal to a maximum static excursion xMAX occurring at low frequencies, in accordance with embodiments of the present disclosure. It is apparent from the graph of <FIG> that linear resonant actuator <NUM> may not be able to tolerate such a voltage level, because at resonance frequency f<NUM>, the excursion x(f) it generates will be over static excursion limit xMAX and therefore cause clipping. In that sense, static excursion limit xMAX may be considered the "clipping-free" excursion limit.

<FIG> illustrates a graph depicting an example transfer function of acceleration of linear resonant actuator <NUM> as a function of frequency (a(f)) and a maximum acceleration aMAX at maximum excursion xMAX, in accordance with embodiments of the present disclosure. In many respects, <FIG> is a translation of <FIG> from the displacement domain to the acceleration domain. From <FIG>, it is seen that, below a certain frequency f<NUM>, the maximum acceleration level linear resonant actuator <NUM> may generate may be restricted by the clipping-free excursion limit, and not by a voltage of amplifier <NUM>. This means that below the certain frequency f<NUM>, linear resonant actuator <NUM> needs to be driven at an attenuated voltage level. On the other hand, for such a maximum voltage level that nearly reaches a maximum excursion limit xMAX without clipping, the maximum achievable clipping-free acceleration level aMAX is achievable not at a resonance frequency f<NUM>, but at a chosen frequency f<NUM>, which is above resonance.

Such chosen frequency f<NUM> may provide a good choice of initialization for the design of haptic clicks and for the timing (e.g., a passage of time T1, as shown in <FIG>) of the change in polarity of the acceleration signal a(t) to achieve an acceleration peak. However, in addition to the specific example of a very short pulse described above, other examples of waveforms with longer cycles may be used, as well as other logics to determine a passage of time T1 (e.g., time T1) for changing polarity of the acceleration signal a(t), the effect of which is to force the moving mass to rapidly change velocity and generate a large acceleration peak. The larger the change rate of velocity, the higher the acceleration peak linear resonant actuator <NUM> may create.

<FIG> illustrates a block diagram of selected components of another example integrated haptic system 112C. In some examples, integrated haptic system 112C may be used to implement integrated haptic system <NUM> of <FIG>. As shown in <FIG>, integrated haptic system 112C may include a detector <NUM> and an amplifier <NUM>.

Detector <NUM> may include any system, device, or apparatus configured to detect a signal (e.g., VSENSE) indicative of a force. In some examples, such signal may be a signal generated by a force sensor. In other examples, such signal may comprise a GPIO signal indicative of a force applied to a force sensor. In some examples, detector <NUM> may simply detect whether GPIO signal is asserted or deasserted. In other examples, signal VSENSE may indicate a magnitude of force applied and may apply logic (e.g., analog-to-digital conversion where signal VSENSE is analog, comparison to a threshold force level, and/or logic associated with other measurements or parameters). In any event, responsive to signal VSENSE indicating a requisite force, detector <NUM> may enable amplifier <NUM> (e.g., by enabling its power supply or power supply boost mode) such that amplifier <NUM> may amplify haptic playback signal VIN (which may be generated by a component internal to or external to integrated haptic system 112C) to generate output signal VOUT. Accordingly, amplifier <NUM> may be maintained in a low-power or inactive state until a requisite input signal is received by integrated haptic system 112C, at which amplifier may be powered up or effectively switched on. Allowing for amplifier <NUM> to be kept in a low-power or inactive state until a requisite input is received may result in a considerable reduction in power consumption of a circuit, and enable "always-on" functionality for a device incorporating integrated haptic system 112C.

In alternative examples, detector <NUM> may be configured to, responsive to a requisite signal VSENSE, enable haptic playback signal VIN to be communicated to amplifier <NUM>, such that amplifier <NUM> may amplify haptic playback signal VIN to generate output signal VOUT.

In some examples, all or a portion of detector <NUM> may be implemented by a DSP.

Amplifier <NUM> may be electrically coupled to detector <NUM> and may comprise any suitable electronic system, device, or apparatus configured to increase the power of an input signal VIN (e.g., a time-varying voltage or current) to generate an output signal VOUT. For example, amplifier <NUM> may use electric power from a power supply (not explicitly shown) to increase the amplitude of a signal. Amplifier <NUM> may include any suitable amplifier class, including without limitation, a Class-D amplifier.

In some examples, integrated haptic system 112C may be formed on a single integrated circuit, thus enabling lower latency than existing approaches to haptic feedback control.

<FIG> illustrates a block diagram of selected components of an example integrated haptic system 112D. In some examples, integrated haptic system 112D may be used to implement integrated haptic system <NUM> of <FIG>. As shown in <FIG>, integrated haptic system 112D may include a digital signal processor (DSP) <NUM>, an amplifier <NUM>, and an applications processor interface <NUM>.

DSP <NUM> may include any system, device, or apparatus configured to interpret and/or execute program instructions and/or process data. In some examples, DSP <NUM> may interpret and/or execute program instructions and/or process data stored in a memory and/or other computer-readable media accessible to DSP <NUM>.

Applications processor interface <NUM> may be communicatively coupled to DSP <NUM> and an applications processor (e.g., controller <NUM> of <FIG>) external to integrated haptic system 112D. Accordingly, applications processor interface <NUM> may enable communication between integrated haptic system 112D and an application executing on an applications processor.

In some examples, integrated haptic system 112D may be formed on a single integrated circuit, thus enabling lower latency than existing approaches to haptic feedback control.

In operation, DSP <NUM> may be configured to receive a force signal VSENSE from force sensor <NUM> indicative of force applied to force sensor <NUM>. In response to receipt of force signal VSENSE indicating a sensed force, DSP <NUM> may generate a haptic playback signal VIN and communicate haptic playback signal VIN to amplifier <NUM>. In addition, in response to the receipt of force signal VSENSE indicating a sensed force, DSP <NUM> may communicate an activity notification to an appropriate applications processor via applications processor interface <NUM>. DSP <NUM> may further be configured to receive communications from an applications processor via applications processor interface <NUM> and generate (in addition to and in lieu of generation responsive to receipt of force signal VSENSE) haptic playback signal VIN and communicate haptic playback signal VIN to amplifier <NUM>.

As the output for an initial haptic feedback response can be generated by the integrated haptic system 112D, integrated haptic system 112D may be configured to provide a low-latency response time for the generation of immediate haptic feedback. Subsequent to the initial feedback being generated, the control of additional haptic feedback signals may be determined by a separate applications processor arranged to interface with integrated haptic system 112D. By offloading the control of subsequent haptic driver signals to a separate applications processor, integrated haptic system 112D may be optimized for low-power, low-latency performance, to generate the initial haptic feedback response. The initial output signal VOUT may be provided at a relatively low resolution, resulting in the generation of a relatively simplified haptic feedback response. For example, the initial output signal VOUT may be provided as a globalized feedback response. Subsequent to the initial response, the applications processor may be used to generate more detailed haptic feedback outputs, for example providing for localized haptic feedback responses, which may require increased processing resources when compared with the relatively straightforward generation of a globalized haptic feedback response.

As another example, in an effort to minimize the power consumption of mobile device <NUM> for always-on operation, the integrated haptic system 112D may be configured to monitor a single input from a single force-sensing transducer (e.g., force sensor <NUM>) to detect a user input. However, once an initial user input has been detected, the power and resources of an applications processor may be used to provide more detailed signal analysis and response. The applications processor may be configured to receive input signals from multiple force-sensing transducers, and/or to generate output signals for multiple haptic transducers.

<FIG> illustrates a block diagram of selected components of an example integrated haptic system 112Elosure. In some examples, integrated haptic system 112E may be used to implement integrated haptic system <NUM> of <FIG>. As shown in <FIG>, integrated haptic system 112E may include a digital signal processor (DSP) <NUM>, an amplifier <NUM>, and a signal combiner <NUM>.

Amplifier <NUM> may be electrically coupled to DSP <NUM> (e.g., via signal combiner <NUM>) and may comprise any suitable electronic system, device, or apparatus configured to increase the power of an input signal VIN (e.g., a time-varying voltage or current) to generate an output signal VOUT. For example, amplifier <NUM> may use electric power from a power supply (not explicitly shown) to increase the amplitude of a signal. Amplifier <NUM> may include any suitable amplifier class, including without limitation, a Class-D amplifier.

Signal combiner <NUM> may be interfaced between DSP <NUM> and amplifier <NUM> and may comprise any system, device, or apparatus configured to combine a signal generated by DSP <NUM> and a vibration alert signal received from a component external to integrated haptic system 112E.

In some examples, integrated haptic system 112E may be formed on a single integrated circuit, thus enabling lower latency than existing approaches to haptic feedback control.

In operation, DSP <NUM> may be configured to receive a force signal VSENSE from force sensor <NUM> indicative of force applied to force sensor <NUM>. In response to receipt of force signal VSENSE indicating a sensed force, DSP <NUM> may generate an intermediate haptic playback signal VINT. Signal combiner <NUM> may receive intermediate haptic playback signal VINT and mix intermediate haptic playback signal VINT with another signal (e.g., the vibration alert signal) received by integrated haptic system 112E to generate a haptic playback signal VIN and communicate haptic playback signal VIN to amplifier <NUM>. Accordingly, a haptic signal generated responsive to a force (e.g., intermediate haptic playback signal VINT) may be mixed with a further signal (e.g., the vibration alert signal), to provide a composite signal (e.g., haptic playback signal VIN) for linear resonant actuator <NUM>. For example, the signal to generate a pure haptic feedback response may be mixed with a signal used to generate a vibratory notification or alert, for example as notification of an incoming call or message. Such mixing would allow for a user to determine that an alert has been received at the same time as feeling a haptic feedback response. As shown in <FIG>, signal combiner <NUM> may perform mixing on an input signal used as input to the amplifier <NUM>. However, in other examples, a signal combiner may perform mixing on an output signal for driving linear resonant actuator <NUM>.

<FIG> illustrates a block diagram of selected components of an example integrated haptic system 112F. In some examples, integrated haptic system 112F may be used to implement integrated haptic system <NUM> of <FIG>. As shown in <FIG>, integrated haptic system 112F may include a digital signal processor (DSP) <NUM>, a detector <NUM>, an amplifier <NUM>, a sampling control <NUM>, and a sensor bias generator <NUM>.

Detector <NUM> may include any system, device, or apparatus configured to detect a signal (e.g., VSENSE) indicative of a force. In some examples, such signal may be a signal generated by a force sensor. In other embodiments, such signal may comprise a GPIO signal indicative of a force applied to a force sensor. In some examples, detector <NUM> may simply detect whether GPIO signal is asserted or deasserted. In other examples, signal VSENSE may indicate a magnitude of force applied and may apply logic (e.g., analog-to-digital conversion where signal VSENSE is analog, comparison to a threshold force level, and/or logic associated with other measurements or parameters). In any event, responsive to signal VSENSE indicating a requisite force, detector <NUM> may communicate one or more signals to DSP <NUM> indicative of signal VSENSE. In some examples, all or a portion of detector <NUM> may be implemented by DSP <NUM>.

Sampling control <NUM> may be communicatively coupled to DSP <NUM> and may comprise any suitable electronic system, device, or apparatus configured to selectively enable force sensor <NUM> and/or components of integrated haptic system 112F, as described in greater detail below.

Sensor bias <NUM> may be communicatively coupled to sampling control <NUM> and may comprise any suitable electronic system, device, or apparatus configured to generate an electric bias (e.g., bias voltage or bias current) for force sensor <NUM>, as described in greater detail below.

In some examples, integrated haptic system 112F may be formed on a single integrated circuit, thus enabling lower latency than existing approaches to haptic feedback control.

In operation, DSP <NUM>/detector <NUM> may be configured to receive a force signal VSENSE from force sensor <NUM> indicative of force applied to force sensor <NUM>. In response to receipt of force signal VSENSE indicating a sensed force, DSP <NUM> may generate a haptic playback signal VIN and communicate haptic playback signal VIN to amplifier <NUM>, which is amplified by amplifier <NUM> to generate output voltage VOUT.

In addition, DSP <NUM> may be configured to receive one or more timer signals (either from timing signals generated within integrated haptic system 112F or external to integrated haptic system 112F) and based thereon, generate signals to sampling control <NUM>. In turn, sampling control <NUM> may selectively enable and disable one or more components of an input path of integrated haptic system 112F, including without limitation detector <NUM>, force sensor <NUM>, a data interface of integrated haptic system 112F, a switch matrix of integrated haptic system 112F, an input amplifier of integrated haptic system 112F, and/or an analog-to-digital converter of integrated haptic system 112F. As shown in <FIG>, sampling control <NUM> may selectively enable and disable force sensor <NUM> by controlling an electrical bias for force sensor <NUM> generated by sensor bias <NUM>. As a result, DSP <NUM> and sampling control <NUM> may duty cycle durations of time in which force sensor <NUM>, detector <NUM>, and/or other components of integrated haptic system 112F are active, potentially reducing power consumption of a system comprising integrated haptic system 112F.

Although the foregoing figures and descriptions thereof address integrated haptic systems 112A-112F as being representative of particular examples, is it understood that all or a portion of one or more of integrated haptic systems 112A-112F may be combined with all or a portion of another of integrated haptic systems 112A-112F, as suitable.

In addition, in many of the figures above, a DSP is shown generating a haptic playback signal VIN which may be amplified by an amplifier to generate an output voltage VOUT. For purposes of clarity and exposition, digital-to-analog conversion of signals in the output signal path of integrated haptic systems 112A-112F have been omitted from the drawings, but it is understood that digital-to-analog converters may be present in integrated haptic systems 112A-112F to perform any necessary conversions from a digital domain to an analog domain.

This disclosure encompasses all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend.

Claim 1:
An integrated haptic system (<NUM>) comprising:
a digital signal processor (<NUM>; <NUM>; <NUM>; <NUM>; <NUM>) configured to:
receive an input signal indicative of a force applied to a force sensor (<NUM>); and
generate a haptic playback signal responsive to the input signal; and
an amplifier (<NUM>; <NUM>; <NUM>; <NUM>; <NUM>) communicatively coupled to the digital signal processor, integrated with the digital signal processor into the integrated haptic system, and configured to amplify the haptic playback signal for driving a vibrational actuator (<NUM>) with the haptic playback signal as amplified by the amplifier;
wherein the digital signal processor is further configured to, responsive to a condition for changing a polarity of the haptic playback signal, change the polarity of the haptic playback signal, characterized in that the condition for changing the polarity of the haptic playback signal comprises one of:
the passage of a time equal to an inverse of a frequency of the haptic playback signal for which a maximum clipping-free acceleration level of the vibrational actuator (<NUM>) is obtainable; or
an estimated velocity of the vibrational actuator (<NUM>) reaching a threshold velocity level or velocity peak, wherein the digital signal processor is further configured to calculate the estimated velocity based on one or more measured electrical parameters of the vibrational actuator.