阅读说明：本技术 线性谐振致动器控制器 (Linear resonant actuator controller ) 是由 克里斯托弗·马克·马库斯 于 2017-11-01 设计创作，主要内容包括：本发明描述了一种用于具有线性谐振致动器的移动装置的线性谐振致动器控制器。所述线性谐振致动器控制器包括控制器输出端,所述控制器输出端被配置成耦合到线性谐振致动器；音频处理器,所述音频处理器具有音频处理器输入端和音频处理器输出端,所述音频处理器输出端耦合到所述控制器输出端。所述音频处理器被配置成接收包括语音的音频信号,通过使所述线性谐振致动器的谐振频率下的音频信号频率分量相对于至少一些其它音频信号频率分量衰减来处理所述音频信号,并且在所述音频处理器输出端上输出所述处理后的音频信号。(A linear resonant actuator controller for a mobile device having a linear resonant actuator is described. The linear resonant actuator controller comprises a controller output configured to be coupled to a linear resonant actuator; an audio processor having an audio processor input and an audio processor output, the audio processor output coupled to the controller output. The audio processor is configured to receive an audio signal comprising speech, process the audio signal by attenuating audio signal frequency components at a resonant frequency of the linear resonant actuator relative to at least some other audio signal frequency components, and output the processed audio signal on the audio processor output.)

1. A linear resonant actuator controller for a mobile device having a linear resonant actuator, the linear resonant actuator controller comprising:

a controller output configured to be coupled to the linear resonant actuator;

an audio processor having an audio processor input and an audio processor output, the audio processor output coupled to the controller output;

wherein the audio processor is configured to receive an audio signal comprising speech, process the audio signal by attenuating audio signal frequency components at a resonant frequency of the linear resonant actuator relative to at least some other audio signal frequency components, and output the processed audio signal on the audio processor output.

2. The linear resonant actuator controller of claim 1, further comprising a haptic driver having a haptic driver input and a haptic driver output; wherein the linear resonant actuator controller is further configured to:

in a first mode, coupling the haptic driver output to the controller output,

in a second mode, the audio processor output is coupled to the controller output.

3. The linear resonance actuator controller of claim 1, wherein the audio processor is configured to equalize and compress the audio signal prior to outputting the audio signal on the audio processor output.

4. The linear resonance actuator controller of claim 1, further comprising another controller output configured to be coupled to one of a receiver speaker and a piezoelectric transducer, wherein the audio processor comprises another audio processor output coupled to the other controller output, and wherein the audio processor is further configured to process the received audio signal and output another processed audio signal on the other audio processor output.

5. A linear resonant actuator controller according to claim 4, wherein the audio processor is configurable to generate a processed audio signal by applying a first equalization and compression to the audio signal and to generate another processed audio signal by applying a second equalization and compression to the audio signal.

6. The linear resonant actuator controller of claim 5, wherein the first equalization and compression comprises a low pass filter and the second equalization and compression comprises a high pass filter.

7. The linear resonant actuator controller of claim 1, wherein the audio processor further comprises:

a sensor input configured to receive a sensor signal comprising at least one of a user contact position value, a user distance value, and a user contact force value,

wherein the audio processor is further configured to adjust the audio signal processing in dependence on the sensor signal.

8. A mobile device comprising the linear resonant actuator controller of claim 1, and further comprising a linear resonant actuator coupled to the controller output.

9. A mobile device comprising the linear resonant actuator controller of claim 5, and further comprising a linear resonant actuator coupled to the controller output and one of a receiver speaker and a piezoelectric transducer coupled to the other controller output.

10. A mobile device comprising the linear resonant actuator controller of claim 7, and further comprising a linear resonant actuator coupled to the controller output and a touch screen coupled to the sensor input, wherein the touch screen is configured to provide a sensor signal comprising at least one of a use contact location value and a user contact force value in response to a user contact with the touch screen.

11. The mobile device of claim 8, wherein the linear resonant actuator has a Q factor greater than 15.

12. A method for controlling a mobile device including a linear resonant actuator, the method comprising:

processing an audio signal comprising speech for transmission by the linear resonant actuator by attenuating audio signal frequency components at a resonant frequency of the linear resonant actuator relative to at least some other audio signal frequency components.

13. The method of claim 12, further comprising processing the audio signal for transmission by a receiver speaker.

14. The method of claim 12, wherein processing the audio signal further comprises equalizing and compressing the audio signal.

15. The method of claim 14, wherein processing the audio signal further comprises:

applying a first equalization and compression to the audio signal prior to transmission by the linear resonant actuator,

applying a second equalization and compression to the audio signal prior to transmission by the receiver speaker,

wherein the first equalization comprises a low pass filtering operation and the second equalization comprises a high pass filtering operation.

Technical Field

The present disclosure relates to a linear resonant actuator controller for a mobile device.

Background

The increasing adoption of broadband voice for mobile communications places new acoustic demands on mobile phones and other mobile devices. In handset call mode, for example for 3G mobile phones, the required receive sensitivity frequency response is determined by ETSI third generation partnership project (3GPP) (3GPP TS 26.131 release 8.3.0 release 8, month 4 2011). Mobile phones and audio processing receivers or headset speakers are often designed to meet these requirements.

Disclosure of Invention

Various aspects of the disclosure are defined in the appended claims. In a first aspect, there is defined a linear resonant actuator controller for a mobile device having a linear resonant actuator and a handset call mode, the linear resonant actuator controller comprising: a controller output configured to be coupled to a linear resonant actuator; an audio processor having an audio processor input and an audio processor output, the audio processor output coupled to the controller output; wherein the audio processor is configured to receive an audio signal comprising speech, to process the audio signal by attenuating audio signal frequency components at a resonant frequency of the linear resonant actuator relative to at least some other audio signal frequency components, and to output the processed audio signal on the audio processor output.

In an embodiment, the linear resonant actuator controller may further comprise a haptic driver having a haptic driver input and a haptic driver output; wherein the linear resonant actuator controller is further configured to: in a first mode, coupling the haptic driver output to the controller output; in a second mode, the audio processor output is coupled to the controller output.

In embodiments of the linear resonant actuator controller, the audio processor may be configured to equalize and compress the audio signal prior to output onto the audio processor output.

In an embodiment, the linear resonant actuator controller may further comprise a further controller output configured to be coupled to one of the receiver speaker and the piezoelectric transducer, wherein the audio processor comprises a further audio processor output coupled to the further controller output, and wherein the audio processor is further configured to process the received audio signal and to output a further processed audio signal on the further audio processor output.

In embodiments of the linear resonance actuator controller, the audio processor may be configured to generate a processed audio signal by applying a first equalization and compression to the audio signal, and to generate another processed audio signal by applying a second equalization and compression to the audio signal.

In an embodiment, the first equalization and compression may include a low pass filter and the second equalization and compression may include a high pass filter.

In an embodiment, the audio processor may further comprise: a sensor input configured to receive a sensor input signal, the sensor input signal comprising at least one of a user contact location value, a user distance value, and a user contact force value, wherein the audio processor is further configured to adjust the audio signal processing in dependence on the sensor input signal.

Embodiments of a linear resonant actuator controller may be included in a mobile device that includes a linear resonant actuator coupled to a controller output.

In an embodiment, the mobile device may further comprise a linear resonant actuator coupled to the controller output and one of a receiver speaker and a piezoelectric transducer coupled to the other controller output.

In an embodiment, a mobile device may include a linear resonant actuator controller, and further include a linear resonant actuator coupled to the controller output, and a touch screen coupled to a sensor input of the linear resonant actuator controller, wherein the touch screen is configured to provide a sensor input signal in response to a user contacting the touch screen, the sensor input signal including at least one of a user contact location value and a user contact force value.

The linear resonant actuator may have a Q factor greater than 15.

In a second aspect, a method for controlling a mobile device including a linear resonant actuator is described, the method comprising: an audio signal comprising speech is processed for transmission by the linear resonant actuator by attenuating audio signal frequency components at a resonant frequency of the linear resonant actuator relative to at least some other audio signal frequency components.

In an embodiment, the audio signal may be processed for transmission by a receiver speaker.

In an embodiment, the audio signal may be processed by equalizing and compressing the audio signal.

In an embodiment, the audio signal may be processed by applying a first equalization and compression to the speech signal prior to transmission with the linear resonant actuator, and a second equalization and compression to the speech signal prior to transmission with the receiver speaker, wherein the first equalization comprises a low pass filtering operation, and the second equalization comprises a high pass filtering operation.

In a third aspect, a computer program product is described, comprising instructions which, when executed with a processing unit, cause the processing unit to perform the step of processing an audio signal comprising speech for transmission by a linear resonant actuator by attenuating audio signal frequency components at a resonant frequency of the linear resonant actuator relative to at least some other audio signal frequency components.

Drawings

In the drawings and description, like reference numerals refer to like elements. Embodiments will now be described in detail, by way of example only, illustrated by the accompanying drawings, in which:

FIG. 1 illustrates a linear resonant actuator controller according to an embodiment.

FIG. 2 illustrates a linear resonant actuator controller according to an embodiment.

FIG. 3 illustrates a linear resonant actuator controller according to an embodiment.

Figure 4 illustrates a mobile phone including a linear resonant actuator controller, a receiver speaker, and a linear resonant actuator, according to one embodiment.

Fig. 5 shows a graph of a specified receive mask for wideband speech according to ETSI 3GPP TS 26.131 V8.3.0.

Fig. 6 shows HATS receiver frequency responses of example smartphones for different levels of acoustic leakage.

Fig. 7 shows the HATS frequency response of a closed-box speaker used as a receiver.

Fig. 8 shows a plot of the LRA 208 versus a modified frequency response for the receiver speaker of the mobile phone of fig. 4.

FIG. 9 illustrates a linear resonant actuator controller according to an embodiment.

Fig. 10 illustrates a smartphone including a linear resonant actuator controller, a receiver speaker, a linear resonant actuator, and a touch sensitive screen, in accordance with an embodiment.

Fig. 11 illustrates a method of controlling a linear resonant actuator in a mobile device according to an embodiment.

Fig. 12 illustrates a method of controlling a linear resonant actuator in a mobile device according to an embodiment.

Detailed Description

Fig. 1 shows a linear resonant actuator controller 100. The linear resonant actuator controller 100 includes a haptic driver 104, a switch module 108, an audio processor 110, and an audio amplifier 118. The haptic driver input 102 is connected to a haptic driver or amplifier 104. The output 106 of the haptic driver 104 is connected to a first input of a switch module 108. An audio input 112 is connected to the audio processor 110. The audio output 116 of the audio processor 110 may be connected to an audio amplifier 118, which audio amplifier 118 may be, for example, a class D amplifier. The output 120 of the audio amplifier 118 is connected to a second input of the switch module 108. The output of the switch module 108 is connected to the controller output 122 of the linear resonant actuator controller 100. A control input 114 of the audio processor 110 may be connected to a control input of the switch module 108.

In operation, the controller output 122 may be connected to the linear resonant actuator 124. Linear resonant actuators are often used as haptic motors for generating vibration alerts or more complex haptic patterns to enhance human device interaction. Recent mobile devices utilize an AC driven Linear Resonant Actuator (LRA) as opposed to a DC driven Eccentric Rotating Mass (ERM) motor, which can also be used as a haptic motor. Linear resonant actuators are capable of producing more complex haptic effects and can be driven in the same manner as loudspeakers. Linear resonant actuators are designed to resonate at a specific frequency, e.g., 200Hz, which is particularly suitable for haptic feedback, and typically has a high Q factor of 15 or more.

In a first mode of operation of the linear resonant actuator controller 100, which may be referred to as a haptic mode, the switch module 108 may be controlled by an external controller (not shown) via the switch control input 114 to connect the haptic driver output 106 to the controller output 122. In the first mode, the linear resonant actuator controller 100 can drive the linear resonant actuator as designed to act as a haptic motor for generating vibrations in, for example, a mobile phone. In a second mode of operation, which may be, for example, a handset mode in a mobile phone, audio amplifier output 120 may be connected to linear resonant actuator controller output 122 by controlling switch module 108. The audio processor 110 may apply equalization and/or compression to the audio signal received at the audio input 112 to attenuate signal frequencies at the peak resonant frequency of the LRA 124 relative to other frequency components to compensate for the peak resonant frequency. This may result in a more linear frequency response for the combination of the audio processor 110 and the LRA 124. By employing equalization to compensate for the resonance peak of the LRA, the LRA 124 may be used as, for example, a speaker, such as a receiver speaker in a mobile phone when operating in a handset mode of operation. In the handset mode of operation, the LRA or speaker may only be required to transmit voice over a relatively short range, e.g., less than 10 centimeters. The audio processor 110 may also enhance signal frequency components of the audio signal that are outside of the resonant frequency of the LRA 124.

The linear resonant actuator controller 100 may be implemented as a combination of hardware and software. For example, the audio processor 110 may be implemented as logic hardware or a digital signal processor running software. The haptic driver 104 and the audio amplifier 118 may be implemented in hardware. The switch module 108 may be implemented as a multiplexer or other logic. In some examples, the audio input 112 and the haptic driver input 102 may be commonly connected. In other examples, the LRA may be used as the sole speaker rather than its function as a haptic motor designed to generate vibrations. In this case, the switch and the haptic driver may be omitted.

Fig. 2 shows a linear resonant actuator controller 150. The linear resonant actuator controller 150 includes a haptic driver 154, a switch module 158, an audio processor 160, an audio amplifier 168, and a receiver speaker audio amplifier 174. The haptic driver input 152 is connected to a haptic driver or amplifier 154. The output 156 of the haptic driver 154 is connected to a first input of a switch module 158. An audio input 162 is connected to the audio processor 160. The first audio output 166 of the audio processor 160 may be connected to an audio amplifier 168, which audio amplifier 168 may be, for example, a class D amplifier. The output 170 of the audio amplifier 168 is connected to a second input of the switching module 158. The second audio output 167 of the audio processor 160 is connected to a receiver speaker audio amplifier 174, which receiver speaker audio amplifier 174 may be, for example, a class D amplifier. Another controller output 176 may be connected to the output of the receiver speaker audio amplifier 174.

An output of the switch module 158 may be connected to a controller output 172 of the linear actuator controller 150. A control output 164 of the audio processor 160 may be connected to a control input of the switch module 158.

In operation, the linear resonant actuator controller 150 may be connected to the linear resonant actuator 180 via the controller output 172. The linear resonant actuator controller 150 may be connected to a speaker 178 via another controller output or receiver speaker output 176. The speaker 178 may be, for example, a receiver speaker used in a mobile phone handset used during a voice call.

In a first mode of the linear haptic controller 150, which may be referred to as a haptic mode, the audio processor 160 may connect the haptic driver output 156 to the controller output 172 by controlling the switch module 158. In a first mode, the linear haptic controller 150 may drive the linear resonant actuator as designed to act as a haptic motor for generating vibrations, for example, in a mobile phone. In the second mode of operation, the audio processor 160 may connect the first audio amplifier output 170 to the controller output 172 by controlling the switch module 158. The audio processor 160 may apply a first equalization to the audio signal to compensate for the peak resonant frequency of the LRA 180 so that the combination of the audio processor 160 and the LRA 180 has a more linear frequency response. This may allow LRA 180 to be used as a speaker, for example.

In a separate audio path, the audio processor 160 may apply a second equalization to the audio signal prior to driving the connected receiver speaker 178.

The first equalization may be used to enhance lower frequencies, e.g., below 300 Hz. The second equalization may enhance frequencies above 300 Hz. By processing the audio signal with the combination of the LRA 180 and the receiver speaker 178, the quality of the audio signal (typically containing speech) can be improved when used in a mobile phone.

Alternatively or additionally, a first equalization may be applied to enable the LRA 180 to reproduce the entire audio spectrum, for example by increasing the gain of higher frequencies above 300 Hz.

Linear haptic controller 150 may be implemented as a combination of hardware and software. For example, the audio processor 160 may be implemented as logic hardware or a digital signal processor running software. The haptic driver 154, audio amplifier 168, and receiver amplifier 174 may be implemented in hardware. The switch module 158 may be implemented as a multiplexer or other logic.

Fig. 3 shows a linear actuator controller 200, the linear actuator controller 200 comprising an audio processor 210, a first audio amplifier 216 and a second audio amplifier 214. The audio processor 210 includes an LRA equalizer/dynamic range controller 206 and a speaker equalizer/dynamic range controller 204. The audio input 202 may be connected to inputs of both the LRA equalizer/dynamic range controller 206 and the speaker equalizer/dynamic range controller 204. The LRA equalizer/dynamic range controller 206 may have an output 208 connected to an LRA audio amplifier 216, which LRA audio amplifier 216 may be a class D audio amplifier. The output of the LRA audio amplifier 216 may be connected to an LRA controller output 218. The speaker equalizer/dynamic range controller 204 may have an output 212 connected to a speaker audio amplifier 214, which speaker audio amplifier 214 may be a class D audio amplifier. The output of the speaker audio amplifier 214 may be connected to a speaker controller output 222.

In operation, the LRA controller output 218 may be connected to the linear resonant actuator 220 and the speaker controller output may be connected to the receiver speaker 230.

An audio signal may be received on audio input 202 and split into two processing paths, one for LRA 220 and one for receiver speaker 230. An audio signal for LRA 220, referred to as an LRA signal, may be equalized and compressed by LRA equalizer/dynamic range controller 206. The LRA signal may be equalized and compressed to achieve a desired frequency response and to compensate 220 for strong resonance peaks. Equalization and compression may include attenuating some of the frequency components of the audio signal that occur at the resonant frequency of the LRA relative to other frequency components. Equalization and compression may include enhancing or amplifying frequency components of the audio signal at frequencies other than the resonant frequency. The audio signal received by the speaker equalizer/dynamic range controller 204 may be equalized and compressed to achieve a desired frequency response. Because the receiver speaker does not have a resonant peak, the speaker equalizer/dynamic range controller 204 may boost the signal frequency at the LRA resonant frequency to improve the low frequency response of the receiver speaker.

The equalization filters in LRA equalizer/dynamic range controller 206 and speaker equalizer/dynamic range controller 204 may be used as crossover filters such that LRA 220 may only reproduce low frequencies, e.g., below 300Hz, and receiver speaker 230 may only reproduce high frequencies, e.g., above 300 Hz. In some examples, the receiver speaker 230 may be replaced with another audio transducer, such as a piezoelectric audio transducer. In other examples, the speaker equalizer 204 and the speaker audio amplifier 214 may be omitted. In this case, the LRA may be used to reproduce all the required audio frequencies, and thus the receiver speaker may not be required.

Fig. 4 illustrates a mobile phone 250 according to an embodiment. The mobile phone 250 includes an LRA 258, a housing 260, a receiver speaker 264, and a linear resonant actuator controller 254. The linear resonant actuator controller 254 is shown outside the enclosure 260, but it should be understood that in general the linear resonant actuator controller 254 may be contained inside the enclosure 260, in addition to the receiver speaker 264 and the LRA 258. Audio input 252 may be connected to linear resonant actuator controller 254. The controller output 256 may be connected to a linear resonant actuator 258. The speaker output 262 may be connected to a receiver speaker 264.

In a first mode of operation (e.g., a haptic or vibration mode of mobile phone 250), linear resonant actuator controller 254 may drive LRA 258 to provide haptic feedback to user 268, the LRA 258 generating a vibration in housing 260. In a second or handset mode of operation of mobile phone 250, user 268 of mobile phone 250 typically places a handset having receiver speaker 264 near the ear. Linear resonant actuator controller 254 may process the audio signal received at audio input 252 by, for example, applying a first equalization prior to outputting the processed audio signal onto controller output 256. In the parallel audio signal path, linear resonant actuator controller 254 may process the audio signal by, for example, applying a second equalization prior to outputting the processed audio signal onto speaker output 262. A user 268 of the mobile phone 250 may experience audio via sound waves generated by the receiver speaker 264 being emitted via an acoustic receiver port or aperture 266 formed in the housing 260. A user 268 of the mobile phone 250 may experience audio due to vibrations in the handset housing 260 caused by operation of the linear resonant actuator 258. These vibration frequencies will typically be low frequencies in the frequency range below 300 Hz.

By reproducing speech using the combination of the receiver speaker 264 and the linear resonant actuator 258, the mobile telephone 250 can improve low frequency reproduction without overdriving the receiver speaker 264 and its corresponding amplifier (not shown). The intelligibility of speech heard by the user 268 may depend on how close the phone is to the ear. By using the linear resonant actuator 258 in conjunction with the receiver speaker 264, low frequency reproduction may be more stable with respect to acoustic leakage even when the phone 250 is not in physical contact with the ear of the user 268. Further, the speech may be audible even when the receiver port 266 is not positioned in front of the ear canal of the user 268.

In an alternative example, the linear resonant actuator 258 may be used as a complete replacement for the receiver speaker 264. In this example, the linear resonant actuator 258 may reproduce a wideband speech signal consisting of low frequencies below 300Hz and higher frequencies above 300 Hz. The inventors of the present disclosure have appreciated that the linear resonant actuator 258 can be used in this manner because at low frequencies, the linear resonant actuator 258 will induce vibrations on the handset housing 260. These vibrations enable the user 268 to hear sound waves, particularly when the mobile device 250 is proximate to the ear. However, at high frequencies, the linear resonant actuator or vibrator 258 itself may act as a sound source due to the moving mass in the linear resonant actuator, which linear resonant actuator or vibrator 258 then generates pressure field radiation through any acoustic port and any other acoustic leakage in the mobile phone housing 260. The inventors have further appreciated that linear resonant actuators specifically designed to produce vibrations at specific frequencies can also be used to reduce broadband speech in devices without acoustic speaker ports.

Fig. 5 shows the 3GPP TS 26.131 V8.3.0 release mask 8 for wideband speech 300. The x-axis 304 shows the frequency in hertz varying between 100Hz and 8kHz on a logarithmic scale. The y-axis 302 is in dB varying between-10 and +10 on a linear scale. The upper mask line 306 varies between +6dB at approximately 100Hz to +8dB at 8 KHz. The lower mask line 307 defines a lower limit that varies between-10 dB at approximately 200Hz to-6 dB at frequencies up to between 300Hz and 5KHz, and then decreases to-10 dB at 6 KHz. The receive mask 300 is a desired frequency response, and the receive mask 300 may be implemented using a well-designed receiver, also known as an earpiece speaker, that has a sufficiently low resonant frequency and low distortion or Total Harmonic Distortion (THD) level. The required frequency response mask also requires proper acoustic design that minimizes the effects of acoustic leakage on the acoustic response and a properly designed equalization filter.

Fig. 6 shows the response 310 of a typical receiver measuring different acoustic leakage values for a head and torso simulator (HATS) of a commercially available smartphone. The x-axis 314 varies on a logarithmic scale from a frequency of 100Hz to a frequency of 10 kHz. The y-axis 312 shows the change between values of-40 dB and +20dB in decibels (dB) on a linear scale. Graph 310 has an upper mask line 306 and a lower mask line 307. The response lines 316, 318, 320, 322 show the response of the telephone receiver with progressively looser acoustic coupling between the earpiece speaker and the user's ear, whereby the response line 316 has the tightest acoustic coupling and the response line 322 has the loosest acoustic coupling. As can be seen, only the tightest acoustic coupling shown in response lines 316 and 318 is between the upper and lower masked lines 306 and 307 of the receiver mask. Specifically, at lower frequencies, i.e., below 1kHz, the 3GPP masking requirements are not met.

Fig. 7 shows the frequency response of a closed-box speaker 330, which closed-box speaker 330 is typically used in a hands-free mode in a mobile phone. If this closed-box speaker is used in handset mode as well as hands-free mode, its frequency response in receive mode exhibits severe low frequency roll-off, since the closed-box speaker can have a higher resonance frequency (typically at least twice as high) than the receiver speaker, while acoustic coupling with the user's ear can only partially compensate for the severe low frequency roll-off. The x-axis 334 shows frequencies between 100Hz and 10kHz on a logarithmic scale. The y-axis 332 shows the variation in dB between-40 dB and +20dB on a linear scale. The response of the closed-box speaker without any equalization is shown in graph line 336 and the response of the closed-box speaker with broadband equalization is shown in graph line 338. A very low frequency enhancement of at most 18dB at 200Hz is necessary to meet the 3GPP mask shown by upper mask line 306 and lower mask line 307.

Satisfying the 3GPP mask by aggressively enhancing low frequencies to compensate for low frequency deficiencies in the receive response of a mobile device operating in handset mode may not be feasible or may be impractical for one or more of the following reasons:

the speech processor and/or receiver amplifier may not have the headroom available to allow for such enhancement, which may distort the audio due to saturation of the enhanced signal in the digital or analog domain;

driving the receiver speaker at such a high drive level may result in mechanical or thermal damage if no speaker protection mechanism is provided;

the level of distortion caused by the receiver speaker can increase significantly and reach unacceptable levels even when driven safely under the rated mechanical and thermal limits of the receiver speaker.

Furthermore, the sound from the receiver speaker is typically emitted through a small area, such as a grid in front of the receiver speaker, which must be located precisely in front of the ear entrance to obtain a proper acoustic response.

By using an LRA in addition to or instead of the receiver speaker, the low frequency response of the mobile device to audio signals including speech may be improved without over driving the receiver speaker and its amplifier.

Fig. 8 shows a graph 340 of the modified frequency response of the LRA 208 to the receiver speaker 214 for the mobile phone 200. The x-axis 342 shows frequencies in hertz ranging from 100Hz to 10 kHz. The y-axis shows decibels (dB) ranging from-110 dB to-50 dB. As can be seen, by applying equalization and/or compression using the linear resonant actuator controller 204, the LRA may be equalized such that the LRA response 346 is similar to the receiver speaker response 348 at frequencies above 300Hz and below 300 Hz.

By modifying the frequency response of LRA 208, LRA 208 may be used in addition to receiver speaker 214 or instead of receiver speaker 214. In this way, the speech or other audio quality perceived by the user may be improved, as LRA 208 may be more stable as the location of mobile phone 200 changes relative to user 218. In other examples of mobile phones used in handset mode of operation, by using the LRA for the speech, vibrations caused by the LRA in the housing of the mobile phone can be transmitted via bone conduction when the mobile phone is in contact with the user's head. This may lead to a further improvement in the intelligibility of speech.

Fig. 9 illustrates a linear resonant actuator controller 350. The linear resonant actuator controller 350 includes a haptic driver 354, a switch module 358, an audio processor 380, and an audio amplifier 368. Audio processor 380 includes equalizer 378 and touch detector 374. The haptic driver input 352 is connected to a haptic driver or amplifier 354. The output 356 of the haptic driver 354 is connected to a first input of a switch module 358. Audio input 362 may be connected to equalizer 378. The audio output 366 of the equalizer 378 may be connected to an audio amplifier 368, which audio amplifier 368 may be, for example, a class D amplifier. Touch detector output 372 is connected to equalizer 378. The output 370 of the audio amplifier 368 is connected to a second input of the switching module 358. The output of the switch module 358 is connected to a controller output 372 of the linear resonant actuator controller 350. A control output 364 of equalizer 378 may be connected to a control input of switching module 358.

In a first mode of the linear resonant actuator controller 350, which may be referred to as a haptic mode, the audio processor 380 may connect the haptic driver output 356 to the controller output 372 by controlling the switch module 358. In the first mode, linear haptic controller 350 may be connected to drive linear resonant actuator 390 at controller output 372 as designed, i.e., to act as a haptic motor for generating vibrations in, for example, a mobile phone. In the second mode of operation, the audio processor 380 may connect the audio amplifier output 370 to the controller output 372 by controlling the switch module 358. Equalizer 378 may apply equalization and/or compression to the audio signal to compensate for the peak resonant frequency so that the combination of the equalization and connected LRA 390 has a more linear frequency response.

Touch detector 374 can receive sensor input signals on touch detector input 376, which touch detector input 376, in conjunction with linear resonant actuator controller 350, indicates the force and/or location of contact between a mobile device user and the mobile device. This force/position information may determine the degree of acoustic coupling between the user and the mobile device. The force and position information may be used by equalizer 378 to modify the equalization applied to the audio signal. Alternatively or additionally, in other examples, a proximity sensor (not shown) may provide a sensor input signal that includes a value representative of a distance between a user's ear and the mobile device. It will be appreciated that this distance value may be used to modify the equalization applied to the audio signal by equalizer 378.

Thus, speech that is reproduced as experienced by the user may be independent of the location of the LRA 390 as compared to the user's ear.

By employing equalization to compensate for the resonance peak of the LRA, the LRA 390 may be used, for example, as a speaker, such as a receiver speaker in a mobile phone.

The linear resonant actuator controller 350 may be implemented as a combination of hardware and software. For example, equalizer 378 may be implemented as logic hardware or a digital signal processor running software. The touch detector 374, haptic driver 354, and audio amplifier 368 may be implemented in hardware. The switch module 358 may be implemented as a multiplexer or other logic.

Fig. 10 illustrates a mobile phone 400 according to an embodiment. Mobile phone 400 includes LRA 408, housing 410, receiver speaker 414, and linear resonant actuator controller 404. Linear resonant actuator controller 404 is shown outside of housing 410, but it should be understood that linear resonant actuator controller 404 may be contained inside of the housing in addition to receiver speaker 414 and LRA 408 in general. Input 402 may be connected to linear resonant actuator controller 404. A controller output 406 of linear resonant actuator controller 404 may be connected to a linear resonant actuator 408. The speaker output 412 of the linear resonant actuator controller 404 may be connected to a receiver speaker 414. The linear resonant actuator controller 404 can have a detector input 420 connected to a touch screen (not shown). The detection input may receive force and/or position information that may be used to determine contact between the user 418 and the mobile phone 400.

In the handset mode of operation of mobile phone 400, a user 418 of the mobile phone typically places the handset with receiver speaker 414 near the ear. Linear resonant actuator controller 404 may process the audio signal received at input 402 by, for example, applying a first equalization process prior to outputting the processed audio signal onto controller output 412. In the parallel audio signal path, linear resonant actuator controller 404 may process the audio signal by, for example, applying a second equalization prior to outputting the processed audio signal onto speaker output 412. A user 418 of the mobile phone 400 may experience audio via sound waves generated by the receiver speaker 414 being emitted via the aperture 416. A user 418 of the mobile phone 400 may experience audio due to vibrations in the mobile phone housing 410 caused by operation of the linear resonant actuator 408. These vibration frequencies will typically be low frequencies in the frequency range below 300 Hz.

By reproducing speech using the combination of the receiver speaker 414 and the linear resonant actuator 408, the mobile phone 400 can improve low frequency reproduction without overdriving the receiver speaker 414 and its corresponding amplifier (not shown). The intelligibility of speech heard by user 418 may depend on how close the phone is to the ear. By using the linear resonant actuator 408 in conjunction with the receiver speaker 414, low frequency reproduction may be more stable with respect to acoustic leakage even when the phone 400 is not in physical contact with the ear of the user 418. Further, the speech may be audible even when the receiver port 416 is not positioned in front of the ear canal of the user 418. Linear resonant actuator controller 404 can receive force/position information from a touch screen (not shown). The linear resonance actuator controller 404 may further modify the equalization applied to the audio signal in either or both of the LRA audio path and the receiver speaker audio path.

Fig. 11 illustrates a method of controlling a mobile device including a linear resonant actuator. In step 502, an audio signal comprising speech may be received. In step 504, a signal component corresponding to a resonant frequency of the linear resonant actuator may be attenuated. In step 506, the processed signal may be output for transmission by the linear resonant actuator. The processing may include, for example, dynamic range control and equalization of the audio signal to compensate for the particular resonant frequency of the linear resonant actuator. Linear resonant actuators can typically have very high Q factors, for example. A Q factor of greater than 15. Equalization may include attenuating signal frequency components that occur at or near the resonant frequency relative to at least some other frequency components at frequencies further from the resonant frequency. Equalization can increase the effective bandwidth of the linear resonant actuator, thus allowing the use of an LRA rather than a receiver speaker, and the purpose of the linear resonant actuator is designed to produce haptic feedback (i.e., vibration) that can be felt by a user of the mobile device.

Fig. 12 illustrates a method of controlling a linear resonant actuator for a mobile device 550. In step 552, the mobile device may be in a first mode of operation, which may be a tactile or vibratory mode of operation. In step 554, a haptic drive signal may be generated for the linear resonant actuator. In step 556, the mobile device may be changed to a second mode of operation. For a mobile device, such as a mobile phone, this second mode of operation may be a handset mode of operation whereby the mobile phone is used to place and/or receive voice calls. In step 558, the voice signal in the second mode of operation may be processed for transmission by the linear resonant actuator. Such processing may include, for example, dynamic range control and/or equalization or other filtering. In step 560, the voice signal may be processed for transmission by a speaker, such as a receiver speaker in a mobile phone. By combining the speech signal output by the linear resonance actuator and the receiver loudspeaker, the intelligibility of speech can be improved.

The method 550 may be implemented in hardware, software, or a combination of hardware and software. The method may be implemented in a mobile device, such as a mobile phone or other mobile device that outputs audio and includes an LRA for haptic feedback, such as personal digital assistants, portable medical devices, smart watches, and other wearable devices.

A linear resonant actuator controller for a mobile device having a linear resonant actuator is described. The linear resonant actuator controller comprises a controller output configured to be coupled to a linear resonant actuator; an audio processor having an audio processor input and an audio processor output, the audio processor output coupled to the controller output. The audio processor is configured to receive an audio signal comprising speech, to process the audio signal by attenuating audio signal frequency components at a resonant frequency of the linear resonant actuator relative to at least some other audio signal frequency components, and to output the processed audio signal on an audio processor output.

Although the appended claims are directed to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel feature or any novel combination of features disclosed herein either explicitly or implicitly or any generalisation thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention.

Features which are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

The applicants hereby give notice that new claims may be formulated to such features and/or combinations of such features during the prosecution of the present application or of any further application derived therefrom.

For the sake of completeness it is also stated that the term "comprising" does not exclude other elements or steps, the terms "a" and "an" do not exclude a plurality, a single processor or other unit may fulfil the functions of several means recited in the claims and reference signs in the claims shall not be construed as limiting the scope of the claims.