Patent Description:
Aspects of the present disclosure are as set out in the accompanying claims.

Particular implementations of the disclosed technology can, in certain instances, realize one or more of the following advantages. The technology described in this disclosure involves employing an excursion measuring component which, through induction, produces an electrical signal that is monitored to determine an active excursion distance related to the speaker while actuating. Thus, the technology enables an electronic device to dynamically detect that a speaker is operating at a level that is causing an atypical excursion of the voice coil, for example, that may result in an unintended impact (e.g., degrading audio quality or damaging the speaker). This approach can achieve improved accuracy in comparison to techniques that involve estimating and/or modelling for the excursion distance. For instance, some techniques which measures various non-linear parameters (e.g., voltage across the speaker, current through the voice coil) of the speaker to approximate excursion may be less accurate as the speaker oscillates farther from its initial resting position and the behavior of the parameters, in turn, become more non-linear. Moreover, configuring a speaker to include an excursion measuring component, which can be implemented as a sense coil printed onto a flexible printed circuit, can eliminate the need to add more complex mechanical or processing components to the electronic device intended to perform excursion detection/compensation functions. As such, the disclosed techniques can involve various advantages, such as a reduction in size and/or a reduction in cost of the electronic device in comparison to alternative mechanisms.

<FIG> is a diagram of an electronic device <NUM>, e.g., a mobile phone as depicted, that includes a speaker <NUM> and a system <NUM> for measuring an excursion of one or more components of speaker <NUM>, e.g., at low frequency levels. During operation, electronic device <NUM> uses speaker <NUM> to generate audible sound for a user. Such sound may include sound from voice telephone calls, may include recorded sound (e.g., voice messages, music files, etc.) and may also include sound generated by applications operating on electronic device <NUM>.

Speaker <NUM> includes an electroacoustic transducer, which converts an electrical audio signal into a corresponding sound. Although <FIG> shows speaker <NUM> as internal component of electronic device <NUM>, it should be appreciated that speaker <NUM> can also be implemented as an external and/or independent device. For instance, speaker <NUM> can be a stand-alone micro-speaker that communicates with electronic device <NUM> using a wireless technology standard, such as Bluetooth, to output audio generated from the electronic device <NUM>. For purposes of discussion, speaker <NUM> and the excursion measurement techniques are discussed in reference to micro-speakers. However is should be appreciated that the techniques are applicable to larger scale transducers, such as home speakers, automotive speakers, and the like.

<FIG> also illustrates an example of excursion associated with the speaker <NUM> and a physical position of membrane <NUM>. In the example, the excursion limit is shown as the distance of spacing between the membrane <NUM> and a surface of the electronic device <NUM> that may serve as a front plate, or partial covering for speaker <NUM>. In some cases, this distance is approximately measured in millimeters, such as <NUM>. Accordingly, outward movement of the membrane <NUM> is physically prevented from displacement beyond that front surface and, in this case, the excursion limit is a physical constraint defined by the mechanical configuration of the speaker <NUM>. That is, the membrane <NUM> is prevented from reaching the full range of its motion in one direction, due to placement. Although not shown in <FIG>, the membrane <NUM> may also be associated with an excursion limit in the opposite direction, related to moving inwards towards other elements of the speaker <NUM>. As a result, the excursion measuring system <NUM> is configured to measure positive excursion (e.g., + x-axis direction), negative excursion (e.g., - x-axis direction), or both. In some embodiments, the techniques consider excursion from an initial resting position, also referred to as DC level, or the zero position of the transducer.

In some cases, the speaker <NUM> may be driven under various low frequency and high pressure conditions that can cause the membrane <NUM> to oscillate farther, having greater displacement, and potentially contacting the surface of the electronic device <NUM>. In the case of high pressure, the pressure level output can be directly related to the amount of air volume displacement. Higher pressure, may displace the membrane <NUM>, for example, pushing the membrane <NUM> outward due to the pressure inside of the speaker <NUM> being greater than the pressure outside of the device.

As some background regarding speaker operation, a membrane <NUM> of a speaker <NUM> oscillates to produce sound waves in the air and therefore to make noise. It does so by oscillating back and forth past a determinable center location, which may be the same as the location at which the membrane <NUM> is at rest when no electrical signal is being provided to the speaker <NUM> (and when the pressure on both sides of the membrane are equal). In the case of lower frequencies, as illustrated in <FIG>, the speaker <NUM> can output the audio signals <NUM> associated with a low frequency. As such, when an oscillating electrical signal at a lower frequency is applied to the speaker <NUM>, the speaker membrane <NUM> may experience larger oscillations. The membrane <NUM> can be pushed farther outwards due to displacing larger volumes of air in order to produce audio signals <NUM> having the lower audible tones (e.g., bass). In other words, a signal at a higher frequency that would not typically cause a speaker <NUM> to reach the limits of its movement in any given direction, may hit such a limit due to the speaker membrane <NUM> being pushed in the direction due to air displace across the speaker membrane <NUM>. As a result, the membrane <NUM> can begin to hit the limits of its ability to extrude in that direction as an audio output is being played. This contact between the membrane <NUM> and the top surface can result in audible distortion of the audio output <NUM> to the user, such as a buzz that can be heard while playing bass.

In order to remedy the degradation of the audio signal <NUM> that may result from excursion related factors, speaker <NUM> includes excursion measuring system <NUM>. This system <NUM> can include electronics configured to determine an active excursion distance of an element while the speaker <NUM> is actuated, and to subsequently detect whether continuing to drive the speaker <NUM> may violate any known excursion limit constraints. In reference to <FIG>, the measured excursion distance can be the current position of the membrane <NUM> in relation to movement within the free space for the excursion limit. For instance, the excursion measuring system <NUM> can measure that the membrane <NUM> is located at a. <NUM> distance, within a. <NUM> excursion space (e.g.,. <NUM> distance from the top surface). Then, based on the measurement, the excursion measuring system <NUM> can further detect that the speaker <NUM> has reached or exceeded a threshold corresponding to acceptable excursion distances (e.g., no audible distortion or device damage). Optionally, in some embodiments, the excursion measuring system <NUM> can also perform actions allowing the speaker <NUM> to compensate for any such displacement (e.g., reduce gain, activate compressor).

As a general description, the excursion measuring system <NUM> includes an excursion measuring component that is implemented as a sense coil. The system <NUM> monitors an electrical signal produced by a magnetic field that is inductively coupled to the sense coil in order to measure an excursion distance. The excursion measuring techniques and system are discussed in greater detail in reference to <FIG>.

<FIG> are schematic diagrams of a speaker <NUM> including an excursion measuring component that may implement the disclosed technology. Speakers <NUM>, or audio transducer may be used to implement the disclosed technology. As some background regarding operation of speakers, the speaker <NUM> can be configured to convert electrical energy into acoustic energy. Many variations of transducers exist, including a moving coil-permanent magnet transducer, which is illustrated in <FIG>. The speaker <NUM> includes a membrane <NUM>, an excursion measuring component <NUM>, a magnetic system <NUM>, and a diaphragm <NUM>. Also, in <FIG>, the excursion measuring component <NUM> is shown as a sense coil printed onto a flexible printed circuit (FPC) and attached to the frame of the of the speaker. In <FIG>, the speaker <NUM> is configured with the excursion measurement component <NUM> on top of the driver. <FIG> shows an alternative configuration for speaker <NUM>, which includes the excursion measurement component <NUM> on the bottom of driver. Whether a system is designed to implement the configuration in <FIG> or in <FIG>, can be based, at least in part, on the various physical and/or functional aspects of the speaker <NUM> (e.g., relating to the manufactured product).

In reference to the configuration shown in <FIG>, the excursion range can be generally described as the space between the magnetic system <NUM> and the bottom of the diaphragm <NUM>. Accordingly, the excursion measuring component <NUM> is placed on top of the diaphragm <NUM>. This design may provide improved accuracy in tracking displacement upwards (+ y-axis direction).

In referring to <FIG>, the excursion measuring component <NUM> is positioned on the back of the magnetic system <NUM>. This configuration may have functional constraints, due to placing the sensing coil on the bottom of the magnetic elements of speaker <NUM>. In some cases, a DC magnetic field may interfere with the measurements. In other cases, a bottom metal plate can shield the magnetic field generated by a voice coil of the speaker <NUM>, which, in turn, may negatively impact the inductive coupling to the sense coil. A system using the configuration of <FIG> can be designed to account for these and other constraints. The system can be calibrated to subtract a DC component from the electrical signal. For example, a high pass filter can be placed near the ADC path to subtract out the DC component. Additionally, a reference signal can be amplified to compensate for the any experienced shielding.

The speaker <NUM> includes a voice coil, which can be constructed using a thin wire that is suspended within a magnetic field generated by a magnet. Additionally, the voice coil can be used to function as an electromagnet, as the speaker <NUM> includes a soft metal core made into a magnet by the passage of electrical current through the voice coil surrounding it, thus creating an electro-magnetic field. The voice coil is configured to move, or rotate, within the magnetic field.

As speaker <NUM> is actuated, the speaker <NUM> oscillates and causes the voice coil to also become displaced from the movement. As an example, when an analog signal, which can be an input voltage signal, passes through the coil of the speaker <NUM>, an electro-magnetic field is produced and whose signal strength is determined by the current flowing through coil. The electro-magnetic force produced by the field opposes the main permanent magnetic field around it and tries to push/pull the coil in one direction or the other depending upon the interaction with the magnet.

Being that the voice coil is made of inductive material (e.g., metal wiring), the coil can have inductance and impedance characteristics. Moreover, the magnetic field from the voice coil, which is close proximity with the sense coil can also induce current flow in the sense coil. In instances when the voice coil moves closer to the sense coil, the induced current flow increases, thereby increasing the amplitude of the current signal. In contrast, when the voice coil moves to distances farther from the sense coil, the amplitude of the inducted current flow decreases. Thus, the system monitors the amplitude of the induced current signal, to measure excursion. As an example, the induced current signal can be represented by an oscillating (e.g., sinusoidal) signal having a peak-to-peak amplitude. The system can actively monitor changes in the signal's amplitude while the speaker is driven. Then, any monitored fluctuations in amplitude, such as increases or decreases, can be correlated to a physical distance between the voice coil and the sense coil. Consequently, the system can use a known position of the sense coil to determine a physical position of the voice coil, which is indicative of the excursion distance. Accordingly, the excursion measurement component <NUM> realizes a solution that provides an actual measurement, rather than an estimation of sensing the excursion of the voice coil, which can improve overall accuracy of the system. In some cases, excursion of other elements of the speaker <NUM> can be measured using the disclosed techniques, such as membrane <NUM>.

In some embodiments, various calibration techniques can be used to determine a correlation between signal measurements, and active excursion distance measurements. As an example, a calibrating laser is employed to obtain feedback from sense coils during measurements performed on a sample set (e.g., <NUM> samples). Thus, a direct correlation, or one-to-one relationship, from calibration can be stored in the system to implement the disclosed excursion measurement techniques. In continuing with the example, calibrating can determine that receiving a <NUM> V peak voltage in feedback from the sense coil, correlates to. Calibration can be performed at the module level to account for assembly and static distance variation from the induction coil to the voice coil. Calibration may need to also be done on the system level to account for ADC variation, which can depend, at least in part, on a required resolution.

<FIG> is a conceptual diagram of a system configured to measure an active excursion distance for an element (e.g., voice coil) of a speaker <NUM>. As shown, the speaker <NUM> can receive, as input, an electrical signal that has been output from amplifier <NUM>. Additionally, <FIG> shows the excursion sensing component <NUM>, which generates an electrical signal in response to inductive coupling. The electrical signal can be an induced current signal propagating through the sense coil, which is then received the analog-to-digital converter (ADC) <NUM> as input. Subsequently, the induced current signal is analyzed by the system in order to monitor its amplitude. Also, a direct current (DC) component of the electrical signal can be tracked, for example by applying a low pass which averages the electrical signal over tome to detect the DC variation. In some cases, any amplitude variation that may be generated is not considered as the DC component is tracked. DC can be used to determine an absolute resting position for the speaker and the components. For instance, the speaker can be considered at rest when no electrical signal is being provided to the speaker <NUM>.

Moreover, the system is configured to apply an electrical signal at a high frequency (e.g., <NUM>-<NUM>) to an incoming electrical audio signal. Combining the signals can be achieved, as a playback sampling rate can be <NUM> or higher and the Nyquist frequency can be <NUM> or higher, for instance at a <NUM> bit or <NUM> bit depth. Additionally, the ADC can be clocked at high oversampling to obtain a higher fidelity capture of the coil position. A reference electrical signal is generated as a result of combining the high frequency and audio signal. In instances where the speaker <NUM> has a small size, for instance in the case of micro-speakers, inductance of the coils is low (e.g., signal with small peak-to-peak amplitude). Employing a reference signal serves to counter drawbacks associated with analyzing a small induced current, and can improve the accuracy of the system.

<FIG> is a flowchart of an example method for measuring an active excursion distance of an element of a speaker during actuation. The system and techniques described herein may calculate a real-time measurement of the position (and similarly excursion) of the components of a speaker that can be related to an excursion range, including a voice coil, a diaphragm, a magnet, and a membrane. The position measurement is based on electrical parameters monitored while the speaker is reproducing audio, namely monitoring an amplitude of the induced current signal of the sense coil.

The process beings at block <NUM>, where the system applies a high frequency signal to an incoming audio signal. The incoming audio signal can be audio content, such as music, to be reproduced by the speaker. Mixing the incoming audio signal with the high frequency signal results in a reference signal that is further analyzed by the system.

Next, at block <NUM>, the system monitors an electrical signal produced by inducing the excursion measuring component. As disclosed, the system is configured to generate an induced current flow in the sense coil. Subsequently, the system monitors the amplitude of the induced current flow.

Then, at block <NUM>, an active excursion distance, relating to displacement of the voice coil for example, is determined. The system can determine the active excursion distance of the voice coil using the amplitude of the induced current signal (obtained from monitoring), and a predetermined correlation between physical position and amplitude (previously stored in the system). Next, the system performs a check at block <NUM>. The check determines whether the active excursion distance is greater than a threshold, and can potentially violate any excursion constraints set by the system. For example, the system can compare a measured active excursion distance for the voice coil to a predetermined threshold associated with acceptable excursion. For instance, thresholds can be predetermined distances relating to an excursion range (e.g., ±. <NUM>) where the voice coil, for example, has been observed to move freely (avoiding any unintended contact with other elements/barriers). In cases where the system determines that the voice coil has moved to a distance that reaches or exceeds the threshold (i.e., Yes), the process proceeds to block <NUM> and performs one or more actions to compensate for the potentially adverse excursion distance.

Alternatively, in cases where the system determines that the voice coil has moved to a distance that is below the threshold (i.e., No), the system can continue to function nominally. In <FIG>, this is shown as block <NUM>, where the audio signal is output without performing any compensatory actions or signal modifications. <FIG> illustrates excursion measuring as an iterative process that repeats measuring the induced current signal at various time intervals (while driving the speaker), so as to achieve continuous and/or real-time excursing sensing.

Further to the descriptions above, a user may be provided with controls allowing the user to make an election as to both if and when systems, programs or features described herein may enable collection of user information (e.g., information about a user's social network, social actions or activities, profession, a user's preferences, or a user's current location), and if the user is sent content or communications from a server. In addition, certain data may be treated in one or more ways before it is stored or used, so that personally identifiable information is removed. For example, a user's identity may be treated so that no personally identifiable information can be determined for the user, or a user's geographic location may be generalized where location information is obtained (such as to a city, ZIP code, or state level), so that a particular location of a user cannot be determined. Thus, the user may have control over what information is collected about the user, how that information is used, and what information is provided to the user.

Claim 1:
A system comprising:
an audio transducer configured to produce one or more electrical signals associated with reproducing an incoming audio signal, the audio transducer comprising:
a magnetic system (<NUM>);
a vibrating membrane (<NUM>);
a diaphragm (<NUM>), wherein an excursion range of the vibrating membrane is the space between the magnetic system and a bottom surface of the diaphragm;
a flexible printed circuit, FPC, coupled to a top surface of the diaphragm and having a first physical location within the audio transducer, wherein the FPC includes a sense coil (<NUM>); and
a voice coil coupled the magnetic system and attached to the vibrating membrane and having a second physical location within the audio transducer and with respect to the first physical location of the FPC, wherein the voice coil is configured to generate an induced current signal through the sense coil that modifies the one or more electrical signals; and
a signal analysis device that is configured to perform operations while driving the transducer to produce the one or more electrical signals, wherein the operations comprise:
analyzing the one or more electrical signals from the audio transducer for monitoring an electrical parameter of the induced current signal;
measuring, based on the monitored electrical parameter, an excursion distance of the voice coil, wherein the excursion distance is associated with a distance between the second physical location of the voice coil and the first physical location of the FPC; and
determining, based on the measured excursion distance, whether the measured excursion distance exceeds a threshold; and if the measured excursion distance exceeds the threshold
performing an action to compensate for driving the audio transducer to generate the measured excursion distance.