Abstract:
Embodiments herein relate to controlling a connection to an interface. In an embodiment, a protection circuit is to detect a voltage at an input rail of a regulator, where the regulator is to provide power to a peripheral device via an interface. Next, the protection circuit is to compare the detected voltage to a reference voltage. Then, the protection circuit is to generate a detection signal based on the comparison. Lastly, the protection circuit is to disable a connection between the regulator and the interface based on the detection signal.

Description:
BACKGROUND 
       [0001]    Some types of devices, such as portable electronic devices, may be difficult to operate when a user is simultaneously carrying out other tasks, such as running or driving. For example, a user interface of the device may not be readily usable or reachable by the user. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0002]    The following detailed description references the drawings, wherein: 
           [0003]      FIG. 1  is a diagram of an example detector; 
           [0004]      FIG. 2  is another diagram of an example detector; 
           [0005]      FIG. 3  is a diagram of an example sound system including the detector of  FIG. 2 ; 
           [0006]      FIG. 4A  is a diagram of the sound system of  FIG. 3  when a sound output device is not tapped; 
           [0007]      FIG. 4B  is a diagram of the sound system of  FIG. 3  when the sound output device is tapped; 
           [0008]      FIG. 5  is a diagram of part of an example audio device of  FIGS. 3-4B ; 
           [0009]      FIG. 6  is a scope plot of example inputs to the current detection unit and the voltage detection unit of  FIGS. 1 ,  2  and  5 ; and 
           [0010]      FIG. 7  is a flowchart of an example method for detecting tapping of the sound output device. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    Specific details are given in the following description to provide a thorough understanding of embodiments. However, it will be understood by one of ordinary skill in the art that embodiments may be practiced without these specific details. For example, systems may be shown in block diagrams in order not to obscure embodiments in unnecessary detail. In other instances, well-known processes, structures and techniques may be shown without unnecessary detail in order to avoid obscuring embodiments. 
         [0012]    Electronic devices, such as portable electronic devices, may be difficult to use when a user is simultaneously involved in an activity, such as running, participating in a sport, driving, using another electronic device, or any other type of activity that diverts the user&#39;s attention. For example, a user interface of the device may not be readily usable or reachable by the user and/or the user may not be able to easily view the user interface. 
         [0013]    Currently, the user may have to unwillingly stop the present activity in order to use the electronic device, such as if the user stops running to interact with a portable audio device. Some electronic device may provide an additional limited interface that is more easily usable or reachable by the user. However, these types of limited interface may not provide full functionality of the user device and/or still be difficult to use if the user is in constant motion, such as running. Further, some electronic devices, include custom interfaces, such as a headphone with integrated control buttons like play, pause, skip forward, skip backward, etc. However, in this instance, the user is limited to only using the custom interface for the electronic device. Therefore, the user can not user another interface, such as a more generic or higher quality headphone. In addition, providing the custom interface may increase the cost of the electronic device. 
         [0014]    Embodiments provide a generally low cost and reliable method and/or device to control an operation of a user device. For example, embodiments may allow the user to control an operation of the user device by tapping on part of a sound output device, such as a diaphragm of an earphone. Thus, the user device may be more easily operated without the user looking at the user device, such as the user tapping the earphone while running. Moreover, a wide array of readily available sound output devices may be used in embodiments, such as a standard, lower cost and/or higher quality set of earphones. Further, a sensitivity to the tapping and/or type of operations carried out by the user device in response to the tapping, may be configurable by the user in embodiments. In addition, the embodiments may be readily integrated into existing electronics devices at a low cost. 
         [0015]      FIG. 1  is a diagram of an example detector  100 . The detector  100  may be included in an audio device, such as CD or DVD player, a media or digital audio player, a desktop computer, or a portable device like a digital audio player/mp3 player, mobile phone, personal digital assistant (PDA), etc. In the embodiment of  FIG. 1 , the detector  100  includes a voltage detection unit  110 , a current detection unit  120  and a threshold unit  130 . 
         [0016]    The voltage detection unit  110  is to detect a voltage between a first audio terminal and a second audio terminal of an audio amplifier (not shown) to output an audio signal. The current detection unit  120  is to detect a current along a connection between the first and second audio terminals. The threshold unit  130  is to compare a difference between the detected voltage of the voltage detection unit  110  and the detected current of the current detection unit  120  to a threshold value and to assert a threshold signal based on the comparison. The threshold value is to relate to a voltage generated by a diaphragm of a sound output device (not shown) receiving the audio signal. An example of the components of the detector  100  will be shown in greater detail in  FIG. 5  below. 
         [0017]      FIG. 2  is another diagram of an example detector  200 . Components of the detector  200  of  FIG. 2  may be similar to components of the detector  100  of  FIG. 1 , except the detector  200  of  FIG. 2  may also include the length unit  210 . The length unit  210  is to compare a time duration of the asserted threshold signal to a reference range. Further, the length unit  210  is to output a pulse if the time duration of the asserted threshold signal is within the reference range. The reference range may relate to a range of times for which the tapped diaphragm would be expected to cause the threshold signal to be asserted. The reference range will be explained in greater detail with respect to  FIG. 5 . 
         [0018]      FIG. 3  is a diagram of an example sound system  300  including the detector  200  of  FIG. 2 . While the sound system  300  is shown to include the detector  200  of  FIG. 2 , embodiments may instead also include other suitable devices, such as the detector  100  of  FIG. 1 . In the embodiment of  FIG. 3 , the sound system  300  includes an audio device  310  and a sound output device  320 . 
         [0019]    The audio device  310  includes the detector  200 , an audio amplifier  312 , an audio source  314  and a controller  316 . While the audio device  310  is shown to only connect to the single sound output device  320 , embodiments may also include the audio device  310  connecting to a plurality of the sound output devices  320 . Thus, while only a single amplifier channel is shown in  FIG. 3 , embodiments may include a plurality of amplifier channels, such as two amplifier channels if the sound output device  320  is a set of stereo earphones. In such a case, the audio device  320  may also include a plurality of one or more of the detectors  200 , the audio amplifiers  312 , the audio sources  314  and/or the controllers  316 . 
         [0020]    The audio source  314  may be any type of device to provide an audio signal to the audio amplifier  312 , such as an AM/M tuner, a CD player, a digital-to-analog converter (DAC) and the like. The audio amplifier  312  is to amplify and output the decoded and/or decompressed audio data as an audio signal to the sound output device  320 . When the sound output device  320  is connected to the audio device  310  through an interface, such as an audio jack, the amplifier  312  forms a closed loop connection with the sound output device  320  between the first and second audio terminals of the audio amplifier  312 . The audio amplifier  320  may include any type of device to increase a power of a signal. The sound output device  320  is a device, such as electroacoustic transducer, to produce sound in response to the audio signal. An example of the sound output device  320  may include one or more speakers, such as headphones or earphones. 
         [0021]    As shown in  FIG. 3 , the detector  200  connects to the first and second audio terminals of the audio amplifier  312  to detect the current and voltage of the sound output device  320 . Additionally, the detector  200  outputs the threshold signal to the controller  316 . 
         [0022]    The controller  316  is to control an operation of the audio device  310  based on a time pattern of the one or more pulses output by the length unit  210 . The time pattern may be defined by a number and/or duration of time lapses between the one or more pulses for a given time cycle. The operation controlled by the controller  316  may relate to a volume scale, an audio track selection, a power setting, and the like. For example, a time pattern having a single pulse may be interpreted as a toggle between play/pause functions. Another time pattern including a pause between two pulses may be interpreted as a seek function. 
         [0023]    Further, if the audio device  310  is connected to a plurality of the sound output devices  320 , then the operation of the audio device  310  may be based on a plurality of the time patterns. For example, a first pattern may be generated from a first sound output device (e.g. a left earphone) and a second pattern may be generated from a second sound output device (e.g. a right earphone). In this case, simultaneously receiving a single pulse from the first pattern and a single pulse from the second pattern may be interpreted as a power off function. Moreover, two pulses in quick succession from the first pattern may be interpreted as skip forward function while two pulses in quick succession from the second pattern may be interpreted as skip backward function. 
         [0024]    The above correlations between one or more pattern types and an operation of the audio device  310  merely represent some of many possible example correlations for the audio device  310 . Similarly, the above operations merely represent some of the many possible operations to be correlated for the audio device  310 . For example, other operations to be correlated may include placing/ending a call, opening a file, powering on the audio device, etc. Further, the correlations between a type of pattern and a type of operation may be configurable by a user via, for example, a user interface (not shown) included in the audio device  310 . Embodiments may include the controller  316  to correlate any type of one or more patterns to one or more operations of the audio device  310 . 
         [0025]    The controller  316  may communicate with a processor (not shown) and/or a memory (not shown) included in the audio device  310 , to carry out one or more of the above operations and/or correlations. For example, the controller  316  may communicate with the processor to access the memory. The memory may store a database for associating a type of one or more patterns to a type of operation and/or software to execute one or more types of operations. The processor may also communicate with one more components of the audio device  310  to carry out the correlated operation, such as accessing the audio amplifier  312  to control the volume scale. 
         [0026]      FIG. 4A  is a diagram of the sound system  300  of  FIG. 3  when the sound output device  320  is not tapped.  FIG. 4B  is a diagram of the sound system  300  of  FIG. 3  when the sound output device  320  is tapped. The audio device  310  in  FIGS. 4A and 4B  may be similar to that of  FIG. 3 . In the embodiments of  FIGS. 4A and 4B , the sound output device  320  includes a diaphragm  322 , a voice coil  324  and a magnet  328 . The voice coil  324  further includes a coil resistor  325  representing a resistance of the voice coil  324  and a coil inductor  326  representing an inductance of the voice coil  324 . The sound output device  320  may connect to the audio device  310  via a wired connection, such as a cable. The wired connection may have a resistance represented by a connection resistor  330 . 
         [0027]    In  FIGS. 4A and 4B , the diaphragm  322  is attached to the voice coil  324 . The voice coil  324  may be able to move somewhat freely back and forth over the magnet  328 . The diaphragm  322  may be any type of transducer to convert between mechanical motion and sound. For example, the diaphragm  322  may include a thin, semi-rigid membrane. However, embodiments of the sound output device  322  are not limited to having moving coil drivers. 
         [0028]      FIG. 4A  shows the sound output device  320  only outputting sound or acting as a speaker. For instance, the audio signal may pass through the voice coil  324 , causing an alternating magnetic field that reacts to a static magnetic field of the magnet  328 , to vibrate the diaphragm  322  and thus produce sound. 
         [0029]    However, as shown in  FIG. 4B , the sound output device may also act as a microphone when a user taps the diaphragm  322 . The diaphragm  322  may be tapped directly or indirectly. For example, if the sound output device  320  is an earphone or headphone, the diaphragm  322  may be enclosed and/or facing an ear of the user. Therefore, the user may instead tap a casing enclosing the diaphragm  322  or another part of the sound output device  320  to indirectly vibrate the diaphragm  322 . In this case, the vibrating diaphragm  322  may cause the attached voice coil  324  to move back and forth over the magnet  328 , thus generating a coil voltage V c    329 . 
         [0030]    The resistance of the connection resistor  330  and the inductance of the coil inductor  326  may be negligible compared to the resistance of the coil resistor  325 . For example, in some embodiments, the coil resistor may be between 15 and 33 ohms. Further, in both  FIGS. 4A and 4B , an output voltage applied to the sound output device  320  by the audio amplifier  322  may be the same. However, the current along the connection between the audio amplifier  322  and the sound output device  320  may be different among  FIGS. 4A and 4B . For example, in  FIG. 4B , the current along the connection may generally be greater or lesser by a ratio of the coil voltage V c  to the coil resistor  325 . Thus, the current along the connection changes when the sound output device  320  is tapped or is used as a microphone. This change in the current along the connection is detected by the detector  200 . 
         [0031]      FIG. 5  is an example diagram of part of the audio device  310  of  FIGS. 3-4B . In this embodiment, the detector is shown to form a connection with the first audio terminal of the audio amplifier  312  and a plurality of connections with the second audio terminal of the audio amplifier  312 . A resistance of the audio amplifier  312 , as represented by an amplifier resistor  502 , may be negligible compared to that of the coil resistor  325 . 
         [0032]    The detector  200  is shown to include the voltage detection unit  110 , the current detection unit  120 , the threshold unit  130  and the length unit  140 . The voltage detection unit  110  includes a first amplifier  112  and a first filter  114 . The first amplifier  112  includes a first input terminal that connects to the first audio terminal of the audio amplifier  312  and a second input terminal that connects to the second audio terminal of the audio amplifier  312 . The first amplifier  112  may be a differential amplifier that is to output a first amplifier signal based on amplifying a voltage difference detected between the first audio terminal and the second audio terminal. 
         [0033]    The first filter  114  may be a band pass filter to output a first filter signal based on filtering one or more frequencies from the first amplifier signal not related to tapping the diaphragm  322 . For example, the first filter  114  may pass frequencies in approximately the 100 Hz to 10 kHz range. As a result, frequencies related to tapping the diaphragm as well as frequencies related to audio signal may pass through. However, frequencies related to false triggering or false tapping of the diaphragm  322 , such as those caused by background noise and/or electromagnetic noise, may be filtered. 
         [0034]    The current detection unit  120  includes a second amplifier  122  and a second filter  124 . The second amplifier  122  includes a first input terminal that connects to the second audio terminal of the audio amplifier  312  and a second input terminal that connects to the second audio terminal of the audio amplifier  312 . A current sense resistor  504  may be included along the connection between the first and second input terminals of the second amplifier  122  at the second audio terminal. 
         [0035]    The current sense resistor  504  may convert the current along a path between the first and second audio terminals into a voltage. Further, the current sense resistor  504  may have a low value resistance that will have a minimal effect on the output of the audio signal by the audio amplifier  312 . The second amplifier  122  may be a differential amplifier that is to output a second amplifier signal based on amplifying a voltage difference detected between a first resistor terminal and a second resistor terminal of the current sense resistor  504 . 
         [0036]    Further, the second amplifier  122  is shown to receive a gain control signal to match amplitudes of the first and second amplifier signals when the diaphragm  322  is not tapped. The gain control signal may be set by a user or manufacturer and/or by the audio device  310 . 
         [0037]    The gain control signal may be set to different values for different types of sound output devices  320 . For example, different types of earphones may have different resistances. Accordingly, the audio device  310  may allow a user to match the amplitude of the detected current and the detected voltage when the diaphragm  322  is not being tapped. For example, the audio device  310  may include a graphical display and/or user interface that allows the user to align the amplitudes of the first and second amplifier signals. Alternatively, the audio device  310  may detect and align the amplitudes of the first and second amplifier signals automatically. 
         [0038]    While the first and second input terminals of the second amplifier  122  and the current sense resistor  504  are shown to connect along the second audio terminal, embodiments may also include the first and second input terminals of the second amplifier  122  and the current sense resistor  504  connecting along the first audio terminal. Further, while the second amplifier  122  is shown to receive the gain control signal, embodiments may include any combination of the first and/or second amplifiers  112  and  122  receiving the gain control signal. 
         [0039]    The second filter  124  is to output a second filter signal based on filtering one or more frequencies from the second amplifier signal not related to tapping the diaphragm  322 . The second filter  124  may be similar to the first filter  114 . 
         [0040]    The threshold unit  130  includes a comparator  132  and a subtractor  134 . The subtractor  134  is to output a difference signal based on a difference between the first filter signal and the second filter signal. For example, the subtractor  134  may subtract one of the first and second filter signals from another of the first and second filters signals, and then take the absolute value of the subtraction. The difference signal may generally have a value of zero if the diaphragm  322  is not being tapped, due to the amplitudes of the first and second amplifier signals being matched. 
         [0041]    The comparator  132  is to assert the threshold signal based on a comparison between the difference signal and a reference voltage signal. For example, the comparator  132  may compare the difference signal output by the subtractor  134  to the reference voltage signal. Then, the comparator  132  may output the threshold signal at a high logic level when the difference signal is greater than the reference voltage. Otherwise, the comparator  132  may output the threshold signal at a low logic level. Embodiments of the comparator  132  may also switch the output of the threshold signal to have the low logic level when the difference signal is greater than the reference voltage and have the high logic level otherwise. 
         [0042]    The reference voltage signal relates to a net difference generated between the amplitudes of the detected current and the detected voltage when the diaphragm  322  is tapped. Thus, the reference voltage signal may be set to different values for different types of sound output devices  320 . For example, different types of earphones may vary in sensitivity to being tapped and/or generate different amounts of voltage when tapped, such as between 100 to 500 millivolts (mV). 
         [0043]    Accordingly, the audio device  310  may allow a user to adjust a value of the reference voltage signal to correlate to a difference in amplitude between the detected current and the detected voltage when the diaphragm  322  is tapped. For example, the audio device  310  may include a graphical display and/or user interface that allows the user to determine an amplitude of the voltage generated by the diaphragm  322  when tapped by the user. Further, the audio device may also the allow the user to set the value of the reference voltage signal based on determined amplitude of the voltage generated by the diaphragm  322 , so as to reduce the likelihood of erroneous detection or non-detection of taps to the diaphragm  322 . Alternatively, the audio device  310  may set the reference voltage signal automatically upon detecting the amplitude of the voltage generated by the diaphragm  322  when tapped by the user. 
         [0044]    As noted above, the length unit  140  is to compare a continuous time duration the threshold signal is asserted to a reference range, where the length unit  140  is to output a pulse if the continuous time duration of the asserted threshold signal is within the reference range. For example, the length unit  140  may output a fixed length output pulse when the continuous time duration of the asserted threshold signal is between a minimum and maximum value, such as between 0.1 milliseconds (ms) and 0.6 ms. Ignoring values outside this reference range may reduce false triggering due to background noise. The pulse may indicate that a tap has occurred to the controller  316  of the audio device  310 . The length unit  140  may be implemented via a combination of logic gates. 
         [0045]    Embodiments of the detector  200  are not limited to the above configuration. For example, embodiments of the detector  200  may be implemented by a combination of various different analog and/or digital components. 
         [0046]      FIG. 6  is a scope plot of example inputs to the current detection unit  110  and the voltage detection unit  120  of  FIGS. 1 ,  2  and  5 . In  FIG. 6 , the gray waveform represents the voltage sensed by the voltage detection unit  110  and the black waveform represents the current sensed by the current detection unit  110 . In this example, both the gray and black waveforms are output at one kilohertz (kHz), with the gray waveform being scaled to 10 mV/division and the black waveform being scaled to 30 mV/division. 
         [0047]    As shown in  FIG. 6 , the waveforms of the sensed voltage and current have been adjusted so that they track each other or have a same amplitude when no tapping is occurring, such as at the beginning of the scope plot. However, when a tap occurs, such as at approximately 1.3 ms, the gray waveform for the sensed current increases in amplitude, denoting ringing or vibrating of the diaphragm  322  from the tap. This ringing vibrating of the diaphragm  322  causes the gray or current waveform to temporarily not track or have the same amplitude as the black or voltage waveform. This change in amplitude is detected by the threshold unit  130 . Further, a time duration of this change in amplitude may be detected by the length unit  210 . 
         [0048]      FIGS. 7A-7B  are a flowchart of an example method  700  for detecting tapping of the sound output device  320 . Although execution of the method  700  is described below with reference to the audio device  310  of  FIG. 3 , other suitable devices for execution of at least part of the method  700  will be apparent to those of skill in the art. In  FIG. 7A , at block  705 , the voltage detection unit  110  detects the voltage between the first audio terminal and the second audio terminal of the audio amplifier  312  to output the audio signal. Next, at block  710 , the current detection unit  120  detects the current along the connection between the first and second audio terminals. The voltage and current detection at blocks  705  and  710  may be carried out interchangeably and/or simultaneously. 
         [0049]    Then, at block  715 , the voltage detection unit  110  amplifies the detected voltage, and, at block  720 , the current detection unit  120  amplifies the detected current. The voltage and current amplification at blocks  715  and  720  may be carried out interchangeably and/or simultaneously. Next, at block  725 , at least one of the voltage detection unit  110  and the current detection unit  120  receives the gain control signal so that the amplitudes of the detected voltage and the detected current match when the diaphragm  322  is not tapped. Further, the matching at block  725  may also be carried out simultaneously with or after at least one of the voltage and current amplification at blocks  715  and  720 . 
         [0050]    Then, at block  730 , the current detection unit  120  filters frequencies from the detected current not related to tapping. Next, flowing to block  735  at  FIG. 7B , the voltage detection unit  110  filters frequencies from the detected voltage not related to tapping. The filtering of the detected voltage and current detection at blocks  730  and  735  may be carried out interchangeably and/or simultaneously. 
         [0051]    Subsequently, at block  740 , the threshold unit  130  compares a difference between the filtered voltage and the filtered current to a threshold value. Next, at block  745 , the threshold unit  130  asserts a threshold signal based on the comparison. Then, at block  750 , the length unit  210  compares the time duration of the asserted threshold signal to the reference range. Afterward, at block  755 , the length unit  210  outputs the pulse if the time duration of the asserted threshold signal is within the reference range. Lastly, at block  760 , the controller  316  controls an operation of an audio device  310  outputting the audio signal based on a pattern of the one or more outputted pulses. The operation may relate to a volume scale, audio track selection, power setting and the like, of the audio device  310 . 
         [0052]    According to the foregoing, embodiments provide a generally low cost and reliable method and/or device to control an operation of a user device, such as an audio device. For example, embodiments may allow the user to control an operation of the user device by tapping on part of a sound output device, such as a diaphragm of an earphone. Thus, the user device may be more easily operated without the user looking at the user device. Moreover, existing sound output devices may be used in embodiments, such as a standard set of earphones. Further, a type of operation carried out by the user device in response to the tapping may be configurable by the user.