PATENT DOCUMENT

Publication Number: US-8467828-B2
Application Number: US-201113038172-A
Country: US
Kind Code: B2

Title: Audio I O headset plug and plug detection circuitry

Abstract:
A single prong, multiple signal conducting plug and plug detection circuitry is provided. The plug may be electrically coupled to a stereo headset including a microphone. The plug may include four signal conducting regions arranged in a predetermined order along the length of the prong. Detection circuitry may be operative to determine whether a microphone type of plug (e.g., a four region plug including a microphone region and two audio regions, or a three region plug including microphone region and only one audio region) or a non-microphone type of plug (e.g., stereo plug) is inserted into the jack of an electronic device (e.g., mobile phone). Detection circuitry may also detect user activated functions performed in response to user activation of one or more switches included with the headset. For example, the headset may include a single switch for performing a function with respect to a microphone (e.g., end-call function).

Claims:
What is claimed is: 
     
       1. A system for detecting a type of plug to be received by a portable electronic device, the system comprising:
 a jack constructed to receive a plug selected from at least a microphone type and a non-microphone type, wherein the jack comprises at least a microphone connector electrically coupled to microphone detection circuitry, and a ground connector coupled to a ground source; 
 the microphone detection circuitry operative to determine whether the received plug is the microphone type or the non-microphone type, the microphone detection circuitry including:
 a bias power source to be applied to the microphone connector while the plug is detected in the jack, wherein the microphone connector is coupled to the bias power source; 
 a transistor whose control electrode is coupled to the microphone connector, and whose output electrode provides a signal which indicates whether the received plug is the microphone type or the non-microphone type; 
 a separate HEADSET DETECT signal that indicates whether a plug is received by the jack; 
 headset switch detection circuitry to monitor the microphone connector for a headset switch activation event and provide a further signal in response to a monitored headset switch activation event executed by a headset switch; and 
 
 wherein the headset switch is a first headset switch, wherein the headset switch activation event is a first headset switch activation event, wherein the microphone is electrically connected to a second headset switch, the headset switch detection circuitry to:
 monitor the plug for a second headset switch activation event executable by the second headset switch; 
 change a state of the further signal in response to a monitored first headset switch activation event; and 
 change a state of the further signal in response to a monitored second headset switch activation event. 
 
 
     
     
       2. The system of  claim 1 , wherein the jack comprises a headset detect switch electrically coupled to a power source and at least one of a right and a left connector of the jack, and further comprising a node coupled between the headset detect switch and the power source, the node provides the separate HEADSET DETECT signal that indicates whether a plug is received by the jack. 
     
     
       3. The system of  claim 1 , wherein the bias power source is to monitor the HEADSET DETECT signal and provide a bias power signal to the transistor in response to the HEADSET DETECT signal. 
     
     
       4. The system of  claim 1 , wherein the headset switch activation event is one of an open circuit event and a short circuit event. 
     
     
       5. The system of  claim 1 , wherein the bias power source is to:
 if the received plug has a microphone region in an anticipated microphone region, provide the bias power to a transistor operative to provide the signal; and 
 
       if the received plug does not have a microphone region in the anticipated microphone region, electrically coupling the transistor to ground. 
     
     
       6. The system of  claim 1 , wherein the detection circuitry is operative to cease supplying the microphone bias voltage after the plug is removed.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. patent application Ser. No. 11/650,132, filed Jan. 5, 2007, titled “AUDIO I O HEADSET PLUG AND PLUG DETECTION CIRCUITRY” which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     This relates to portable electronic devices, and more particularly to headset plugs and plug detection circuitry. 
     Portable electronic devices may include jacks or sockets for receiving connector plugs (e.g., stereo plug) for headphones or headsets. Audio signals may be passed from the jack to the headset through electrical connections formed between the plug and the jack when the plug is inserted into the jack. Known jacks include single prong monaural and stereo plugs and double prong stereo plugs. A drawback of such plugs is that they lack the ability to handle additional signals which may be provided by either the headset or the jack. In addition, the double prong plug requires a double prong jack, which may occupy valuable real estate in the media device. 
     What is needed is a single prong plug capable of handling at least one additional signal in addition to one or more audio signals. What is also needed is plug detection circuitry to detect which type of plug is received in the jack and to detect user activated functions that may be performed with a headset connected to the plug. 
     SUMMARY OF THE INVENTION 
     A single prong, multiple signal conducting plug is provided. This plug may be electrically coupled to a stereo headset including a microphone. The plug may include four signal conducting regions arranged in a predetermined order along the length of the prong. As such, this plug may be referred to as a four region plug. The signal conducting regions include a left audio signal region, a right audio signal region, a ground region, and a microphone region, where the ground region is located between the microphone region and either the left or right audio signal regions. 
     Detection circuitry may be operative to determine whether a microphone type of plug (e.g., a four region plug including a microphone region and two audio regions, or a three region plug including a microphone region and only one audio region) or a non-microphone type of plug (e.g., stereo plug) is inserted into the jack of the electronic device (e.g., mobile phone). The detection circuitry may provide a signal that indicates whether the received plug is a microphone or non-microphone type. For example, when the plug is received, the signal may indicate that a microphone type of plug is received. Detection circuitry may provide another signal that indicates whether a plug is received by the jack. Both signals may be provided to other circuitry, such as a processor, within the electronic device for further processing. 
     Detection circuitry may also detect user activated functions performed in response to user activation of one or more switches included with the headset. For example, the headset may include a single switch for performing a function with respect to a microphone (e.g., end-call function). When the user presses the switch, the detection circuitry may detect the occurrence of a switch activation event and provide a signal indicative of that activation that switch to other circuitry (e.g., a processor) located in the device. In other embodiments, the headset may include multiple switches (e.g., two switches). The detection circuitry may detect which one of the switches is activated and provide a signal indicative of which switch is activated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features of the present invention, its nature and various advantages will become more apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which: 
         FIG. 1  shows a simplified block diagram of portable media player in accordance with an embodiment of the present invention; 
         FIG. 2  shows an illustrative personal media device capable of receiving two different types of plugs in accordance with an embodiment of the present invention; 
         FIG. 3  is a simplified schematic diagram of headset system including stereo headphones, a microphone, and a four region plug in accordance with an embodiment of the present invention; 
         FIG. 4  shows a more detailed yet simplified view of a four region plug in accordance with an embodiment of the present invention; 
         FIG. 5  shows a schematic diagram of detection circuitry in accordance with an embodiment of the present invention; 
         FIG. 6  is an exemplary timing diagram showing the state of the signals provided by detection circuitry in accordance with an embodiment of the present invention; 
         FIG. 7  shows another exemplary timing diagram illustrating operation of detection circuitry using power management in accordance with an embodiment of the present invention; 
         FIG. 8  illustrates an exemplary timing diagram when a plug that does not have a microphone region is inserted into jack  510  in accordance with an embodiment of the present invention; 
         FIG. 9  shows a schematic diagram of detection circuitry including secondary switch detection circuitry according to an embodiment of the present invention; 
         FIG. 10  shows an exemplary timing diagram; 
         FIG. 11  shows a schematic diagram of detection circuitry including alternative secondary switch detection circuitry according to an embodiment of the present invention; 
         FIG. 12  shows an exemplary timing diagram illustrating assertion of signals based on detected current levels using detection circuitry operating in accordance with an embodiment of the present invention; 
         FIGS. 13 and 14  show two illustrative examples of dual switch configurations that may be implemented with respect to a microphone in accordance with a embodiments of the present invention; 
         FIG. 15  is a flowchart illustrating steps that may be implemented by detection circuitry in accordance with an embodiment of the present invention; 
         FIG. 16  is flowchart showing in more detail how one of the steps of  FIG. 15  may be implemented in accordance with an embodiment of the present invention; and 
         FIG. 17  is a flowchart of steps that may be taken when one or more switch activation events are detected in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a simplified block diagram of illustrative portable electronic device  100  in accordance with the principles of the present invention. Device  100  may include processor  102 , storage device  104 , user interface  108 , display  110 , CODEC  112 , bus  118 , memory  120 , communications circuitry  122 , and jack  130 . Processor  102  can control the operation of many functions and other circuitry included in media player  100 . Processor  102  may drive display  110  and may receive user inputs from user interface  108 . 
     Storage device  104  may store media (e.g., music and video files), software (e.g., for implementing functions on device  100 , preference information (e.g., media playback preferences), lifestyle information (e.g., food preferences), exercise information (e.g., information obtained by exercise monitoring equipment), transaction information (e.g., information such as credit card information), wireless connection information (e.g., information that may enable media device to establish a wireless connection such as a telephone connection), subscription information (e.g., information that keeps tracks of podcasts or television shows or other media a user subscribes to), telephone information (e.g., telephone numbers), and any other suitable data. Storage device  104  may include one more storage mediums, including for example, a hard-drive, permanent memory such as ROM, semi-permanent memory such as RAM, or cache. 
     Memory  120  may include one or more different types of memory which may be used for performing device functions. For example, memory  120  may include cache, Flash, ROM, and/or RAM. Memory may be specifically dedicated to storing firmware. For example, memory may be provided for store firmware for device applications (e.g., operating system, user interface functions, and processor functions). 
     Bus  118  may provide a data transfer path for transferring data to, from, or between storage device  104 , codec  112 , communications circuitry  123 , baseband circuitry  124 , memory  120 , and processor  102 . 
     Coder/decoder (CODEC)  112  may be included to convert digital audio signals into an analog signal, which may be provided to jack  130 . For example, CODEC  112  may provide audio signals (e.g., left and right audio signals to jack  130  to be converted into sound by a headset (not shown). In one embodiment, CODEC  112  may provide the left and right audio signals as single ended outputs. CODEC  112  may receive one or more signals from jack  130 . For example, jack  130  may receive audio signals from a microphone included with a headset connected to the jack. In one embodiment, CODEC  112  may receive the microphone audio signals as a differential monaural input. 
     Jack  130  may be constructed to receive single prong plugs of a predetermined length and diameter. For example, jack  130  may receive four region plugs and three region plugs. The plugs may be connected to headsets that may provide microphone and mono or stereo functionality. If desired, the headsets may include integrated switches, that when activated, cause a function to be executed. Examples of headsets that include switches can be found, for example, in commonly assigned Eric Daniels et al. U.S. patent application Ser. No. 11/650,001, filed Jan. 5, 2007, entitled “Bend Switch for Wired Headset,” and Evans Hankey et al. U.S. patent application Ser. No. 60/879,155, filed Jan. 6, 2007, entitled “Wired Headset with Integrated Switch,” both disclosures of which are hereby incorporated by reference herein in their entireties. 
     In addition, jack  130  may include detection circuitry  132 . Various embodiments of detection circuitry are discussed in more detail below. Jack  130  may be electrically coupled to processor  102  to transmit signals between jack  130  and processor  102 . For example, detection circuitry  132  may provide a HEADSET DETECT signal and MIC signal to processor  102 . The MIC signal may indicated the presence of headset having a microphone connected to jack  130  and may indicate when a microphone switch is activated. Processor  102  may interpret the signals received from detection circuitry  132  to determine, for example, which plug type is connected to jack  130  and whether a microphone switch is activated. In other embodiments, detection circuitry  132  may provide three or more signals to processor  102 . For example, when a headset includes two or more switch functions, a signal conducting pathway may be need for each switch function, where one of the pathways may also be used to indicate to processor  102  whether a four region plug is inserted into jack  130 . 
     Communications circuitry  122  may be included in a carrier circuitry portion (delimited by dashed lines  125 ) of device  100 . Carrier circuitry portion  125  may be dedicated primarily to processing telephone functions and other wireless communications (e.g., Wi-Fi or Bluetooth). For example, baseband circuitry  124  may handle telephone functions. It is understood that the carrier circuitry portion operate independent of other device components operating in device  100 . That is, carrier circuitry may be an independently operating subsystem within device  100  that may communicate with other components within device  100 . 
     User interface  108  may allow a user to interact with the device  100 . For example, the user input device  108  can take a variety of forms, such as a button, keypad, dial, a click wheel, or a touch screen. Communications circuitry  122  may include circuitry for wireless communication (e.g., short-range and/or long range communication). For example, the wireless communication circuitry may be wi-fi enabling circuitry that permits wireless communication according to one of the 802.11 standards or a private network. Other wireless network protocols standards could also be used, either in alternative to the identified protocols or in addition to the identified protocol. Another network standard may be Bluetooth. 
     Communications circuitry  122  may also include circuitry that enables device  100  to be electrically coupled to another device (e.g., a computer or an accessory device) and communicate with that other device. As indicated above, communications circuitry  122  may also include baseband circuitry for performing relatively long-range communications (e.g., telephone communications). If desired, communications circuitry  122  may include circuitry for supporting both relatively long-range and short-range communications. For example, communications circuitry  122  may support telephone, Wi-Fi, and Bluetooth communications. 
     In one embodiment, device  100  may be a portable computing device dedicated to processing media such as audio and video. For example, device  100  may be a media player (e.g., MP3 player), a game player, a remote controller, a portable communication device, a remote ordering interface, an audio tour player, a mobile telephone, or other suitable personal device. In another embodiment, media player  100  may be a portable device dedicated to providing media processing and telephone functionality in single integrated unit. Media player  100  may be battery-operated and highly portable so as to allow a user to listen to music, play games or video, record video or take pictures, place and take telephone calls, communicate with others, control other devices, and any combination thereof. In addition, device  100  may be sized such that it fits relatively easily into a pocket or hand of the user. By being handheld, device  100  is relatively small and easily handled and utilized by its user and thus may be taken practically anywhere the user travels. 
       FIG. 2  shows an illustrative portable electronic device  210  capable of receiving two different types of plugs. As shown, plug  230  of headset system  220  and plug  250  of headphone system  240  may be inserted into jack  212 . Headset system  220  can include stereo headset with a microphone  224  which is connected to four region plug  230  via wired link  224 . Stereo headset with a microphone  224  may include left and right speakers and a microphone. 
     Plug  230  may include four signal conducting regions arranged in a predetermined order along the length of a single prong. As shown, plug  230  includes, starting from the tip of plug  230 , a left audio signal region  231 , a right audio signal region  232 , a ground region  233 , and a microphone region  234 . The left and right audio signal regions may be interchanged, however, in this embodiment, ground region is located between the microphone region and the right audio signal region. The regions may be separated by insulating rings  235  that electrically isolate the regions from each other. The electrical connection of headset system  220  is discussed below in more detail in connection with  FIG. 3  and a more detailed of four region plug is discussed below in connection with  FIG. 4 . 
     Headphone system  240  can include stereo headset  242  which is connected to plug  250  via wired link  244 . Stereo headset  242  may include left and right speakers. Plug  250  includes, starting from the tip, a left audio signal region  251 , a right audio signal region  252 , and a ground region  253 . The location of left and right audio regions  251  and  252  may be switched. The regions may be isolated from each by insulating rings  255 . 
       FIG. 3  is an illustrative simplified schematic diagram of headset system  300  including stereo headphones, a microphone, and a four region plug.  FIG. 3  shows how the regions of plug  310  electrically connect to the left and right acoustic elements  330  and  332  (e.g., speakers), and microphone  340 . As shown, the left audio signal region, the right audio signal region, and microphone region can be connected to the positive terminals of left acoustic element  330 , right acoustic element  332 , and microphone  340 , respectively. The ground region can be connected to the negative terminals of left acoustic element  330 , right acoustic element  332 , and microphone  340 , respectively. 
     Headset system  300  may include a switch  350 , for example, to enable a user to activate a function with respect to the microphone. Switch  350  may be connected to the microphone and ground regions of plug  310 . Switch  350  may be a normally OPEN switch, meaning that in its normal state, microphone  340  is permitted to transmit signals to the microphone portion of plug  310 . When switch  350  is CLOSED, microphone  340  is shorted. 
       FIG. 4  shows a more detailed yet illustrative simplified view of a four region plug  400 . Plug  400  includes four regions, delineated by the numbers  1 - 4 , separated by insulating rings  405 . Plug  400  may be a 3.5 mm plug, where the outer diameter of regions  2 - 4  is 3.5 mm. Depending on which headset or headphone system plug  400  is connected to, the regions may be used for different signal conducting purposes. The table accompanying  FIG. 4  shows the signal conducting purpose of each region for several different systems. For example, for a monaural headset, region  1  may be used for a speaker, regions  2  and  3  may be used as ground, and region  4  may be used for a microphone. Note that for the headset, regions  3  and  4  may be combined to form a single region (not separated by an insulating ring), thereby providing a three-region plug. Further note that for the monaural headset, regions  2  and  3  may be combined to form a single region, providing a three-region plug with a ground region between a microphone region and an audio signal region. Alternatively, in the monaural headset, region  2  may exist but may not connect to, for example, a speaker in the headset and region three may be dedicated to ground. 
       FIG. 5  shows an illustrative schematic diagram of detection circuitry  500 . Detection circuitry  500  may be operative to determine whether a microphone type of plug (e.g., a four region plug including a microphone region and two audio regions, or a three region plug including microphone region and only one audio region) or a non-microphone type of plug (e.g., stereo plug) is inserted into the jack of the electronic device (e.g., mobile phone). The detection circuitry may provide a MIC signal that indicates whether the received plug is a microphone or non-microphone type. For example, when the plug is received, a LOW MIC signal may indicate that a microphone type of plug is received. Detection circuitry  500  may also provide a HEADSET DETECT signal that indicates whether a plug is received by the jack. The MIC and HEADSET DETECT signals may be provided to other circuitry, such as a processor, with the electronic device for further processing by that other circuitry. 
     Circuitry  500  includes jack  510  for receiving a plug (e.g., a four region plug). Jack  510  includes MIC connector  512 , GND connector  513 , right connector  514 , left connector  515 , and headset detect connector  516 . Connectors  512 - 515  are staggered such that each connector contacts a different region of a plug inserted into jack  510 . For example, assuming plug  230  of  FIG. 2  is inserted into jack  510 , microphone region  234  contacts MIC connector  512 , ground region  233  contacts GND connector  513 , right region  232  contacts right connector  514 , and left region  231  contacts left connector  515 . 
     Connectors  512 - 515  may be arranged in a particular order to ensure desired jack connector to plug regions contacts are made and to ensure that detection circuitry  500  is able to correctly determine which type of headset (e.g., headset with or without microphone) is connected to jack  510 . The arrangement of connectors  512 - 515  can match that of a four region plug according to the invention. That is, GND connector  513  may be located between MIC connector  512  and right connector  514 . In another embodiment, GND connector  513  maybe located between MIC connector  512  and left connector  515 . 
     MIC connector  512  may be electrically coupled to CODEC circuitry  520  via bias resistor  527  and transistor  532  (e.g., a FET) via resistor  530 . GND connector  512  may be connected to a ground source. Right and left connectors  514  and  515  may be electrically connected to CODEC circuitry  520 . In addition, right and left connectors  514  and  515  may be electrically connected to ground via resistors  522  and  524 , respectively. Headset connector  516  may be electrically connected to a power source, called Vdd, via resistors  528  and  529 . Vdd may also be connected to a terminal of transistor  532  via resistor  534 . 
     Left connector  515  and headset detect connector  516  may be selectively connected together by a normally closed switch  518 . Switch  518  may be CLOSED when no plug is inserted into jack  510 . When CLOSED, Vcc is pulled to ground through resistor  522 . Thus, when switch  518  is CLOSED, the HEADSET DETECT signal, which may be provided to a processor (e.g., processor  102  of  FIG. 1 ), is LOW. A LOW HEADSET DETECT signal may indicate that no plug is inserted in jack  510 . A HIGH HEADSET DETECT signal may indicate that a plug is inserted in jack  510 . The HEADSET DETECT signal may go HIGH when a plug is inserted into jack  510 , the plug causes switch  518  to OPEN. When switch  518  is OPEN, headset detect connector  516  can be pulled up to Vdd. 
     Detection circuitry  500  may provide a MIC signal, for example, to a processor (e.g., processor  102  of  FIG. 1 ). The state of the MIC signal may indicate whether a headset with a microphone is connected to jack  510 . In addition, if a microphone headset is connected to jack  510 , changes in the state of the MIC signal may indicate the occurrence of a switch activation (e.g., a user presses a switch to end a telephone call). 
     MIC signal may be HIGH when transistor  532  is OFF and LOW when transistor  532  is ON. Transistor  532  may be an NMOS transistor. CODEC  520  may bias the gate of transistor  532  so that it is turned ON when a plug is absent from jack  510  and when a plug including a microphone region is inserted into jack  510 . 
     The operation of detection circuitry  500  is now discussed in combination with  FIG. 6 , which is an exemplary timing diagram showing the state of the HEADSET DETECT and MIC signals in accordance with an embodiment of the present invention. Starting at time t 0 , when jack  510  is empty, the both the HEADSET DETECT and MIC signals are LOW. HEADSET DETECT may be LOW because switch  518  is CLOSED, effectively tying connector  516  to ground. MIC signal may be low because CODEC circuitry  520  is biasing transistor  532  to be turned ON, pulling MIC signal to ground. 
     At time t 1 , when a plug with a microphone region is inserted into jack  510 , HEADSET DETECT signal goes HIGH and MIC signal may pulse HIGH due to shorting of wire contacts during plug insertion, but goes LOW. The processor may be configured to ignore any MIC signal until at least a predetermined period of time after HEADSET DETECT goes HIGH to avoid erroneous detection. HEADSET DETECT signal may go HIGH because switch  518  OPENS in response to jack  510  receiving a plug. MIC signal may continue to stay LOW because transistor  532  is still biased to be turned ON (by CODEC circuitry  520 ). 
     Between times t 2  and t 3 , a switch activation event occurs. During this event, MIC signal goes HIGH because transistor  532  is turned OFF. Transistor  532  may be turned OFF when MIC connector  512  is shorted to ground through resistor  524 . For example, MIC connector  512  may be shorted when a switch such as switch  350  of  FIG. 3  is CLOSED. When shorted, the voltage, including a bias voltage provided by CODEC  520 , on connector  512  drops below a threshold voltage on transistor  532 , thereby causing transistor  532  to turn OFF. When transistor  532  is turned OFF, the MIC signal is pulled to Vdd via resistor  534 . After time t 3 , the switch activation event ends, at which point transistor  532  turns back ON, pulling the MIC signal down to ground. 
       FIG. 7  shows another exemplary timing diagram illustrating operation of headset detection circuitry  500  using power management in accordance with the principles of the present invention. Using power management, CODEC circuitry  520  may provide a bias voltage only when a plug is inserted into jack  510 . Starting at time t 0  (an empty jack  510 ), HEADSET DETECT signal is LOW, which may prevent CODEC circuitry  520  from supplying a bias voltage, thus providing power savings. MIC signal is HIGH because no bias voltage is provided to turn transistor  532  ON. At time t 1 , when a plug with a microphone region is inserted into jack  510 , HEADSET DETECT goes HIGH, which may cause CODEC circuitry  520  to provide a bias voltage that turns transistor  532  ON, pulling MIC signal LOW. Between times t 2  and t 3 , a switch activation event occurs, during which MIC signal is HIGH. At time t 4 , the plug is removed, causing HEADSET DETECT signal to go LOW. This causes CODEC circuitry  520  to cease supplying a bias voltage and MIC signal goes HIGH. 
     With respect to  FIGS. 6 and 7 , a processor may determine whether the type of plug inserted into jack  510  is a plug having a microphone region by checking the state of the MIC signal a predetermined time after the HEADSET DETECT signal goes HIGH. In both  FIGS. 6 and 7 , the MIC signal is LOW a predetermined time (e.g., 10 ms) after HEADSET DETECT goes HIGH, thus indicating that a microphone is present. 
       FIG. 8  illustrates an exemplary timing diagram when a plug that does not have a microphone region is inserted into jack  510 . Starting at step to, when no plug is inserted into jack  510 , both HEADSET DETECT and MIC are LOW. At time t 1 , when a plug with a MIC region is inserted into jack  510 , both HEADSET DETECT and MIC go HIGH. MIC may go HIGH because the MIC connector  512  is tied to ground, effectively pulling the gate of transistor  532  to ground, turning it OFF. MIC connector  512  may be coupled to ground connector  513  by a ground region of the plug. For example, assuming that plug  250  of  FIG. 2  is inserted into jack  510 , ground region  255  may electrically couple MIC connector  512  to ground connector  513 . 
       FIG. 9  shows a schematic diagram of detection circuitry  900  including secondary switch detection circuitry  950 . Detection circuitry  900  may be the same as detection circuitry  500 , therefore a detailed discussion of all the components and operation of circuitry  900  is not needed. Secondary switch detection circuitry  950  may be included for detecting switch activation events of headsets including multiple switches. For example, a headset may include two switches, where activation of each switch may perform a different function, and where simultaneous activation of both switches may perform yet another function.  FIGS. 13 and 14  show two illustrative examples of dual switch configurations that may be implemented with respect to a microphone.  FIGS. 13 and 14  show a normally closed switch connected in series with the MIC region of a plug (not shown) and a normally open switch connected in parallel with the MIC region of the plug. The tables accompanying  FIGS. 13 and 14  show which switch is activated, if any, depending on the open and close positions of switches S 1  and S 2 . The table also indicates whether an MIC OPEN event (e.g., an event in which the MIC is electrically disconnected from the jack) or MIC SHORT event (e.g., an event in which the MIC is short circuited to ground. A normal action may occur when switches S 1  and S 2  are in their normal positions. 
     Referring back to  FIG. 9 , secondary switch detection circuitry  950  may monitor a voltage level to determine the occurrence of switch activation events. Detection circuitry  950  may include voltage detection circuitry  952  electrically coupled to node  948 . Voltage detection circuitry  952  provide a HIGH or LOW signal, labeled MIC ACTION DETECT, depending on the voltage seen at node  948 . In one embodiment, the voltage detection circuitry may include a comparator that compares to the voltage at node  948  to a reference voltage. The voltage at node  948  may vary among several different voltage levels. For example, node  948  may see a no plug present voltage, a first switch activation voltage, a second switch activation voltage, a combined first and second switch activation voltage, and a normal operating voltage. Depending on the voltage seen at node  948 , detection circuitry  900  provides the appropriate signals for MIC and MIC ACTION DETECT. 
       FIG. 10  shows an exemplary timing diagram illustrating assertion of signals based on detected voltage levels using detection circuitry  900  operating in connection with a dual switch, such as those shown in  FIGS. 13 and 14 .  FIG. 10  shows the state of the MIC and MIC ACTION DETECT signals and the voltage detected at node  948 , labeled VDETECT. The detected voltage may range from an OPEN MIC voltage to a normal voltage to a MIC short circuit voltage. A normal voltage may be detected when a plug with a microphone is inserted into jack  910  and the microphone is operating in a normal mode (e.g., no switches are being activated), as indicated at time t 0 . The normal voltage may be the voltage produced when the CODEC circuitry biases the microphone and the transistor  932 . Between times t 1  and t 2 , a MIC short circuit event occurs. During the MIC short circuit event, MIC signal goes HIGH and VDETECT goes to the MIC short circuit voltage (or ground). Also, during the MIC short circuit event, the bias voltage is driven to ground, resulting in a negligible voltage at node  948 . Between times t 2  and t 3 , detection circuitry  900  returns to normal operation. Between times t 3  and t 4 , a MIC OPEN event occurs. During the MIC OPEN event, VDETECT may go to OPEN CIRCUIT voltage, which results in MIC ACTION DETECT going HIGH. The voltage at node  948  may be higher during a MIC OPEN event than normal operation because the microphone is no longer biased by the CODEC circuitry. 
       FIG. 11  shows a schematic diagram of detection circuitry  1000  including alternative secondary switch detection circuitry  1050 . Detection circuitry  1000  may be the same as detection circuitry  500 , therefore a detailed discussion of all the components and operation of circuitry  1000  is not needed. Secondary switch detection circuitry  1050  may include current detection circuitry  1054  for detecting a current level flowing through resistor  1052 . Depending on the detected current level, circuitry  1050  may provide the appropriate signal (e.g., HIGH or LOW signal) to MIC ACTION DETECT. 
     In one embodiment, three different current levels may exist. A first current level may correspond to a microphone short condition (e.g. current flow may be high). A second current level may correspond to a normal microphone bias condition (e.g., current flow may be such that the microphone is biased). And a third current level may correspond to a microphone open condition (e.g., current flow may be low and the microphone is no longer biased). Current detection circuitry  1050  may assert MIC ACTION DETECT when the third current level is detected. The MIC signal may be asserted when a microphone short condition exist. 
       FIG. 12  shows an exemplary timing diagram illustrating assertion of signals based on detected current levels using detection circuitry  1100  operating in connection with a dual switch, such as those shown in  FIGS. 13 and 14 .  FIG. 12  shows the state of the MIC and MIC ACTION DETECT signals and the current voltage detected at node  948 , labeled DETECTION CURRENT. DETECTION CURRENT may range from a short circuit current to a normal bias current to an open circuit current. The normal bias current may be detected when a microphone electrically connected detection circuitry  1100  is operating in a normal mode, as indicated between times t 0  and t 1 . Between times t 1  and t 2 , a MIC short event occurs, which may result in MIC signal going HIGH and DETECTION CURRENT going increasing to short circuit current. Between times t 3  and t 4 , a MIC OPEN event occurs, which may result in MIC ACTION DETECT going HIGH and DETECTION CURRENT decreasing to a open circuit current. 
     It is understood that although  FIGS. 9-14  are discussed in terms of handling switch activation event executed by two different switches, circuitry may be provided to detect simultaneous activation of two switches and additional switches. 
       FIG. 15  is an illustrative flowchart of various steps that may be implemented by detection circuitry. Starting at step  1510 , one of at least two types of plugs is received, for example, in a jack of the detection circuitry. For example, the plug may be a four region plug including a microphone region (with a ground region located between the mic region and an audio signal region), a three region plug including a microphone region (with a ground region located between the mic region and an audio signal region), or a three region plug with no microphone region. At step  1520 , a HEADSET DETECT signal may be provided (e.g., asserted) to indicate that a plug has been received. After the HEADSET DETECT signal is asserted, the bias power may be provided to bias, for example, the MIC DETECT transistor (e.g., transistor  532 ), if it is not already being biased. 
     At step  1530 , a determination is made as to which one of the at least two types of plugs is received. This determination may be made a predetermined period of time after the HEADSET DETECT signal has been asserted to provide sufficient “settling time” before making the determination. The determination may be made in one of several different ways, one of which is illustrated in the steps shown in  FIG. 16 . Referring to  FIG. 16 , at step  1610 , bias power is provided. For example, bias power may be provided by CODEC circuitry. At step  1620 , a determination is made as to whether the plug has a microphone region in the anticipated microphone region. If yes, the process proceeds to step  1630 , which provides the bias power to the microphone region. At step  1632  the bias power is provided to MIC detect circuitry. If no, the process proceeds to step  1640 , which provides the bias power to ground. At step  1642 , MIC detect circuitry is electrically coupled to ground. 
     Referring back to  FIG. 15 , after the determination is made at step  1530 , the appropriate MIC signal is provided at step  1540 . For example, if a microphone region is detected, the MIC signal may be LOW, and HIGH if not detected. If a microphone region is not detected, then the MIC DETECT transistor (e.g., transistor  532 ) may be turned OFF to save power. MIC DETECT transistor may be turned by ceasing the supply of the bias power. 
       FIG. 17  is an illustrative flowchart of various steps that may be taken when one or more switch activation events are detected in accordance with the principles of the present invention. Starting at step  1710 , a plug having a microphone region and is electrically connected to at least one microphone switch is received. For example, the plug may be electronically connected to a single or dual switch headset. At step  1720 , the plug may be monitored for a switch activation event. If the headset has two switches, switch activation event caused by both switches may be monitored. For example, one switch may cause an OPEN MIC switch activation event and the other switch may cause a MIC short circuit activation event when activated (e.g. pressed by the user). At step  1730 , a signal is provided in response to a monitored switch activation event. For example, if a single switch headset is connected to the detection circuitry and is activated, the MIC signal may be asserted (for at least the duration of the switch activation event). 
     It is understood that the steps shown in  FIGS. 15-17  are merely illustrative and that steps may be modified, added, or omitted. 
     Thus it is seen that plug with microphone regions and systems and methods detecting such plugs and switch activation events are provided. Those skilled in the art will appreciate that the invention can be practiced by other than the described embodiments, which are presented for purposes of illustration rather than of limitation, and the invention is limited only by the claims which follow.

Metadata:
Filing Date: 20110301
Publication Date: 20130618
Grant Date: 20130618
Priority Date: 20070105
Inventors: JOHNSON TIMOTHY
PANTFOERDER ACHIM
Assignee: APPLE INC
CPC Classifications: [{"code": "H01R13/703", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01R2201/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01R29/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01R24/58", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R29/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/1041", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R3/00", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01R24/58", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04M1/6058", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01R2201/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01R29/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/72412", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04M1/72409", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01R13/703", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04M1/72409", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/6058", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/72412", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 39447475