Abstract:
Power is delivered from a power source in a head-mounted device to a separate accessory that is coupled to the head-mounted device. Power and signals are delivered on a common conductor that couples the head-mounted device to an accessory. One or both of the head-mounted device and the accessory are configured based on the signals. Power may be received at an accessory from the head-mounted device through a dedicated power conductor. Power may be delivered from a power source in a portable accessory to a head-mounted device that is coupled to the portable accessory and uses the power for circuitry in the head-mounted device that delivers audio to a user.

Description:
BACKGROUND  
       [0001]     This description relates to electronic interfacing with a head-mounted device.  
         [0002]     Audio signals, for example, are typically carried to a headphone through a multiple-conductor cable ending in a plug that fits into a jack of a player or radio. When a microphone is added to the headphone to form a headset, the microphone signal also may be carried through the same cable to a device that uses the microphone signal, such as a telephone set or a recorder. In aviation headsets, the cable may be detachable at a jack on the headset to permit changes in the use of the headset.  
         [0003]     The connecting cable may also be disconnected from typical noise reduction headphones when the user is using only the noise reduction feature and is not using audio from a player or radio. The circuits that are part of noise reduction headphones may be powered by batteries mounted in the headphones.  
         [0004]     In some military communication headsets, a detachable microphone plug may both carry the microphone signal to an intercom circuit and microphone power.  
         [0005]     Headsets that can be plugged into cell phones for hands-free use commonly use electret microphones that receive bias voltage from the cell phone&#39;s power source.  
         [0006]     Portable music players may provide power to run electronics in peripheral devices such as transmitters to an FM radio in, for example, an automobile.  
         [0007]     In the Universal Serial Port (USB) standard, power may be provided by a USB host or hub to a USB peripheral through a USB connector. The host and peripheral may exchange messages (using the USB standard&#39;s handshaking and power management features) regarding one another&#39;s identity and operational parameters. The messages may include how much power the peripheral will use in different operational states or the amount of memory available in the peripheral. USB headsets may be configured as peripherals in interaction with other devices.  
       SUMMARY  
       [0008]     In general, in one aspect, power is delivered from a power source in a head-mounted device to a separate accessory that is coupled to the head-mounted device.  
         [0009]     In general, in another aspect, power and signals are delivered on a common conductor that couples a head-mounted device to an accessory.  
         [0010]     In general, in another aspect, signals are passed back and forth between a head-mounted device and an accessory that is coupled by conductors to the head-mounted device, and one or both of the head-mounted device and the accessory are configured based on the signals.  
         [0011]     In general, in another aspect, power is received at an accessory from a head-mounted device through a power conductor, for example, a dedicated power conductor.  
         [0012]     In general, in another aspect, an audio device to be mounted on a head comprises a transducer to deliver sound to an ear and a power source, and a conductor delivers power from the power source to an accessory coupled to the audio device.  
         [0013]     In general, in another aspect, an audio device mounted on a head includes a transducer to deliver sound to an ear, a power source, and a signaling device, and a common conductor carries power from the audio device to an accessory and signals between the audio device and the accessory.  
         [0014]     In general, in another aspect, an audio device to be mounted on a head includes a transducer to deliver sound to an ear, a signaling device to communicate with an accessory that is connected to the audio device, and a wired channel to carry configuration signals back and forth between the head-mounted audio device and the accessory.  
         [0015]     In general, in another aspect, an audio device to be mounted on a head includes a transducer to deliver sound to an ear, a power source, and a dedicated power conductor to deliver power from the power source to an accessory coupled to the audio device, and a wired channel carries configuration signals back and forth between the head-mounted audio device and an accessory that is connected to the audio device.  
         [0016]     In general, in another aspect, an accessory to be coupled to a head-mounted device has a conductor to connect to a dedicated power conductor of the device to receive power for the accessory.  
         [0017]     In general, in another aspect, an accessory having a signaling device conducts wired communication of configuration signals with a head-mounted device.  
         [0018]     In general, in another aspect, an accessory having a common conductor carries power and signals between the accessory and a head-mounted device.  
         [0019]     In general, in another aspect, an accessory has a device that uses power and a conductor receives power for the device from a head-mounted device.  
         [0020]     In general, in another aspect, power is delivered from a power source in a portable accessory to a head-mounted device that is coupled to the portable accessory and uses power for circuitry in the head-mounted device that delivers audio to a user.  
         [0021]     Implementations may include one or more of the following features. The head-mounted device comprises at least one of a headphone and a headset. The head-mounted device comprises an audio device. The head-mounted device includes at least one of active noise reduction circuitry, amplification circuitry, or audio processing circuitry. The accessory comprises at least one of a music player, a wireless receiver, a wireless transceiver, or a radio. The device and the accessory are coupled using a detachable cable that includes the conductor. The signals comprise at least one of command, control, or management signals. The power is delivered from a source of power in the head-mounted device. The source of power comprises a battery. The accessory is peripheral to the head- mounted device. The power conductor is dedicated to delivering power.  
         [0022]     Other advantages and features will become apparent from the following description and the claims. 
     
    
     DESCRIPTION  
       [0023]      FIG. 1  is a front view of a headphone partially cutaway.  
         [0024]      FIG. 2  is a perspective view of an accessory module and a headphone.  
         [0025]      FIGS. 3 and 4  are schematic diagrams.  
         [0026]      FIG. 5  is a side view of a headphone jack.  
         [0027]      FIG. 6  is a block diagram. 
     
    
       [0028]     As shown in the specific example of  FIG. 1 , an audio headphone  100  is served by a detachable accessory cable  400  that provides an interface between the headphone and an accessory (not shown), for example, a stereo or MP 3  player, a microphone for voice sensing, an aviation or helicopter interface cable, a cable connection to a USB host, or a module  162  (described below) that connects directly to the headphone  100 . The headphone  100  is an example of a head-mounted device. A headset (which includes a microphone) is another example. The phrase head-mounted device is meant to include every possible sort of electronic device that is mounted on the head or any part of the head (for example an ear or a nose or the hair) for use by a wearer.  
         [0029]     The detachable accessory cable  400  may allow for a functional reconfiguration of the headphone  100  for various platforms. For example, an internal battery  160  that is used to power electronics  134  and  136  (e.g., Active Noise Reduction, ANR) in the headphone  100  may also be used to power electronics in the accessory cable  400  or in the accessory to which the cable is connected.  
         [0030]     The connection between the detachable accessory cable  400  and the headphone  100  may be through a 3.5 mm, 0.25 in, or other diameter jack plug or telephone plug  410 . Other types of connectors may be used, for example connectors similar to the parallel- contact ones commonly found on some cell phones. Power may be supplied from the headphone  100  to the accessory cable  400  by one of the four metal contacts of the plug  410 . The power provided by the headphone  100  to the electronics in the accessory cable  400  may be voltage regulated power, current regulated power, raw battery power, DC, AC, fuel cell, or solar cell, or any other power source.  
         [0031]     In addition to providing power, the detachable accessory cable  400  may serve as a wired channel to carry control or management signals between the headphone  100  and the accessory, for example, for use in handshaking and configuration (described below).  
         [0032]     The headphone  100  includes a left earcup  102  and a right earcup  104  connected to a headband  106  that includes a left adjustment sleeve  108  fixed to a center span  112  by a connector  109  and a right adjustment sleeve  110  connected to the center span  112  by a connector  111 . In some examples, the headband  106  may be comprised of other numbers and configurations of elements. The left adjustment sleeve  108  and the right adjustment sleeve allow the wearer to adjust the position of the left earcup  102  and the right earcup  104  relative to the center span  112  to accommodate size requirements and comfort preferences of different wearers.  
         [0033]     Shown as a partial cutaway in  FIG. 1 , the left earcup  102  includes an earcup housing  114 , an earcup cover  118 , an earcup audio seal (not shown in  FIG. 1 ), and an earcup angular adjustment mount  126 .  
         [0034]     Similarly, the right earcup  104  (also shown as a partial cutaway in  FIG. 1 ) includes an earcup housing  116 , an earcup cover  120 , an earcup audio seal  124 , and an earcup angular adjustment mount  128 .  
         [0035]     The earcup cover  118  is connected to the earcup housing  114  to define a left earcup chamber  130 . The earcup cover  120  is connected to the earcup housing  116  to form a right earcup chamber  132 . The left and right earcup chambers  130  and  132  contain left and right electronics  134  and  136 , respectively. In the example of  FIG. 1 , the left and right electronics  134  and  136  provide and control headphone  100  functions that may include ANR, headphone power supply, and accessory power management (described below).  
         [0036]     The left earcup  102  is rotatably connected to the left adjustment sleeve  108  by the earcup adjustment mount  126 . The earcup adjustment mount  126  may comprise one or more rotational connectors  142  and  146 . The earcup adjustment mount  126 , as shown in this example, may comprise a rotational pin  146  and a rotational connector  142 . The rotational pin  146  enables the left earcup  102  to be rotatably adjusted about an axis  150 . The rotational connector  142  enables the left earcup  102  to be rotatably adjusted about a longitudinal axis  138 .  
         [0037]     Similarly, the right earcup  104  is rotatably connected to the right adjustment sleevel  10  by the earcup adjustment mount  128 . The earcup adjustment mount  128  may comprise one or more rotational connectors  144  and  148 . The earcup adjustment mount  128 , as shown in this example, may comprise a rotational pin  148  and a rotational connector  144 . The rotational pin  148  enables the right earcup  104  to be rotatably adjusted about an axis  152 . The rotational connector  144  enables the right earpiece  104  to be rotatably adjusted about a longitudinal axis  140 .  
         [0038]     In  FIG. 1 , the audio headphone  100  is shown in a stowage position. The left earcup  102  and the right earcup  104  have been rotated about longitudinal axes  138  and  140 , respectively. In the stowage position, the earcup cover  118  of the left earcup  102  and the earcup cover  120  of the right earcup  104  lie in a common plane.  
         [0039]     The cutaway of the earcup cover  118  reveals an opening to an accessory insertion channel  153  for the accessory plug  410 . The cutaway of the earcup cover  118  also reveals the electronics  134  that may be contained within the left earcup chamber  130 . The electronics  134  may include a jack  154  that mates with the plug  410  of the accessory cable  400  to permit electronic interfacing with the accessory power management circuit, left earcup speaker, and the left earcup ANR electronics. Similarly, the cutaway of the earcup cover  120  reveals the electronics  136  which may be contained within the right earcup chamber  132 . The electronics  136  includes an ANR enable switch  158 , the battery  160  for the headphone power supply, the headphone power supply circuit, the right earcup speaker, and the right earcup ANR electronics.  
         [0040]     Referring to  FIG. 2 , an example accessory module  162  connects directly through the accessory insertion channel  153  using an accessory plug  410  mounted on the accessory module  162 , rather than using a cable. The earcup cover  118  of the left earcup  102  has been removed to reveal the electronics  134  mounted within the left earcup chamber  130 . The electronics  134  revealed by the removal of the earcup cover  118  may include the accessory power management electronics  164 , left earcup speaker  166 , and the left earcup ANR electronics  168 .  
         [0041]     The example accessory module  162  includes electronics  170  that provide the wearer with a hands-free wireless (e.g., Bluetooth) connection to a cell phone (not shown). The accessory module  162  also may include a microphone  172  that may pick up the sound of a wearer&#39;s voice. The accessory module  162  and the microphone  172  receive power from the headphone battery  160 . In some implementations, the accessory module may include electronics  170  that, for example, provide the wearer with a wireless connection to a stereo or MP3 player audio source, an aviation or helicopter interface, a USB host, or the like.  
         [0042]     The detachable module  162  may allow for a functional reconfiguration of the headphone  100  for use on a variety of platforms. For example, the headphone  100  may contain an internal battery (not shown) to power the ANR electronics  168  in the headphone  100 . The internal battery may be used to power electronics in the accessory module  162  that may interface with the headphone  100 . The power may be supplied from the headphone  100  to the accessory module  162  by one of the contacts on the plug  410 .  
         [0043]     The power provided by the headphone battery  160  to the electronics  170  in the accessory module  162  may be raw battery power, power that is voltage or current regulated by the accessory power management electronics  164  (discussed in  FIGS. 3 and 4 ), or any other power source.  
         [0044]     Some implementations may include signaling capabilities between the headphone  100  and the accessory module  162 . The signaling capabilities may be used for a wide variety of purposes and functions, including handshaking, power supply configuration, or signal configuration between the headphone  100  and the accessory module  162 .  
         [0045]     As shown in  FIG. 3 , an example circuit  200  that may be mounted in the headphone includes a boost converter  202  to power the ANR headphone electronics  204  and an accessory power management circuit  206 . Circuit  200  is a portion of headphone right earcup electronics  136  or alternatively a part of left earcup electronics  134  or in some other location in the headphone. The accessory power management circuit  206  may turn off the power supply to the accessory (e.g.,  400  and  162 ) if the current drawn by the accessory (e.g.,  400  and  162 ) exceeds a maximum predetermined supply threshold.  
         [0046]     The operation of the accessory power management circuit  206  is as follows. When the headphone  100  is first turned on using switch  230 , Vcc  208  increases to a nominal value of 2.8 Vdc because of the action of boost circuit  202 . The +input pin  210  of comparator Uc  212  is held to a low voltage as capacitor Cto  214  charges. The −input pin  216  of comparator Uc  212  is held to a higher voltage through Rb  218  so the comparator Uc  212  will initially pull its output low, turning on MOSFET Qa  220 . MOSFET Qa  220  provides power Va  222  to the accessory (e.g.,  400  and  162 ). The time constant which is approximately R 11 *Cto (items  224  and  214 ), since R 12  is normally much greater than R 11  may be chosen so that Qa  220  may be held on by +input pin  210  of comparator Uc  212  being held to a low enough voltage for the duration of any initially high turn-on current spikes drawn by the accessory (e.g.,  400  and  162 ).  
         [0047]     Subsequently, if the current drawn from Va  222  by the accessory (e.g.,  400  and  162 ) exceeds a predetermined value such that the voltage drop across the sense resistor Rs  228  exceeds the drop across R 11   224  in the R 11 /R 12   224 / 226  divider, then comparator Uc  212  output will go to logic high level, Qa  220  will turn off, and Va  222  will fall to essentially zero, latching the accessory (e.g.,  400  and  162 ) power off. The wearer would need to turn the headphone  100  power off and back on using the switch  230  in order to once again provide power to the accessory (e.g.,  400  and  162 ). This example is just one possible implementation.  
         [0048]     Some implementations of the accessory power management circuit  206  may include replacing the accessory power management circuit  206 , as shown in  FIG. 3 , with no power management. In such examples, Va  222  may be directly connected to Vcc  208  and current limiting in the power supply  202  may be desirable. Possible current limiting implementations may include a resistor, a circuit, or a device that clamps the current to a maximum value (e.g., a Junction Field Effect Transistor (JFET) connected to limit current to its saturation value Idss). Another example may include a voltage regulator (either switching or linear) to regulate Vcc  208  to the Va  222  required by the cable or module accessories  400  and  162 . In some implementations for power management, the headphone power supply  202  may also be a raw voltage or a higher voltage (e.g., lithium polymer) from a battery  232  and a buck converter to create the Vcc  208  that the headphone  100  requires.  
         [0049]     Referring to  FIG. 4 , in some examples of the circuit  300  power management and signaling electronics  304  enable signaling between the headphone  100  and the powered accessory device  302  on a conductor shared with voltage Va  318  provided to the accessory  302 . For example, the circuit  300  may enable electrical handshaking and configuration signaling between the headphone  100  and the powered accessory device  302 . The electronics  304  could replace the power management circuitry  206  with circuitry to implement an exemplary handshaking and configuration protocol between the headphone  100  and accessory  302  while also managing power flow. The protocol may allow the accessory  302  to pass a binary or integer value N to the headphone  100  upon power-up. This value N may be used to identify whether the accessory  302  is compatible for use with that headphone  100  or to configure the headphone  100  in some fashion.  
         [0050]     Examples of headphone  100  configurations may include presenting a 32 ohm load through a cable connection accessory cable  400  to a typical audio source (e.g., home stereo) to emulate traditional passive consumer headphones. Another example may include switching the left and right inputs  306  and  308  of the headphone  100  to a high impedance state when connected to a wireless accessory module  162  to minimize power consumption and draw on the battery  310 .  
         [0051]     In such examples, the circuit includes two microcontrollers  312  and  314 . The microcontroller Uh  312  is part of the headphone electronics  134 . The microcontroller Ua  314  is part of the accessory  302  electronics. The two microcontrollers  312  and  314  may be Microchip Technology Inc. PIC-10F integrated circuits. Some implementations may use more sophisticated controllers that may already be present in the electronics of either the headphone  100  or the accessory  302  to accomplish similar or additional functions. The microcontrollers  312  and  314  may have code that may be flashed into memory to allow the implementation of the following handshaking and configuration protocol: while the headphone  100  power switch  352  is turned to the on position, the microcontroller Uh  312  checks input I  316  periodically (typically every 10 milliseconds) to see if the voltage Va  318  is low. This is to detect the mating (or presence upon power up) of an accessory  302 .  
         [0052]     When an accessory  302  is mated, the capacitor Cdd  320  (typically 10 uF) charges through the resistor Rb  322  (typically 2 Kohm) until the voltage is high enough for the microcontroller Ua  314  to be enabled. The microcontroller Ua  314  then waits several time constants Rb*Cdd  322  and  320 , allowing Ua&#39;s  314  supply input feed by the voltage of Cdd to approach Vcc  326  less the drop across the Schottky diode Ddd  328 , before pulling the output S  330  to a logic low level. S  330  is held at a logic low level long enough (typically 15 milliseconds) for the microcontroller Uh  312  to detect the presence of accessory  302 . Rhs  332  is of a small enough value to ensure that Va  318  is pulled below a predetermined threshold of microcontroller Uh  312  input I  316 . At wake-up, and during all handshaking, microcontroller Ua  314  pin O  350  is held high to keep MOSFET Qa  336  off, preventing the accessory  302  from operating. After having held output S  330  to a logic low level for 15 milliseconds (typically), microcontroller Ua  314  then releases S  330  to allow Cdd  320  to recharge to ensure sufficient voltage to keep powering microcontroller Ua  314  (typically 40 milliseconds). When microcontroller Uh  312  detects that input I  316  (voltage Va  318 ) has returned to a logic high state it begins checking pin I  316  much more often (i.e., every 100 microseconds). This begins the accessory handshake sequence. After Cdd  320  recharges, the microcontroller Ua  314  pulls S  330  to a logic low level for 150 microseconds (typically), ensuring that the microcontroller Uh  312  detects that the input I  316  (voltage Va  318 ) is at a logic low level. When the microcontroller Uh  312  detects Va  318  is at a logic low level it zeros a handshake register. The microcontroller Ulh  312  continues checking the state of input I  316  every 100 microseconds. Every fourth check (i.e., every 400 microseconds) the value in the handshake register is incremented by one.  
         [0053]     After the first 150 microsecond (typically) strobe of pin S  330 , the microcontroller Ua  314  waits some multiple N of 400 microseconds to strobe output S  330  low for another 150 microsecond (typically) interval. The value of N is the information the accessory  302  wishes to pass to the headphone  100  during the handshaking process. When the microcontroller Uh  312  detects that the microcontroller Ua  314  has pulled Va low a second time, the 100-microsecond checking cycle and the handshaking process is complete with the handshake register now containing the value N passed from the accessory  302 . In the circuit  300 , as shown, N is compared against a stored list in the headphone  100  to determine if the accessory is compatible. If the accessory is compatible, the microcontroller Uh  312  pulls output O  334  low turning on the MOSFET Qh  338  to provide power to the accessory  302 . The gate of Qh  338  has been held to a logic high level by a pull-up resistor Rgh  340 . The output O  334  could also be passed to the ANR electronics  336  to accomplish some other configuration, such as the impedance matching mentioned earlier.  
         [0054]     Meanwhile, after the second handshake-completing strobe of pin S  330 , the microcontroller Ua  314  waits for the microcontroller Uh  312  to complete the handshake process and configure the headphone  100 . It then pulls the output O  350  low, turning on the MOSFET Qa  336 , providing power to the accessory  302  electronics. After the microcontroller Uh  314  turns on Qh  338 , the microcontroller Uh  312  then begins monitoring comparator inputs C+  342  and C−  324 . If C−  324  falls below the value at C+  342 , the accessory  302  has drawn current exceeding the designed limit and transistor Qh  338  is turned off by microcontroller Uh  312  output O  334 . The current limit is determined by current sense resistor Rcl  344  (typically 1 ohm) and limit setting resistors R 11   346  and R 12   348 .  
         [0055]     Referring to  FIG. 5 , the body  470  of the accessory plug  410  may contain embedded or in-line electronics to perform various functions, such as audio and voice level control or passive configuration to an accessory. The body  470 , as shown, may also contain a switch  480  that may be configured for use as an on/off power switch, an audio attenuation switch, a mute switch, or the like. Alternatively, body  470  may be enlarged as shown in  FIG. 2  to house all accessory electronics.  
         [0056]     The plug  410  may mate with the jack  154  through the accessory insertion channel  153  in the headphone  100 . The accessory plug  410  may contain a strain relief  490  and be coupled to a single, dual, or multiple conductor cable  420  connection to an accessory. The cable  420  and plug  410  may provide the headphone  100  with the physical ability to interface with, for example, an audio output from a stereo or MP3 player, a hands-free connection to a cell phone (wired or wireless), a microphone for voice sensing, an aviation or helicopter, a connection to a USB host, or the like. For this purpose the other end of the cable may be fitted with a plug, a socket, or another kind of connector or be wired directly to the accessory. Or as previously described, the accessory can be attached directly to the plug without the use of any cable.  
         [0057]     The plug  410  of the accessory cable  400  comprises four separate contacts that allow the headphone to connect to the accessories. The contacts may, in this example be configured to serve a power circuit  430 , a left audio channel  440 , a right audio channel  450 , and a common or ground circuit  460 . In some implementations, the power circuit  430  may be configured as a handshaking, configuration control, or communication interface line (e.g., Va  318 , as described above) between the headphone  100  and the accessory. Conductors in the cable are connected respectively to each of the contacts.  
         [0058]     In some implementations, one or more of the contacts and cable conductors can be dedicated to and carry only power, one or more others may be dedicated to and carry only audio signals, one or more others may be dedicated to carry only control, management, or command signals, or one or more contacts and cable conductors may carry any combination of power, audio signals, and control/command/management signals by appropriate multiplexing techniques. In some implementations, connectors other than a coaxial multi-contact phone plug may be used to connect the headphone to the accessory. In some implementations, the cable is permanently attached to the head-mounted device, and accessories are connected to the free end of the cable.  
         [0059]     In some implementations, for example, as shown in  FIG. 6 , an accessory  600  such as a portable music player, radio, cell phone, or other audio communication device may have its own internal power source  604 , and the power from that source may be carried by a conductor  605  to power electronic circuits  606  involved in providing audio to a user within a head-mounted device  608 , for example, an ANR circuitry, amplification circuitry or other audio processing circuitry in a headphone.  
         [0060]     Other embodiments are also within the scope of the following claims.