U.S. patent application number 13/220274 was filed with the patent office on 2011-12-22 for electronic interfacing with a head-mounted device.
Invention is credited to Daniel M. Gauger, JR., Roman Sapiejewski.
Application Number | 20110311071 13/220274 |
Document ID | / |
Family ID | 37137473 |
Filed Date | 2011-12-22 |
United States Patent
Application |
20110311071 |
Kind Code |
A1 |
Gauger, JR.; Daniel M. ; et
al. |
December 22, 2011 |
Electronic Interfacing with a Head-Mounted Device
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.
Inventors: |
Gauger, JR.; Daniel M.;
(Cambridge, MA) ; Sapiejewski; Roman; (Boston,
MA) |
Family ID: |
37137473 |
Appl. No.: |
13/220274 |
Filed: |
August 29, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11191873 |
Jul 28, 2005 |
8031878 |
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13220274 |
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Current U.S.
Class: |
381/74 |
Current CPC
Class: |
H04R 1/1025 20130101;
H04R 1/1008 20130101; H04R 1/1058 20130101; H04R 5/033 20130101;
H04R 1/1083 20130101; H04R 1/1041 20130101 |
Class at
Publication: |
381/74 |
International
Class: |
H04R 1/10 20060101
H04R001/10 |
Claims
1. A method comprising: upon coupling of a first device to a second
device, providing power from the second device to the first device;
receiving a signal conveying a preset value from the first device
at the second device; on the basis of the preset value, determining
whether the first device is compatible with the second device; and
if the first device is determined to be compatible with the second
device, providing the power from the second device to the first
device at a greater power level than if the first device is not
determined to be compatible with the second device.
2. The method of claim 1 further comprising: if the first device is
determined to be compatible with the second device, accepting
signals from the first device at the second device.
3. The method of claim 1 wherein the communicating of the signal
and the providing of the power are carried out over a shared
conductor between the first device and the second device.
4. The method of claim 1 wherein the first device comprises at
least one of a headphone and a headset.
5. The method of claim 1 wherein the second device comprises at
least one of a portable music player, a radio, or a cell phone.
6. The method of claim 1 wherein the first device comprises at
least one of a portable music player, a radio, or a cell phone.
7. The method of claim 1 wherein the second device comprises at
least one of a headphone and a headset.
8. An apparatus comprising: a connector for coupling to a cable
bearing one or more electrical conductors; a power supply for
providing power to at least one conductor in the cable; and a
processor coupled to the connector and to the power supply and
configured to: receive a signal conveying a preset value on one of
the conductors in the cable, on the basis of the preset value,
determine whether a source of the signal is compatible with the
apparatus, and if the source of the signal is determined to be
compatible with the apparatus, cause the power supply to provide
the power to the at least one conductor at a greater power level
than if the source of the signal is not determined to be compatible
with the apparatus.
9. The apparatus of claim 8 wherein the processor is further
configured to accept signals from the source of the signal if the
source was determined to be compatible with the second device.
10. The apparatus of claim 8 wherein the power supply provides
power to the source over the same electrical conductor on which the
signal was received.
11. An apparatus comprising: a cable bearing one or more electrical
conductors; and a processor coupled to the conductor and configured
to: receive power from at least one of the conductors in the cable,
in response to receiving the power, transmit a signal conveying
preset value on one of the conductors in the cable, and use the
power from the at least one conductor to operate additional
circuitry.
12. The apparatus of claim 11 wherein the processor is further
configured to transmit additional signals.
13. The apparatus of claim 11 wherein the processor is configured
to receive the power and transmit the signal over the same
electrical conductor.
14. The apparatus of claim 11 further comprising at least one of a
headphone and a headset.
15. The apparatus of claim 11 further comprising at least one of a
portable music player, a radio, or a cell phone.
16. A system comprising a first device and a second device, the
first device comprising: a cable bearing one or more electrical
conductors; and a first processor coupled to the conductors in the
cable and configured to: receive power from the second device over
at least one of the conductors in the cable, and in response to
receiving the power, transmit a signal conveying preset value to
the second device on one of the conductors in the cable; the second
device comprising: a connector for coupling to the cable; a power
supply providing the power to the first device over the at least
one conductor; and a second processor coupled to the connector and
to the power supply and configured to: receive the signal from the
first device on the one conductor, on the basis of the preset
value, determine whether the first device is compatible with the
second device, and if the first device is determined to be
compatible with the second device, cause the power supply to
provide the power to the first device over the one or more
conductors at a greater power level than if the first device is not
determined to be compatible with the second device.
17. The system of claim 16, wherein the first processor is
configured to receive the power and transmit the signal over the
same electrical conductor.
18. The system of claim 16, wherein the power supply provides the
power to the first device over the same electrical conductor on
which the signal was received.
19. The system of claim 16 wherein the first device comprises at
least one of a headphone and a headset.
20. The system of claim 16 wherein the second device comprises at
least one of a portable music player, a radio, or a cell phone.
21. The system of claim 16 wherein the first device comprises at
least one of a portable music player, a radio, or a cell phone.
22. The system of claim 16 wherein the second device comprises at
least one of a headphone and a headset.
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'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's handshaking and power management features) regarding
one another'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.
BRIEF DESCRIPTION OF THE FIGURES
[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.
DETAILED DESCRIPTION
[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 MP3 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 sleeve 110 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'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.
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.
[0043] 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.
[0044] 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.
[0045] 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 RI1*Cto (items 224 and 214),
since RI2 is normally much greater than RI1 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).
[0046] 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 RI1 224 in the RI1/RI2 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.
[0047] 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.
[0048] 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.
[0049] 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.
[0050] 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.
[0051] 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'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 Uh 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.
[0052] 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.
[0053] 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 RcI
344 (typically 1 ohm) and limit setting resistors RI1 346 and RI2
348.
[0054] 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.
[0055] 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.
[0056] 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.
[0057] 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.
[0058] 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.
[0059] Other embodiments are also within the scope of the following
claims.
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