U.S. patent application number 10/796526 was filed with the patent office on 2004-12-23 for automatic turn-on and turn-off control for battery-powered headsets.
Invention is credited to Wurtz, Michael.
Application Number | 20040258253 10/796526 |
Document ID | / |
Family ID | 31890792 |
Filed Date | 2004-12-23 |
United States Patent
Application |
20040258253 |
Kind Code |
A1 |
Wurtz, Michael |
December 23, 2004 |
Automatic turn-on and turn-off control for battery-powered
headsets
Abstract
Some workers wear headsets to protect their hearing from loud
persistent noises, such as airplane engines and construction
equipment. These headsets are generally passive or active, with the
active ones including ear speakers and automatic noise-reduction
(ANR) circuitry to cancel or suppress certain types of loud
persistent noises. One problem with active headsets, particulary
those that are battery-powered, concerns battery life. Workers
often take the headset off or store them without turning them off
and thus wasting costly battery life. Accordingly, the inventor
devised active headsets with automatic turn-on and/or turn-off
circuits. One exemplary embodiment senses a condition of the
headsets, for example, the light, pressure, or temperature within
one earcup, and then turns the headset on or off in response to the
sensed condition.
Inventors: |
Wurtz, Michael; (St. Paul,
MN) |
Correspondence
Address: |
SCHWEGMAN, LUNDBERG, WOESSNER & KLUTH, P.A.
P.O. BOX 2938
MINNEAPOLIS
MN
55402
US
|
Family ID: |
31890792 |
Appl. No.: |
10/796526 |
Filed: |
March 9, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10796526 |
Mar 9, 2004 |
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09518917 |
Mar 6, 2000 |
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6704428 |
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60123150 |
Mar 5, 1999 |
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Current U.S.
Class: |
381/71.6 ;
381/72 |
Current CPC
Class: |
G10K 11/17875 20180101;
H04R 2460/03 20130101; G10K 2210/108 20130101; A61F 2011/145
20130101; G10K 11/17855 20180101; H04R 1/1041 20130101; H04R 1/1083
20130101; H04R 5/033 20130101; G10K 11/1783 20180101; G10K
2210/1081 20130101; G10K 11/17821 20180101 |
Class at
Publication: |
381/071.6 ;
381/072 |
International
Class: |
A61F 011/06; G10K
011/16; H03B 029/00 |
Claims
1-8. (Canceled)
9. An active headset having at least two operating states and
comprising: one or more earcups; means for sensing a condition that
is within at least one of the earcups; and means, responsive to a
perceived absence of the condition, for changing the operating
state of the headset.
10. The active headset of claim 9 wherein the condition is
inaudible.
11. The active headset of claim 10 wherein the means for sensing a
condition within at least one of the earcups includes a microphone
coupled to a bandpass filter, the bandpass filter coupled to a
threshold detector, the threshold detector coupled to a processor,
and the processor coupled to a power switch.
12. The active headset of claim 9 wherein one of the two operating
states is an on state and the other is an off or standby state, and
wherein the means for changing the operating state of the headset
is responsive to the sensed condition to change from the on state
to the off or standby state.
13. The active headset of claim 9 wherein the means for sensing a
condition includes an audio transducer, light sensor, a pressure
sensor, or a temperature sensor.
14. The active headset of claim 9 wherein the means for sensing a
condition senses movement or acceleration.
15. An ANR headset having at least two operating states and
comprising: one or more earcups; means for sensing a condition
based on user jaw movements or blood movement within a user's head;
and means for changing the operating state of the headset from an
on state to an off state in response to a perceived absence of the
condition.
16. The headset of claim 15 wherein the predetermined period of
time is at least one minute.
17. An ANR headset having at least two operating states and
comprising: one or more earcups; means for sensing a condition
based on user jaw movements or blood movement, wherein the means
for sensing includes a first audio transducer within one of the
earcups; and means, coupled to the means for sensing the condition,
for changing the operating state of the headset from an on state to
an off or standby state, wherein the means for changing the
operating state includes a bandpass filter, a threshold detector, a
processor, and a power switch, with the bandpass filter coupled
between the threshold detector and the first audio transducer and
the processor coupled between the threshold detector and the power
switch.
18. The headset of claim 17, wherein the means for changing the
operating state of the headset changes the operating state from the
on state to the off state in response to perceived absence of the
condition for at least one minute.
19. The headset of claim 17 further including means for changing
the operating state of the headset from the off state to the on
state.
20. The headset of claim 17, wherein the one earcup engages the
head of a user to define a volume and the means for sensing senses
changes of the volume.
21. An ANR headset having at least an active operating state and an
inactive or standby operating state and comprising: one or more
earcups; an ANR microphone for sensing a condition based on user
jaw movements or blood movement within the user's head; a timer
circuit for measuring duration of a perceived absence of the
condition; and a switch coupled to the timer circuit for switching
the ANR headset from one of the active and inactive operating
states to the other of the active and inactive operating
states.
22. The ANR headset of claim 21, wherein the timer circuit
comprises: a threshold detector; and a microprocessor coupled to
the threshold detector and to the switch.
23. The ANR headset of claim 21, wherein the predetermined amount
of time is at least one minute.
24. A method of operating an ANR headset including an audio
transducer attached to an earcup for engaging the ear of a user,
the method comprising: sensing a condition; and switching at least
a portion of the ANR headset from an active state to an inactive or
standby state in response to a perceived absence of the condition
for at least a predetermined amount of time.
25. The method of claim 24, wherein switching at least the portion
of the ANR headset comprises switching in response to sensing an
absence of certain frequency content from the output of an audio
transducer within the cavity for an amount of time of at least one
minute.
26. The method of claim 24, wherein the ANR headset includes an ANR
driver within the cavity and ANR circuitry coupled to the ANR
driver; and wherein the method further comprises switching the ANR
circuitry from the inactive state to the active state in response
to sensing deflection of a portion of the ANR driver.
27. The method of claim 24, wherein the certain frequency content
is no greater than five Hertz.
28. The method of claim 27, wherein switching at least a portion of
the ANR headset from an active state to an inactive state in
response to a perceived absence of the condition comprises:
starting a timer in response to sensing the condition, with the
timer configured to expire after measuring the predetermined amount
of time; and switching at least the portion of the ANR headset from
the active state to the inactive state in response to expiration of
the timer.
29. An ANR headset comprising: an input node for receiving an
electrical signal correlated with a user wearing the headset; and a
digital processor coupled to the input node and configured to issue
a turn-off command signal for at least a portion of the ANR headset
after perceiving an absence of the electrical signal at the input
node for at least a predetermined period of time.
30. The ANR headset of claim 29, wherein the electrical signal has
a frequency less than 5 Hertz.
31. The ANR headset of claim 29, further comprising: circuitry,
coupled to the input node, for detecting and indicating detection
of a condition based on user jaw movements or blood movement.
32. The ANR headset of claim 31, wherein the circuitry for
detecting and indicating detection of the condition, includes a
microphone, a bandpass filter, and a threshold detector, with the
bandpass filter coupled between the threshold detector and the
microphone.
33. The ANR headset of claim 29, further comprising a switch
coupled to receive the turn-off signal from the processor.
34. The ANR headset of claim 33, further comprising: a plurality of
battery connection terminals for coupling to one or more batteries;
and a switching regulator circuit coupled to the plurality of
battery terminals, with the regulator circuit having a shutdown pin
coupled to a terminal of the switch.
35. An ANR headset comprising: at least one audio transducer for
placement adjacent an ear of a user; circuitry for sensing a
low-frequency electrical signal having a frequency no greater than
five Hertz; and circuitry responsive to a perceived absence of the
low-frequency electrical signal to reduce power usage of the
headset.
36. The ANR headset of claim 35, wherein the circuitry for sensing
a low-frequency electrical signal comprises: a bandpass filter; and
a threshold detector coupled to the bandpass filter.
37. The ANR headset of claim 35, wherein the circuitry responsive
to a perceived absence of the low-frequency electrical signal, to
reduce power usage of the headset, comprises: means, responsive to
the perceived absence of the low-frequency electrical signal, for
reducing power usage of the headset.
38. The ANR headset of claim 35, wherein the circuitry responsive
to a perceived absence of the low-frequency electrical signal to
reduce power usage of the headset, comprises: circuitry for
determining whether the perceived absence has lasted at least a
predetermined amount of time; and circuitry for reducing power
supplied from a power supply circuit to a portion of the ANR
headset in response to determining the perceived absence has lasted
at least the predetermined amount of time.
39. The ANR headset of claim 38, wherein the circuitry for reducing
power supplied from the power supply circuit, comprises: a
processor having an output pin; and a transistor coupled to the
output pin of the processor.
40. The ANR headset of claim 38, wherein the predetermined period
of time is at least one minute.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This patent application is a continuation of U.S.
provisional patent application 60/123,150 filed Mar. 5, 1999. This
application is incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention concerns headphones or headsets,
particularly battery-powered headsets with automatic
noise-reduction circuitry.
BACKGROUND OF THE INVENTION
[0003] Headsets typically include two earcups which are worn over
ears of users to enhance or protect their hearing. For example,
many workers wear headsets to protect their hearing from loud
persistent noises, such as airplane engines and construction
equipment. These headsets are generally passive or active. Those
that are passive only cover the ears with a sound-muffling
material, whereas those that are active include ear speakers and
automatic noise-reduction (ANR) circuitry. The noise-reduction
circuitry automatically cancels or suppresses certain types of loud
persistent noises. Active headsets are often battery-powered and
include an on-off switch to turn them on and off.
[0004] One problem with battery-powered headsets, particularly
those with automatic noise-reduction circuitry, concerns battery
life. Workers having these headsets generally put on and take off
their headphones many times throughout a workday, often forgetting
to turn them off and wasting costly battery life. Moreover, for
those headsets that are used infrequently with long storage times
between uses, the turn-off problem is worse not only because their
batteries are more apt to die, but fresh batteries are too often
unavailable or inconvenient to obtain.
SUMMARY OF INVENTION
[0005] To address this and other needs, the inventor devised active
headsets with automatic turn-on and/or turn-off circuits and
related mode-control methods for active headsets. One exemplary
embodiment senses a condition of the headsets, for example, the
light, pressure, or temperature within one earcup, and then turns
the headset on or off in response to sensed condition. Other
embodiments that include automatic noise-reduction (ANR) circuitry
use an ANR driver to sense engagement of an earcup with a user's
head and an ANR microphone to sense disengagement of the earcup
from the user's head.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a block diagram of a first exemplary headset 100
incorporating the present invention.
[0007] FIG. 2 is a block diagram of a second exemplary headset 200
incorporating the present invention.
[0008] FIG. 3 is a schematic diagram of an exemplary turn-on
circuit 300 incorporating the present invention.
[0009] FIG. 4 is a schematic diagram of an exemplary turn-off
circuit 400 incorporating the present invention.
[0010] FIG. 5 is a schematic diagram of an exemplary power-supply
circuit 500 for with turn-on circuit 300 and/or turn-on circuit
400.
[0011] FIG. 6 is a schematic diagram of an exemplary headset 600
incorporating turn-off circuit 400 of FIG. 4.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0012] The following detailed description, which references and
incorporates FIGS. 1-6, describes and illustrates one or more
specific embodiments of the invention. These embodiments, offered
not to limit but only to exemplify and teach, are shown and
described in sufficient detail to enable those skilled in the art
to implement or practice the invention. Thus, where appropriate to
avoid obscuring the invention, the description may omit certain
information known to those of skill in the art.
[0013] FIG. 1 shows a first exemplary embodiment of an active,
automatic-noise-reduction (ANR) headset 100 incorporating an
automatic mode control feature in accord with the present
invention. Headset 100 includes an earcup 110 attached to a bridge
member 112. Earcup 110 fits over an ear and against the head of a
user, represented generally as surface 111 in the Figure. (For
simplicity, the figure omits a second earcup.) Headset 100 also
includes a mode sensor 120, and a mode-control circuit 130, an ANR
sensor or microphone 140, ANR circuitry 150, and an ANR driver 160.
(ANR circuitry 150 includes one or more batteries and a power
supply which are not shown.) (In some embodiments, the ANR function
is implemented digitally.)
[0014] In operation, mode sensor 120, which is shown in broken form
to emphasize that its placement can be virtually anywhere in or on
the headset, senses a condition of earcup 110 (or more generally
headset 100) and outputs a corresponding electrical signal to
mode-control circuit 130. Mode-control circuit 130 processes the
electrical signal, either switching the headset from a first
operating mode to a second operating mode or leaving the headset in
its current operating mode (or state.) For example, if the signal
indicates that the earcup has been disengaged from the head of the
user, mode-control circuit 130 deactivates ANR circuitry 150 or
otherwise puts it in a standby mode to reduce power
consumption.
[0015] However, if the signal indicates that the earcup has been
engaged with the head of the user, mode-control circuit 120 enables
or activates ANR circuitry 140 to control or otherwise affect the
perceived acoustic energy within earcup 110. This generally entails
ANR sensor 120 outputting an electrical signal representative of
acoustic energy within earcup 110 to the ANR circuitry. In turn,
the ANR circuitry processes the electrical signal and outputs a
responsive electrical signal to ANR driver 140. ANR driver 140
ultimately produces an acoustic signal intended to cancel,
suppress, or otherwise alter the acoustic energy within earcup
110.
[0016] In some variants of this first embodiment, the sensor
comprises one or more mechanical switches, photo-sensors,
temperature sensors, or pressure sensors. As used herein, light or
photoelectric sensor includes any electrical or electromechanical
device or component with useful photon-sensitive characteristics,
coupled for use as a sensor. Temperature sensor includes any
electrical device or component with useful temperature-dependent
characteristics, coupled for use as a sensor. Pressure sensor
includes any electrical or electromechanical device or component
with useful pressure-dependent characteristics, coupled for use as
a sensor.
[0017] In some mechanical variants, a normally open or normally
closed mechanical switch closes or opens on sufficient deflection
of at least a portion of the earcup, such as an ear cushion, or
deflection of a bridge between two earcups, upon engagement or
disengagement of the headset with the head of the user (head
surface or more generally user surface). Engagement or
disengagement makes or breaks a normally open or normally closed
electrical contact which in turn operates a switch (not shown)
between a power supply and the ANR circuitry.
[0018] In some photo-sensing variants, the photo-sensors sense
light or temperature levels or changing light or temperature levels
within or without the earcup. For photo sensors within the earcup
or for photo sensor on other interior (head-confronting) surfaces
of the headset (such as a bridge between two earcups), engagement
of the headset generally reduces the sensed light and disengagement
generally increases the sensed light.
[0019] Some temperature-sensing variants place the temperature
sensors the head of the user, for example within the earcup on the
bridge member. Thus, the sensors generally see increases in
temperature upon engagement of the headsets and decreases upon
disengagement.
[0020] It is also contemplated that some photo-sensing or
temperature-sensing variants would facilitate automatically
changing operational modes as a user wearing a headset moves
between indoor and outdoor environments or between two indoor
environments. For example, one can tune the sensors and/or mode
control circuit to distinguish indoor environments from outdoor
environments, correlate the distinction to the intended use of the
headset, and switch the headset on or off or otherwise change the
acoustic control function of the headset.
[0021] FIG. 2 shows a second exemplary embodiment of an ANR headset
200 including an automatic mode control feature in accord with the
invention. (FIG. 2 omits earcups for clarity.) Headset 200 includes
an ANR microphone 140, ANR circuitry 150, an ANR driver 160, and
implements automatic mode control using a turn-off circuit 130a, a
turn-off circuit 130b, and a power switch 130c. Turn-off circuit
130a is responsive to signals from ANR microphone 140 to control
power switch 130c, and turn-on circuit 130b is responsive to
signals from ANR driver 160 to control the power switch. Thus,
unlike headset 100 in the first exemplary embodiment, headset 200
omits a dedicated mode sensor, and instead uses ANR driver 160 and
microphone 130 as respective headset engagement and headset
disengagement sensors.
[0022] More specifically, engaging earcup 110 with the head of a
user generally results in an appreciable mechanical deflection of
ANR driver 150, which responsively outputs an appreciable
electrical signal to turn-on circuitry 130a. If the signal exceeds
a threshold, turn-on circuitry 130a activates power switch 130c,
thereby providing power to ANR circuitry 150.
[0023] On the other hand, after engagement, the earcup and surface
111 define a substantially closed volume that changes with user
movements, such as head and jaw movements and the pulsating flow of
blood through the confronting surface. In turn, these volume
changes cause momentary pressure changes within the earcup, which
are generally inaudible low-frequency events correlated only to
engagement of the earcup with surface 111. In response to these
events, microphone 130 produces a low-frequency electrical signal
which turn-off circuitry 130b monitors. If the turn-off circuitry
detects that this signal is absent for a sufficient period of time,
such as 2 or 3 or 5 or more minutes, it deactivates power switch
130c.
[0024] FIG. 3 shows details of an exemplary embodiment of turn-on
circuit 130a. In this embodiment, the turn-on circuit includes a
high-pass filter 310, a preamplifier 320, threshold detector 330,
an inverter 340, a processor 350, a switch 360, power supply
terminals V+ and Vgnd, and a positive battery terminal Vbattery+.
V+ and Vgnd are respectively +2.5 and zero volts in the exemplary
embodiment. (Not shown in the diagram are one or more batteries,
for example, AA batteries, and a switching regulator which provides
the voltages of +2.5 and -2.5 volts.) In operation, turn-on
circuitry draws on the order of 10 microamps from one or more
supplied batteries. Hence, its impact on battery life is generally
negligible.
[0025] More particularly, filter 310 comprises a 100-nanofarad
capacitor C4k and a resistor R6k. Capacitor C4k has first and
second terminals, with the first terminal coupled to the output of
the ANR circuitry, or more precisely the ANR driver. The second
terminal of capacitor C4k is coupled to ground via resistor R6k and
to the input of preamplifier 320.
[0026] Preamplifier 320 comprises an LT1495 operational amplifier
U1a, a one-mega-ohm resistor R6k, a 33 kilo-ohm resistor R7k, a
470-kilo-ohm resistor R15a, and 100-kilo-ohm input resistor R16a.
Amplifier U1a has a negative and positive inputs and an output. The
positive input is coupled via resistor R16a to a second terminal of
capacitor C4k, and the negative input is coupled to terminal Vgnd
via resistor R7k. Resistor R6k is coupled between the second
terminal of capacitor C4k and ground, and resistor R15a is coupled
between the output and the negative input of amplifier U1a. The
output of amplifier U1a is coupled to the input of threshold
detector 330.
[0027] Detector 340, which detects signals swings greater than 50
millivolts, includes an LT1495 operational amplifier U1b, a 1N914
diode D1, and a one-mega-ohm resistor R8k. Amplifier U1b has a
positive input coupled to the output of amplifier U1a, and a
negative input coupled to the positive terminal of diode D1. The
negative terminal of diode D1 is coupled to ground, and resistor
R8k is coupled between the positive terminal of diode D1 and
positive supply terminal V+. Inverter 166 has its input coupled to
the output of amplifier U1b, and its output coupled to an input of
processor 350,
[0028] Processor 350 responds to an output signal indicating
engagement of the headset with the user by activating switch 360.
Activating switch 360, which in this embodiments comprises a
p-channel mosfet transistor, connects power to the ANR circuitry
enabling it to cancel or otherwise alter the acoustic energy within
the earcup. A terminal of the mosfet is coupled to a shutdown pin
of integrated switching regulator.
[0029] FIG. 4 shows an exemplary embodiment of turn-off circuit
130b. Turn-off circuit 130b includes a microphone preamplifier 410,
a bandpass filter 420, a threshold detector 430, a processor 450, a
switch 460, respective positive and negative power-supply terminals
V+ and V-, and a positive battery terminal (or node) Vbattery+. In
the exemplary embodiment, terminals V+ and V- respectively provide
2.5 and -2.5 volts.
[0030] In operation, ANR microphone 140 senses pressure within
earcup 120. When engaged with each other earcup 110 and surface 111
defines a substantially closed space with a volume that changes
with user movements, such as head and jaw movements and the
pulsating flow of blood through surface 111. In turn, these volume
changes cause momentary pressure changes within the earcup, which
are generally inaudible, low-frequency events. On the other hand,
when disengaged from surface 111, earcup 110 is not pressed against
surface 130 and thus no longer defines a volume subject to user
movements. Thus, microphone 140 generally provides preamplifier 410
a signal with low-frequency content that changes during engagement
of earcup 110 with surface 130 and that remains relatively constant
after disengagement.
[0031] More particularly, preamplifier 410 has a gain of 20
decibels and comprises an input capacitor C10a of 470 nanofarads,
an input resistor R10a of 470 kilo-ohms, an LMV324 operational
amplifier U1d, and feedback resistors R12a of 6.8 kilo-ohms and
R14a of 62 kilo-ohms. Amplifier U1d provides an output signal
proportional to the signal from preamplifier 410 to band-pass
filter 420. (In some embodiment, preamplifier 410 also functions as
a portion of ANR circuitry 150 (shown in FIG. 2).
[0032] Band-pass filter 420, which defines a one-to-five hertz
passband with an approximate gain of 30 decibels, comprises a
resistor R1k of 330 kilo-ohms, a resistor R2k of 330 kilo-ohms, a
resistor R3k of 33 kilo-ohms, a resistor R4k of 1 kilo-ohm, a
resistor R5k of 620 kilo-ohms, and a resistor R1m of 470 kilo-ohms.
Filter 18 also comprises three 100-nanofarad capacitors C1k, C2k,
and C3k, and one 470-nanofarad capacitor C1m. Filter 180 also
comprises an operational amplifier U5b which provides a pressure
signal indicative of the pressure in earcup 120 via capacitor C1m
to threshold detector 430.
[0033] Threshold detector 430, which comprises an LMV324
operational amplifier, a 470-kilo-ohm resistor R2m, a 1-kiloohm
resistor R3m, and a 10-kilo-ohm resistor R4m, compares the pressure
signal to a 225-millivolt reference voltage at a node C and outputs
a signal indicating the result of the comparison to processor 440.
When the pressure signal at node B is greater than the reference
voltage at node C, detector 430 outputs a low signal, which
indicates an "on-head" event, that is, engagement of earcup 110
with surface 110, to processor 440.
[0034] In response to receiving an "on-head" event, processor 440
starts a timer which runs for a predetermined period of time, for
example, two to three minutes. If during this period, another
"on-head" event does not occur, that is, there are no sensed
low-frequency events of sufficient magnitude, processor 440 assumes
that the headset has been removed and sends an appropriate turn-off
signal to a power-supply shutdown circuit, which turns off the
headset. In some embodiments, processor 440 directly drives a
shut-down pin on a switching regulator that provides the V+ and V-
supply voltages.
[0035] FIGS. 3 and 4 are shown as separate stand-alone circuits
which are adaptable to virtually any active ANR headset to provide
automatic mode control. When used together in the same headset,
certain components of the circuits are shared to reduce the number
of parts. For example, some embodiments use a single programmable
processor and power switch. Moreover, some embodiments implement
all or one or more portions of the circuit as an integrated
circuit.
[0036] FIG. 5 shows an exemplary embodiment of a power supply 500.
Supply 500 includes, among other things, battery connection
terminals 510a and 510b, one or more batteries 520, and a
integrated switching regulator circuit 530. Regulator circuit 530
includes a shutdown pin, which in the exemplary embodiment,
ultimately coupled to a terminal of switch 360 or switch 460 in the
turn-on and turn-off circuits of FIGS. 3 and 4. The present
invention is not limited to any particular power supply
arrangement.
[0037] FIG. 6 shows an exemplary embodiment of active headset 600
including a turn-off circuit in accord with the invention. FIG. 6
also shows details of an exemplary ANR circuitry.
Conclusion
[0038] In furtherance of the art, the inventor has presented one or
more embodiments of active headsets incorporating an automatic mode
control feature. One exemplary embodiment provides an turn-on and
turn-off circuits which automatically detect engagement and
disengagement of a headset to or from the head of a user to
activate or deactivate the headset. The turn-off circuit is
especially useful to conserve battery life in battery powered ANR
headsets. However, the invention is generally applicable to
automatically control the operational mode of any active headsets
or headphones, regardless of the power source.
[0039] The embodiments described above are intended only to
illustrate and teach one or more ways of practicing or implementing
the present invention, not to restrict its breadth or scope. The
actual scope of the invention, which encompasses all ways of
practicing or implementing the concepts of the invention, is
defined by the following claims and their equivalents.
* * * * *