Wireless headset

A wireless headset comprising a sound transducer, said sound transducer and a wireless power receiver. The sound transducer comprises a sound transducer coil configured to at least one of convert a first electrical signal to a first sound signal and convert a first sound signal to a first electrical signal comprising first audio information. The wireless power receiver is configured to receive wireless power through an antenna comprising said sound transducer coil.

BACKGROUND

Wireless headsets are commonly used with a computer, phone, tablet, or music system to provide focused audio support without inhibiting flexibility of motion of the user. These wireless headsets typically employ lithium ion batteries that need to be charged periodically. Charging is typically accomplished by plugging one end of a USB cord (or micro or mini USB cord) into the headset and the other end into a USB charger. This is inconvenient and results in connector wear-out from repeated cycles of plugging and unplugging the USB cord.

Wireless headsets typically use Bluetooth® to transmit and receive audio information and sometimes use Bluetooth® Smart (BLE) to transmit and receive metadata and other data. Bluetooth® functions well to provide an audio link for voice transmission; however, it provides relatively poor-quality audio information for music. Furthermore, Bluetooth® uses 2.4 GHz radio frequency. Radio energy at 2.4 GHz may be absorbed by water in the human body and so performance degrades when the transmitter and the headset receiver are located on opposite sides of a person.

A further drawback of conventional wireless headsets is the possibility of running out of battery power during use. Wireless charging would eliminate these drawbacks; however, the small available area of most headsets negates the possibility of adding conventional wireless power receiving antennas. Conventional wireless charging systems also do not solve the problem of running out of battery power during wireless headset use.

SUMMARY OF THE INVENTION

These and other problems are generally solved or circumvented, and technical advantages are generally achieved, by advantageous embodiments of the present invention, including a wireless headset comprising a sound transducer and a wireless power receiver. The sound transducer has a sound transducer coil configured to convert a first electrical signal to a first sound signal and/or to convert a first sound signal to a first electrical signal comprising audio information. The wireless power receiver includes an antenna comprising said sound transducer coil such that the wireless power receiver receives wireless power through the antenna via the sound transducer coil.

In one embodiment, the wireless headset further comprises a receiver configured to receive a modulated signal through the antenna. In another embodiment, the sound transducer comprises a permanent magnet and a magnetic flux path through the permanent magnet and the sound transducer coil such that the magnetic flux path is closed through a ferrite material that is configured to saturate due to flux created by the permanent magnet.

In another embodiment, the sound transducer comprises a first radially-magnetized permanent magnet with a cross-section located within the inner circumference of the sound transducer coil and a second radially-magnetized permanent magnet with a cross-section surrounding the sound transducer coil such that the magnetic polarity of the first permanent magnet's outer circumference has opposite polarity of the second permanent magnet's inner circumference. The first and second permanent magnets may be affixed to a non-conductive, non-ferromagnetic structure.

In another embodiment, a wireless headset system comprises a wireless headset and a wireless transmitter. The wireless headset includes a sound transducer and a wireless power receiver. The sound transducer includes a sound transducer coil configured to convert a first electrical signal to a first sound signal comprising first audio information. The wireless power receiver includes an antenna comprising the sound transducer coil and receives wireless power transmitted from the wireless transmitter through the antenna via the sound transducer coil.

The above-described invention provides several advantages. For example, the wireless headset and wireless headset system do not wear out from charging and do not run out of power during use. The wireless headset does not need a large antenna and operates at frequencies that do not have degraded performance due to the proximity of users and other external interference.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention will be described with respect to exemplary embodiments in a specific context, namely, a wireless headset, and methods of operating and forming the same. While the principles of the present invention will be described in the context of a wireless headset, any application that may benefit from wireless transfer of power is well within the broad scope of the present invention.

Turning now toFIG. 1, illustrated is a schematic diagram representing an embodiment of a wireless headset100comprising Speaker Coil150, Speaker155, Filter110, Wireless Power Receiver111, Charger112, Battery113, System Bus114, Micro Controller Unit (MCU)140, Filter130, Frequency Modulated (FM) Transceiver131, Microphone170, Pre-amplifier171, and Amplifier160.

Speaker Coil150is configured to function as part of speaker155. That is, Speaker Coil150is configured to produce movement of a diaphragm to create sound in the audio range (between 20 Hz and 20 kHz) in accordance with an electrical signal placed across Speaker Coil150. Additionally, Speaker Coil150is configured to function as, or as part of, an antenna for receiving electromagnetic waves in a high-frequency band. For example, Speaker Coil150may be configured to function as an antenna for electromagnetic waves in a frequency band comprising a range between 5 MHz and 30 MHz. Thus, the electrical signal across Speaker Coil150may be a superposition of driving low-frequency electrical signals in the audio range (20 Hz to 20 kHz) with received high-frequency signals (5 MHz to 30 MHz) due to the presence of electromagnetic radiation in the vicinity of Speaker Coil150. It will be understood that although the following discussions refer to a speaker and a speaker coil, any sound transducer comprising a coil that produces sound in response to an electrical signal or produces an electrical signal in response to sound, such as a microphone, can be used.

Speaker Coil150is coupled to Filter110, Amplifier160, and Filter130. Filter110is coupled to Wireless Power Receiver111which in turn is coupled to Charger112. The output from Charger112is coupled to Battery113. Charger112and Battery113are each coupled to System Bus114. System Bus114distributes power to all of the system components in Wireless Headset100.

Filter110is coupled to FM Transceiver131which is coupled to Microcontroller Unit (MCU)140. Microcontroller Unit (MCU)140functions as the system controller and is coupled to Wireless Power Receiver111, Charger112, FM Transceiver131, Pre-amplifier171, and Amplifier160.

Three different operating modes of Wireless Headset100, designated as charge mode, audio receive mode, and audio transmit mode, will now be described in more detail. These three operating modes are illustrated inFIGS. 2, 3, and 4respectively.FIGS. 2, 3, and 4illustrate the same components that are illustrated inFIG. 1, except that unused system components and couplings are shown in dashed lines, and input signals are illustrated as appropriate for the operating mode being discussed. The following discussions refer to a frequency modulated signal to be used for transmitting from or receiving to FM Transceiver131for purposes of exchanging information with a remote transmitter or receiver. It will be understood that other forms of signal modulation and associated transceivers could also be used including, but not limited to, phase-shift keying, frequency-shift keying, amplitude modulation, amplitude-shift keying, on-off keying, quadrature amplitude modulation, and continuous phase modulation.

FIG. 2illustrates the charge mode in which the Wireless Headset100may be removed from the user's head and placed onto a surface of a wireless power transmitter. The wireless power transmitter transmits a Wireless Power Signal101to Wireless Headset100. Wireless power transmission may occur in the form of magnetic resonance. The frequency of Wireless Power Signal110will typically be 6.78 MHz; however, other transmission frequencies are also possible. Wireless Power Signal101is received by Speaker Coil150and coupled to Wireless Power Receiver111through Filter110. Filter110passes power transmitting frequency (such as 6.78 MHz) and removes audio and other unwanted frequencies. Charger112uses the power received through Wireless Power Receiver111to charge Battery113. In this mode of operation, Charger112supplies power to System Bus114, which in turn distributes the power to the rest of the system. MCU140controls charging of Battery113by controlling Wireless Power Receiver111and Charger112. MCU140also communicates with the wireless power transmitter by sending FM Feedback Signal105(typically at a frequency of 27 MHz) through FM Transceiver131, Filter130, and Speaker Coil150. The information in the feedback signal may comprise battery status information such as whether or not the battery has reached full charge. In charging mode, Speaker Coil150acts as a receiving antenna for Wireless Power Signal101and a transmitting antenna for FM Feedback Signal105.

FIG. 3illustrates the audio receive mode for Wireless Headset100in which Wireless Headset100may receive an audio signal such as a voice or music audio signal. FM Transceiver131receives FM Audio Signal103from a remote client through Speaker Coil150and Filter130. FM Transceiver131sends the received audio signal to MCU140which in turn sends the signal to Amplifier160. Amplifier160causes Speaker Coil150to move a speaker diaphragm in Speaker155, thus producing Sound Signal104. In audio receive mode, Speaker Coil150acts as a receiving antenna for FM Audio Signal103and a transducer coil to operate Speaker155to create Sound Signal104. In practice, FM Audio Signal103is likely to be broadcast with a center frequency of 27 MHz. Other broadcast frequencies are possible; however, 27 MHz is a practical broadcasting frequency because existing standards typically allow for side-bands at 27 MHz which are wide enough to support high-quality music transmission.

FM Audio Signal103which is received by Speaker Coil150is passed on to FM Transceiver131through Filter130. Filter130may be a notch filter configured to pass an FM signal transmitting frequency (such as 27 MHz) and its sidebands and to remove audio and other unwanted frequencies. Filter130may be designed to remove a frequency of resonant power transmission (such as 6.78 MHz). FM Transceiver131then passes the received audio (e.g. music) signal to MCU140which then creates a Sound Signal104(e.g. music) via Amplifier160and Speaker Coil150. It should be noted that in the here-to-fore mentioned audio receive mode, Speaker Coil150functions simultaneously as the coil of wire in a loud-speaker and as an FM signal antenna as indicated inFIG. 3by the presence of Sound Signal104simultaneously with FM Audio Signal103. The ability of Speaker Coil150to function in two roles simultaneously is enabled by Filter130which filters out audio frequencies from reaching FM Transceiver131. In some embodiments, the Wireless Headset100can be trickle charged in audio receive mode.

FIG. 4illustrates the audio transmit mode in which the Wireless Headset100may transmit sound picked up by a microphone attached to the Wireless Headset100. More specifically, Microphone170receives Sound175and generates a corresponding electrical signal that is sent to Pre-amplifier171. Pre-amplifier171sends the electrical signal to MCU140. MCU140then sends the electrical signal to FM Transceiver131which transmits a corresponding transmission signal using frequency modulation through antenna Speaker Coil150. The resulting transmission signal is illustrated as FM Audio Signal107. In practice, FM Audio Signal107will typically be broadcast at a center frequency of 27 MHz; however, other broadcast frequencies are possible. In audio transmission mode, Speaker Coil150acts as an FM broadcasting antenna.

Turning now toFIG. 5, illustrated is a circuit diagram of here-to-fore described Wireless Headset100ofFIGS. 1-4. Speaker Coil150is coupled to Filter110which comprises Capacitor C501. Capacitor C501is configured to form a resonance with Speaker Coil150at a frequency equal to a frequency of wireless power transmission (such as 6.78 MHz). Filter110is coupled to Wireless Power Receiver111which comprises Output Capacitor C502and a full-bridge comprising high-speed semiconductor switches Q501, Q502, Q503, and Q504. Semiconductor Switches Q501, Q502, Q503, and Q504may be Gallium-Nitride Enhancement Mode Power Transistors.

Other configurations are possible for Wireless Power Receiver111, such as, but not limited to, a full-wave diode bridge in series with a capacitor that resonates with Speaker Coil150at the frequency of the wireless power transmission. In choosing components for Wireless Power Receiver111, it is important that the components are configured to rectify the voltage across Speaker Coil150and that the net input impedance of Wireless Power Receiver111combined with Filter110resonates with Speaker Coil150at the frequency of the wireless power transmission.

When wireless power is being received by Wireless Headset100, Semiconductor Switches Q501, Q502, Q503, and Q504will typically be driven at a frequency equal to a frequency of the wireless power transmission (such as 6.78 MHz). These switches may be driven such that Semiconductor Switches Q501and Q504are driven simultaneously with a pulse-width modulated duty cycle slightly less than 50% and Semiconductor Switches Q502and Q503are driven simultaneously with a pulse-width modulated duty cycle slightly less than 50% and 180 degrees out-of-phase with respect to Semiconductor Switches Q501and Q504. The output from the full-bridge comprising Semiconductor Switches Q501, Q502, Q503, and Q504acts as an active rectifier for wireless transmitted power, and therefore charges Output Capacitor C502to a DC voltage. Gate drives for Semiconductor Switches Q501, Q502, Q503, and Q504can be enabled or disabled by a connection to MCU140.

Charger112takes power from Output Capacitor C502to regulate the voltage across Battery113in such a way as to charge Battery113. Charging may typically be controlled by MCU140. The output from Charger112is coupled to Battery113, and both Charger112and Battery113may be coupled to System Bus114which is also labeled as VCC inFIG. 5. As can be seen inFIG. 5, a VCC node is also coupled to MCU140, Pre-amplifier171, Amplifier160, Amplifier U511, Amplifier U512, Modulator X512, and Demodulator X511. All of these here-to-for mentioned modules can therefore be powered either directly from Battery113or from Charger112.

Speaker Coil150is also coupled to Filter130which comprises Capacitors C511, C512, and C513as well as Inductor L511. The purpose of Filter130is to filter out any frequencies outside of a transmitted FM signal frequency and its side bands (for example any frequencies outside of 26.7 MHz to 27.3 MHz). Filter130also filters out any audio-frequency signals (20 Hz to 20 kHz) and any frequencies of resonant power transmission (such as 6.78 MHz). Capacitor C511acts as a low-frequency blocking capacitor that filters out all audio-frequencies (20 Hz to 20 kHz). Capacitor C512, Capacitor C513, and Inductor L511act as a notch filter tuned to the center frequency of FM signal transmission (such as 27 MHz). This notch filter also filters out any frequencies of resonant power transmission (such as 6.78 MHz). It should be appreciated that many other filter combinations are possible to accomplish the task of blocking voice signals, blocking wireless power transmission, and allowing FM signal transmission at a particular frequency.

Filter130is coupled to FM Transceiver131. FM Transceiver131can both transmit and receive frequency-modulated signals. The transmitting section of FM Transceiver131comprises Modulator X512, AC Coupling Capacitor C517, Amplifier U512, and AC Coupling Capacitor C516. Modulator X512mixes the signal to be transmitted from MCU140with a carrier frequency. The resulting FM modulated signal is coupled to amplifier U512via AC Coupling Capacitor C517. AC Coupling Capacitor C516couples the output from Amplifier U512to Filter130which in turn couples the frequency-modulated signal to Speaker Coil150. Speaker Coil150acts as a transmitting antenna for the frequency-modulated signal.

The receiving section of FM Transceiver131comprises AC Coupling Capacitor C514, Amplifier U511, AC Coupling Capacitor C515, and Demodulator X511. Capacitor C514couples the output from Filter130to Amplifier U511. Amplifier U511amplifies the signal and couples it to Demodulator X511via AC Coupling Capacitor C515. Demodulator X511demodulates the FM signal, reducing the signal frequency by the carrier frequency.

When an FM signal is received by Speaker Coil150, the FM signal is filtered by Filter130, Demodulated by FM Transceiver131, and sent to MCU140. MCU140couples the resulting demodulated signal to Amplifier160which in turn drives the loud speaker through Speaker Coil150.

When the Wireless Headset100is used in audio transmit mode, Microphone170receives incoming sound signals and generates a corresponding electrical signal which is then amplified by Pre-amplifier171and subsequently sent to MCU140. MCU140sends the appropriate signal (sound signal for audio transmitting mode or charging feedback for charging mode) to FM Transceiver131which then broadcasts a corresponding transmission signal through Speaker Coil150.

Turning now toFIG. 6, illustrated is a schematic diagram of a wireless transmitter600configured to be used with Wireless Headset100ofFIGS. 1-5. Wireless Transmitter600comprises MCU620coupled to FM Transceiver651and to Power Transmitter641. Power Transmitter641and FM Signal Transmitter651are each coupled to Coil680via Filters642and652, respectively.

There are three different operating modes for Wireless Transmitter600which correspond to the three different operating modes of the here-to-for described Wireless Headset100and which will be designated as charging mode, audio receiving mode, and audio transmit mode. It should be appreciated that despite the naming of the three modes as charging mode, audio receiving mode, and audio transmit mode, each of these modes is not limited only to the function described by the name of the mode. These three operating modes are illustrated inFIGS. 7, 8, and 9respectively.FIGS. 7, 8, and 9illustrate the same schematic diagrams that are illustrated inFIG. 6, except that unused system components and couplings shown in dashed lines, and input signals are illustrated as appropriate for the operating mode being discussed.

FIG. 7illustrates charging mode for Wireless Transmitter600. Power Source640provides power to Power Transmitter641. Power source640could for example be a USB power port or an AC-to-DC power supply coupled to the electric grid. Power Transmitter641transmits resonant wireless power through Coil680at a frequency above 1 MHz, for example at 6.78 MHz. Power Transmitter641transmits resonant power through Coil680but also uses Coil680to receive FM Feedback Signal605as a frequency-modulated signal. FM Feedback Signal605contains information from the device receiving the charging power (such as Wireless Headset100inFIGS. 1-4). FM Feedback Signal605may contain information about end-of-charge cycle for a battery in a wireless headset. The information contained in FM Feedback Signal605is sent to MCU620via Filter652and FM Transceiver651.

Coil680may typically comprise a trace on a PCB such as is typically used by resonant power transmission devices.FIG. 7illustrates a common Coil680used for both wireless power transmission and FM signal transmission/reception; however, separate coils could also be used for each of these two functions.

Filters642and652simultaneously allow FM signal transmission/reception and wireless power transmission through Coil680by filtering out frequencies of the opposing function. For example, if wireless power transmission occurs at 6.78 MHz and the FM transmission occurs at 27 MHz, Filter642will filter out 27 MHz and pass 6.78 MHz while Filter652will filter out 6.78 MHz and pass 27 MHz.

FIG. 8illustrates audio transmit mode in which Audio Signal650is an electrical signal representing an audio signal of, for example, voice or music. MCU620sends the electrical signal to FM Transceiver651which frequency-modulates the electrical signal and transmits a corresponding transmission signal via Filter652and Coil680as FM Audio Signal603.

FIG. 9illustrates audio receive mode in which FM Audio Signal605is received by Coil680, filtered by Filter652, demodulated by FM Transceiver651, and then sent to MCU620. MCU620sends the demodulated signal as Received Audio signal610to an external device such as a phone or computer.

It is critical that Speaker Coil150(shown inFIGS. 1-4) not only provide standard speaker functionality, but that it also allows reception of wireless power (typically at 6.78 MHz) and reception of a high-frequency FM signal (typically at a center frequency of 27 MHz). To accomplish this wide range of functionality for Speaker Coil150, it must be constructed so that high frequencies (e.g. 5 MHz-30 MHz) are not significantly attenuated within the coil/magnet structure and so that Speaker Coil150will resonate at the appropriate frequency (e.g. 6.78 MHz or 27 MHz) when connected to appropriate external components.

FIGS. 10A and 10Billustrate an embodiment of a construction for Speaker1000that can be used for operating a headset loudspeaker and for transmitting or receiving FM signals or receiving resonant power.FIG. 10Aillustrates an elevation cross-sectional view of Speaker1000whileFIG. 10Billustrates a plan view of Speaker1000with diaphragm1050removed to expose underlying components.

Permanent Magnet1030is affixed to Base1040. Base1040comprises a ferromagnetic substance which may have minimal or no conductivity such as a ferrite or ferromagnetic insulator. Permanent Magnet1030is configured with a magnetization along its vertical axis—for example, with magnetic north (illustrated by “N” inFIG. 10A) on top and magnetic south (illustrated by “S” inFIG. 10A) on the bottom. Magnetic flux produced by Permanent Magnet1030traverses Path1035through Base1040and Coil1020. Diaphragm1050is a flexible membrane and is affixed in its center to Coil1020. Diaphragm1050is also affixed along its outermost edge to Base1040.

Changes in current flowing through Coil1020induce a force on Coil1020with respect to Permanent Magnet1030, thus causing movement of Coil1020. The movement of Coil1020is transferred to Diaphragm1050which produces sound in accordance with its movement. Holes1045in Base1040provide pressure relief for Diaphragm1050to enable greater movement for a given amount of force.

Speaker1000is thus able to convert electrical signals to sound. Coil1020may also act as an antenna to receive either frequency-modulated signals or resonant power. The use of a minimally-conductive material (such as ferrite) or non-conductive material (such as a ferromagnetic insulator) in Base1040allows high-frequency signals to be received by Coil1020with minimal attenuation. Permanent Magnet1030causes a fixed flux density within parts of Base1040that reside within Path1035. The thickness of Base1040may be optimally sized to cause the fixed level of flux density along Path1035to be close to the level of flux density required to saturate the ferromagnetic material used in Base1040. Causing the ferromagnetic material used in Base1040to be nominally magnetically saturated reduces the effect of Base1040on reception of frequency-modulated signals or resonant power by Coil1020.

FIGS. 11A and 11Billustrate another embodiment of a construction for a speaker that can be used for operating a headset loudspeaker and for receiving FM signals or resonant power.FIG. 11Aillustrates a cross-sectional perspective of Speaker1100whileFIG. 11Billustrates a top-view perspective of Speaker1100with diaphragm1150removed to expose underlying components.

Permanent Magnets1130and1133are affixed to Base1140. Permanent Magnet1130is rod shaped and configured with a radial magnetization—for example, with magnetic north (illustrated by “N” inFIG. 11A) in the center and magnetic south (illustrated by “S” inFIG. 11A) on the outer rim. Permanent Magnet1133is a cylinder, also radially magnetized as shown by the north “N” and south “S” poles illustrated inFIG. 11A. Base1140comprises a non-conductive, non-ferromagnetic substance such as plastic. Magnetic flux produced by Permanent Magnet1130traverses Path1135through Coil1120. The return flux path from the center of Permanent Magnet1130to the outer rim of Permanent Magnet1135is partly through the air and thus is not illustrated inFIG. 11A.

Diaphragm1150is a flexible membrane and is affixed in its center to Coil1120. Diaphragm1150is also affixed along its outermost edge to Base1140.

Changes in current flowing through Coil1120induce a force on Coil1120with respect to Permanent Magnets1130and1133, thus causing movement of Coil1120. The movement of Coil1120is transferred to Diaphragm1150which produces sound in accordance with its movement. Holes1145in Base1140provide pressure relief for Diaphragm1150to enable greater movement for a given amount of force.

Speaker1100is thus able to convert electrical signals to sound. Coil1120may also act as an antenna to receive either frequency-modulated signals or resonant power. The use of non-conductive non-ferromagnetic material in Base1140allows high-frequency signals to be received by Coil1120with no attenuation.

Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. For example, many of the processes discussed above can be implemented in different methodologies and replaced by other processes, or a combination thereof. As an example, a microphone coil could be used as an antenna rather than using a speaker coil. As another example, other forms of signal modulation could be used instead of frequency modulation. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods, and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.