WIRELESS POWER TRANSMISSION AUDIO SYSTEM AND DEVICE ON TRANSMITTING END AND LOUDSPEAKER FOR USE IN SUCH A SYSTEM

• US 20120163619A1
• Filed: 12/19/2011
• Published: 06/28/2012
• Est. Priority Date: 12/22/2010
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: KINOSHITA, Keisuke, KAWAMURA, Junichi, OKAMURA, Shutai
• Granted Patent: US 8,929,563 B2
• Time in Patent Office: Days
• US Class Current: 381/77
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/20 using microwaves or radio frequency waves
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H04L 25/4902 Pulse width modulation; Pulse position modulation
• CPC Class Codes: H04R 2420/07 Applications of wireless loudspeakers or wireless microphones

Abstract

The transmitter of a wireless power transmission audio system includes: a transmission signal generating section for generating a transmission signal comprised of an RF signal; a first resonant circuit which receives and sends out the transmission signal; a detecting section for sensing a variation in the transmission signal; and a transmission signal adjusting section. The loudspeaker of the system includes: a second resonant circuit for receiving the transmission signal by producing a magnetic field resonant coupling phenomenon; and an audio output section for reproducing the audio signal. At least one of the transmitter and the loudspeaker includes an impedance adjusting section which changes an impedance value on the transmission line of the transmission signal. When the impedance adjusting section changes the impedance value, the transmission signal adjusting section changes the signal waveform of the transmission signal.

Claims

1. A wireless power transmission audio system comprising a device on the transmitting end and a loudspeaker, which is associated with the device on the transmitting end, the system being configured to transmit electric power and an audio signal wirelessly from the device on the transmitting end to the loudspeaker,

wherein the device on the transmitting end includes:

a transmission signal generating section for generating a transmission signal, which is comprised of an RF signal for use to transmit the electric power and the audio signal;

a first resonant circuit, which receives and sends out the transmission signal and of which the resonant frequency is equal to the frequency of the RF signal;

a detecting section for sensing a variation in the transmission signal; and

a transmission signal adjusting section for controlling the signal waveform of the transmission signal, and

wherein the loudspeaker includes;

a second resonant circuit, which receives at least a part of the transmission signal that has been sent out by the first resonant circuit by producing either a magnetic resonant coupling phenomenon or an electric field resonant coupling phenomenon at the resonant frequency; and

an audio output section for reproducing the audio signal in accordance with a signal supplied from the second resonant circuit, and

wherein at least one of the device on the transmitting end and the loudspeaker includes an impedance adjusting section, which is connected to its associated first or second resonant circuit and which changes an impedance value on the transmission line of the transmission signal according to the variation of the transmission signal that has been sensed by the detecting section, and

wherein when the impedance adjusting section changes the impedance value, the transmission signal adjusting section changes the signal waveform of the transmission signal at the device on the transmitting end.

2. The audio system of claim 1, wherein the transmission signal generating section includes a PWM signal generating section for generating a pulse-width-modulated audio signal, and

wherein the transmission signal is obtained by multiplying the pulse-width-modulated audio signal and the RF signal together.

3. The audio system of claim 2, wherein the transmission signal adjusting section includes an amplitude control section for controlling the amplitude of the pulse-width-modulated audio signal.

4. The audio system of claim 2, wherein the transmission signal adjusting section includes a pulse width control section for controlling the pulse width of the pulse-width-modulated audio signal.

5. The audio system of claim 1, wherein the detecting section senses a variation to be caused in the transmission signal depending on the relative positions of the first and second resonant circuits, and

wherein in accordance with a signal supplied from the detecting section, the impedance adjusting section controls the impedance value and the transmission signal adjusting section controls the signal waveform of the transmission signal.

6. The audio system of claim 5, wherein by sensing a variation in the waveform of the transmission signal at the first resonant circuit, the detecting section determines the relative positions of the first and second resonant circuits.

7. The audio system of claim 5, wherein by sensing a variation in the waveform of the transmission signal at the transmission signal generating section, the detecting section determines the relative positions of the first and second resonant circuits.

8. The audio system of claim 1, wherein in accordance with the output of the detecting section, the impedance adjusting section changes the impedance value discretely and the transmission signal adjusting section changes the signal waveform of the transmission signal stepwise.

9. The audio system of claim 2, wherein in a no-signal interval between pulses of the transmission signal, which is defined by the pulse-width-modulated audio signal, the impedance adjusting section changes the impedance value.

10. The audio system of claim 2, further comprising a control section, which outputs a control signal to the impedance adjusting section and the transmission signal adjusting section in accordance with a signal supplied from the detecting section,

wherein the control section includes a storage section, which stores the relative positions that have been detected by the detecting section and also stores information about how transfer efficiency between the first and second resonant circuits changes with the impedance value that has been set by the impedance adjusting section, and

wherein the control section performs a control so that the product of the amplitude and the pulse width of the pulse-width-modulated signal remains the same before and after the impedance value has been changed by the impedance adjusting section, thereby keeping the volume of the audio output through the audio output section unchanged.

11. The audio system of claim 1, wherein the loudspeaker includes the impedance adjusting section, and

wherein the device on the transmitting end further includes a control signal transmitting circuit for sending a control signal to the loudspeaker'"'"'s impedance adjusting section, and

wherein the loudspeaker'"'"'s impedance adjusting section changes the impedance value in accordance with the control signal.

12. The audio system of claim 1, wherein each of the device on the transmitting end and the loudspeaker has its own impedance adjusting section.

13. The audio system of claim 1, wherein the loudspeaker includes:

an envelope detecting section for detecting the envelope of a signal that has been received by the second resonant circuit;

a low-pass filter circuit for retrieving the audio signal based on the output of the envelope detecting section; and

an audio converting section for reproducing the audio based on the output of the low-pass filter circuit.

14. A device on a transmitting end for use in a wireless power transmission audio system, the audio system comprising the device on the transmitting end and a loudspeaker, which is associated with the device on the transmitting end, and being configured to transmit electric power and an audio signal wirelessly from the device on the transmitting end to the loudspeaker,

wherein the device on the transmitting end includes:

a transmission signal generating section for generating a transmission signal, which is comprised of an RF signal for use to transmit the electric power and the audio signal;

a first resonant circuit, which receives and sends out the transmission signal and of which the resonant frequency is equal to the frequency of the RF signal;

a detecting section for sensing a variation in the transmission signal; and

a transmission signal adjusting section for controlling the signal waveform of the transmission signal, and

wherein the loudspeaker includes;

a second resonant circuit, which receives at least a part of the transmission signal that has been sent out by the first resonant circuit by producing either a magnetic resonant coupling phenomenon or an electric field resonant coupling phenomenon at the resonant frequency; and

an audio output section for reproducing the audio signal in accordance with a signal supplied from the second resonant circuit, and

wherein at least one of the device on the transmitting end and the loudspeaker includes an impedance adjusting section, which is connected to its associated first or second resonant circuit and which changes an impedance value on the transmission line of the transmission signal according to the variation of the transmission signal that has been sensed by the detecting section, and

wherein when the impedance adjusting section changes the impedance value, the transmission signal adjusting section changes the signal waveform of the transmission signal at the device on the transmitting end.

15. A loudspeaker for use in a wireless power transmission audio system, the system comprising the device on the transmitting end and a loudspeaker, which is associated with the device on the transmitting end, and being configured to transmit electric power and an audio signal wirelessly from the device on the transmitting end to the loudspeaker,

wherein the device on the transmitting end includes:

a transmission signal generating section for generating a transmission signal, which is comprised of an RF signal for use to transmit the electric power and the audio signal;

a first resonant circuit, which receives and sends out the transmission signal and of which the resonant frequency is equal to the frequency of the RF signal;

a detecting section for sensing a variation in the transmission signal; and

a transmission signal adjusting section for controlling the signal waveform of the transmission signal, and

wherein the loudspeaker includes;

a second resonant circuit, which receives at least a part of the transmission signal that has been sent out by the first resonant circuit by producing either a magnetic resonant coupling phenomenon or an electric field resonant coupling phenomenon at the resonant frequency; and

an audio output section for reproducing the audio signal in accordance with a signal supplied from the second resonant circuit, and

wherein at least one of the device on the transmitting end and the loudspeaker includes an impedance adjusting section, which is connected to its associated first or second resonant circuit and which changes an impedance value on the transmission line of the transmission signal according to the variation of the transmission signal that has been sensed by the detecting section, and

wherein when the impedance adjusting section changes the impedance value, the transmission signal adjusting section changes the signal waveform of the transmission signal at the device on the transmitting end.