JP2011155427A - Magnetic resonance type radio sound transmission device, magnetic resonance type radio sound reception device, and magnetic resonance type radio sound transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein, in an output device for outputting sound, even when a sound signal is received and reproduced by radio transmission, power must be supplied through a wire. <P>SOLUTION: This magnetic resonance type radio sound transmission device is equipped with: a resonance frequency oscillator 3 for oscillating a specific frequency; a stream modulator 2 for generating a serial signal becoming a sound signal by a low-pass filtration process; a transmission modulator 4 for converting the serial signal to a modulation signal modulated by a specific frequency; a power amplifier 5 for subjecting the modulation signal to power amplification; and resonators 6, 7 for subjecting the modulation signal subjected to the power amplification to magnetic resonance with a specific frequency. Power is then wirelessly transmitted along with sound, and a wireless speaker without an AC cord is provided. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a magnetic resonance type wireless audio transmission system in which a transmitter that wirelessly transmits sound and power using magnetic resonance, a receiver that wirelessly receives sound using magnetic resonance, and a transceiver are combined. It is about.

  As a conventional wireless audio transmission reception technology, there is one in which audio data is transmitted from a transmitter, and the received audio is output by a speaker driven by an external power source. (For example, refer to Patent Document 1).

  FIG. 15 is a block diagram showing a conventional wireless audio transmission / reception system described in Patent Document 1. In FIG. In FIG. 15, 100 is a wireless music player, 101 is a wireless speaker, and 102 is a power supply unit. The music player 100 includes a wireless communication unit 103 such as Bluetooth. The power supply unit includes an AC / DC converter 108 and a charging unit 109. The wireless speaker 101 includes a wireless communication unit 104 such as Bluetooth, a rechargeable battery 105, speaker driving means (power amplifier) 106, and a speaker 107.

  Music data reproduced by the music player 100 is transmitted to the wireless speaker 101 by the wireless communication unit 103. In the wireless speaker 101, music data transmitted from the music player is received by the wireless communication unit 104, power is amplified by the speaker driving means 106, and the speaker 107 is driven to play a sound. The wireless communication unit 104 and the speaker driving means 106 are supplied with power from the rechargeable battery 105 so that the electronic circuit is operated. In addition, the rechargeable battery 109 is externally fed by the charging unit 109 to charge power. The charging unit 109 is configured such that power is supplied in a wired manner from an AC power source via an AC / DC converter. With this configuration, audio data wirelessly transmitted from the music player 100 can be played with a wireless speaker.

JP 2008-278328 A

  However, in the conventional wireless audio transmission reception technology of the prior art, only audio data is transmitted wirelessly and power is not wirelessly transmitted. Therefore, a power supply using an AC power source or a rechargeable battery is required on the receiving side, and the speaker is completely wireless. Had the problem of not being able to.

  The present invention solves the above-described conventional problems, and an object thereof is to provide a complete wireless speaker in which an AC power supply and a rechargeable battery are not required for a speaker on the receiving side.

  In order to solve the above-described conventional problems, a magnetic resonance type wireless audio transmission apparatus according to the present invention includes a resonance frequency oscillator that oscillates a specific frequency, and a stream modulator that generates a serial signal that becomes an audio signal by low-pass filtering. A transmission modulator that converts the serial signal into a modulated signal modulated at the specific frequency, a power amplifier that amplifies the power of the modulated signal, and a resonator that magnetically resonates the modulated signal at the specific frequency. Are provided.

  In addition, the magnetic resonance type wireless audio receiving apparatus of the present invention includes a resonator that magnetically resonates at a specific frequency, a transmission demodulator that demodulates an input from the resonator and restores a serial signal, and a low frequency band of the serial signal. A low-pass filter that converts the sound signal into a sound signal by filtering; and a speaker that outputs the sound signal.

  A magnetic resonance type wireless audio transmission system is configured by using the above magnetic resonance type radio audio transmitting apparatus and magnetic resonance type radio audio receiving apparatus.

  As described above, it is possible to wirelessly transmit power as well as voice and provide a wireless speaker without an AC code.

  According to the magnetic resonance type wireless audio transmission device, magnetic resonance type radio audio reception device, and magnetic resonance type radio audio transmission system of the present invention, it is possible to install the speaker by completely eliminating the wiring of the reception side radio speaker which could not be performed conventionally. The degree of freedom and ease can be improved.

Block configuration diagram of a magnetic resonance type wireless audio transmission device, a magnetic resonance type wireless audio reception device, and a magnetic resonance type radio audio transmission system according to Embodiment 1 Block configuration diagram showing a pulse width modulator of a stream modulator in the first embodiment Waveform diagram showing audio signal waveform, sawtooth waveform, and pulse width modulation signal waveform in the first embodiment Block configuration diagram showing a pulse density modulator of the stream modulator in the first embodiment Block configuration diagram of resonant frequency oscillator in the first and second embodiments Waveform diagram showing an amplitude modulation waveform in the first embodiment Block configuration diagram showing a power amplifier in the first embodiment and the second embodiment Characteristic diagram showing resonance characteristics of LC resonator in Embodiment 1 and Embodiment 2 Block configuration diagram showing a transmission demodulator in the first embodiment Waveform diagram showing a signal waveform after full-wave rectification in the first embodiment Waveform diagram showing a signal waveform for driving the speaker in the first embodiment Block configuration diagram of a magnetic resonance type wireless audio transmission device, a magnetic resonance type radio audio reception device, and a magnetic resonance type radio audio transmission system according to Embodiment 2 Waveform diagram representing a ternary stream waveform in the second embodiment Waveform diagram showing a post-modulation waveform of the ternary stream waveform in the second embodiment Block diagram showing a conventional wireless audio transmission / reception system

(Embodiment 1)
FIG. 1 is a configuration diagram illustrating a magnetic resonance type wireless audio transmission device, a magnetic resonance type radio audio reception device, and a magnetic resonance type radio audio transmission system according to the present embodiment. In FIG. 1, 1 is an input terminal, 2 is a stream modulator, 3 is a resonant frequency oscillator, 4 is a transmission modulator, 5 is a power amplifier, 6 and 7 are LC resonators having a resonant frequency fr, 8 is a transmission demodulator, 9 is a low-pass filter, and 10 is a speaker. Details of the magnetic resonance type wireless audio transmission apparatus, the magnetic resonance type radio audio reception apparatus, and the magnetic resonance type radio audio transmission system configured as described above will be described below with reference to the drawings.

  In FIG. 1, a sound is input from an input terminal 1. The input sound is converted into a 1-bit serial signal in a form that becomes a sound signal by performing low-pass filtering in the stream modulator 2. The 1-bit serial signal is, for example, pulse width modulation (PWM) or pulse density modulation (PDM).

  FIG. 2 is a configuration diagram of the 1-bit modulator 2 when performing pulse width modulation. 11 is an input terminal, 12 is a sawtooth wave generator, 13 is a comparator, and 14 is an output terminal. The audio signal sig (t) input from the input terminal 11 is input to the minus input of the comparator 13, and simultaneously the sawtooth wave k (t) generated by the sawtooth wave generator is applied to the plus input of the comparator 13. The pulse width modulation signal pwm (t) is output from the comparator 13.

  FIGS. 3A and 3B show input / output waveforms of the comparator 13 and show how the audio signal sig (t) is converted into the pulse width modulation signal pwm (t). In FIG. 3A, the sawtooth wave k (t) and the audio signal sig (t) are compared, and pwm (t) in FIG. 3B is output. That is, pwm (t) = 1 is output when sig (t) ≧ k (t), and pwm (t) = 0 is output when sig (t) <k (t). This pwm (t) is a signal waveform in which sig (t) is restored by low-pass filtering. The sawtooth wave used for generating the pulse width modulation signal may be replaced with a triangular wave.

  Next, the pulse width signal pwm (t) is input to the transmission modulator 4 and subjected to AM modulation at the frequency fr oscillated by the resonant frequency oscillator 3. The resonant frequency oscillator 3 is configured, for example, in FIG.

  In FIG. 5, 21 is a crystal resonator, 22 is a CMOS inverter, 23 is a resistor, 24 and 25 are capacitors, and 26 is an output terminal. The CMOS inverter 22 is self-biased by a resistor 23 and is connected to a crystal resonator 21 having a steep band-pass filter characteristic of a frequency fr, and oscillates at an accurate frequency fr. The signal of the frequency fr is expressed by a mathematical expression of sin (2π × fr × t). The frequency fr is input to the transmission modulator 4 together with the previous pulse width modulation signal pwm (t) and multiplied in the transmission modulator to obtain an amplitude modulation output am (t) = pwm (t) × sin (2π Xfr * t).

  FIG. 6 shows a signal waveform of am (t), indicating that only the frequency fr exists when pwm (t) = 1, and that the signal becomes 0 when pwm (t) = 0.

The amplitude modulation output am (t) is then input to the power amplifier 5 to be amplified for transmission.
Considering the amplification efficiency and the characteristics of the modulation signal, the power amplifier should amplify the frequency fr efficiently with the amplifier circuit shown in FIG.

  7 shows a switching-type amplifier, 27 is an input terminal, 28 is a drive circuit, 29 and 30 are transistors S1, S2, and 31 are band-pass filters, and 32 is a matching circuit. The amplitude modulation signal am (t) input from the input terminal 27 passes through the drive circuit 28 and is amplified by switching the two transistors at the frequency fr. The switching output passes through a bandpass filter having a pass frequency fr, and then impedance matching is performed by a matching circuit, and is output to the output terminal 33. The output signal is input to an LC resonator having a resonance frequency fr, and is sent to the LC resonator 7 on the reception side using a magnetic resonance phenomenon.

  FIG. 8 shows an example of the characteristics of the LC resonator, and shows that power is transmitted from the LC resonator 6 to the LC resonator 7 with high efficiency only at the specific frequency fr. High efficiency is achieved when the transmission impedance and the reception impedance are matched. The power-amplified amplitude modulated signal received by the LC resonator 7 is demodulated by the transmission demodulator 8.

  The transmission demodulator 8 is configured as shown in FIG. Reference numeral 34 is an input terminal, 35 is a matching circuit, 36 is a rectifier, 37 is an envelope detector, and 38 is an output terminal. The amplitude modulation signal input from the input terminal 34 is input to the rectifier 36 through a matching circuit 35 that matches impedance and realizes high efficiency. The rectifier 36 is a full-wave rectifier and is usually realized by a bridge circuit of four diodes.

  FIG. 10 shows a signal in which the amplitude-modulated wave is full-wave rectified at the output of the rectifier 36. The envelope of the signal is extracted by the envelope detector 37 and the pulse-width modulated wave is extracted from the envelope detector 37. Restore. The envelope detector is realized by a capacitor, for example.

  The restored pulse width modulation is low-pass filtered by the low-pass filter 9 to restore the original audio signal shown in FIG. The restored audio signal is amplified by the power amplifier 5 on the transmission side and is generated from the signal transmitted with power in the LC resonators 6 and 7, so that the speaker is driven without the power amplifier. This is a power amplified audio signal.

  Although the stream modulator in FIG. 1 has been described with pulse width modulation (PWM), pulse density modulation (PDM) may be used. The pulse density modulation can be generated by using, for example, a ΔΣ modulator shown in FIG. As shown in FIG. 4, the ΔΣ modulator has an input terminal 15, an adder 16, an integrator 17, a quantizer 18, a delay unit 19, and an output terminal 20.

There is a “Δ modulation encoding method” that is often used as a method of encoding an analog signal into a 1-bit bit stream. This is a method of tracking the analog signal waveform with a stepped waveform,
・ When the rising slope of the input signal is large, “1”
• “0” when the slope of the input signal is small
Is encoded. That is, the 1-bit stream obtained by Δ modulation represents the slope of the analog signal, that is, the magnitude of the differential value with the frequency of “0” and “1”.

  If the input signal is integrated in advance with respect to the above-described Δ modulation, an encoded sequence corresponding to the amplitude of the original signal should be generated. This is the basic configuration of ΔΣ modulation shown in FIG. In FIG. 4, an audio signal is input from the input terminal 15, and the feedback signal is subtracted by the adder 16. The output is integrated by an integrator 17 and then converted into “1” and “0” signals by using a quantizer 18 to obtain a pulse density modulation signal pdm (t). In order to generate a differential waveform with respect to the original signal, pdm (t) is fed back to the adder 16 through the delay unit 19 of one sample, and the differential signal is recirculated and integrated.

  The pulse density modulation waveform generated in such a configuration is also a signal that can restore the original audio signal by low-pass filtering with a low-pass filter, as in the previous pulse width modulation waveform. Similar magnetic resonance type wireless audio transmission can be performed by replacing the previously described pwm (t) with pdm (t).

  According to such a configuration, the magnetic resonance type wireless audio transmission system is configured by using the magnetic resonance type wireless audio transmission device and the magnetic resonance type radio audio reception device, thereby providing a wireless speaker without wiring and the degree of freedom of arrangement. Can be increased.

(Embodiment 2)
FIG. 12 is a configuration diagram illustrating the magnetic resonance type wireless audio transmission device, the magnetic resonance type radio audio reception device, and the magnetic resonance type radio audio transmission system according to the present embodiment. In FIG. 12, the same components as those in FIG. Reference numeral 40 is a data demodulator, 41 is an amplifier, and 42 is a power extractor.

  Here, an example in which the ternary stream d (t) shown in FIG. 13 is handled as a representative of a multi-value stream other than a 1-bit bit stream will be described. The ternary values are three values “−1”, “0”, and “1”, and are streams in which a current signal can be generated by a low-pass filter in the same manner as the binary stream described above.

  Details of the magnetic resonance type wireless audio transmission apparatus, the magnetic resonance type radio audio reception apparatus, and the magnetic resonance type radio audio transmission system configured as described above will be described below with reference to the drawings. In FIG. 12, audio is input from the input terminal 1. The input audio is converted into the above-described ternary serial signal d (t) in the form of an audio signal by performing low-pass filtering by the stream modulator 2. Is done.

  Next, the ternary stream signal d (t) is input to the transmission modulator 4 and subjected to AM modulation at the frequency fr oscillated by the resonant frequency oscillator 3. The resonant frequency oscillator 3 can be realized by the configuration shown in FIG. 5 as in the first embodiment. The operation when the resonant frequency transmitter 3 is applied to the ternary stream signal d (t) is as follows.

  The signal of the frequency fr is expressed by a mathematical expression of sin (2π × fr × t). The frequency fr is input to the transmission modulator 4 together with the ternary stream signal d (t), and multiplied in the transmission modulator to obtain an amplitude modulation output d (t) × sin (2π × fr × t). Get. FIG. 14 shows a signal waveform after modulation. When d (t) = 1, only the frequency fr exists, and when pwm (t) = 0, the signal becomes 0, and d (t) = − 1. It sometimes shows that there is only a frequency fr whose phase is inverted.

  The amplitude modulation output is amplified by the power amplifier 5 in the same manner as in the first embodiment, and is transmitted to the reception side via the LC resonators 6 and 7.

  The power-amplified amplitude modulation signal received by the LC resonator 7 is demodulated by the data demodulator 40. Unlike the transmission demodulator 8 of the first embodiment, the data demodulator 40 can use envelope detection because it has the same envelope when d (t) is “1”, “−1”. Absent. That is, the signal whose amplitude is modulated from the ternary stream is not subjected to envelope detection of the waveform, and the signal modulated according to whether the phase of the oscillation frequency is 0 or π needs to be phase-demodulated.

Generally, synchronous detection is used to demodulate a signal in which information is superimposed on a phase. The synchronous detection is a method of obtaining an original signal by generating a modulation frequency fr by another means and multiplying it with a signal.
When d (t) = 1, sin (2π × fr × t) × sin (2π × fr × t) = (1−cos (2π × fr × t)) / 2
When d (t) = 0, 0 × sin (2π × fr × t) = 0
When d (t) = − 1, −sin (2π × fr × t) × sin (2π × fr × t) = − (1−cos (2π × fr × t)) / 2
Therefore, if cos (2π × fr × t) is removed by the low-pass filter, 1/2, 0, and −1/2 are demodulated. If the signal is doubled, 1, 0 and -1 can be restored.

  The data demodulator 40 operates as described above. At this time, the power required for generation and multiplication of the modulation frequency may be extracted by 42 power extractors. The power extractor can be configured in the same configuration as the transmission demodulator of FIG.

  After performing synchronous detection and generating the ternary stream d (t), power amplification is performed by the amplifier 41 as necessary, the original audio signal is restored by the low-pass filter 9, and the speaker 10 is played.

  According to such a configuration, even when a ternary stream is transmitted by amplitude modulation, an audio signal can be restored by synchronous detection, and a wireless speaker without wiring can be provided.

  The magnetic resonance type wireless audio transmission device, the magnetic resonance type wireless audio reception device, and the magnetic resonance type radio audio transmission system according to the present invention can be used for a wireless speaker that can be freely installed because it can transmit power and audio simultaneously by radio. it can. Further, if a signal other than audio (for example, a video signal) is transmitted, the present invention can be applied to all devices using both data and power, such as a video display device.

1, 11, 15, 27, 34 Input terminal 2 Stream modulator 3 Resonant frequency oscillator 4 Transmission modulator 5 Power amplifier 6, 7 LC resonator 8 Transmission demodulator 9 Low pass filter 10 Speaker 12 Sawtooth generator 13 Comparator 14, 20, 26, 33, 38 Output terminal 16 Adder 17 Integrator 18 Quantizer 19 Delay device 21 Crystal oscillator 22 CMOS inverter 23 Resistor 24, 25 Capacitor 28 Drive circuit 29, 30 Transistor 31 Band pass filter 32 , 35 Matching circuit 36 Rectifier 37 Envelope detector 40 Data demodulator 41 Amplifier 42 Power extractor 100 Wireless player 101 Wireless speaker 102 Power supply unit 103, 104 Wireless communication unit 105 Rechargeable battery 106 Speaker drive means 107 Speaker

Claims (7)

A resonant frequency oscillator that oscillates a specific frequency;
A stream modulator that generates a serial signal that becomes an audio signal by low-pass filtering;
A transmission modulator that converts the serial signal into a modulated signal modulated at the specific frequency;
A power amplifier for amplifying the modulation signal;
A resonator that magnetically resonates the modulated signal with power amplified at the specific frequency;
A magnetic resonance type wireless voice transmitting apparatus comprising: The stream modulator uses any one of pulse width modulation, pulse density modulation, and ternary modulation when generating a serial signal.
The magnetic resonance type radio | wireless audio | voice transmission apparatus of Claim 1. The modulation performed by the transmission modulator is amplitude modulation.
The magnetic resonance type radio | wireless audio | voice transmission apparatus in any one of Claim 1 thru | or 2. A resonator that magnetically resonates at a specific frequency;
A transmission demodulator that demodulates the input from the resonator and restores the serial signal;
A low-pass filter that converts the serial signal into an audio signal by low-pass filtering;
A speaker for outputting the audio signal;
A magnetic resonance type radio sound receiving apparatus comprising: The transmission demodulator demodulates the signal by full-wave rectification and envelope detection,
The magnetic resonance type radio | wireless audio | voice receiving apparatus of Claim 4. The transmission demodulator demodulates the signal by synchronous detection;
The magnetic resonance type radio | wireless audio | voice receiving apparatus of Claim 4. A magnetic resonance type wireless audio transmission apparatus according to any one of claims 1 to 3,
A magnetic resonance type wireless audio receiver according to any one of claims 4 to 6,
Magnetic resonance type wireless audio transmission system.

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