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JPH0290894

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DESCRIPTION JPH0290894
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker circuit, particularly to a speaker circuit suitable for a full range speaker. SUMMARY OF
THE INVENTION In the speaker circuit, the present invention comprises means for separating an
input signal into a high frequency component and a low frequency component, a means for
inverting the phase of a low frequency component or a component related to low frequency, and
low frequency. The intermodulation distortion of the speaker is provided with means for
frequency modulating the high frequency component by the component or the low frequency
related component, and means for mixing the low frequency component or low frequency related
component with the above-mentioned FM modulation output. To prevent the [Prior Art] In a
direct radiation type speaker, when the frequency characteristic is made flat as shown in FIG. 5,
the velocity characteristic of the vibration system is the lowest resonance frequency f as shown
in the sixth time. Is increased by 6 dBloCT, while decreased by 6 dBloCT in the frequency range
above the lowest resonance frequency fo. [Problems to be Solved by the Invention] In the case of
a so-called full-range type speaker that radiates a low-range to high-range sound in the same
vibration system, the high-range component is radiated with a large low-range amplitude. It will
be Therefore, when the sound source gets close to the listener, the frequency rises, and when it
goes away, the so-called doppler effect occurs, and the high frequency component is frequency
modulated with the low frequency component, causing intermodulation distortion. There was a
point. When this intermodulation distortion occurs, the sound becomes turbid and there is a
problem that a good sound can not be reproduced. In particular, recently, downsizing of the
speaker is desired due to space, but when the speaker is miniaturized, the area of the diaphragm
is reduced. Therefore, in order to obtain the necessary sound pressure, the vibration system The
amount of amplitude must be increased. As a result, the above-mentioned intermodulation
distortion is likely to occur, which makes it difficult to reproduce good quality sound. Therefore,
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1
an object of the present invention is to provide a speaker circuit capable of preventing cross
modulation distortion of the speaker. According to the present invention, there is provided a
circuit 2.3 for dividing an input signal into a high band component and a low band component, a
circuit 6 for inverting the phase of a low band component or a component related to the low
band, A circuit 8 FM-modulates a high frequency component with a low frequency component or
a low frequency related component, and a circuit 5 mixing the low frequency component or low
frequency related component with the FM modulation output. (Function) The high frequency
component radiated from the speaker is frequency-modulated with the low frequency component
by the above-mentioned Doppler effect. That is, in the high frequency component sound wave
radiated from the speaker, a sparse portion and a dense portion are formed corresponding to the
polarity of the low frequency component.
Therefore, in order to cancel this, the phase of the low frequency component is inverted, and the
high frequency component is FM-modulated by the inverted low frequency component of this
phase. That is, when the sound wave is emitted from the speaker, the dense portion is expanded
in advance in accordance with the polarity of the low frequency component (as well as the sparse
portion is compressed in advance. Then, the low frequency component or the component related
to the low frequency and the above-mentioned FM modulation output are mixed and supplied to
the speaker. Therefore, when the high frequency component sound wave is emitted from the
speaker, the expanded part of the period is compressed in advance, and the compressed part of
the period is expanded. As a result, the Doppler effect is canceled and overall high-frequency
component sound waves that are not subjected to frequency modulation at all are obtained.
Embodiments of the present invention will be described below with reference to FIGS. 1 to 4. FIG.
The present invention is commonly used for full range type speakers. FIG. 1 shows a first
embodiment of the present invention. FIG. 1 shows the configuration of an open loop type
speaker circuit, and FIG. 2 shows the waveforms of a low band component and a high band
component. This speaker circuit is to control the intermodulation distortion of the speaker in the
dimension of the velocity of the diaphragm. Further, this speaker circuit corresponds to the
polarity of the low frequency component, and forms a signal for canceling the tompler effect in
the circuit. In FIG. 1, the audio signal SA supplied to the terminal 1 is supplied to the low pass
filter 2 and the bypass filter 3 respectively. The low pass component SL is separated by the low
pass filter 2, and the high pass component SH is separated by the bypass filter 3. As the low pass
filter 2, one having a steep separation characteristic is used, and the low frequency component
SL separated by the low pass filter 2 is further supplied to the integration circuit 4 and the
mixing circuit 5. The integration circuit 4 is configured to have an attenuation of 6 dBloCT from
the low frequency range to the high frequency range down to the right, and obtains a voltage
corresponding to the speed of the speaker diaphragm. Then, the output of the integrating circuit
4 is supplied to the phase inverting circuit 6. In the phase inverting circuit 6, for example, as
shown in FIG. 2B, the phase of the low frequency component SL is inverted by 180 degrees to
form an inverted signal SI. The inverted signal SI output from the phase inverting circuit 6 is
08-05-2019
2
level-adjusted by the volume 7 and then supplied to the FM modulation circuit 8. In the FM
modulation circuit 8, the high frequency component SH supplied from the high pass filter 3 as
shown in FIG. 2A is frequency-modulated by the inverted signal SI to obtain the high frequency
component SHO as in the second scheme. Do.
The high frequency component SHO frequency-modulated by the FM modulation circuit 8 is
supplied to the mixing circuit 5. The mixing circuit 5 mixes the low frequency component SL and
the FM high frequency component SHO, and supplies the mixed signal to the speaker 10 via the
power amplifier 9. Conventionally, from the speaker 10, the frequency is modulated by the low
frequency component SL shown by the solid line in FIG. 2B and the above-mentioned low
frequency component SL, and the high frequency component S HO2 shown in FIG. The That is, a
sparse portion W1 and a dense portion W2 are formed, which causes intermodulation distortion.
Therefore, in order to solve this, the audio signal SA is divided into the high frequency
component S1 (and the low frequency component SL, and the phase of the low frequency
component SL is inverted as shown by the broken line in FIG. sr is formed, and the highfrequency component St (frequency-modulated in advance as in the second scheme) by the
inverted signal Sr. That is, in accordance with the polarity of the inversion signal sr, the dense
portion W2 to be formed is expanded in advance and the sparse portion W1 is compressed in
advance at the time of sound wave emission from the speaker 10. The low-frequency component
SL indicated by the solid line in FIG. 2B and the high-frequency component SHO, which is shown
in the second plan, are FM-modulated and supplied to the speaker 10 and are radiated. In the
high frequency component SHO of the sound wave radiated from the speaker 10, a sparse
portion W1 and a dense portion W2 are formed as shown in FIG. 2C by the above-described
Doppler effect. Since the high frequency component SH is modulated by the inverted signal SI,
the sparse portion W1 corresponds to the compressed portion W3 of the period, and the dense
portion W2 corresponds to the expanded portion W4 of the period. It will be. Thus, the
decompressed portion W4 of the cycle is compressed, and the compressed portion W3 of the
cycle is decompressed. As a result, it is possible to cancel the above-described Doppler effect and
to prevent intermodulation distortion. On the whole, it is possible to listen to the original high
frequency component not subjected to frequency modulation. 3 and 4 show a second
embodiment of the present invention. FIG. 3 shows the configuration of the feedback type
speaker circuit, and FIG. 4 shows a detector for feedback. In the speaker circuit of this
embodiment, the speaker is provided with a detector for capturing the low frequency component
of the diaphragm, and this output is fed back to eliminate intermodulation distortion. In FIG. 3,
the audio signal SA supplied to the terminal 21 is supplied to the low pass filter 22 and the
bypass filter 23, respectively. The low pass filter 22 separates the low frequency component SL,
and the bypass filter 23 separates the high frequency component SH.
The low pass component SL separated from the low pass filter 22 is supplied to the mixing
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3
circuit 24. The high frequency component SH separated from the bypass filter 23 is supplied to
the FM modulation circuit 25. The high frequency component SHO frequency-modulated by the
FM modulation circuit 25 is supplied to the mixing circuit 24. The low frequency component SL
and the high frequency component SHO mixed by the mixing circuit 24 are supplied to the
speaker 27 via the power amplifier 26. As shown in FIG. 4, an electromagnetic detector 31
composed of a coil 29 and a magnet 30 is disposed outside the diaphragm 2 of the speaker 27.
The vibration extracted from this detector 31 The output signal from the plate 28 is supplied to
the low pass filter 33 through the pickup amplifier 32. Since the detector 31 is an
electromagnetic type, it generates a detection signal according to the speed of displacement of
the diaphragm 28. Therefore, it is not necessary to provide the integrating circuit 4 as shown in
the first embodiment in the feedback system. Only the low frequency component SL is separated
by the low pass filter 33 in the feedback system, and after being level-adjusted by the volume 34,
it is supplied to the phase inverting circuit 35. The low frequency component SL is inverted by
180 degrees in phase by the phase inversion circuit 35 to form an inverted signal Sl, and is
supplied to the FM modulation circuit 25. The high frequency component S) I is FM-modulated
by the above-mentioned inverted signal Sl in the FM modulation circuit 25. The second
embodiment is different from the first embodiment in that the low frequency component SL is
fed back from the speaker 27 to the FM modulation circuit 25 to frequency modulate the high
frequency component SH. With respect to the high frequency component SHO in the sound wave
radiated from the speaker 27, the influence by the Doppler effect is canceled in the same manner
as in the first embodiment of the detailed description. As a result, it is possible to listen to the
entire high-frequency component SH which is not subjected to the frequency modulation as a
whole. In the second embodiment, the electromagnetic detector 31 including the coil 29 and the
magnet 30 is used. However, the present invention is not limited to this, and a piston capacitor or
a microphone can also be used. In the case of using a piston type capacitor, since the capacitor is
proportional to amplitude, it has to be converted to a speed characteristic, and therefore, it is
necessary to provide a differential circuit in the feedback system. When a microphone is used,
the sound pressure of the microphone is proportional to the acceleration, so it is necessary to
provide an integration circuit in the feedback system in order to convert it into the speed
characteristic. Although not described in detail, the speaker circuits of the first and second
embodiments described above can also be processed by digital circuits.
According to the present invention, the high frequency component is frequency-modulated by
the signal of the low frequency component whose phase is inverted, and the low frequency
component and the FM modulation output are radiated from the speaker, so that the Doppler
effect is canceled. There is an effect that cross modulation distortion of the speaker can be
prevented. This effect has the effect of being able to eliminate the muddyness of the sound. In
addition, since cross modulation distortion can be prevented even if the amount of amplitude
increases, there is an effect that a compact speaker with good sound quality can be configured.
08-05-2019
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[0002]
Brief description of the drawings
[0003]
FIG. 1 is a circuit diagram showing a first embodiment of the present invention, FIG. 2 is a
waveform diagram for explaining the respective embodiments, FIG. 3 is a circuit diagram
showing a second embodiment, and FIG. And FIG. 5 and FIG. 6 are characteristic diagrams for
explaining the conventional example.
Descriptions of major symbols in the drawings 2.22: low-pass filter, 3.23: bypass filter, 5.24:
mixing circuit, 6.35: phase inversion circuit, 8.25: FM modulation circuit, SA: audio signal, SL:
Low frequency component, SH, 5HO 1 SHO 2: High frequency component. Agent Attorney
Sugiura Masatoshi
08-05-2019
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