WO2002013573A1

WO2002013573A1 - Loudspeaker device

Info

Publication number: WO2002013573A1
Application number: PCT/JP2000/005271
Authority: WO
Inventors: Hidekazu Tanaka; Fumiyasu Konno
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 1999-05-19
Filing date: 2000-08-07
Publication date: 2002-02-14
Also published as: CZ20021168A3; CN1377566A; HK1049940A1; EP1221824B1; HK1049940B; EP1221824A1; EP1221824A4; CZ299745B6; DE60031558T2; CN1186965C; DE60031558D1

Abstract

A loudspeaker device comprising a subtracter (6), a power amplifier (13) to which an input signal is inputted through the subtracter (6), a loudspeaker unit (1) for reproducing the output signal from the amplifier (13), a sound tube (2) coupled to the front of the loudspeaker unit (1) so as to guide the sound wave from the loudspeaker unit (1), and a negative feedback circuit constituted of a microphone (4) for detecting the sound output radiated from the loudspeaker unit (1), a microphone amplifier (5) for amplifying the sound signal detected by the microphone (4) and feeding its output signal directly to the subtracter (6), and a high-pass filter (7) through which the output signal from the microphone amplifier (5) is also fed to the subtracter (6), whereby the peak dip of the sound pressure frequency characteristic is suppressed to flatten the acoustic characteristic.

Description

Speaker device

Technical field

The present invention relates to a speaker device used for various audio equipment and a television receiver.

In particular, a sound tube is connected to the front of the speaker unit, and a microphone for detecting the sound reproduced from the speed unit is provided in the sound tube. The sound reproduced from the speaker unit is corrected by the detection signal. It relates to a speaker device.

Background art

A conventional speaker device of this type will be described with reference to FIGS. 7, 8 (A) and 8 (B). Fig. 7 is a block diagram, Fig. 8 (A) is the microphone output signal diagram, Fig. 8 (B) is the acoustic output characteristic diagram, a is the sound pressure characteristic, and b is The phase characteristic is shown.

According to FIG. 1, reference numeral 1 denotes a speaker unit for generating a sound wave, and the speaker unit 1 is connected to an acoustic tube 2. Sound absorbing materials (not shown) are arranged on both sides of the acoustic tube 2 to suppress resonance. Inside the acoustic tube 2, a microphone 4 for detecting an acoustic output signal is arranged near the speaker unit 1.

When a signal is input to the speaker unit 1 via the subtractor 6 and the power amplifier 3, a sound output is emitted from the speaker unit 1, and the sound output passes through the sound tube 2 and radiates from the opening of the sound tube 2. Is done. At this time, a standing wave generated by the length of the acoustic tube 2 inside the acoustic tube 2 or a standing wave generated inside the speaker tube 2 causes This standing wave is suppressed by a sound absorbing material in order to prevent the reproduction sound pressure frequency characteristic having a sharp peak dip from being produced, but the sound wave is a standing wave that is insufficient and cannot be suppressed. The output is detected by the microphone 4 and fed back to the subtractor 6 via the microphone amplifier 5 to suppress the standing wave generated in the acoustic tube 2 and realize a flat reproduced sound pressure frequency characteristic.

It is known that when an acoustic tube is coupled to the front of a speaker, tube resonance occurs, and the generated resonance frequency is

f = (n + 1) CZ4L

(f: tube resonance frequency, n: nth order resonance, C: sound speed, L: tube length)

It is represented by

Accordingly, in the above-described speaker device, the primary resonance generated in the length of the acoustic tube 2 due to the phase difference between the electric signal input to the speaker unit 1 and the sound output signal radiated from the speaker unit 1 When n = l) was corrected, the resonance component shifted in the corrected sound output characteristics and a peak appeared, and it was difficult to flatten the sound output characteristics. In addition, since feedback control is performed from the low-frequency component to the high-frequency component, it is not possible to control only an arbitrary frequency component.

The relationship between input and output is

V o u t / V i n = A (1 + AT (S))

(Vout: output voltage, Vin: input voltage, A: overall amplification of the amplifier, T (S): transfer function)

Assuming that T (S) is almost the transfer function of speaker unit 1 because the characteristics of microphone 4 are almost flat, the secondary or tertiary tube of speaker unit 1 and acoustic tube 2 T (S) becomes minus 1 due to the phase change due to resonance.

That is, in some cases, the denominator becomes 0 and the condition for oscillation occurs. From this, Considering the oscillation margin, large feedback could not be achieved, and it was difficult to control efficiently from low frequencies to tube resonance.

An object of the present invention is to solve the above-mentioned problems, and to provide a speaker device that can exhibit stable characteristics. Disclosure of the invention

In order to solve the above problems, a speaker device according to the present invention includes a power amplifier to which an input signal is input via a subtractor, a speed unit for reproducing an output signal of the power amplifier, and a sound wave of the speaker unit. An acoustic tube coupled to the front surface for guiding the sound, a microphone for detecting the acoustic output radiated from the speaker unit, a microphone amplifier for amplifying the acoustic output signal detected by the microphone, and an output signal of the microphone amplifier Is connected to a subtractor, and the output signal of the microphone amplifier is connected to the subtractor via a high-pass filter to form a negative feedback circuit to suppress the peak dip of the sound pressure frequency characteristic, thereby making the speaker device As a result, stable characteristics can be obtained. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram of an embodiment of the splicing device of the present invention, FIG. 2 is a diagram of the sound output characteristic, FIG. 3 is a block diagram of the other embodiment, FIG. Figure (A) is a microphone output signal characteristic diagram, Figure 4 (B) is an acoustic output characteristic diagram, Figure 5 is a block diagram of another embodiment, and Figure 6 (A). Fig. 6 (B) is the same sound output characteristic diagram, Fig. 7 is a block diagram, Fig. 8 (A) is the same microphone output signal diagram, FIG. 8 (B) is the same sound output characteristic diagram. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the spinning device according to the present invention will be described with reference to FIGS. 1 to 6 (B).

Note that the same parts as those of the prior art will be described with the same reference numerals.

(Example 1)

FIG. 1 is a block diagram of an acoustic circuit according to the first embodiment, and FIG. 2 is an acoustic output characteristic diagram, wherein a shows a sound pressure characteristic and b shows a phase characteristic. First, the overall configuration of the speed controller will be described with reference to FIG.

According to the figure, 1 is a speaker unit, 2 is an acoustic tube coupled to the front of the speaker unit 1, 4 is a microphone mounted in the acoustic tube 2, and radiated from the speaker unit 1. The sound wave is detected by the microphone 4 in the acoustic tube 2 and is input to the subtractor 6 through the high-pass filter 7, and the signal detected by the microphone 4 is directly input to the subtractor 6. The configuration is such that the input signal is corrected by mixing with an external input signal, amplified by the power amplifier 13 and input to the speaker unit 1.

The relationship between the speaker unit 1 and the sound tube 2 is as follows. The sound tube 2 for guiding sound waves is connected to the front of a speaker unit 1 attached to a speaker box (not shown). The tube resonance generated in the acoustic tube 2 is detected by the microphone 4, and the detected sound output signal is a second-order high-pass (−1 2 dB / oct) pass filter. The signal is returned to the subtractor 6 via 7 and the signal detected by the microphone 4 is directly fed back to the subtractor 6.

FIG. 2 shows the sound output characteristics of the present embodiment. Compared to the conventional technique of FIG. 8 (B), a peak due to a shift appears due to a phase change of the resonance component. Not in. In the embodiment of FIG. 2, the frequency characteristics are flattened without any shift of the resonance component.

As described above, the tube resonance generated in the sound tube 2 is detected by the microphone 4, and the detected sound output signal is fed back to the subtractor 6 through the second-order (12 dB / oct) high-pass filter 7. At the same time, the signal detected by the microphone 4 is directly fed back to the subtractor 6, and the cut-off frequency of the second-order (-12 dB Zoct) high-pass filter 7 is adjusted to the frequency of the tube resonance. It is possible to provide an excellent spinning device by performing phase correction.

(Example 2)

FIG. 3 is a block diagram of an acoustic circuit according to another embodiment of the present invention. FIG. 4 (A) is a microphone output signal characteristic diagram, FIG. 4 (B) is an acoustic output characteristic diagram, Sound pressure characteristic, b shows phase characteristic. Explaining only the structural differences from the first embodiment, the acoustic output signal detected by the microphone 4 is connected to the subtractor 6 via two high-pass filters 7 and 8 connected in parallel to form a negative feedback circuit. 7 is a second-order (one 12 dBZo ct) high-pass filter, and 8 is a first-order (6 dBZo ct) high-pass filter.

According to the frequency characteristics of the conventional microphone signal shown in FIG. 8 (A), even the low-frequency components are returned, and the low-frequency components are enhanced. However, in this embodiment, as shown in FIG. 4 (A), the level of the low frequency component is reduced, and the low frequency component is not enhanced.

Also, comparing the output acoustic characteristics of the conventional one (Fig. 8 (B)) with the output acoustic characteristics of the second embodiment (Fig. 4 (B)), the conventional technology shows a low frequency response. Although the characteristics are enhanced, it can be seen that the low-frequency characteristics are not enhanced in this example. As described above, the acoustic output signal detected by the microphone 4 is used to connect the output signal of the microphone amplifier 5 to two parallel-connected primary and secondary high-pass filters 8 and 7, and the output signal Is connected to the subtractor 6 to form a negative feedback circuit, so that the microphone output signal only in the vicinity of the resonance frequency component can be fed back, the enhancement of low frequency components can be suppressed, and the output frequency characteristic is flat. It is possible to provide a speaker device having excellent acoustic characteristics capable of realizing and correcting.

(Example 3)

FIG. 5 is a block diagram of an acoustic circuit according to another embodiment of the present invention. FIG. 6 (A) is a microphone output signal characteristic diagram, FIG. 6 (B) is the same acoustic output characteristic diagram, Sound pressure characteristic, b shows phase characteristic. Explaining only the differences from the first embodiment, a second-order high-pass filter 7 that processes the output signal detected by the microphone 4 is connected, the output signal is connected to the subtractor 6, and the output signal of the microphone 4 is The negative feedback circuit is constructed by connecting the low pass filter 9 of 1 2 d BZ oct or-6 d BZ oct to be processed to the subtractor 6.

The low-pass filter 9 extracts only low-frequency components and performs phase correction to correct output acoustic characteristics using only low-frequency components, and the second-order high-pass filter 7 also independently corrects tube resonance. Thus, it is possible to arbitrarily control the output frequency characteristics, and to provide a speaker device having excellent acoustic characteristics that can easily and easily realize the flattening and correction of the output frequency characteristics.

As is clear from the comparison between the sound output characteristic of the present embodiment shown in FIG. 6 (B) and the conventional one (FIG. 8 (B)), it is possible to simultaneously control the low-frequency characteristic and the tube resonance. It was confirmed that it was possible to control any sound output characteristics.

In each of the above embodiments, the high-pass filter is controlled by the secondary tube resonance. Although the description has been made assuming that the control is of order n (n is a positive integer), control of the tube resonance can be realized, and the present invention can be applied to the present invention.

The present invention is applicable even when the back cover connected to the acoustic tube is a bass reflex or when there is no back force cover. Industrial applicability

A speaker device of the present invention is coupled to a power amplifier to which an input signal is input via a subtractor, a speaker unit for reproducing an output signal of the power amplifier, and a front surface for guiding sound waves of the speed unit. Sound tube, a microphone for detecting the sound output radiated from the speaker unit, a microphone amplifier for amplifying the sound output signal detected by the microphone, and an output signal of the microphone amplifier connected to a subtractor. In addition, in the case where the output signal of the microphone amplifier is connected to the subtractor through a high-pass filter to form a negative feedback circuit, the microphone output signal is fed back through the high-pass filter and The phase is corrected by directly feeding back the microphone output signal, In addition to suppressing peaks due to shifts in frequency components, direct feedback of the microphone output signal makes it possible to enhance low-frequency components, flattening output frequency characteristics and improving bass reproduction. A speaker device having acoustic characteristics can be provided.

In the case where the high-pass filter is a secondary high-pass filter, a greater effect can be obtained by adjusting the cut-off frequency to the supplied frequency.

A power amplifier to which an input signal is input via a subtractor; a speaker unit for reproducing an output signal of the power amplifier; An acoustic tube coupled to the front surface for guiding sound waves of the unit, a microphone for detecting an acoustic output radiated from the speaker unit, a microphone amplifier for amplifying an acoustic output signal detected by the microphone, and the microphone In the case where the output signal of the amplifier is connected to the above-described subtractor via primary and secondary high-pass filters connected in parallel to form the negative feedback circuit, a microphone only near the resonance frequency component is used. The output signal can be fed back, the enhancement of low frequency components can be suppressed, and the output frequency characteristics can be flattened and corrected, and a speaker device with excellent acoustic characteristics can be provided.

A power amplifier to which an input signal is input via a subtractor; a speaker unit for reproducing an output signal of the power amplifier; an acoustic tube coupled to a front surface for guiding sound waves of the speaker unit; A microphone for detecting the sound output radiated from the unit, a microphone amplifier for amplifying the sound output signal detected by the microphone, and a second-order high-pass filter connected in parallel with the output signal of the microphone amplifier. When a negative feedback circuit is constructed by connecting to the above subtractor via a primary or secondary low-pass filter, the microphone output signal near the low-frequency component and the resonance frequency component is fed back. The low-pass filter enables low-frequency component phase correction, low-frequency component control, and independent frequency component control. This makes it possible to control the resonance frequency component while enhancing and suppressing bass reproduction, flattening and correcting output frequency characteristics can be arbitrarily and easily realized, and achieve excellent sound characteristics. A speaker device can be provided.

Claims

The scope of the claims

1. A power amplifier to which an input signal is input via a subtractor, a speaker unit for reproducing an output signal of the power amplifier, an acoustic tube coupled to a front surface for guiding sound waves of the speaker unit, and the speaker A microphone for detecting the sound output radiated from the unit, a microphone amplifier for amplifying the sound output signal detected by the microphone, a microphone amplifier for connecting the output signal of the microphone amplifier to a subtractor, A speaker device comprising a negative feedback circuit by connecting the output signal of the above to the subtractor via a high-pass filter.

2. The speaker device according to claim 1, wherein the high-pass filter is a second-order high-pass filter, and the cut-off frequency is a resonance frequency of the acoustic tube.

3. A power amplifier to which an input signal is input via a subtractor, a speaker unit for reproducing an output signal of the power amplifier, an acoustic tube coupled to a front surface for guiding sound waves of the speaker unit, and a speaker unit for the speaker unit. A microphone that detects the sound output radiated from the microphone, a microphone amplifier that amplifies the sound output signal detected by this microphone, and a primary and secondary high-pass that is connected in parallel with the output signal of this microphone amplifier A speaker device comprising a negative feedback circuit connected to the subtractor via a filter.

4. A power amplifier to which an input signal is input via a subtractor, a speaker unit for reproducing an output signal of the power amplifier, an acoustic tube coupled to a front surface for guiding sound waves of the speaker unit, A microphone for detecting the sound output radiated from the speaker unit, a microphone amplifier for amplifying the sound output signal detected by the microphone, and a second-order high-pass filter in which the output signal of the microphone amplifier is connected in parallel. Primary again Is a loudspeaker device connected to the above subtractor via a second-order low-pass filter to form a negative feedback circuit.