JPH10200988A - Speaker device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the low frequency characteristic and the distortion characteristic of a rear open speaker equipment. SOLUTION: An enclosure builds in an adjustment circuit 13C, an output amplifier 14C, a speaker unit 15C, and a level detection circuit 16 that detects a level of a low frequency component. The adjustment circuit 13C gives an audio signal MC whose low frequency level is enhanced to the speaker unit 15C and is controlled by a detection output V16 of the level detection circuit 16 so as to reduce the enhanced amount of the low frequency level when the level of the low frequency component is high.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speaker device having a built-in output amplifier.

[0002]

2. Description of the Related Art An open rear speaker device has a low air resistance in an enclosure, so that the response of the speaker unit is improved, there is almost no reflection in the enclosure, and the musicality of reproduced sound is enhanced. There are features.

[0003]

However, in an open-back speaker system, the sound radiated from the back of the speaker unit goes around to the front and interferes with the sound reproduced from the front. Assuming that the reproduction frequency characteristics of the device are indicated by the broken line characteristics in FIG. 5, the reproduction frequency characteristics of the rear open speaker device of the same size lacks bass as shown by the solid line in FIG. . Especially,
When the sound volume is low, the loudness characteristic of the audibility also has a large effect, so that the lack of bass is noticeable.

[0004] Of course, if the enclosure is made sufficiently large, the band in which interference occurs can be made a sufficiently low frequency band, so that practically sufficient low band characteristics can be obtained. However, in the case of a small-sized speaker device, for example, a postcard-sized speaker device used in combination with a headphone stereo, it is impossible to enlarge the enclosure in such a manner.

Therefore, a method has been considered in which an amplifier for driving a speaker unit is provided with, for example, a low-frequency enhancement characteristic as shown in FIG. However, when boosting the low range in this way, at high output, even if the mid-high range does not exceed the allowable input level of the amplifier, the enhanced low range exceeds the allowable input level of the amplifier, so the bass is distorted. I will.

[0006] The present invention is to solve such a problem.

[0007]

According to the present invention, there is provided, in the present invention, an enclosure having a rear open type, a speaker unit built in the enclosure, and a signal circuit built in the enclosure. A signal circuit to which an audio signal is supplied, a frequency characteristic adjusting circuit for enhancing a low frequency component of the audio signal, an output amplifier for amplifying an output signal of the adjusting circuit and supplying the output signal to the speaker unit; A level detection circuit for detecting the level of the component, wherein the audio signal whose low-frequency level is enhanced by the adjustment circuit is supplied to the speaker unit, and the adjustment circuit is controlled by a detection output of the level detection circuit. When the level of the low-frequency component is large, the amount of enhancement of the level is reduced. It is an location. Therefore,
When the volume of the low tone is low, the bass is enhanced, and when the volume of the low tone is high, the occurrence of distortion in the output amplifier is suppressed.

[0008]

1 and 2 are a front view and a rear view, respectively, of an example of a speaker device according to the present invention.
Reference numeral 1 denotes the enclosure, and its size is, for example, 145 mm (width) × 110 mm (height) × 35 mm
(Depth), and a speaker unit 15C for bass is built in the center of the front. In addition, a large number of through holes 2 are formed on the rear surface of the enclosure 1, and the enclosure 1 is of a rear open type with respect to the speaker unit 15C. The diameter of the speaker unit 15C is, for example, 65 mm.

[0009] Enclosures 3L and 3R are provided on the right and left rear sides of the rear surface of the enclosure 1, and inside the enclosures 3L and 3R, speaker units 15L and 15R for the middle and high frequencies of the left and right channels are provided.
R is provided. And enclosures 3L, 3
Through holes 4L, 4R are formed on the rear surface of the R, and the enclosures 3L, 3R are also of a rear open type with respect to the speaker units 15L, 15.

Further, recesses 5L, 5R are formed on the rear surface of the enclosure 1. When the speaker device is not used, the enclosures 3L, 3R can be folded back by their legs to be stored in the recesses 5L, 5R. Has been. The diameter of the speaker units 15L and 15R is, for example, 16 mm.

Further, inside the enclosure 1, for example, an amplifier as shown in FIG. 3 is provided. That is, in FIG. 3, reference numerals 10L and 10R denote signal circuits of stereo left and right channels, respectively.
C indicates a bass signal circuit.

The input plug 11 is connected to, for example, a headphone jack of a headphone stereo (not shown) to extract left and right channel audio signals L and R. These signals L and R are output to a signal circuit 10L, 1
0R high-pass filters 13L and 13R to extract signals LMH and RMH of middle and high frequency components of, for example, 3 kHz or more. These signals LMH and RMH are output to output amplifiers 14L and 1L.
The signal is supplied to the speaker units 15L and 15R through the 4R.

Further, the signals L and R from the input plug 11 are supplied to an addition circuit 12, and an addition signal of the signal L and the signal R, that is, a monaural signal (L + R) is taken out.
This signal (L + R) is supplied to the frequency characteristic adjustment circuit 13C. The adjustment circuit 13C has a low-pass filter whose overall frequency characteristic is a low-pass filter characteristic and a cut-off frequency of 3 kHz corresponding to the high-pass filters 13L and 13R.
For example, the characteristics of a band centered on 200 Hz change.

Therefore, in the adjustment circuit 13C, a resistor R1 and a capacitor C1 are connected in series to a signal line from the addition circuit 12, and these elements R1,
A resistor R2 is connected in parallel to the series circuit of C1. On the output side of these elements R1, R2, C1, a series circuit of a resistor R3 and a capacitor C2 is connected in parallel to a signal line, and a resistor R5 and a capacitor C3 are connected in parallel. Further, a series circuit of the collector and the emitter of the transistor Q1 for the variable impedance element and the resistor R4 is connected in parallel to the capacitor C2.

Therefore, by selecting the values of the elements R1 to R5 and C1 to C3, the circuit 13C exhibits a low-pass characteristic with a cut-off frequency of 3 kHz and has a function corresponding to the impedance between the collector and the emitter of the transistor Q1. Then, the response characteristic around 200 Hz changes (strictly speaking, the frequency characteristic around 200 Hz does not change, and the frequency characteristic of the pass band except around 200 Hz changes).

In this manner, the low-frequency component signal MC of the signal (L + R) is extracted from the adjustment circuit 13C. Then, this signal MC is supplied to the speaker unit 15C through the output amplifier 14C.

Further, the signal MC from the amplifier 14C is
For example, a level detection circuit 1 composed of a dual-wave rectifier circuit
A DC voltage V16 having a level corresponding to the level of the signal MC is supplied to the transistor 6, and the voltage V16 is supplied to the base of the transistor Q1.

According to such a configuration, the input plug 11
Are supplied with the audio signals L and R, the signals LMH and RMH of the middle and high frequency components are supplied to the high-pass filters 13L and 13L.
R, and these signals LMH and RMH are
L and 14R are supplied to the speaker units 15L and 15R, so that the speaker units 15L and 15R output middle and high frequencies of the left and right channels.

Further, a low-frequency component signal MC of the monaural signal (L + R) is extracted from the adjustment circuit 13C, and the signal MC is supplied to the speaker unit 15C through the amplifier 14C.
, The bass sound of the left and right channels is output from the speaker unit 15C.

In this case, the level of the detection voltage V16 changes in accordance with the level of the signal MC, and this detection voltage V16
Since the impedance between the collector and the emitter of the transistor Q1 changes due to 16, the frequency characteristic of the adjustment circuit 13C changes according to the level of the signal MC, for example, as shown in FIG.

That is, when the level of the signal MC is small, as shown by the curve A, the characteristic is such that the band centered on the frequency of 200 Hz is considerably enhanced. However, the signal M
As the level of C increases, the rate of the enhancement gradually decreases, as shown by the curve A → curve B → curve C, and the level of the signal MC becomes maximum (allowable input level).
At this time, as shown by the curve D, the enhancement near the frequency of 200 Hz is not performed.

When the level of the signal MC of the low-frequency component is low, the level is increased and supplied to the speaker unit 15C. There is no. Also, as the level of the signal MC increases, the signal MC does not increase, so that the signal MC does not exceed the allowable input level of the amplifier 14C, and therefore, distortion of the bass output from the speaker unit 15C can be suppressed. .

As described above, according to the speaker device shown in FIGS. 1 to 3, the low frequency band of the signal MC supplied to the speaker unit 15C is enhanced.
There is no shortage of bass reproduced even if it is open back. Further, when the sound volume is low, the sound volume of a low tone that is difficult to hear due to the loudness characteristic is corrected.

Further, as the level of the signal MC increases, the amount of enhancement in the low frequency band is reduced.
Generation of distortion in C can be suppressed. Moreover,
Since the speaker device is an open-back speaker device, the response of the speaker unit 15C is improved, and the reproduced sound is more musical.

In the above description, the low frequency band is enhanced, and the amount of the enhancement is changed according to the signal level. However, the frequency for the variable enhancement can be arbitrarily selected. In FIG. 3, the amplifier 14C
Is a feedback type configuration in which the level of a signal MC output from the amplifier 14C is detected and the frequency characteristic of the signal MC input to the amplifier 14C is controlled by the detected voltage V16, but the signal (L + R) input to the adjustment circuit 13C , The level of the low-frequency component of the control circuit 13C is detected, and the frequency characteristic of the adjustment circuit 13C is controlled by the detected voltage.

Further, instead of the adjustment circuit 13C, AGC
It can also be a circuit or an ALC circuit. The present invention is also applicable to a headphone device having a built-in amplifier.

[0027]

According to the present invention, even if the enclosure is of the open-back type, the bass reproduced does not become insufficient. In addition, the volume of a low tone that is difficult to hear when the volume is low is corrected. Further, generation of distortion in the output amplifier can be suppressed. In addition, the response of the speaker unit is improved, and the musicality of the reproduced sound is enhanced.

[Brief description of the drawings]

FIG. 1 is a front view showing one embodiment of the present invention.

FIG. 2 is a rear view showing one embodiment of the present invention.

FIG. 3 is a connection diagram illustrating one embodiment of the present invention.

FIG. 4 is a characteristic diagram for explaining the present invention.

FIG. 5 is a characteristic diagram for explaining the present invention.

FIG. 6 is a characteristic diagram for explaining the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Enclosure, 2 ... Through-hole, 3L and 3R ... Enclosure, 4L and 4R ... Through-hole, 10C, 10L and 10R ... Signal circuit, 11 ... Input plug, 12 ... Addition circuit, 13C ... Frequency characteristic adjustment circuit, 13L and 13
R ... High-pass filter, 14C, 14L and 14R ...
Output amplifier, 15C, 15L and 15R: speaker unit, 16: level detection circuit

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Masao Fujihira 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation

Claims (2)

[Claims] 1. An enclosure having an open rear surface, a speaker unit built in the enclosure, and a signal circuit built in the enclosure, wherein the signal circuit is supplied with an audio signal, A frequency characteristic adjusting circuit for enhancing a low frequency component of the signal; an output amplifier for amplifying an output signal of the adjusting circuit and supplying the signal to the speaker unit; and a level detecting circuit for detecting a level of the low frequency component. When the audio signal whose low-frequency level has been enhanced by the adjustment circuit is supplied to the speaker unit, and when the level of the low-frequency component is large by controlling the adjustment circuit based on the detection output of the level detection circuit, A speaker device in which the above level of enhancement is reduced. 2. The speaker device according to claim 1, wherein the audio signal output from the output amplifier is supplied to the level detection circuit as an input signal for detecting the level of the low-frequency component. Speaker device.