JP2010178323A - Speaker system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To overcome the problem that a shape, an installation location and securement of performance required from the aspect of design of a compact speaker conflict with one another, the flexibility of design is extremely tight in relation to bass reproduction capability, and the effect of mechanical vibration on a product with the speaker applied thereto in reproducing bass is large. <P>SOLUTION: A driver side and a passive radiator side of a speaker are separated from each other, and separate enclosures are provided for them, and installed in a place easy to install them. By connecting both the enclosures to each other with a tube, the flexibility in terms of design of a built-in destination product of this speaker system is improved. A weight for adjusting a bass reproduction characteristic is arranged on a vibration film of the passive radiator. In order to reduce mechanical vibration in reproducing bass, two vibration films are arranged in the form of a facing structure. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

Definition of terms

Throughout the entire sentence including the claims, the description in {} in the sentence takes precedence over the description outside {}.

First, technology for improving the bass reproduction capability of small speaker systems and small acoustic products.
Second, when trying to increase the bass reproduction capability of a small speaker, {realizable performance}, {expected performance} and {balance or compromise} due to external design constraints.
Thirdly, the case of a liquid crystal television is a typical example, but mechanical vibrations during low-pitched sound reproduction of a speaker are {buzzing sound generated by vibrating a product structure in which the speaker is used} or {liquid crystal {Adverse technology for problems} such as adverse effects on images caused by vibrations of TV liquid crystal panels.

Speaker structure and vibration analysis Enclosure structure and acoustic analysis Analysis of resonance mode and vibration mode of each part of acoustic vibration system

Problems to be solved by the invention

First, it allows a free appearance design without sacrificing acoustic performance.
Second, a {speaker system with good bass performance} is constructed in a {narrow and complex space}.
Third, a speaker system that is {small, lightweight, and inexpensive} that has a very wide design freedom in bass reproduction performance and a powerful bass reproduction capability.
Fourth, a speaker system in which the vibration of the enclosure is small and {the influence on the vibration of the structure of the applied product} is extremely small.

Generally, in a speaker system, the vibration amplitude of a voice coil increases as the reproduced sound becomes lower. As a result, the {coil in the non-linear region of the magnetic flux density} of the voice coil and the {mixed frequency component signal} are subjected to amplitude modulation by the bass component due to the non-linear characteristics of the {edge and damper}. In an extreme case, the vibration amplitude of the voice coil becomes large, and it strikes a mechanical part and generates an abnormal noise.
Such a phenomenon is often combined with a desire to produce a low sound even with a small speaker, and is often finished into a product that causes distortion.
Under such constraints, {compromise between mutually contradictory factors} must be sought and {design freedom} is narrowed.

As background technology for improving the bass reproduction capability of small speakers,
First, {increase the linear range of driver vibration amplitude}
Second, {enclose the enclosure to resonate with the bass and expand the bass reproduction range}
Third, {expand bass reproduction range using the characteristics of electronic circuits}
and so on. Neither method is definitive, and {cost, weight, strain, size, shape}, etc. The current situation is that a compromise is unavoidable. In particular, as of 2008, televisions have been made thinner in recent years, and most of the products whose acoustic performance is sacrificed due to installation location and size problems with priority on external design.

On the other hand, even though the sound reproduction performance is improved by using {expensive driver unit with excellent bass reproduction capability}, there are various problems due to {structure vibration} of {product incorporating the driver unit}. Occurs, and the cost is further increased. In the product design process, {subjective factor} in {subjective method} is routinely generated in {subjective groups} having a contradictory relationship.
Particularly in the {LCD liquid crystal television design process} as of 2008, it is necessary to {avoid thinning and cost increase of materials}, so the tendency to reduce the thickness of {plastic and chassis} is remarkable.
As a result, the current situation is that the sound reproduction performance has to be sacrificed.
Furthermore, as a result, the {reactive needs} of {want to improve sound reproduction performance} are strong {both in the market and in design work}.

Means for solving the problem

The present invention is {designed {vibration membrane and enclosure}} so that {the vibration amplitude of the voice coil in the necessary bass reproduction region} is much smaller than {{speaker unit alone}} and is limited In order to increase the degree of freedom in designing the shape and dimensions of the space, {Enclosure on the speaker unit side} and {Enclosure on the passive radiator side} are separated and connected by a tube, {Effect of the passive radiator} And {increase the degree of freedom of shape design in a narrow space}.
The {inner diameter and length} of the tube affects the acoustic characteristics, but the overall bass reproduction characteristics are {mainly {the volume of the radiator enclosure} and {the mass of the diaphragm of the passive radiator}} {the acoustic wave of the diaphragm of the passive radiator. Radiation area}}.
Place the driver enclosure in the {place to be accommodated} and {the radiator enclosure connected by the tube} in the {easy place}.
Since bass sounds have a very low directivity, it is difficult to affect the low-level feeling of the sound image.
Since the role of the radiator enclosure is low-pitched sound reproduction, the degree of freedom in installing the radiator enclosure is increased.
By placing the diaphragm of the passive radiator facing each other so as to cancel the reaction caused by the low-frequency vibration reproduction of both, the mechanical vibration of the radiator enclosure is eliminated.

FIG. 1 is a diagram showing an embodiment of the present invention.
The case where {one driver enclosure} and {one radiator enclosure} are connected by a tube is shown.
Reference numeral 1 denotes a loudspeaker unit enclosure, 2 denotes a loudspeaker unit, and 3 denotes a {vibration amplitude during voice coil bass reproduction} of the loudspeaker unit.
4 is the enclosure on the passive radiator side,
5 is one of {2 passive radiators}, 6 is a {weight for adjusting the mass of the diaphragm} attached to the passive radiator, and 7 is {vibration amplitude during bass reproduction} of 5 passive radiators .
8 is the other of {2 passive radiators}, 9 is a {weight for adjusting the mass of the diaphragm} attached to the passive radiator, and 10 is {vibration amplitude during bass reproduction} of 8 passive radiators .
A tube 11 acoustically connects the {speaker side enclosure} and the {passive radiator side enclosure}.

FIG. 2 is a diagram showing an embodiment of the present invention.
A case where two left and right speaker units are connected to one {passive radiator enclosure} by a tube is shown.
1L indicates the enclosure of the left speaker unit, 2L indicates the left speaker unit, and 3L indicates the {vibration amplitude at the time of low-frequency reproduction of the voice coil} of the left speaker unit.
1R represents the enclosure of the right speaker unit, 2R represents the right speaker unit, and 3R represents the {vibration amplitude during low-frequency reproduction of the voice coil} of the right speaker unit.
4 is the enclosure on the passive radiator side,

5 is one of {the two vibrating membranes of the passive radiator}, 6 is a {weight for adjusting the mass of the vibrating membrane} attached to the passive radiator, and 7 is the vibration amplitude of the passive radiator of 5 during the bass reproduction. }.
8 is {the vibration membrane of two passive radiators}, 9 is a weight for adjusting the mass of the vibration membrane attached to the passive radiator, and 10 is the vibration amplitude of the passive radiator of 8 during the bass reproduction. }.
A tube 11 acoustically connects the {left speaker enclosure} and the {passive radiator enclosure}.
A tube 12 acoustically connects the {right speaker enclosure} and the {passive radiator enclosure}.

In the design of this loudspeaker system, the bass resonant frequency of the passive registrar is important. For example, if the reproduction frequency range is 50 Hz or more, the bass resonance frequency of the passive registrar is set from 60% to 80% of 50 Hz, roughly.
The target resonance frequency is {the value obtained by multiplying the constant 50.2 by the area of the {vibration membrane of the passive registrar}} {{the square root of {the mass of the vibration membrane}} {the value obtained by multiplying the inner volume of the enclosure}} Design based on the value divided by.
Since the above design calculation formula does not include a fine factor that is difficult to calculate, finally, {enclosure volume}, {mass of diaphragm}, etc. are corrected to match the target frequency. Originally, the degree of freedom of design has been remarkably widened, so there is no need to pay attention to the problem of by-products caused by correction, and the target value can be adjusted by simple correction work.
And {vibration amplitude of voice coil} can be remarkably reduced as compared with {vibration amplitude of diaphragm}. Although experimentally, an example of {good reproduction characteristics in all bands} is confirmed in a state where the ratio is 1/6.

The amplitude, that is, the Q value of the diaphragm at the resonance point is roughly determined in two stages.
In the first stage, {the inner volume of the enclosure}, {the mass of the diaphragm}, and {the distance between the opposing passive radiators} are {the major factor in determining the Q value}. However, since these factors {have a major role in determining the resonance frequency}, changes are not preferable. There are other factors that affect the Q factor. In particular, the sound propagation conditions in the tube have a small {influence on resonance frequency} and a large {influence on Q value}.
For these reasons, it is convenient to adjust the Q value by {adjusting the {length, inner diameter and internal sound absorbing material} of the tube}. Can be determined by the sound absorption coefficient inside the enclosure. The Q value is complicated to calculate and troublesome to design, but it is easy to adjust the Q value by the above method.

At the above resonance point of the vibration film, {electric impedance of the voice coil} is smaller than that without the vibration film. This means that the current flowing through the voice coil is increased, and as a result, the driving force of the voice coil is increased. The fact that the vibration amplitude of the voice coil can be reduced makes it easier to design {specifications relating to the voice coil and the magnetic circuit} and to design a smaller linear range of {damper and edge}.

For example, even if a small driver unit having a fo of about 150 Hz is used, it is extremely easy to design the resonance frequency of the vibration film to 40 Hz. Of course, since the vibration amplitude of the voice coil is small, {distortion problem, especially intermodulation distortion due to the nonlinear characteristics of the driver unit during strong bass reproduction} is extremely small. Satisfied.

In the entire reproduction bass range, {the voice coil impedance is lowered, the current is increased and the driving force is increased}. Will spread significantly. As a result, {low-distortion powerful super bass} is reproduced even under the maximum allowable input condition of the driver unit.

The invention's effect

The design freedom of {small speaker with excellent bass reproduction performance} is greatly expanded.
What is design freedom?
First, since the dry enclosure and the passive enclosure can be installed in different locations, the degree of freedom in designing the entire product is widened.
Secondly, the mechanical vibration is small and the influence of vibration on the incorporated structure or product is small, greatly expanding the degree of freedom of {planning and design} of the product to be incorporated.
Second, the bass reproduction frequency range does not depend on the performance of the driver unit.
Thirdly, the dynamic range of bass reproduction required for the speaker driver unit can be greatly reduced.
Fourthly, in connection with the reasons {1st, 2nd and 3rd}, the driver unit can be reduced in weight and cost.
Fifth, because of the small size and high performance, the range of {shape selection and application} is wide.

First, it is applied to a general speaker system that is small and has excellent bass reproduction capability and low price.
Second, although {thin and light weight} is the biggest feature of the product, the feature is {generates abnormal sound in low-pitched sound reproduction and prevents good sound quality reproduction}, {image quality by vibration of liquid crystal panel A speaker system for a liquid crystal television that has problems such as
Third, despite {requires strong bass reproduction performance}, {{miniaturization}, {strict cost requirements}, {avoidance of chatter noise caused by vibration of windows and door internal structures}} {Passenger car speaker system}.

Desktop speaker system LCD TV passenger car speaker

First, shortening the acoustic design process of {Speaker systems for small AV products and AV products that are vulnerable to vibration}.
Second, improvement in quality and performance of {speaker systems for small AV products and AV products vulnerable to vibration}.

Illustration of one embodiment Illustration of one embodiment

Claims (2)

The box containing the driver unit of the speaker system is the driver enclosure,
The box containing the passive radiator of the speaker system is the radiator enclosure,
The vibration film of the passive radiator is the vibration film,
The tube that acoustically connects the driver enclosure and radiator enclosure is a tube,
The first feature is that {driver enclosure} has {holes for connecting tubes}
The second feature is that {the hole for connecting the tube} is provided in the {radiator enclosure}.
The third feature is that one radiator enclosure {the two vibrating membranes are provided symmetrically so as to cancel each other's bass vibrations}
A fourth feature is that the above {driver enclosure hole} and {radiator enclosure hole} are connected by a tube.
{Driver unit attribute}, {Driver enclosure volume}, {Radiator enclosure volume}, {Vibration membrane sound radiation area}, {Vibration membrane mass}, {Tube inner diameter and length} connected by tubes The main feature is to determine the bass reproduction characteristics of the speaker system as a fifth feature,
{Vibration amplitude of voice coil in bass reproduction} is {Playback amplitude of driver unit alone} by {{Physical properties mainly of radiator enclosure volume} and {mass of diaphragm}} In the bass region to be reduced, the vibration characteristic of the driver unit alone is made smaller}
The speaker system having the characteristics of the first, second, third, fourth and {fifth or sixth}. The above {radiator enclosure} described in claim 1 is provided with two holes, two driver enclosures described in claim 1 are provided, and one of the two driver enclosures is for left side reproduction, and the other. Of the two holes of {Radiator enclosure}, {connect one hole to {hole of driver enclosure for left regeneration} with {tube}} and {the other hole { A speaker system having a seventh feature of {connecting with a tube} to a hole of a driver enclosure for right reproduction}.

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