WO2004107803A1

WO2004107803A1 - Virtual multi-channel speaker unit

Info

Publication number: WO2004107803A1
Application number: PCT/KR2003/001157
Authority: WO
Inventors: Soon-Teak Shim
Original assignee: Soon-Teak Shim
Priority date: 2003-05-30
Filing date: 2003-06-12
Publication date: 2004-12-09
Also published as: KR100494293B1; KR200336075Y1; KR20040103299A; AU2003234939A1

Abstract

Disclosed herein is a virtual multi-channel speaker unit. The virtual multi-channel speaker unit basically comprises a case partially formed with a permeable portion for use as a passage of sound, a solenoid coil provided inside the case and used to transmit sound signals, a magnetic substance on which the solenoid coil is wound to produce a magnetic field, and a vibrator plate, one surface of which faces the magnetic substance to vibrate by the magnetic field, causing sound waves to be propagated through the permeable portion. In addition to the above components, the speaker unit of the present invention further comprises a transmission tube connected to a prescribed position of a rear portion of the case. The transmission tube has an inlet for use as an entrance of the sound waves and air pressures produced at a rear side of the vibrator plate during vibration of the vibrator plate, and an outlet hole formed toward a front side of the vibrator plate for propagating the sound waves and air pressures, which were entered through the inlet hole, to the outside. The virtual multi-channel speaker unit has an effect of relieving listener fatigue and improving sound quality, thereby transmitting sounds similar to original sounds.

Description

VIRTUAL MULTI-CHANNEL SPEAKER UNIT

Technical Field

The present invention relates to a virtual multi-channel speaker unit, and more particularly to a virtual multi-channel speaker unit which internally defines multiple virtual channels through simple physical re-forming of a case of the speaker unit, such as, for example, an earphone for use in sound reproducing apparatuses including CDPs and MP3 players, thereby enabling removal of air pressures applied to the eardrum of a listener to relieve listener fatigue, and achieving improved sound quality of the speaker unit.

Background Art

As well known, speakers are apparatuses for converting electrical signals to sounds enough to be heard at a distance. Explaining in detail, if the electric signals are transmitted to a solenoid coil provided inside a speaker case, both the solenoid coil, and a permanent magnet on which the solenoid coil is wound produce electromagnetic fields therearound. As the produced electromagnetic fields strike a vibrator plate, one surface of which faces the permanent magnet, the vibrator plate is vibrated to cause oscillation of the peripheral air, thereby allowing the electric signals to be converted into sound waves that travel to the eardrum of a listener.

Fig. 6 is a side view explaining various kinds of speaker units. On the basis of their appearance, the speaker units are classified into an enclosed type speaker unit and a reflected type speaker unit. The enclosed type speaker unit comprises an enclosure 62a, which is sealed at all surfaces thereof against the external environment except for a not-shown hole perforated in a speaker 61a. Inside the enclosure 62a is provided a sound-absorbing material for preventing sounds produced therein from being transmitted to the outside.

Different from the enclosed type speaker unit as stated above, the reflected type speaker unit, which is commonly called a bass reflected type or phase-inversion type speaker unit, has a duct 63 perforated at the front or rear surface of an enclosure 62b. In case of such a reflected type speaker unit, air pressures produced due to vibration of a not-shown vibrator plate are transmitted to the outside through the duct 63, resulting in sounds through reaction of the air pressures. When the sounds are transmitted rearward of a speaker 61b through the duct 63, a temporal phase- difference of sound waves occur, resulting in phase-coincidence with the sounds transmitted forward of the speaker 61b. In common, the above described enclosed type and reflected type speaker units are constructed in such a fashion that their vibrator plates are used to produce sounds at both front and rear sides thereof, which are equal in volume and symmetric in phase. If the sounds produced at the front and rear sides of the vibrator plate interfere with each other, it results in change of frequency properties. A solution adopted to effectively intercept or deal with such change of frequency properties is the above enumerated enclosure.

Referring to Fig. 7 which is a cross-sectional view illustrating a conventional speaker unit, such as, for example, an earphone, it is conventionally configured in such a fashion that sound waves produced rearward of a vibrator plate as well as air pressures produced simultaneously with the sound waves are propagated to the outside through a plurality of fine holes la and lb formed at the rear end of a case of the speaker unit. That is, the speaker unit configured in this fashion belongs to the reflected type speaker unit adapted to propagate the sound waves from the rear end of the case, and thus acts to propagate the sound waves and air pressures through the fine holes la and lb.

Herein, the air pressures are a factor increasing listener fatigue when it is applied to the eardrum of the listener. For example, in case of a conventional dual- channel earphone, the sound waves and air pressures propagated rearward of the vibrator plate may cause sounds different from original sounds to be transmitted to the eardrum.

In addition, there exists only a short sound field between the earphone and the eardrum, resulting in transmission of unnatural sounds to the listener.

Disclosure of the Invention

Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a virtual multichannel speaker unit which internally defines four virtual channels through simple physical re-forming of the small micro-speaker unit, thereby enabling removal of air pressures applied to the eardrum of a listener to relieve listener fatigue, and achieving improved sound quality of the speaker unit through production of deep and abundant tones.

In accordance with the present invention, the above and other objects can be accomplished by the provision of A virtual multi-channel speaker unit comprising: a case partially formed with a permeable_. portion for use as a passage of sound; a solenoid coil provided inside the case and used to transmit sound signals; a magnetic substance on which the solenoid coil is wound to produce a magnetic field; and a vibrator plate, one surface of which faces the magnetic substance to vibrate by the magnetic field, causing sound waves to be propagated through the permeable portion, wherein the virtual multi-channel speaker unit further comprises: a transmission tube connected to a prescribed position of a rear portion of the case, the transmission tube having an inlet hole for use as an entrance of the sound waves and air pressures produced at a rear side of the vibrator plate during vibration of the vibrator plate, and an outlet hole formed toward a front side of the vibrator plate for propagating the sound waves and air pressures, which were entered through the inlet hole, to the outside. i Brief Description of the Drawings

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

Fig. 1 is a cross-sectional view schematically explaining the principle of a virtual multi-channel speaker unit in accordance with the present invention;

Fig. 2 is a cross-sectional view illustrating one embodiment of a transmission tube in accordance with the present invention;

Fig. 3 is a cross-sectional view illustrating another embodiment of the transmission tube in accordance with the present invention;

Fig. 4 is a front view of the virtual multi-channel speaker unit in accordance with the present invention; Fig. 5 is a perspective view of the virtual multi-channel speaker unit in accordance with the present invention;

Fig. 6 is a side view explaining various kinds of speaker units; and Fig. 7 is a cross-sectional view illustrating a conventional speaker unit.

Best Mode for Carrying Out the Invention

Now, a preferred embodiment of a virtual multi-channel speaker unit in accordance with the present invention will be explained in detail with reference to the annexed drawings.

Fig. 1 is a cross sectional view schematically explaining the principle of a virtual multi-channel speaker unit in accordance with the present invention. Figs. 2 and 3 are cross sectional views illustrating preferred embodiments of a transmission tube in accordance with the present invention. Fig. 4 is a front view of the virtual multi-channel speaker unit in accordance with the present invention, and Fig. 5 is a perspective view of the virtual multi-channel speaker unit in accordance with the present invention.

The virtual multi-channel speaker unit according to the present invention features a transmission tube 10. The transmission tube 10 is connected to a rear end of the speaker unit for the propagation of sound waves and air pressures produced at the rear side of a vibrator plate 20.

If sound signals are outputted from an audio amplifier, etc., the sound signals flow through a solenoid coil, and simultaneously, magnetic fields are produced by the solenoid coil, and a magnetic substance on which the solenoid coil is wound, causing vibration of the vibrator plate 20 placed adjacent to one surface of the magnetic substance. Here, the vibrator plate 20 is designed so that its vibration strength is variable depending on not only the strength of the sound signals, but also the varying size of the magnetic field of the solenoid coil. That is, by interaction of the variable magnetic field of the solenoid coil and the magnetic field of the magnetic substance, the vibrator plate 20 is vibrated with a varying strength corresponding to the strength of the sound signals, acting to oscillate a peripheral transmission medium, namely, the peripheral air, resulting in propagation of the sound waves.

That is, if electric signals are transmitted to the vibrator plate 20 of the speaker unit, the vibrator plate 20 is vibrated by making use of electromagnetic forces of the solenoid coil and the magnetic substance, such as a permanent magnet. Such vibration of the vibrator plate 20 oscillates the peripheral air, allowing the electric signals to be converted into sound waves.

In consideration of an audible frequency band perceptible by the ear is in the range of 20 to 20000 Hz, the electric signals are converted into sounds having a frequency band belonging to the above range. As the vibrator plate 20 is vibrated in a variable manner corresponding to the strength of electric currents, and such fluctuation of the vibrator plate 20 is transmitted to the ear of a listener, the listener can recognize the sounds.

During vibration of the vibrator plate 20, air pressures, which are equal and opposite to each other, are produced at front and rear sides of the vibrator plate 20. For example, if a positive air pressure having a prescribed value is produced at the front side of the vibrator plate 20, at the rear side of the vibrator plate 20, a negative air pressure having the same value as the prescribed value is produced.

In the present invention, the negative air pressure is applied into a space defined between the vibrator plate 20 and the eardrum through the transmission tube 10, which is connected at one end thereof to a prescribed position of the rear portion of the case. In this case, the negative air pressure existing in the space between the vibrator plate 20 and the eardrum, and the positive air pressure produced at the front side of the vibrator plate 20 are canceled by their interaction.

Now, one preferred embodiment of the transmission tube 10 according to the present invention will be explained.

Referring to Fig. 2, in a prescribed space inside the speaker unit, in which the solenoid coil, the magnetic substance and the vibrator plate 20 are located, a partition for separating the vibrator plate 20 from a space near the rear surface of the case is provided. The partition is perforated with an inlet hole 10a for use as the entrance of the sound waves and air pressures propagated rearward of the vibrator plate 20. That is, on the basis of the partition, the vibrator plate 20 and the rear surface of the case are positioned at front and rear sides thereof. Preferably, the partition is made of rubber, silicon, or the like, capable of preventing resonance in the sound waves. Between the rear surface of the case and the partition there is defined a duct, namely, the transmission tube 10. Both upper ends of the case and the partition extend forward toward the front side of the vibrator plate 20, so that at a front end of the transmission tube 10 facing the front side of the vibrator plate 20, an outlet hole 10a for use in the propagation of the sound waves and air pressure to the outside is formed. Alternatively, the virtual multi-channel speaker unit according to the present invention may be formed by integrating the transmission tube 10 to a conventional speaker unit case, instead of using the partition. For this, the interior space of the case must be divided into two sections in the manufacture of the conventional speaker unit. Therefore, the case is configured in such a fashion that the inner surface thereof partially protrudes near the rear surface of the vibrator plate 20 to extend in parallel to the rear surface of the case, and the upper end of the rear surface of the case and the outer side of the protruded portion extend toward the front side of the vibrator plate 20. In another embodiment of the transmission tube 10 of the present invention, as shown in Fig. 3, the transmission tube 10 may be externally coupled to the conventional speaker unit. For example, in a state wherein the inlet hole 10a is perforated at a prescribed position of the rear surface of a speaker unit case, the transmission tube 10 is formed along the rear surface and the curved upper surface of the case so that an inlet hole perforated at the transmission tube 10 communicates with the inlet hole 10a of the case. In this case, the front end of the transmission tube 10 faces the front side of the vibrator plate 20 so that the sound waves and air pressures to the outside, which entered through the inlet hole 10a, are propagated to the outside through the outlet hole 10b formed at the front end of the transmission tube 10. In the present embodiment, the transmission tube 10 is bonded to the case by making use of adhesive means having a good coupling force, such as epoxy resin, etc.

Considering the operation of the virtual multi-channel speaker unit according to the present invention in more detail, the sound waves and the negative air pressures produced at the rear side of the vibrator plate 20 are propagated to the front side of the vibrator plate 20 through the transmission tube 10. During such a propagation of the sound waves, the sound waves create tones affected by temporal variation corresponding to the length of the duct. Thereby, sounds having various tones are produced according to the varying length of the transmission tube 10, and the produced sounds are perceptible by the listener as if they have tones different from those of the sounds produced at the front side of the vibrator plate 20. As the tones produced at the rear side of the vibrator plate 20 are propagated through the transmission tube 10 and the outlet hole 10b toward the front side of the transmission tube 10, they are differentiated from the tones produced at the front side of the vibrator plate 20. Such differentiated tones produced at the rear side of the vibrator plate 20 are perceptible as elevated tones, resulting in an increase in sound volume, and achieving a multi-channel sound producing effect.

The sounds propagated rearward of the vibrator plate 20 produce a sound field equal to the length of the transmission tube 10 while passing through the transmission tube 10, creating tones having a temporal variation with the tones produced at the front side of the vibrator plate 20. Herein, the term "sound field" indicates an area of a sound source which is perceptible when listening to the sound. That is, the sound field corresponds to an audible area defined according to the arrangement of the speaker unit. Thus, a speaker unit exhibiting a wide sound field enables the listener to perceive sounds which are louder than original sounds.

Meanwhile, the term "tone" refers to characteristic sound, which is variable according to the external environment or sound reproducing apparatuses, etc. even when the same sounds are propagated. Even if the sounds have the same tones as each other, they show a difference in their sound components. Therefore, even when the same sounds are propagated at the same volume, their characters, namely, the tones, show a difference according to vibrating manners or different sound producing sources.

Such a difference in the tones allows the listener to perceive the sounds, produced at opposite sides of the dual-channel speaker unit, as different sounds obtainable from multiple channels. According to the present invention, therefore, through the use of a pair of speaker units adapted to propagate the sound waves through the transmission tubes, a deep and abundant multi-channel sound reproducing effect is obtainable.

Industrial Applicability

As apparent from the above description, the present invention provides a virtual multi-channel speaker unit which can remove air pressures applied to the eardrum of a listener, thereby relieving listener fatigue, and achieving improved sound quality through diversification of tones. Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

Claims:

1. A virtual multi-channel speaker unit comprising: a case partially formed with a permeable portion for use as a passage of sound; a solenoid coil provided inside the case and used to transmit sound signals; a magnetic substance on which the solenoid coil is wound to produce a magnetic field; and a vibrator plate, one surface of which faces the magnetic substance to vibrate by the magnetic field, causing sound waves to be propagated through the permeable portion, wherein the virtual multi-channel speaker unit further comprises: a transmission tube connected to a prescribed position of a rear portion of the case, the transmission tube having an inlet hole for use as an entrance of the sound waves and air pressures produced at a rear side of the vibrator plate during vibration of the vibrator plate, and an outlet hole formed toward a front side of the vibrator plate for propagating the sound waves and air pressures, which were entered through the inlet hole, to the outside.