CN1151699C - speaker - Google Patents

Abstract

There is provided a speaker which is small and which allows the low sound range to be generated and a low sound level to be fully obtained. A speaker 10 comprises a cylindrical main body 12. Both ends of the main body 12 constitute open sections thereof and a sounding body 16 pinched by ringed first dampers 14 is secured to each of the open sections so that the inside of the main body 12 is kept air-tight. A circular first opening 18 is created at the middle part of the side of the main body 12. Bottomed cylindrical lid members 20 are secured on the outside of the two sounding bodies 16 via ringed second dampers 24 so as to keep the inside of the lid member 20 air-tight. A circular second opening 22 is created around the middle of the bottom of the lid member 20.

Description

Loud speaker

Technical field

The present invention relates to loud speaker, relate in particular to a kind of loud speaker that is applicable to 3D center channel woofer system, this woofer system applies is in some stereophonic reproducing system.

The invention still further relates to the loud speaker that adopts the ceramic piezoelectrics of making, this loud speaker is applicable to 3D center channel woofer, and it is a loud speaker in the stereophonic reproducing system.

Background technology

So-called 3D system is a system that only produces the bass frequency range in the stereo generation systems, this audio frequency is about 100 hertz to 150 hertz or lower, its direction almost be low system for electrical teaching (comprising) corresponding to the sounding body of left channel signals with corresponding to the sounding body of right-channel signals a loud speaker can not experience.

Fig. 5 represents to be used for the loud speaker of a kind of prior art of low system for electrical teaching, and this low system for electrical teaching is used for producing a kind of like this signal, and wherein having made up is 100 to 150 hertz or lower left and right sound channels signal.

Loud speaker 60 comprises main body 100, places the dividing plate 200 in the main body 100, is installed in two sounding bodies 300 and 400 on the dividing plate 200, and the sender 500 that places main body 100 front panel bottoms.Sounding body 300 and 400 is provided with towards the bottom of main body 100.

Although not shown, when for example left channel signals inputs to sounding body 300, when right-channel signals inputed to sounding body 400, the output left and right acoustic channels was the sound of 100 to 150 hertz or lower bass frequency range.

At this moment, the sound that directly sends from sounding body 300 and 400 is not transmitted into the outside of main body 100.The resonance frequency that has only sound mouth 500 and main body 100 to produce just is transmitted into the outside of main body 100.

Yet, owing in the loud speaker of above-mentioned prior art, adopted the sounding body of for example conical plate and so on that allows the big amplitude volume of acquisition, to obtain big output, so loud speaker must be very big in the bass frequency range.Can make sounding body to address this problem with a kind of tabular piezoelectric element.Yet, when this piezoelectric element as with the corresponding sounding body of loud speaker of above-mentioned prior art the time, because it is less that the sounding body made from conical plate is compared its displacement amplitude, so this loud speaker can not obtain enough bass frequency ranges, thereby can not obtain corresponding enough amplitudes of structure (size) with the loud speaker of prior art.In order to address this problem, just must enlarge the size of piezoelectric element, to increase the amplitude of piezoelectric element, increased the size of loud speaker therefrom inevitably.

Moreover, because the bass frequency range depends on the resonance frequency between sound mouth and the main body, and a resonance frequency is only arranged in the loud speaker of prior art, so can not obtain enough low sound level for the bass frequency range of separating with resonance frequency, the sound level that is produced in the audio range of broad is very little.

Moreover in the loud speaker of being made by piezoelectrics, because the piezoelectrics that pottery is made are as sounding body usually, the amplitude of the sound wave that sounding body produces is big inadequately.Therefore, up to now, the loud speaker of being made by this piezoelectrics can't be used as the loud speaker of the low system for electrical teaching that produces the bass frequency range.

And the present inventor has applied for Japanese patent application No. 9327091, and it is a kind of loud speaker that is used for low system for electrical teaching, is made up of also piezoelectrics to produce all-bottom sound.

Referring now to Fig. 6 this loud speaker is described.This loud speaker 1 comprises that its two ends have the cylinder-shaped body 2 of opening portion.Annular damper 6 is separately positioned on main body 2 openings at two ends parts, and sounding body 3 is installed on the damper 6.Sounding body 3 is closely to be provided with, and makes main body 2 inner maintenances airtight.The middle part of main body 2 sides forms the first circular open 2a.

In addition, the cylindrical lid 4 of band bottom is set on the outside of two sounding bodies 3, with main body covered 2 openings at two ends parts, and it is airtight that the inside maintenance that makes lid 4 closely is set.Form the second circular open 4a around in the middle of lid 4 bottoms.The inside of main body 2 and lid 4 is provided with acoustic(al)absorbent 5, the acoustic component of absorption and decay high pitch frequency range.

Here, in bimorph structure, sounding body 3 comprises the dish type oscillating plate 3a that metal is formed, and dish type piezoelectric element 3b closely is arranged on the middle part of two first type surface on the oscillating plate 3a concentric circles as vibration source.

Although do not illustrate, constitute piezoelectric element 3b by on two first type surfaces of dish type piezoelectrics, forming electrode film.

The size of the first opening 2a and the second opening 4a is less than the size of the oscillating plate 3a of sounding body 3.

Then, be connected to an input (not shown) that places main body 2 outsides by a lead-in wire (not shown) with one in two sounding bodies 3, and, another sounding body 3 is connected to another input (not shown) that places main body 2 outsides by another root lead-in wire (not shown).At this moment, when the signal of telecommunication when amplifier (not shown) is input to an input, a vibration in two sounding bodies 3, when the signal of telecommunication when amplifier (not shown) is input to another input, another sounding body 3 vibrations.

Then, drive sounding body 3, make main body 2 pressure inside increase/reduce by two sounding bodies 3 simultaneously.That is, when a sound channel signal in stereophonic signal when for example right-channel signals is input to an input, another sound channel signal in the stereophonic signal, promptly left channel signals then inputs to another input.

By input signal as mentioned above, in main body 2, produce sound waves, and send from the first opening 2a of main body 2 by two sounding bodies 3.Simultaneously, sound wave is also produced by two sounding bodies 3 in lid 4, and sends from the second opening 4a of lid 4.

At this moment, because the size of the first opening 2a of main body 2 is less than the size of the oscillating plate 3a of sounding body 3, and because the sonic wave amplitude that sends from the first opening 2a of main body 2 is greater than the sonic wave amplitudes that produced by two sounding bodies 3 in the main body 2, so the bass frequency range is strengthened and sends.

Moreover, since two sounding bodies 3 produce in/phase place of high pitch frequency range is cancelled in main body 2 inside mutually on the contrary, so have only the bass segment signal to be strengthened and send from the first opening 2a.

Therefore, by adopting piezoelectrics rather than big oscillating plate, big housing or big reflecting plate, loud speaker 1 can produce the sound wave of bass frequency range.

In addition, since the high pitch frequency range component in the sound wave that produces by two sounding bodies 3 in acoustic(al)absorbent 5 absorptions and decay main body 2 and the lid 4, the result, and the bass frequency range in the sound wave that is produced is further strengthened.

Yet, make in the loud speaker of prior art of sounding body adopting piezoelectrics, because sounding body is made up of tabular piezoelectrics, the vibration area of sounding body is the piston vibration zone and cuts apart vibration area by its mode division according to the signal frequency that is input to it.

Like this, in utilizing the loud speaker of covibration,, owing to subjecting to big distortion inherently, it is not having covibration by cutting apart on the sound wave that vibration produces although covibration occurs on the sound wave that piston vibration produces.

When not producing covibration, the bass frequency range fails to be strengthened.As a result, in/the high pitch frequency range strengthened, and loud speaker can not be as the loud speaker of low system for electrical teaching.

On the contrary, adopt the loud speaker of making the prior art of sounding body by piezoelectrics, utilize the covibration that is limited by the main volume and first opening shape, and the loud speaker that hangs down system for electrical teaching by the covibration conduct that the lid volume and second opening shape are limited.

Sounding body produced when cutting apart vibration and causing sound wave when two that exist in the main body of the loud speaker of prior art, since from two sounding bodies produce respectively/phase place of high pitch frequency range sound wave is opposite mutually, so in the main body/sound wave of high pitch frequency range is cancelled, not by in cutting apart that vibration produces/sound wave of high pitch frequency range sends from first opening.

Yet, different with body interior, lid inboard only exist by in two sounding bodies a sounding body produced cuts apart vibration and the sound wave that forms, so by this cut apart vibrate generation in/sound wave in the high pitch frequency range is not cancelled.

Therefore, in cutting apart that vibration produces/when sound wave in the high pitch frequency range came from second opening of lid, it still had been issued.Acoustic(al)absorbent can not absorb the high pitch frequency range fully, the result, and the sound wave of high pitch frequency range and bass frequency range all will send from second opening.In addition, do not form covibration, so the sound of the loud speaker of low system for electrical teaching has many turbidity and a spot of low sound level when sending owing to cut apart the sound wave of vibration generation.

Summary of the invention

Therefore, main purpose of the present invention is to address the above problem, and a kind of loud speaker is provided, and its volume is little and allow generation bass frequency range, and can obtain enough low sound level in the bass frequency range of broad.

Moreover, another object of the present invention is to provide a kind of loud speaker, its volume is little and allow to produce the bass frequency range, obtains low clearly sound level by only producing the bass frequency range.

To achieve these goals, loud speaker of the present invention comprises that its two ends have the cylinder-shaped body of opening portion; Two sounding bodies that place main body both ends open part and vibrate by the signal of telecommunication; Be arranged to cover two cylindrical lids of the band bottom of two sounding bodies; And be arranged on first opening of main body sidepiece and be arranged on second opening of lid bottom, wherein, along make press in the main body and lid in press two sounding bodies of direction driving that strengthen/weaken.The characteristics of this loud speaker are that the resonance frequency of body interior is different from the resonance frequency of two lid inboards.

Preferably, sounding body adopts the piezoelectrics of being made by pottery.

Preferably, a sound channel signal input is connected to a sounding body in two sounding bodies in the input stereo audio signal, and another input of another sound channel signal is connected to another sounding body in the input stereo audio signal.

Preferably, between the sounding body of lid inboard and second opening, a barrier film is set.

For this reason,, make the scope of bass frequency range obtain broadening, be improved in the bass frequency range of broad by the low sound level that loud speaker produced because of there are a plurality of resonance frequencys in the bass frequency range.

The interior pressure that is input to two sounding body causative subjects when the signal of telecommunication causes by two sounding bodies and strengthens/when weakening, sound wave is produced by two sounding bodies in main body, and outwards send from first opening of main body.Simultaneously, because the diameter of first opening is less than sounding body, the amplitude of the sound wave that sends from first opening becomes the amplitude greater than the sound wave that produces from sounding body.

Therefore, the present invention has not only realized subminiaturized loud speaker because it has adopted thinner, the littler tabular piezoelectrics of sounding body of the conical plate formation more used than the woofer of prior art, and, can realize and can complete generation hang down the woofer of sound level.

In addition, might obtain a kind of loud speaker, it allows fully with simple structure and the low sound level of low-cost acquisition, such loud speaker is applicable to that the 3D central passage hangs down system for electrical teaching, because by two sounding bodies are installed on the main body, take out total output of left and right sound channels signal and only be used to autonomous agent and the acoustic pressure of lid upper shed, can constitute the acoustics low pass filter.

Moreover, the sound wave that causes by the cutting apart vibration of a sounding body generation, through after the damping of barrier film from placing second opening on the lid outwards to send, barrier film is inboard as a wall at lid, and when cutting apart sound wave bump barrier film that vibration causes and evenly being caused displacement, be converted into undistorted sound wave.Thus, loud speaker of the present invention can suppress undesirable cacophony and produce a kind of sound clearly as woofer.

From the following description and accompanying drawing (wherein identical parts are represented with identical reference number), ins and outs of the present invention and other purpose, purposes and advantage will be more clear.

Description of drawings

Fig. 1 is the perspective view of expression according to the loadspeaker structure of first embodiment of the invention;

Fig. 2 is the sectional view of expression according to the loadspeaker structure of first embodiment of the invention;

Fig. 3 is the perspective view of expression according to the loadspeaker structure of second embodiment of the invention;

Fig. 4 is the sectional view of expression according to the loadspeaker structure of second embodiment of the invention;

Fig. 5 is the schematic diagram of the loadspeaker structure of expression prior art;

Fig. 6 is the profile of the loadspeaker structure of another routine prior art of expression.

Embodiment

Describe embodiments of the invention in detail hereinafter with reference to accompanying drawing.

Fig. 1 and Fig. 2 represent the loud speaker according to first embodiment of the invention.

Loud speaker 10 comprises a cylinder-shaped body 12.The two ends of main body 12 form opening portion, and first damper 14 of annular is arranged on each opening portion.Sounding body 16 places first damper 14, and another first damper 14 is arranged on the outside of sounding body 16.That is, sounding body 16 closely is provided with, and makes the inside of main body 12 keep airtight, is compressed by two first dampers 14 simultaneously.

Then, form first opening 18 of a circle at the middle part of main body 12 1 sides.Moreover second damper 24 of annular is set in place on first damper 14 on two sounding body 16 outsides.The cylindrical lid 20 of band bottom places on second damper 24.Lid 20 closely is provided with, and makes it main body covered 12 opening portion, makes the inside of lid 20 keep airtight.The second circular opening 22 forms around the center of lid 20 bottoms.

Here, main body 12 and lid 20 are made such as cutting into columniform plastics or timber by the synthetic resin material.

Sounding body 16 also comprises the dish type oscillating plate 16a that for example is made of metal, and dish type piezoelectric element 16b closely is arranged on the middle part of two first type surfaces of oscillating plate 16a, forms concentric circles with oscillating plate 16a, respectively as the vibration source in the bimorph structure.Although do not illustrate, piezoelectric element 16b makes by form electrode film on two first type surfaces of dish type piezoelectrics.

Preferably, first damper 14 and second damper 24 and a kind of material that have high-seal big by quality made.

Moreover although do not illustrate, loud speaker 10 places on the support (not shown), makes first opening, 18 face down of main body 10.

Then, in two sounding bodies 16 one is connected to an input (not shown) that places main body 12 outsides by lead-in wire (not shown), another sounding body 16 by another root go between (not shown) be connected to another input (not shown) that places main body 12 outsides.

At this moment, when the signal of telecommunication is input to an input by amplifier (not shown), sounding body 16 vibrations, when the signal of telecommunication from amplifier (not shown) is input to another input, another sounding body 16 vibrations.

Then, drive sounding body 16, increase/reduce the interior pressure of main body 12 simultaneously by two sounding bodies 16 in the loud speaker 10 of formation like this.That is, when a sound channel signal in the stereophonic signal for example during input of right-channel signals input, another sound channel signal in the stereophonic signal, promptly left channel signals is input to another input.

By input signal as mentioned above, produce sound waves by two sounding bodies in the main body 12 16, and between main body 12 and first opening 18, produce and resonate.Have only the sound of strengthening by resonance just to send to the outside of main body 12 from first opening 18.

Wherein, the bass frequency range does not have phase difference between right-channel signals and left channel signals, and as wherein synthesized right-channel signals and left channel signals have the sound of dual acoustic pressure the time send to the outside of main body 12, even the size of main body 12 is less, also can obtain enough acoustic pressures, like this, even loud speaker is less, also can obtain the complete loud speaker 10 that sends low sound level.

Notice that owing to synthesized right-channel signals and left channel signals, the middle pitch frequency range/high pitch frequency range that has phase difference between right-channel signals and left channel signals is cancelled, therefore, the bass frequency range of the sound that is sent is further strengthened.

Lid 20 inboards also produce sound wave by two sounding bodies 16, and resonate between the lid 20 and second opening 22.Then, the sound that strengthens through resonance that only produces is to some extent just sent to lid 20 outsides by second opening 22.

Here, can represent resonance frequency in order to following equation according to Helmholtz's law:

$f=\frac{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="C9810693800182.png"\; state="\{\{state\}\}">c</figure-callout>}}{2\mathrm{\&pi;}}\sqrt{\frac{{\mathrm{\&pi;r}}^2}{V(1+1.3r)}}$

Wherein, (f) expression resonance frequency, (c) the expression velocity of sound, (V) expression resonator volume, (1) expression resonator thickness, (r) radius of expression opening.

So, in loud speaker 10, when the resonance frequency of main body 12 is f12, when the resonance frequency of lid 20 is f18, the range widens of bass frequency range, when constituting loud speaker 10, for example make it to make f12 ≠ f18 greater than the volume of lid 20 by the volume that increases main body 12, can in the bass frequency range of broad, improve the low sound level that loud speaker 10 is produced.

Moreover although do not illustrate, main body 12 and lid 20 inboards also can be provided with the acoustic(al)absorbent of being made by glass fabric.Because the sound wave of the middle pitch/high pitch frequency ranges that produce in their absorptions and decayed main body 12 and the lid 20 is so the bass frequency range of the sound wave that is produced is further enhanced.

In loud speaker 10 of the present invention,, the interior pressure of main body 12 is increased/when reducing, produce sound wave in main body 12 inside by sounding body 16, and deliver to the outside by two sounding bodies 16 from first opening 18 of main body 12 when the signal of telecommunication is input to two sounding bodies 16.Simultaneously, because the diameter of first opening 18 is provided with less than sounding body 16, so the sound wave that sends from first opening 18, its amplitude becomes greater than the sound wave from sounding body 16 generations.Therefore, the present invention has not only realized subminiaturized loud speaker because it has adopted thinner, the littler tabular piezoelectrics of sounding body of the conical plate formation more used than the woofer of prior art, and, adopt these piezoelectrics can realize and can complete generation hang down the woofer of sound level.

In addition, loud speaker 10 allows with simple structure and the low sound level of low-cost acquisition, and can realize being applicable to that the 3D central passage hangs down system for electrical teaching, because, by two sounding bodies 16 are installed on the main body 12, take out total output of left and right sound channels signal and only be used to autonomous agent 12 and lid 20 on the acoustic pressure of opening, can constitute the acoustics low pass filter.

Notice that although in realizing pattern of the present invention, it is cylindrical that main body is formed, also can make main body form any other post shapes beyond cylindrical, such as the square column shape.Equally, lid also can be the cylindrical shape of cylindrical other any band bottom in addition of band bottom, such as the square column shape of band bottom.

In addition, oscillating plate and the piezoelectric element of forming sounding body can be shaped to dish type any other shape in addition, such as square plate.And oscillating plate also can be made by material such as rubber or synthetic resin beyond the metal.

Moreover sounding body not only can adopt the piezoelectric element of bimorph structure, and can adopt the piezoelectric element of single piezoelectric chip structure, perhaps adopts the piezoelectric element that is become stepped construction by ceramic, adopts 3 layers or multilayer laminated piezoelectrics.

Next describe second embodiment of the present invention in detail with reference to Fig. 3 and Fig. 4.

Fig. 3 and Fig. 4 represent the loud speaker according to second embodiment of the present invention.

Loud speaker 10 comprises cylinder-shaped body 12, and its two ends have opening portion.First damper 14 of annular is arranged on main body 12 openings at two ends parts, and sounding body 16 closely is provided with to such an extent that make the inside of main body 12 keep airtight, simultaneously by first damper, 14 chuckings.Form first opening 18 of a circle at the middle part of main body 12 sides.

In addition, Huan Xing second damper 24 is along closely being set to first damper 14 from sounding body 16 to the direction near main body 12 opening portions.Disc-shaped diaphragm 26 closely is set to second damper 24, and the cylindrical lid 20 of band bottom is arranged on the barrier film 26.Lid 20 closely is provided with to such an extent that make its opening portion of main body covered 12, and makes the inside of lid 20 keep airtight.Form second opening 22 of a circle around the bottom centre of each lid 20.

Like this, barrier film 26 is located between second opening 22 and sounding body 16 of lid 20.

Preferably, first damper 14 and second damper 24 are made by the big material of quality.

In addition, barrier film 26 is preferably made such as silicone rubber plate by elastomeric material.

Moreover although do not illustrate, loud speaker 10 ' is arranged on the not shown fixture, and therefore, first opening 18 of main body 12 upside down.

Then, a sounding body in two sounding bodies 16 is connected to an input (not shown) that is provided with on main body 12 outsides via lead-in wire (not shown), and another sounding body 16 is connected to another input (not shown) that is provided with on main body 12 outsides via another root lead-in wire (not shown).

At this moment, when the signal of telecommunication when amplifier (not shown) inputs to an input, a vibration in the sounding body 16, when the signal of telecommunication when amplifier (not shown) inputs to another input, another sounding body 16 vibrations.

Then, drive sounding body 16, increase/reduce the interior pressure of main body 12 simultaneously by the sounding body 16 in the loud speaker 10 ' that so constitutes.That is, when a sound channel signal in the stereophonic signal for example during input of right-channel signals input, another sound channel signal in the stereophonic signal is that left channel signals is input to another input.

By input signal as mentioned above, produce sound waves by two sounding bodies in the main body 12 16, and between main body 12 and first opening 18, produce and resonate.Have only the resonance frequency that produces by resonance just to send to the outside of main body 12 from first opening 18.

Wherein, the bass frequency range does not have phase difference between right-channel signals and left channel signals, and send to the outside of main body 12 as the resonance of wherein having synthesized the dual acoustic pressure of right-channel signals and left channel signals, even the size of main body 12 is less, also can obtain enough acoustic pressures, like this, even loud speaker is less, also can obtain the complete loud speaker 10 ' that sends low sound level.

Notice that when right-channel signals and left channel signals were synthetic, the middle pitch/high pitch frequency range that has phase difference between right-channel signals and left channel signals was cancelled, therefore, the bass frequency range of the sound that is sent is further strengthened.

Lid 20 inboards also produce sound wave by two sounding bodies 16, and resonate between the lid 20 and second opening 22.Then, have only the resonance that produces through resonance just to send to lid 20 outsides by second opening 22.

In loud speaker 10 ' of the present invention, because sounding body 16 is made up of tabular piezoelectrics, according to the frequency of the signal that is input to sounding body 16, the vibration area of sounding body 16 is divided into the piston vibration zone and cuts apart vibration area according to its inherent characteristic.

Like this, although form covibration on the sound wave that is produced in the piston vibration zone of sounding body 16, cutting apart on the sound wave that vibration area produces because its intrinsic big distortion and do not form covibration.

Wherein, when having the sound wave of cutting apart vibration by two sounding bodies 16 produced and causing in the main body 12, because the phase place of the sound wave of the middle pitch/high pitch frequency range that is produced by two sounding bodies 16 respectively is opposite mutually, so the sound wave of middle pitch/high pitch frequency range is cancelled in main body 12 inside, the sound wave of the middle pitch/high pitch frequency range that produces by cutting apart vibration does not send from first opening 18.

In addition, different with the inside of main body 12, only exist in lid 20 inboards by in two sounding bodies 16 a sounding body produced cuts apart vibration and the sound wave that causes, so be not cancelled because of cutting apart the sound wave that vibrates the middle pitch/high pitch frequency range that causes.Yet, vibration is cut apart by a sounding body 16 produced and the sound wave that causes in lid 20 inboards, after barrier film 26 dampings that between through the lid 20 and second opening 22, are provided with, outwards send from second opening 22 of lid 20, barrier film 26 is played the part of the role of a wall, when cutting apart vibration and run into barrier film 26 and evenly caused its displacement, cut apart the sound wave that vibration causes and be converted into undistorted sound wave.So, loud speaker 10 ' can suppress undesirable cacophony and produce a kind of sound clearly.

In addition, the effect of barrier film 26 is that protection sounding body 16 exempts from through the dust of second opening, 22 infiltrations and the destruction of similar thing, and loud speaker 10 ' environmental change on every side is such as variations in temperature.

Notice that although do not illustrate, the acoustic(al)absorbent of being made up of glass fabric also can be arranged on main body 12 and lid 20 inboards.Since their absorb and damping the sound wave of middle pitch/high pitch frequency ranges of being produced of main body 12 and lid 20 inboards, so the sound wave of the bass frequency range that is produced is further strengthened.

When the signal of telecommunication is input to two sounding bodies 16 make the interior pressure of main body 12 increased by two sounding bodies 16/when reducing, in main body 12, produce sound waves by two sounding bodies 16, and outwards send from first opening 18 of main body 12.Simultaneously, because the diameter of first opening 18 is provided with less than sounding body 18, so the amplitude of the sound wave that sends from first opening 18 becomes greater than the amplitude from the sound wave of sounding body 16 generations.Therefore, the present invention has not only realized subminiaturized loud speaker because it has adopted thinner, the littler tabular piezoelectrics of sounding body of the conical plate formation more used than the woofer of prior art, and, can realize and can complete generation hang down the woofer of sound level.

In addition, loud speaker 10 ' allows with simple structure and the low sound level of low-cost acquisition, and applicable to the low system for electrical teaching of 3D central passage, because, by two sounding bodies 16 are installed on the main body 12, take out total output of left and right sound channels signal and only be used to autonomous agent 12 and lid 20 on the acoustic pressure of opening, can constitute the acoustics low pass filter.

In the above-described embodiments, although the barrier film and second damper are formed separately, they also needn't specially separate formation, and the barrier film and second damper also can be integrally molded.

As mentioned above, according to loud speaker of the present invention, by the resonance frequency of body interior and the resonance frequency of two lid inboards are made a distinction, there are a plurality of resonance frequencys in the bass frequency range, therefore, the scope of bass frequency range obtains broadening, is improved in the bass frequency range of broad by the low sound level that loud speaker produced.

Moreover, when the signal of telecommunication is input to two sounding bodies make the interior pressure of main body increased by two sounding bodies/when reducing, in main body, produce sound waves by two sounding bodies, and outwards send from first opening of main body.Simultaneously, because the diameter of first opening is less than sounding body, so the amplitude of the sound wave that sends from first opening becomes greater than the amplitude from the sound wave of sounding body generation.Therefore, the present invention has not only realized subminiaturized loud speaker because it has adopted thinner, the littler tabular piezoelectrics of sounding body of the conical plate formation more used than the woofer of prior art, and, by adopting this piezoelectrics, can realize and complete generation to hang down the woofer of sound level.

In addition, the invention provides a kind of loud speaker, it allows with simple structure and the low completely sound level of low-cost acquisition, and applicable to the low system for electrical teaching of 3D central passage, by two sounding bodies are installed on the main body, take out total output of left and right sound channels signal and the acoustic pressure that only is used to the opening on autonomous agent and the lid, can obtain to hang down system for electrical teaching by what the acoustics low pass filter was formed.

Moreover, according to loud speaker of the present invention, the sound wave that causes by the cutting apart vibration of a sounding body generation, through after the damping of barrier film from placing second opening on the lid outwards to send, barrier film is played the part of the role of a wall in the lid inboard, when cutting apart vibration and running into barrier film and evenly caused the sound wave displacement, cut apart the sound wave that vibration causes and be converted into undistorted sound wave.Thus, loud speaker of the present invention can suppress undesirable cacophony and produce a kind of sound clearly as woofer.

Claims (4)

1. A loudspeaker (10; 10'), comprising a cylindrical body (12) having open portions at both ends; Two sounding bodies (16) placed at the openings at both ends of the main body and vibrated by electrical signals; Two cylindrical covers (20) with bottoms arranged to cover the two sound emitting bodies; and a first opening (18) provided on the side of the main body and a second opening (22) provided at the bottom of the cover; Wherein, the two sounding bodies are driven in a direction to increase/decrease the internal pressure of the main body and the internal pressure of the cover; It is characterized in that the resonant frequency inside the main body (12) is different from the resonant frequency inside the two covers (20). 2. The loudspeaker according to claim 1, characterized in that the sound emitting body (16) is a piezoelectric body made of ceramics. 3. The loudspeaker as claimed in claim 1 or 2, characterized in that an input end of a sound channel signal in the input stereo signal is connected to a sound emitting body (16) in the two sound emitting bodies, and another sound emitting body (16) in the input stereo signal The other input end of a channel signal is connected to another sounding body (16). 4. The loudspeaker (10; 10') according to claim 1 or 2, characterized in that, between the sound emitting body (16) inside the cover (20) and the second opening (22) A diaphragm (26) is arranged between them.

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