CN2217861Y

CN2217861Y - Phase-reversal loudspeaking device

Info

Publication number: CN2217861Y
Application number: CN 94209956
Authority: CN
Inventors: 陈锦海
Original assignee: JIADIANBAO INDUSTRIAL Co Ltd
Current assignee: JIADIANBAO INDUSTRIAL Co Ltd
Priority date: 1994-04-16
Filing date: 1994-04-16
Publication date: 1996-01-17
Anticipated expiration: 2004-04-16

Abstract

The utility model relates to a phase-reversal loudspeaker device with a waveguide opening. The utility model uses the standing wave resonance of the waveguide to cause the medium frequency band of a loudspeaker not to be undistorted. The phase-reversal loudspeaker device comprises one or more openings on the partition walls at both ends of the waveguide, and a flexible film which is coated on the openings, wherein the flexible film can be a film made of latex material or a rigid film with flexible edges. The additional openings can prevent parasitic standing waves from adding pressures at the quarter wave length, so the standing waves can be eliminated, and the work of the waveguide can not be influenced at the helmholtz frequency of the phase-reversal loud speaking device.

Description

The inverted phase type speaker unit

The present invention relates to have the inverted phase type speaker unit of waveguide mouth.This loud speaker is well-known in the loudspeaker design field, and just sells and use in the U.S. since 1938.The inverted phase type loud speaker has higher efficient and lower frequency limitation than the loud speaker that is contained in the sealing audio amplifier.This is to have the function of helmholtz resonator because of it, and it is sending the audio amplifier outside from sound source low-frequency sound wave behind and making this sound wave and direct sound wave homophase from sound source the place ahead.Effectively resonance frequency is determined by the compliance that air had in the air quality of waveguide mouth and the audio amplifier.

Though waveguide itself also can play resonator to the sound wave that half-wavelength equals waveguide length or its isodisperse, this is a undesirable phenomenon, because the pairing frequency of these resonance can pass to the outside from audio amplifier inside, influences the middle range of loud speaker.The sounding phenomenon of these undesirable resonance can alleviate or eliminates with following method, promptly forces the different piece of sound wave by the waveguide cross section so that the distance of different length is arranged, and perhaps increases a low pass filter in the waveguide back.

First kind of solution can use the waveguide with sharp turn roughly to accomplish.Also can be by United States Patent (USP) 4,933, the method described in No. 982 is promptly used a straight wave guide that comprises concentric insert, forces sound wave to walk the path of different length between import and export.Yet these two kinds of waveguides all involve great expense, and the latter is also very heavy.

An example of second workaround is at United States Patent (USP) 4,953, mentions in No. 655, and promptly the terminal in the paraphase waveguide has a chamber that separates, and this chamber has a passage to lead to the audio amplifier outside.This chamber that separates and its passage play a part low pass filter, and sound wave arrived the loudspeaker enclosure outside from waveguide before, resonance had been eliminated.Yet loudspeaker enclosure has all increased overall size, complexity and cost owing to increased this extra chamber.

An object of the present invention is to provide a kind of inverted phase type speaker unit, it uses the waveguide mouth, but can not make the intermediate frequency signal of loudspeaker enclosure inside that undesirable leakage take place, not need complexity, heaviness or expensive design are done in waveguide or loudspeaker enclosure yet by the waveguide mouth.

Additional objects and advantages of this invention, a part will paraphrase in the specification part of back, and a part is understood after having seen specification naturally, perhaps realizes when enforcement is of the present invention.Can be understood and be obtained in method that objects and advantages of the present invention are specially pointed out in dependent claims and the combination.

Reaching of the object of the invention is by an inverted phase type speaker unit, it has an audio amplifier, one is contained in the sound source of launching sound wave in the audio amplifier outside audio amplifier, paraphase waveguide mouth on this audio amplifier wall, one is contained in the waveguide that connects the both ends open of paraphase waveguide mouth in the audio amplifier with an end, this waveguide has at least one additional opening between two ends, and a flexible film that covers on this additional opening.

Following accompanying drawing is a part that participates in explanation and constitute specification, has shown various embodiments of the present invention and comment together, is used for explaining principle of the present invention.

Fig. 1 is by the vertical cross section according to inverted phase type speaker unit first embodiment of the present invention.

Fig. 2 is a view seeing waveguide from the left side that is used for Fig. 1 inverted phase type speaker unit.

Fig. 3 is a chart, and the acoustic pressure of the paraphase mouth of inverted phase type speaker unit is as the function of frequency in the displayed map 1, and solid line represents to have the waveguide of rigid walls among the figure, and dotted line is represented according to waveguide of the present invention.

Fig. 4 is the vertical cross section of doing according to the non-elastomeric film in the waveguide of inverted phase type speaker unit second embodiment of the present invention by being contained in.

Fig. 5 is the front view that is contained in the film in the waveguide shown in Fig. 4.

Fig. 6 is the horizontal sectional drawing that is contained in the film in the tubular waveguide shown in Fig. 4.

Now with reference to the accompanying drawings preferential embodiment of the present invention is described in detail.

Fig. 1 shows the vertical cross section of being done by two-way inverted phase type speaker unit 10, comprises 11, one basses of a loudspeaker enclosure/16 and waveguide mouths 19 of 12, one high-frequency sound sources of middle pitch sound source (high pitch head).For the sake of clarity, the element that all and the present invention have nothing to do in the inverted phase type speaker unit for example is used for frequency divider, the electric wire of sound source 12 and high pitch head 16, and it is not shown in Figure 1 to be used for the sound-absorbing material of loudspeaker enclosure.

This bass/middle pitch sound source 12 has a cone 13, and it is driven by the voice coil loudspeaker voice coil (not shown) that is arranged in magnetic devices 14, and is supported by a metal sound basin frame 15.The openend of cone 13 is called the flexible rings of encircling muscle by one and is connected with basin frame 15, and this ring muscle forms sealing between the outside of cone 13 and audio amplifier 11, but allows cone to do into/go out motion.The ring muscle is semi-round ring shape normally, so when cone 13 motions, material just curls and not stretching.The small end of cone 13 is connected with magnetic devices by a film that is called as latch plate (spider) with a plurality of concentric scrimps.This ring muscle and this latch plate allow cone to do pure advancing/go out motion, therefore when the voice coil loudspeaker voice coil of sound source 12 is connected on the lead-out terminal of audio frequency amplifier, the front of cone 13 is directly to the broadcast of audio amplifier outside, and the sound that 180 ° of phase differences are broadcast by open basin frame in the back of cone 13 enters in the audio amplifier 11 of sealing.High pitch head 16 has a sound film 17 that is driven by the voice coil loudspeaker voice coil (not shown) that is positioned among the magnetic devices 18.Sound film 17 is supported by the ring muscle, but is not had latch plate usually.When the voice coil loudspeaker voice coil of high pitch head was connected on the lead-out terminal of audio frequency amplifier, the front of sound film 17 was directly to the broadcast of the outside of audio amplifier.The back broadcast of sound film 17 enters in the confined chamber that loads magnetic devices, so the high pitch head does not influence the acoustic pressure of audio amplifier 11 inside.

The inside of audio amplifier 11 can only be by waveguide mouth 19 and extraneous logical sound and sound wave earlier the opening 22 of process with waveguide 20 of wall 21 just arrive waveguide mouth 19, waveguide 20 usefulness paperboards or plastics are made.Waveguide 20 and audio amplifier be inner to form a helmholtz resonator, and the quality of air is determined in compliance that its resonance frequency is had by the air in the audio amplifier 11 and the waveguide 20.The frequency response curve of the helmholtz resonator that records at waveguide mouth 19 places is shown in Fig. 3.Sound wave with the resonance frequency fo that is equal to helmholtz resonator, by 180 ° of waveguide mouth 19 back paraphase, therefore the frequency of coming out from mouth 19 is that the acoustic pressure of fo directly is superimposed upon on the acoustic pressure of coming out previously from cone 13.The sound wave of every other frequency all is attenuated.Hang down the frequency of half scale as resonance frequency fo by selecting a roll-off frequency than sound source 12, just can obtain than the level and smooth response curve of lower half scale of bass frequencies of loud speaker in the sealed type audio amplifier and do not need to increase the power of amplifier, this is the purpose of inverted phase type speaker unit.

If waveguide 20 has the wall 21 of rigidity, as being used always in the art, frequency response curve is just shown in solid line among Fig. 3.Two spurious resonance peaks are arranged on frequency f 1 and f2 in this example.Its fo=42 is conspicuous in a loud speaker, and using a waveguide 20 is 250 millimeters long, and when internal diameter was 35 millimeters, each resonance peak was located to measure at f1=550 hertz and f2=1200 hertz, and waveguide 20 this moment is to use rigid walls 21.The airborne velocity of sound is 344 meter per seconds when normal atmosphere is depressed 20 ℃, so the half-wavelength of 550 hertz sound wave is 313 millimeters, the half-wavelength of 1200 hertz sound wave is 143 millimeters.Waveguide 20 is 250 millimeters long, and this approaches a half-wave length and two half-wave lengths at above-mentioned two sound wave peaks.These two peaks that are in 550 hertz and 1200 hertz are caused by the standing wave in the waveguide 20 with rigid walls 21 significantly.

The intensity of acoustic wave peak value that is positioned at frequency f 1 and f2 that comes out from waveguide mouth 19 is significantly less than the acoustic pressure from sound source 12 fronts that is positioned at this f1 and f2 frequency, even but still can be heard distortion that Here it is during in amount of bass at other peak of high-fidelity loudspeaker middle pitch part.

According to the present invention, each standing wave in waveguide 20 can be eliminated, and this is to utilize wall 21 in waveguide 20 that additional opening 31,32 is set to be covered with flexible film 35 on those openings, and for example elastic membrane is seen illustrated in figures 1 and 2.Helmholtz resonator among Fig. 1 has a waveguide 20, and two

openings

31 and 32 that are covered with film are arranged on its wall 21, and the frequency response curve of this resonator is represented by dotted lines in Fig. 3.Two peaks that are positioned at 550 hertz and 1200 hertz are eliminated, and whole intermediate-frequency section has obtained much level and smooth frequency response curve.

Opening

31 and 32 are set can appearing in the waveguide 20 that frequency is attenuated near the peak pressure variable.Opening 31 is near the quarter-wave strong point of frequency f 1, and opening 32 is near the quarter-wave strong point of frequency f 2.Film 35 can be bonded at the form of plain film waveguide 20 wall 21 the outside as depicted in figs. 1 and 2, maybe can be made into sleeve pipe, be enclosed within on the wall 21, pinion with rope.

Must be sufficiently soft as the film of film 35, make each film when frequency f 1 and f2 in waveguide just as an opening, but enough rigidity is arranged again, make this film when helmholtz resonance frequency f 0, can seal.Acoustic impedance and frequency with film of known flexibility are inversely proportional to, so huge ratio makes it obtain above-mentioned effect easily between f1 or f2 and f0.Thin latex film work gets fine, but it can wear out and become fragile.0.025 millimeter thickness urethane film of selling with trade name WALOPUR has the long life-span, is used in the loud speaker, and its frequency response curve as shown in phantom in Figure 3.Other suitable thin-film materials also can have been bought on market.

The elasticity sound absorbing power of latex film is very little, so when using latex film, must add sound-absorbing material in addition and produce uncontrolled vibration with the film that prevents to cover on opening 31 and 32.This can make it contact the film that covers on opening 31 and 32 gently by be wrapped with twisting thread that cotton or similar cotton material make at the outside of waveguide 20 pine loose ground.When the sound absorbing power of the material of film own is not enough, also can adopt additive method to increase the sound absorbing power of film.Urethane film has enough sound absorption properties, so do not need to add the sound-absorbing measure.

Flexible film 35 also can be made by stiff material basically, and this is shown in Fig. 4 to Fig. 6.Fig. 4 to Fig. 6 shows a kind of according to non-elastomeric film 35 of the present invention, and it is installed in the tubular waveguide 20, and the wall 21 of waveguide 20 has opening.This non-elastomeric film 35 is utilized ring muscle 36 and is made into deflection, around forming ring muscle 36 around the film 35.The effect of ring muscle 36 is the same with the ring muscle of common cone, allows film 35 to do/go out to scratch.Ring muscle 36 can be bonded on the film 35 after perhaps can making with different materials with making with the film identical materials.Outside at ring muscle 36 is a limit portion 37, is used for installing and being sealed on the wall 21 of waveguide 20 having the film 35 that encircles muscle 36.The function of the flexible film that in Fig. 4 to Fig. 6, shows with above the formed flexible film of described single elastic membrane that sees figures.1.and.2 be the same.

When waveguide 20 is cylindrical shape, see Fig. 4 to shown in Figure 6, the limit portion 37 that usefulness is installed should make corresponding complicated shape as shown in Figure 6 like that, because whole ring muscle 36 must be in the plane so that operate as normal.If waveguide 20 has a flat wall portion, limit portion 37 energy and film 35 and ring muscle 36 then are installed in same plane, therefore have movable film 35 that encircles muscle 36 and the plastic material that installation limit portion 37 can approach from a slice very simply and make, for example make with pressure sintering.

A kind of flexible film of being made by non-elastic material sees that Fig. 4 to shown in Figure 6, do manyly than a kind of single elastic membrane difficulty, but its cost be still very low, and can be used a variety of materials that can not be used for doing elastic membrane

Required opening (31,32) number on the wall 21 of waveguide 20 by different situations and different, depends on the upper limit of the crossover frequency that the length of waveguide 20 and bass/middle pitch sound source 12 are required.Enough at opening of most of occasions, seldom can need the opening more than three.The present invention does not limit the number of opening.

Therefore, it is to be noted the present invention comprise by in dependent claims and the equivalent scope thereof according to the improvement and the variation of inverted phase type speaker unit of the present invention, be not subjected to environmental limitations.

Claims

1. inverted phase type speaker unit is characterized by and comprises:

(a) audio amplifier;

(b) sound source that is used for from this audio amplifier, outwards launching sound wave that is contained in this audio amplifier;

(c) paraphase waveguide mouth on this audio amplifier wall;

(d) both ends open be contained in the waveguide that is connected with this waveguide mouth with the one end in this audio amplifier, this waveguide has an additional opening between its two ends;

(e) flexible film that covers this additional opening.

2. the inverted phase type speaker unit described in claim 1 is characterized by, and this flexible film is made by an elastic membrane.

3. the inverted phase type speaker unit described in claim 2 is characterized by, and also comprises the device that absorbs this elastic membrane resonance.

4. the inverted phase type speaker unit described in claim 2 is characterized by, and this elastic membrane is made with polyurethane.

5. the inverted phase type speaker unit described in claim 1 is characterized by, and this flexible film comprises a rigid film and the ring muscle supporting this rigid film and allow this rigid film motion.

6. the inverted phase type speaker unit described in claim 1 is characterized by, and this waveguide is a straight basically pipe.

7. the inverted phase type speaker unit described in claim 1 is characterized by, and this additional opening is disposed in and leaves this waveguide mouth to equal the distance of 1/4th length of standing wave in this waveguide haply last.

8. the inverted phase type speaker unit described in claim 7 is characterized by, and this flexible film is made with elastic film.

9. the inverted phase type speaker unit described in claim 7 is characterized by, and this flexible film comprises a rigid film and a kind of ring muscle of supporting this rigid film and allowing this rigid film motion.

10. the inverted phase type speaker unit described in claim 1 is characterized by, this waveguide have a plurality of by this waveguide length and the additional opening of the crossover frequency upper limit decision of this sound source.

11. the inverted phase type speaker unit described in claim 10 is characterized by, this flexible film is made by elastic film.

12. the inverted phase type speaker unit described in claim 10 is characterized by, this flexible film comprises a rigid film and the ring muscle supporting this rigid film and allow this rigid film motion.

13. the inverted phase type speaker unit described in claim 1 is characterized by, this flexible membrane has the opening that plays a part this waveguide when a sufficiently high flexibility can make the frequency of this film standing wave in corresponding to this waveguide basically.

14. the inverted phase type speaker unit described in claim 13 is characterized by, this flexible membrane is made by elastic film.

15. the inverted phase type speaker unit described in claim 13 is characterized by, this flexible membrane comprises a rigid film and the ring muscle supporting this rigid film and allow this rigid film motion.

16. the inverted phase type speaker unit described in claim 1 is characterized by, this waveguide has flat wall portion.

17. the inverted phase type speaker unit described in claim 16 is characterized by, this flexible membrane comprises a rigid film and the ring muscle supporting this rigid film and allow this rigid film motion.