MXPA99008448A - Broadband loudspeaker - Google Patents

Abstract

The invention concerns a broadband loudspeaker which emits in an approximately punctiform manner and whose movable components are secured to a dome-shaped loudspeaker front which, at the rear, opens into a housing shell disposed coaxially around the centre axis of the housing. Opposite the rear side of the diaphragm lies a diagonal deflection plane which can take the form of a rear wall. The inner cross-section of the housing shell is preferably designed as an irregular polygon, as is the dome-shaped loudspeaker front and the preferably cup-shaped loudspeaker diaphragm which can be secured directly to the loudspeaker front.

Description

XI WIDESPREAD LOUDSPEAKER DESCRIPTION OF THE INVENTION: The invention relates to a broadband speaker that emits approximately in a punctiform manner, with improved amplification properties. The thought of the invention is thus oriented to the ideal of a sound source that emits in a sphere form as small as possible. - In general, boxes or housings have a great influence on the acoustic properties of a loudspeaker, where each box shape and property of the box as well as the arrangement of the sound transformer in the box have very characteristic effects on the quality of the loudspeaker. reproduction. The failure of reproduction caused by the box are including even the digital very difficult and in general not corregibles and coordinated as primary causes the following: 1. In the box stationary waves are formed, which act in a disruptive way on the. back side of the diaphragm or diaphragm. 2.- The sound waves are refracted in the area of the diffraction frequency and under the outer edges of the front of the speaker, which leads in inadequate box forms to an irregular fall of the amplitude. 3. -The cylindrical waves form on the straight edges of the box, which interfere with the direct sound depending on the angle REF .: 31152 auditory. 4.-Depending on the construction of the box and the materials used there are more or less strong resonances oscillating the front and rear plates. ~~ As unfavorable of the usual box forms in relation to the mentioned sources of failure, the cube is presented, in which with a centered installation of the chassis powerful standing waves are formed and in the outer edges of the front of the speaker strong cylindrical waves In a compromise solution the rectangular box widens a lot with three different edge lengths, because this way the standing waves are presented in three frequencies and therefore they are not applied with such force. It is also possible to establish additionally installed sound reflectors, which should reduce this effect. Also pyramid-shaped boxes fulfill similar objectives. Interference faults are made smoother by the inclination of the edges. Refractive and interference faults are minimized by sphere-shaped boxes, as shown in DE-G 750 2568, but where the sphere without other measures causes the strongest standing waves. It is advantageous in the mentioned model to place the fixation of the diaphragm directly in the box, in the drawing however the position of the diaphragm in relation to the outer edge of the box is so unfortunately represented, that the advantages of the box front in the form spherical do not come to manifest. For this, faults that are caused by the diaphragm enter: 5. There is a concentration "fb" [fb = C / (Ó.d] fb = frequency of concentration, C = sound speed, d = diameter of the diaphragm) audible frequencies (the formula refers to a flat diaphragm, while a conical diaphragm still concentrates more strongly as a consequence of its principle). 6. Depending on the properties of the material (torsional stiffness, internal damping, and others) material resonances are presented at different frequencies in the form of partial oscillations (strange sound of disorder due to a partial flexion of the diaphragm). the hanging of the diaphragm (nutation movements) in the case of diaphragms in the form of cups 8. Failures that occur due to the hanging of the diaphragm and the centering (mass / spring effect) similar to a second filter arrangement causing A decrease in amplitude in the lower limit frequency The most important faults in relation to the quality of spatial or stereophonic reproduction are, however, the transit times different from sound waves in multi-channel non-coaxial systems. they are in a plane, failures of transit time occur. The originally faithful or high-fidelity three-dimensional reproduction of a recording with 2 microphones is not possible or is only possible for a fixed listening place. In addition, the Hall or reverberation effect is presented, which, among other things, gives the impression of an artificial spatial sound and a greater volume of sound. Therefore it seems that a coaxial speaker could be suitable to eliminate those defects. Coaxial loudspeakers are known in the form of cone / cup and cone / horn combinations. In both embodiments there is the sound output for the high tone area at the funnel mouth of a cone. The diaphragm, which no longer modulates the high-pitch fraction addressed to it, is now activated in the form of the cup more, in the horn somewhat less, by the sound waves of the high-tone system. It is also disadvantageous that the sound fraction of the cup that otherwise broadly radiates through the cone becomes a beam or concentrates depending on the frequency. In the horn they disrupt the multiple reflections in the walls of the horn body in different consideration. A practical principle is given by the coaxial realization of a high / medium tone loudspeaker by GB 2 250 658, which, however, as regards the suppression of partial oscillations, does not give information. It is therefore the task of the invention to create a loudspeaker with improved reproduction properties where the described faults are largely avoided. The object is achieved by the two methods according to the invention, as illustrated in the characteristic features of claims 1 and 8. The following dependent claims relate to further advantageous developments of the subject matter of the invention and present possible embodiments. In the first method the front of the dome-shaped loudspeaker offers the advantage that the pressure sound waves are refracted gradually and not abruptly at the outer edges of the box or housing, therefore neither interference nor irregularities develop in the amplitude-frequency curve. The transition region between the conditions in a wall of infinite sound or baffle and those at the end of a long tube progresses smoothly in this case. The sound pressure decreases regularly to -6dB and can easily be compensated by the equalization of the impedance, for example, in the case of a passive solution by a known circuit in the signal channel. Such a circuit compensates for the drop in sound pressure below the diffraction frequency (ffd). Because it allows the level to be lowered as a function of frequency, with a cutoff frequency equal to fd. Therefore the frequency response is linearized and the frequency response - amplitude of an infinite deflector is established.

Inside this dome, the axially radiated sound waves are guided directly to the rear portion of the housing or box, while the radially radiated sound components are guided inward by the conically disposed baffle surfaces. There the components collide on the deflector plane, which is preferably arranged at 45 ° and can be formed by the rear wall of the box. It deflects the sound waves so that they are reflected numerous times on the inside walls of the case cover, which preferably has a polygonal cross section. They must pass several times through the buffer material placed in the cavity of the box. Stationary axial waves can not develop. Because the internal cross section of the box is a polygon with an odd number of sides, the stationary radial waves are distributed at several frequencies depending on the number of segments - and thus are greatly attenuated before they are also eliminated by the damping material . The extremely stable housing or box has an extremely low resonance, making it possible to do so without the normal structure of the loudspeaker and to fix the suspension of the diaphragm and drive unit directly in the housing assuming that aluminum or plastic is used, for example, as materials.

The other method involves improving the radiation or emission of the diaphragm or in other words extending the radiation angle, the diaphragm is designed as a cup. Consequently, an almost perfect radiation behavior in the described transition region is achieved in combination with a dome-shaped loudspeaker front. Partial vibrations of the diaphragm are greatly suppressed if the cup-shaped diaphragm is divided into stabilizing segments by providing it with a polygonal cross-section. If an asymmetric subdivision is also chosen, the vibration fields, which occur first in opposite positions, can not be formed. By folding the edge region inwards to obtain a circular flange, stability is obtained additionally and a plane is created to fix the suspension of the diaphragm. The division of the diaphragm into two zones and the elastic connection of the areas between each other. , for which purpose a permanent elastic adhesive can be used, it improves once more the radiation behavior, and also improves the efficiency for high frequencies. The discontinuity that the elastic coupling causes in the frequency-response-amplitude can be corrected with a band-pass filter. Division into other ring zones is possible within a certain limit. The coil former is always fixed in the center. The nodal movements of the diaphragm can be prevented with a centering axis that is supported at one or both ends, and preferably comprises a light hollow member. You can refrain from using the centering star that causes interference (damping and reflection). Finally the FM distortions can be reduced by uncoupling the central area of the annular zone and providing it with its own impeller and its own diaphragm suspension. The impeller of the central zone has a space in front of the impeller for the annular zone, and the central zone can also be represented by a complete deflection element such as "a neodymium cup." The internal diaphragm suspension of the annular zone is fixed to that sound transducer impeller, thus ensuring simultaneously the complete sealing with respect to the housing Depending on the material properties of the diaphragm suspensions, it can be achieved with only one centering and null position being measured, any slight phase discrepancy it can be corrected electronically The attached housing or housing leads to the first method, but can be, for example, a spherical housing with an appropriate internal contour.As a result the basic structure of the speaker - assuming that it is placed with a suitable spacing (not too close to the walls) already makes a surprisingly realistic stereophonic reproduction of aud events possible properly recorded. It is also preconditioned as possible for active pre-processing of auditory signals if, among other requirements, the entire dynamic range is used. Practical examples will now be explained in greater detail with reference to the drawings, where: Figure 1 schematically shows the longitudinal section of the broadband speaker, wherein a sound transducer (2) with a conical diaphragm (4) is installed in a dome-shaped front (6) that can be fixed by means of a diaphragm suspension (5) in either a frame or a box (1). The drive unit (3) can also be attached to a frame or to the box (1) or the back wall (9). The baffle plane (9) placed diagonally can be formed by the rear wall. The tapered inner contour deflects the sound components radiated radially in the rear region of the housing (1) while subjecting those components to the removal process described above. Figure 2 shows convex and concave versions (dotted lines) of the sound transducer fixed directly to the housing together with the drive unit (3) and the diaphragm suspension (5). In this example the centering axis (15) is supported at the end. The support (16) thereof is not described in detail, but may, for example, be an elastic blocking bed. Figure 3 shows a cup-shaped diaphragm (10) divided into annular zone (12) and central zone (13). The fixing of the zones to each other, by means of the elastic joint (14) is illustrated schematically. The annular zone (12) must receive rigidity in the coupling area, for example by bending it. Figure 3a shows an enlarged detail of that region. Figure 4 shows an array with a central zone driven separately (13, 19). The internal diaphragm suspension (17) joins the annular zone (13) with the second impeller (19J or with the coil former (18) .The central zone (13) is in this case equipped with its own diaphragm suspension and can represent a completely independent sound transducer Figure 5 shows a housing or box (1) without a speaker in a three-dimensional view.In this example practical the external cross section is completely round, while the internal space is polygonal, as shown by the view of the housing and the rear wall (9) tucked in. Figure 6 shows a three-dimensional representation of Figure 3. This view is also suitable for the illustration of Figures 2 and 4. Corresponds to Figure 2 if the break in the center is not taken into account, but corresponds to Figure 4 if that break is interpreted as the suspension of the diaphragm.At the same time a practical combination of the two methods is shown by the conto. external polygon of the front of the dome-shaped speaker (6).

It is noted that in relation to this date, the method known to me by the applicant to carry out the aforementioned invention, is the conventional method for the manufacture of the objects to which it refers.

Having described the invention as above, the content of the following is claimed as property.

Claims (18)

1. CLAIMS 1.- Loudspeaker with a box or housing that has a dome or dome-shaped loudspeaker front, which backs into a box sleeve arranged around the central axis of the loudspeaker, and with a sound transducer that has a unit of impulsion, a diaphragm or membrane and a diaphragm suspension, -where the sound transducer is fixed to the front of the speaker in the form of a dome; characterized in that, a diagonal plane of deflection on the inner side of the box is placed on the rear side of the diaphragm, and the cross section of the box sleeve describes on the inner side a polygon, which has an odd number of sides.
2. 2. Loudspeaker according to claim 1, characterized in that the diagonal deflection plane is formed by the rear wall of the box.
3. 3. - Loudspeaker according to claim 1 or 2, characterized in that the angle between the deflection plane and the central axis of the loudspeaker is preferably 45 °.
4. 4. Loudspeaker according to one of claims 1 to 3, characterized in that the deflection plane is so directed that it opposes an open angle of the polygon.
5. 5. Loudspeaker according to one of claims 1 to 4, characterized in that the internal contour of the front of the dome-shaped loudspeaker presents a cone-shaped course backward from the external fixing flange of the diaphragm towards the liner of the loudspeaker. box.
6. 6. - Speaker according to one of the claims 1 to 5, characterized in that, the sleeve of the box runs in the form of a cone.
7. 7. - Speaker with a sound transducer, which has a drive unit, a diaphragm and a suspension for the diaphragm, where the diaphragm is constructed as a cup, characterized in that the cup has a polygonal base surface.
8. 8. Loudspeaker according to claim 7, characterized in that the polygonal base surface of the cup has an odd number of sides.
9. 9. Loudspeaker according to claim 7 or 8, characterized in that the suspension of the diaphragm is connected to a box.
10. 10. Speaker according to one of claims 7 to 9, characterized in that the cup in the edge area is shaped inwardly as a round flange.;
11. 11. - Loudspeaker according to claim 10 characterized in that the diaphragm suspension is fixed to the flange.
12. 12. Loudspeaker according to one of claims 7 to 11, characterized in that the cup is connected to a centering shaft which is mounted on the box.
13. 13. - Speaker according to one of the claims 7 to 12, characterized in that the cup is divided into an annular zone and a central zone.
14. 14. Loudspeaker according to claim 13, characterized in that the annular zone is permanently elastic and is connected by a connecting element to the central area.
15. 15. Loudspeaker according to claim 13 or 14, characterized in that the drive unit acts on the central zone.
16. 16. Loudspeaker according to claim 13 to 15, characterized in that the central area is a separate sound transducer with separate impeller.
17. 17. Loudspeaker according to claim 16, characterized in that the impeller for the central zone is arranged before the drive unit for the annular zone.
18. 18. Loudspeaker according to claim 17, characterized in that the annular zone is fixed with a second internal diaphragm suspension to the coil carrier of the drive unit and also to the second impeller.