Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R1/00—Details of transducers, loudspeakers or microphones
  • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
  • H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only 
  • H04R1/28—Transducer mountings or enclosures modified by provision of mechanical or acoustic impedances, e.g. resonator, damping means
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R1/00—Details of transducers, loudspeakers or microphones
  • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
  • H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only 
  • H04R1/28—Transducer mountings or enclosures modified by provision of mechanical or acoustic impedances, e.g. resonator, damping means
  • H04R1/2807—Enclosures comprising vibrating or resonating arrangements
  • H04R1/283—Enclosures comprising vibrating or resonating arrangements using a passive diaphragm
  • H04R1/2834—Enclosures comprising vibrating or resonating arrangements using a passive diaphragm for loudspeaker transducers

Definitions

• the invention is a closed loudspeaker housing in which, in addition to active electromechanical transducers, one or more passive membranes for amplifying the sound radiation are installed, which sets the pressure fluctuations in the interior of the housing in motion and is as free as possible and driven with low damping.
• Conventional passive membranes are constructed like electrodynamic loudspeakers, but without a voice coil / magnet drive system.
• electrodynamic loudspeakers such as membranes, beading centering spiders and loudspeaker cages are used for their manufacture.
• Their membranes are made of stiff, but as light as possible material and vibrate like a piston without deforming.
• the bass-enhancing effect is limited to a relatively small frequency range and is achieved by an additional resonance. This leads to a louder but not always clean bass reproduction.
• the development goal for loudspeakers is a deep bass reproduction with good efficiency with small housing dimensions. In conventional constructions of closed housings, the cutoff frequency, the efficiency and the volume are interlinked. A damping factor of 0.7 for the mass / spring system of the active membrane is sought, which is perceived as optimal in terms of sound.
• Bass reflex systems conventional systems with a passive membrane and transmission line are similar in effect. They generate an additional resonance below the limit frequency of the converter. This leads to a slight expansion of the radiated frequency range. However, the sound pressure drops below the cutoff frequency.
• Horn systems require sound channel dimensions that correspond to the 4th part of the wavelength of the lowest emitted frequency. Their dimensions cannot be reduced and they audibly produce typical discolorations and a strong directivity.
• the invention has for its object to provide loudspeaker housings that allow deep, clean bass reproduction with small dimensions.
• one or more passive air-impermeable membranes for sound radiation are installed in the loudspeaker housing, which are excited to vibrate in the housing as a result of the pressure fluctuations generated by the active membrane of the transducer, and are designed so that they are connected to the spring force the enclosed air volume and its own internal spring force, which counteracts deformation, can form as many resonances as possible in the largest possible frequency range.
• the passive membrane In contrast to internals in the housing ; which are used for sound damping, the passive membrane generates a higher ren pressure in the housing against which the diaphragm of the converter must work.
• a loudspeaker housing that is as airtight as possible is a prerequisite for good functioning.
• the passive membrane must also be designed so that it is impermeable to air.
• the broadband radiation of the passive membrane also significantly improves the acoustic adaptation of the active membrane to the radiation field,. which leads to a clean and impulsive sound image.
• the entire rear wall of the loudspeaker housing 1 consists of a flat, elastic membrane 2, for example made of rubber or silicone. It is set into vibrations by pressure fluctuations in the housing 1, generated by the active membrane of the transducer 4, which should take place with as little damping and uninhibited as possible.
• the thickness of the membrane and its material properties essentially determined the lowest resonance frequency.
• the thickness is typically a few millimeters.
• the geometrical shape of the clamping profile of the passive membrane 2 has an influence on the frequency position of the individual vibration modes. It can be designed to adjust the frequency response and bandwidth.
• FIG. 2 shows a further embodiment of the passive membrane 2, which is constructed from elements of different mass and elasticity. In this way. very easily set the desired characteristics of the vibration modes.
• the membrane is made up of heavy and rigid mass elements 5 and elastic connecting elements 6.
• FIG. 3 shows a particularly cost-effective construction of a housing loudspeaker using the cylindrical shape 9.
• the transducer is installed asymmetrically on the end face.
• the rear, radial cut surface is covered by the passive membrane 2.
• FIG. 4 shows the invention in a pyramid-shaped housing.
• the passive membrane 2 either replaces one or more rear walls or the bottom surface.
• the passive membrane 2 can therefore be attached on all sides of a loudspeaker housing. Several membranes can also be provided. It is also possible to attach a passive membrane to the remaining surface of the front. A symmetrical arrangement in such a way that two membranes oscillate in push-pull compensates for the forces introduced into the housing by the membranes.
• Passive membranes of the form described are installed according to the invention in housings which are equipped as follows:
• Two or more woofers acoustically in series, to increase the force exerted on the enclosed air volume.
• the additional housing 3 can have the following features:
• All such inner housings must have at least one elastic wall 2 for varying their volume as a function of pressure.
• the invention is applicable to a wide variety of loudspeaker systems, e.g. :
• the area of the passive membrane (s) is chosen to be larger than the area of the active membrane of the transducer.
• the passive membrane is also heavier than the active membrane of the transducer.
• All boundary surfaces of the loudspeaker housing can be equipped with a passive membrane.
• the passive membrane is preferably flat, but it can also have a non-planar shape that is adapted to the shape of the housing.
• the shape of the passive membrane can be stretched over fixed mechanical support points or support lines.
• the formation of the resonance distribution can be favored in that the passive membrane consists of a combination of elastic and less elastic or solid elements, the focal points of which are located within the membrane plane.
• the passive membrane has location-dependent mechanical properties over the surface, the distribution function of the mechanical properties preferably having geometric symmetry properties.
• the lowest resonance frequency of the passive membrane is approximately one octave below the resonance frequency of the active transducer when the passive membrane is held firmly.
• additional masses are fastened to the membrane on the passive membrane via spring elements.
• the Auslessness ⁇ will supply by as many modes of vibration possible. Earth points are attached to the passive membrane.
• the passive membrane is designed and arranged so that the vibrations - 3 -
• passive membrane can be done as undamped and unchecked as possible.
• passive membranes can be arranged in a loudspeaker housing in such a way that they touch the enclosed and external air volume.
• passive diaphragms these are arranged in such a way that they move in a push-pull manner and the forces introduced into the housing due to diaphragm movement are compensated.
• the housing can be equipped with a full-range converter, but it can also accommodate a multi-way speaker system.
• Two or more transducers can be connected acoustically in series in such a way that the force of their membranes is added to the enclosed and external air volume.
• transducers can be installed in such a way that their membranes touch the enclosed and external air volume.
• the passive membrane is silicone with a low Shore hardness. Additional weights can be incorporated into the passive membrane. Homogeneous thickness and formation of the passive membrane are advantageous.
• the bass reproduction can be influenced if the passive membrane is preloaded.
• the loudspeaker housing can be divided into two or more chambers, which are connected to one another via openings smaller than the membrane diameter of the largest transducer in terms of area.
• the passive membrane is opposed to a solid wall in the housing, which is provided with one or more openings, which make the acoustic contact with the active transducer.
• the passive membrane covers a radial cut surface and the active transducer is built into this cut surface or into the opposite housing wall.
• the transducer can be outside the center of the radial cutting surface O
• the cylinder has a height that is smaller or not significantly larger than the diameter.
• the operating position of the cylinder is horizontal.
• the loudspeaker membrane is dimensioned such that the restoring force of the passive membrane is mainly applied from the spring force of the enclosed air volume.
• the passive membrane has a thickness of at least one millimeter. That is e.g. trained round.
• the loudspeaker housing is preferably made of plastic. There is no material in the loudspeaker housing for damping cavity vibrations.

Landscapes

• Health & Medical Sciences (AREA)
• Otolaryngology (AREA)
• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Signal Processing (AREA)
• Details Of Audible-Bandwidth Transducers (AREA)
• Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6323887

Family Applications (1)

Country Status (4)

Cited By (2)

Families Citing this family (7)

Citations (5)

Family Cites Families (3)

• 1987
  • 1987-03-25 DE DE19873709700 patent/DE3709700A1/de active Granted
• 1988
  • 1988-03-23 EP EP88104667A patent/EP0284051A1/de not_active Withdrawn
  • 1988-03-23 WO PCT/EP1988/000237 patent/WO1988007802A1/de unknown
  • 1988-11-25 KR KR1019880701540A patent/KR890700996A/ko not_active Withdrawn

Patent Citations (5)

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