CA2108696A1 - Improvements in and relating to transmission line loudspeakers - Google Patents
Improvements in and relating to transmission line loudspeakersInfo
- Publication number
- CA2108696A1 CA2108696A1 CA002108696A CA2108696A CA2108696A1 CA 2108696 A1 CA2108696 A1 CA 2108696A1 CA 002108696 A CA002108696 A CA 002108696A CA 2108696 A CA2108696 A CA 2108696A CA 2108696 A1 CA2108696 A1 CA 2108696A1
- Authority
- CA
- Canada
- Prior art keywords
- drain
- back chamber
- chamber
- loudspeaker
- transmission line
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 230000005540 biological transmission Effects 0.000 title claims abstract description 26
- 230000006872 improvement Effects 0.000 title description 3
- 239000007788 liquid Substances 0.000 claims description 7
- 230000004044 response Effects 0.000 claims description 5
- 238000009423 ventilation Methods 0.000 claims 2
- 238000006243 chemical reaction Methods 0.000 description 5
- 238000006073 displacement reaction Methods 0.000 description 5
- 241000318656 Masca Species 0.000 description 3
- 230000005520 electrodynamics Effects 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 101000935117 Homo sapiens Voltage-dependent P/Q-type calcium channel subunit alpha-1A Proteins 0.000 description 1
- 208000036758 Postinfectious cerebellitis Diseases 0.000 description 1
- 101150112439 SMAP gene Proteins 0.000 description 1
- 101150014929 TPS2 gene Proteins 0.000 description 1
- YSIITVVESCNIPR-UHFFFAOYSA-N Troxipide Chemical compound COC1=C(OC)C(OC)=CC(C(=O)NC2CNCCC2)=C1 YSIITVVESCNIPR-UHFFFAOYSA-N 0.000 description 1
- 102100025330 Voltage-dependent P/Q-type calcium channel subunit alpha-1A Human genes 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000009795 derivation Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 231100000989 no adverse effect Toxicity 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 229960001341 troxipide Drugs 0.000 description 1
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
- H04R1/2807—Enclosures comprising vibrating or resonating arrangements
- H04R1/2838—Enclosures comprising vibrating or resonating arrangements of the bandpass type
- H04R1/2842—Enclosures comprising vibrating or resonating arrangements of the bandpass type for loudspeaker transducers
-
- 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
- H04R1/30—Combinations of transducers with horns, e.g. with mechanical matching means, i.e. front-loaded horns
Landscapes
- Health & Medical Sciences (AREA)
- Otolaryngology (AREA)
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Soundproofing, Sound Blocking, And Sound Damping (AREA)
- Exhaust Silencers (AREA)
- Circuit For Audible Band Transducer (AREA)
Abstract
The sound wave radiated from the front surface (UF) of a loudspeaker driver diaphragm is of opposite polarity with respect to that radiated from the back surface (UB). If the two signals are directly combined, they will tend to cancel one another. An acoustic phase inversion network (5) is used to ensure that the backwave is in phase with the front wave, and the combined signals are used to drive the inlet of a loudspeaker transmission line (6).
Description
1 - 21 D 8 6 3 S PCr/US91/027~1 Improvement~ In zLnd Relating to Tran~mis~ioll Li~ Lou~lspeaXers BACKGROUND OF THE INVENTION
1. Field of the Invention.
This invention relates to a method of and apparatus for improving the performance of transmission line loudspeakers and has particular applications in active noise control, high fidelity audio, and sound reinforcement systems.
1. Field of the Invention.
This invention relates to a method of and apparatus for improving the performance of transmission line loudspeakers and has particular applications in active noise control, high fidelity audio, and sound reinforcement systems.
2. Discussion of the ~elevant Art.
The simplest form of a loudspeaker system is the direct radiator. Such a loudspeaker radiates sound directly form the enclosure aperture(s)--the driver diaphragm and, in the case of vented-box syst~ms, a vent or port. There are no additional devices through which the sound passes.
A transmission line loudspeaker adds an additional device, such as a horn ~or impedance matching, through which some or all o~ the sound passes. Prior forms of transmission line systems may be divided into three classes. A type A
transmission line system consists of a closed-box direct radiator loudspeaker with a transmission line added to the driver aperture. All radiated sound passes through the transmission line. A Type B or C system consists of a direct radiator system with the transmission line coupled to the back chamber of the enclosure. Both the Type B or Type C form exhibit the fault that the transmission line presents an acoustical short circuit to the back of the. driver at least at some frequencies. This can cause serious dips in the system response .
SUMMARY OF THE INVENTION
This invention relates to an improved form of the Type A
System in which the signals from both the drive aperture and the port of a vented-box direct radiator system are combined to drive the transmission line. The original form of the Type A
system prevents the back wave from the drive diaphragm from interfering with the front wave by trapping the back wave in the closed cavity behind the driver. The improved system passes the back wave trough an acoustic phase inverter so that it may be combined with the output ~rom the front side of the W0~)2/19080 ~ ~ PCT/US91/02731 driver. This doubles the energy available to ~rive the transmission line~ This improvement should not be confused with hybrid systems which used a vented-box system with the transmission line coupled to either the driver aperture or the vent but not both.
The improved performance is roughly analogous to that seen in a vented-box direct radiator system as compared to a closed-box system. Either the efficiency or the bandwidth may be increased; or the system size may be decreased; or a tradeoff may be made among these possible benefits.
In one arrangement of the apparatus according to the present invention one or more electrodynamic loudspeaker drivers is installed in a vented-box direct radiator enclosure, and a cover is added to the front of the enclosure. This cover forms a front chamber into which both the driver and the vent radiate sound. The sound passes through the front chamber and into the transmission line~ For applications requiring high 2~ efficiency over a wide bandwidth the transmission line should be a horn. However, a compact system mi-Jht use a short tube.
Such a tube is too short to exhibit transmission line characteristics. It will act as lumped parameter acoustic mass instead.
The transmission characteristics of the improved system using a horn will be determined in great ~easure by the horn and the acoustic load it presents to the ~ront chamber, but will r in general, be high-pass in nature. The transmission characteristics of the short tube system will be band-pass in nature. the driver and the vented-box portion of the enclosure will provide a 4-pole high-pass response, and the front chamber and the outlet tube will provide a 2-pole low-pass response.
Anbther arrangement of the apparatus according to the present invention is particularly useful for active noise cancellation applications such as exhaust mufflers or duct WO92/19080 2 1 ~ ~ 6 ~ ~ PC~/US9l/0273l ..
silencers. In this arrang~m~nt the pipe or duct through which the noisy signal is flowing passes through the enclosure and exists through the outlet tube. The end of the noisy pipe or duct is aligned with the end of the loudspeaker and the two are coaxial. Thus, the antinoise signal radiated by the loudspeaXer during the active cancellation is coaxial with the noise. Very good cancellation may be obtained at frequencies with wavelenghts which are long compared to the size of the outlet.
Another arrangement of the apparatus according to the current invention which also has particular application in active noise cancellation systems is similar to that described immediately above. However, in this arrangmeent the pipe or duct containing the noisy flow does not pass through the loudspeaker. Instead, the loudspeaker outlet tube connects the loudspeaker front chamber to the pipe as a tee fitting into the pipeO In this case, the pipe need not end at the point where the noise and antinoise are mixed. This arrangement is useful for "in duct" cancellation.
The invention will now be further described by way of examples, with reference to the accompanying drawings, in which:
25BRIEF_DESCRIPTION OF THE DRAWINGS
FIGS. 1 and 3 are signal flow graphs of the improved loudspeaker with a long transmission line and a ~hort outlet tube, FIGS. 2 and 4 are simplfied drawings of the invention, and 30FIGS. 5 to 9 show two ways ln which the invention may be put to practical use in noise cancellation applications.
FIG. lO shows a gPneral form of a vented box bandpass loudspeaker.
FIG. 11 shows a simplified acoustical analagous circuit.
35Description of the Preferred Embodiments Consider first FIGS. 1 and 2. FIG. 2 shows an electrodynamic loudspeaker driver 1 mounted in an enclosure 2 W092/1~08~ PCT/~S91/02731 2:~8~96 so that one side of the driver diaphragm radiates sound into the fornt chamber of the enclosure 3. The sound form the other side of the driver passes through the acoustic phase inverter comprising the back chamber 4 and the inner vent 5 which connects the front and back chambers. The total system o11tput consists of the sum of the front wave and the phase corrected back wave flowing through the front chamber and out via the transmission line 6.
FIG. l shows the basic signal flow graph of the system using an electroydnamic driver l. Electric potential Eg is applied accross the driver voice coil which has a resistance RE
and a resulting current IVc flows. The electrodynamic coupling Bl of the motor causes a driving force. The sum of this force and the various reaction forces in the system gives in the total force driving the diaphra~m FD. This force accelerates the diaphrgam at a rate inversely proportional to the moving mass MMS of the driver. The resulting acceleration of the diaphragm aD is integrated once with respect to time ~the l/s operation in the ~aPlace domain) to find the velocity of the diaphragm uD and a second time to find the displacement o~ the diaphragm XD. Now, moving the diaphragm results in some reaction forces. As the diaphragm is displaced against the mechancial springs in its suspension, an opposing force inversely proportional to the mechanical compliance CMs of the driver is added to the total force FD. Another opposing force results from the motion through the mechanical losses RM~ f the system and is equal to the product of RMS and UD. Also, as the voice coil moves through the magnetic field of the motor a back emf is generated which tends to oppose the driving potential. This back emf, which is equal to the electromagnetic coupling Bl times the diaphra~m velocity UD, sums with the input potential Eg to give the voice coil potential EVC.
As the diaphragm moves, the front side pushes against the surrounding air and a flow into the front chamber 3 results.
This volume ~D is equal to the product of the diaphragam velocity uD and its effective area ~D~ This volume velocity is WO92/19080 21 Q ~ ~ ~ 6 PCT/US91/02731 one of the components of the total flow into the from chamber UF. The conservation ~f matter requires that the flow into the back chamber ~B across the boundary between it and the fro~t chamber be equal to ~F but opposite in polarity. The volume velocity UB presurizes the back chamber ~. The acoustic pressure of the back chamber PB is equal to the lntegral of ~B
with respect to time divided by the acoustic compliance to the back chamber CAB. This pressure exerts another reaction force against the back of the diaphragm which is equal to the pressure PB times the diaphragm area ~D. This another component of FD.
For the purpose of an orderly description of the system, assume that the inner vent 5 is blocked. This is equivalent to the unimproved form of the transmission line loudspeaker. The flow into the from chamber 3 pressurizes it. This component of the front chamber acoustic pressure PF is equal to the inteyral f ~F with respect to time divided by the acoustic compliance of the front chamber CAF. The front chamber pressure drives the flow through the transmision line 6 at a rate inversely proportional to the i~put reactance X~ of the line. The resistive part of the line impedance RAT causes a reaction pressure which is also a component of PF~ X~T and RA~ are frequency dependent line characteristics. The front chamber pressure also causes a reaction force on the diaphragm equal to PF times 8D. This is another component of FD.
Now, assume that the inner vent 5 is no longer blocked.
The pressure in the back chamber PB will drive a flow through the inner vent with a volume velocity ~p which is equal to the integral of the pressure PB with respect to time divided by the acoustic mass of the vent ~AP. The volume velocity components ~D and ~p now add to form the total flow into the front chamber which, in turn, drives the system output ~O.
In the arrangement of FIGS. 3 and 4, the analysis of the system is similar, except that the line impedance is simplifed because the short tube presents a l~mped parameter element. In this case, the output flow ~O is equal to the front chamber pressure PF i~tegrated with respect to time and divided by the WO92/1908() ~ P~T/US91/027~1 acoustic mass of the outlet vent MAF. The opposing pressure component f PF results from the flow losses in the outlet R~F.
Analysis of the signal flow graphs yields the approriate design equations which allow the correct driver and enclosure parameters to specify for a desired system.
FIGS. 5 to 8 show views of a practical loudspeaker system using the present invention which has particular application in active noise control systems. In this apparatus an additional component, a flow tube 7 for the noisy flow (such as the exhaust of an engine), has been added. Also, a drain tube 8 has been added between the front and back chamber so that water or other liquids trapped in the back chamber may escape. If the loudspeaker were used in an active noise cancellation system on a vehicle and if the vehicle were driven through deep water, the muffler could be flooded. The drain tube would allow the trapped water to flow out of the back ~hamberO The drain tube must be sized so that it acts as an acoustic mass rather than an acoustic leak between the chambers. Its mass must either be considered when adjusting the enclosure tuning or be trivial compared to the inner vent 5 so that the effect of the drain may be ignored.
FIG. 9 shows an apparatus using the present invention which also has particular application for active noise control.
In this instance, the short tube 6 is formed by the area between the heat shield plate ~ and the connection to the noisy duct 8. A long, narrow tube 9 allows outsider air to enter the enclosure. This tube, like the drain tube discussed above, should be sized so that it has no adverse effect on the system acoustic per~ormance. It may enter the enclosure through either the front or back chamber. Air is forced through the system because of the venturi-like dPtail lO in the noisy duct.
The flow through the duct over the "venturi" cause a low pressure reyion which "draws" the outside air. This air may be useful for cooling or removal of corrosive gases.
The simplest form of a loudspeaker system is the direct radiator. Such a loudspeaker radiates sound directly form the enclosure aperture(s)--the driver diaphragm and, in the case of vented-box syst~ms, a vent or port. There are no additional devices through which the sound passes.
A transmission line loudspeaker adds an additional device, such as a horn ~or impedance matching, through which some or all o~ the sound passes. Prior forms of transmission line systems may be divided into three classes. A type A
transmission line system consists of a closed-box direct radiator loudspeaker with a transmission line added to the driver aperture. All radiated sound passes through the transmission line. A Type B or C system consists of a direct radiator system with the transmission line coupled to the back chamber of the enclosure. Both the Type B or Type C form exhibit the fault that the transmission line presents an acoustical short circuit to the back of the. driver at least at some frequencies. This can cause serious dips in the system response .
SUMMARY OF THE INVENTION
This invention relates to an improved form of the Type A
System in which the signals from both the drive aperture and the port of a vented-box direct radiator system are combined to drive the transmission line. The original form of the Type A
system prevents the back wave from the drive diaphragm from interfering with the front wave by trapping the back wave in the closed cavity behind the driver. The improved system passes the back wave trough an acoustic phase inverter so that it may be combined with the output ~rom the front side of the W0~)2/19080 ~ ~ PCT/US91/02731 driver. This doubles the energy available to ~rive the transmission line~ This improvement should not be confused with hybrid systems which used a vented-box system with the transmission line coupled to either the driver aperture or the vent but not both.
The improved performance is roughly analogous to that seen in a vented-box direct radiator system as compared to a closed-box system. Either the efficiency or the bandwidth may be increased; or the system size may be decreased; or a tradeoff may be made among these possible benefits.
In one arrangement of the apparatus according to the present invention one or more electrodynamic loudspeaker drivers is installed in a vented-box direct radiator enclosure, and a cover is added to the front of the enclosure. This cover forms a front chamber into which both the driver and the vent radiate sound. The sound passes through the front chamber and into the transmission line~ For applications requiring high 2~ efficiency over a wide bandwidth the transmission line should be a horn. However, a compact system mi-Jht use a short tube.
Such a tube is too short to exhibit transmission line characteristics. It will act as lumped parameter acoustic mass instead.
The transmission characteristics of the improved system using a horn will be determined in great ~easure by the horn and the acoustic load it presents to the ~ront chamber, but will r in general, be high-pass in nature. The transmission characteristics of the short tube system will be band-pass in nature. the driver and the vented-box portion of the enclosure will provide a 4-pole high-pass response, and the front chamber and the outlet tube will provide a 2-pole low-pass response.
Anbther arrangement of the apparatus according to the present invention is particularly useful for active noise cancellation applications such as exhaust mufflers or duct WO92/19080 2 1 ~ ~ 6 ~ ~ PC~/US9l/0273l ..
silencers. In this arrang~m~nt the pipe or duct through which the noisy signal is flowing passes through the enclosure and exists through the outlet tube. The end of the noisy pipe or duct is aligned with the end of the loudspeaker and the two are coaxial. Thus, the antinoise signal radiated by the loudspeaXer during the active cancellation is coaxial with the noise. Very good cancellation may be obtained at frequencies with wavelenghts which are long compared to the size of the outlet.
Another arrangement of the apparatus according to the current invention which also has particular application in active noise cancellation systems is similar to that described immediately above. However, in this arrangmeent the pipe or duct containing the noisy flow does not pass through the loudspeaker. Instead, the loudspeaker outlet tube connects the loudspeaker front chamber to the pipe as a tee fitting into the pipeO In this case, the pipe need not end at the point where the noise and antinoise are mixed. This arrangement is useful for "in duct" cancellation.
The invention will now be further described by way of examples, with reference to the accompanying drawings, in which:
25BRIEF_DESCRIPTION OF THE DRAWINGS
FIGS. 1 and 3 are signal flow graphs of the improved loudspeaker with a long transmission line and a ~hort outlet tube, FIGS. 2 and 4 are simplfied drawings of the invention, and 30FIGS. 5 to 9 show two ways ln which the invention may be put to practical use in noise cancellation applications.
FIG. lO shows a gPneral form of a vented box bandpass loudspeaker.
FIG. 11 shows a simplified acoustical analagous circuit.
35Description of the Preferred Embodiments Consider first FIGS. 1 and 2. FIG. 2 shows an electrodynamic loudspeaker driver 1 mounted in an enclosure 2 W092/1~08~ PCT/~S91/02731 2:~8~96 so that one side of the driver diaphragm radiates sound into the fornt chamber of the enclosure 3. The sound form the other side of the driver passes through the acoustic phase inverter comprising the back chamber 4 and the inner vent 5 which connects the front and back chambers. The total system o11tput consists of the sum of the front wave and the phase corrected back wave flowing through the front chamber and out via the transmission line 6.
FIG. l shows the basic signal flow graph of the system using an electroydnamic driver l. Electric potential Eg is applied accross the driver voice coil which has a resistance RE
and a resulting current IVc flows. The electrodynamic coupling Bl of the motor causes a driving force. The sum of this force and the various reaction forces in the system gives in the total force driving the diaphra~m FD. This force accelerates the diaphrgam at a rate inversely proportional to the moving mass MMS of the driver. The resulting acceleration of the diaphragm aD is integrated once with respect to time ~the l/s operation in the ~aPlace domain) to find the velocity of the diaphragm uD and a second time to find the displacement o~ the diaphragm XD. Now, moving the diaphragm results in some reaction forces. As the diaphragm is displaced against the mechancial springs in its suspension, an opposing force inversely proportional to the mechanical compliance CMs of the driver is added to the total force FD. Another opposing force results from the motion through the mechanical losses RM~ f the system and is equal to the product of RMS and UD. Also, as the voice coil moves through the magnetic field of the motor a back emf is generated which tends to oppose the driving potential. This back emf, which is equal to the electromagnetic coupling Bl times the diaphra~m velocity UD, sums with the input potential Eg to give the voice coil potential EVC.
As the diaphragm moves, the front side pushes against the surrounding air and a flow into the front chamber 3 results.
This volume ~D is equal to the product of the diaphragam velocity uD and its effective area ~D~ This volume velocity is WO92/19080 21 Q ~ ~ ~ 6 PCT/US91/02731 one of the components of the total flow into the from chamber UF. The conservation ~f matter requires that the flow into the back chamber ~B across the boundary between it and the fro~t chamber be equal to ~F but opposite in polarity. The volume velocity UB presurizes the back chamber ~. The acoustic pressure of the back chamber PB is equal to the lntegral of ~B
with respect to time divided by the acoustic compliance to the back chamber CAB. This pressure exerts another reaction force against the back of the diaphragm which is equal to the pressure PB times the diaphragm area ~D. This another component of FD.
For the purpose of an orderly description of the system, assume that the inner vent 5 is blocked. This is equivalent to the unimproved form of the transmission line loudspeaker. The flow into the from chamber 3 pressurizes it. This component of the front chamber acoustic pressure PF is equal to the inteyral f ~F with respect to time divided by the acoustic compliance of the front chamber CAF. The front chamber pressure drives the flow through the transmision line 6 at a rate inversely proportional to the i~put reactance X~ of the line. The resistive part of the line impedance RAT causes a reaction pressure which is also a component of PF~ X~T and RA~ are frequency dependent line characteristics. The front chamber pressure also causes a reaction force on the diaphragm equal to PF times 8D. This is another component of FD.
Now, assume that the inner vent 5 is no longer blocked.
The pressure in the back chamber PB will drive a flow through the inner vent with a volume velocity ~p which is equal to the integral of the pressure PB with respect to time divided by the acoustic mass of the vent ~AP. The volume velocity components ~D and ~p now add to form the total flow into the front chamber which, in turn, drives the system output ~O.
In the arrangement of FIGS. 3 and 4, the analysis of the system is similar, except that the line impedance is simplifed because the short tube presents a l~mped parameter element. In this case, the output flow ~O is equal to the front chamber pressure PF i~tegrated with respect to time and divided by the WO92/1908() ~ P~T/US91/027~1 acoustic mass of the outlet vent MAF. The opposing pressure component f PF results from the flow losses in the outlet R~F.
Analysis of the signal flow graphs yields the approriate design equations which allow the correct driver and enclosure parameters to specify for a desired system.
FIGS. 5 to 8 show views of a practical loudspeaker system using the present invention which has particular application in active noise control systems. In this apparatus an additional component, a flow tube 7 for the noisy flow (such as the exhaust of an engine), has been added. Also, a drain tube 8 has been added between the front and back chamber so that water or other liquids trapped in the back chamber may escape. If the loudspeaker were used in an active noise cancellation system on a vehicle and if the vehicle were driven through deep water, the muffler could be flooded. The drain tube would allow the trapped water to flow out of the back ~hamberO The drain tube must be sized so that it acts as an acoustic mass rather than an acoustic leak between the chambers. Its mass must either be considered when adjusting the enclosure tuning or be trivial compared to the inner vent 5 so that the effect of the drain may be ignored.
FIG. 9 shows an apparatus using the present invention which also has particular application for active noise control.
In this instance, the short tube 6 is formed by the area between the heat shield plate ~ and the connection to the noisy duct 8. A long, narrow tube 9 allows outsider air to enter the enclosure. This tube, like the drain tube discussed above, should be sized so that it has no adverse effect on the system acoustic per~ormance. It may enter the enclosure through either the front or back chamber. Air is forced through the system because of the venturi-like dPtail lO in the noisy duct.
The flow through the duct over the "venturi" cause a low pressure reyion which "draws" the outside air. This air may be useful for cooling or removal of corrosive gases.
3 5 The analysis and derivation of the analog circuit of the Vented ~ox ~andpass Loudspeaker is as follows: The sy~bol used in Figures lO and ll and in the calculations ar~:
W092/19080 ~ i~ a86~6 Pcr/usgl/o273l l in Flgures 10 and 11 and in the calculations are:
LIST OF SYMBOLS
CAB Acoustic compliance of Rear Box CAp Acoustic compliance of Front Box CAs Acoustic compliance of Driver (Loudspeaker VAS=POC2CAs) MAp Acoustic mass of Front Port MAS Acoustic mass of Driver MAB Acoustic mass of Internal Port RAS Acoustic Resistance of Driver RE Electrical Resistance of Driver voice coil SD Driver Diaphragm, M2 VB Volume of Rear Closed Box ~M3) (VB=POC2CAB) Vp Volume of Front Box (M3) (Vp=POC2CAp) Vd Peak displacement volume driver diaphragm (SDXM) PO Mas densily of air (7.18 kg/m3) C Speed of sound in air (345 m/sec) Xm Peak linear displacement of driver diaphragm Sp Area of the front port SB Area of the internal port B Magnetic flux density in driver airgap l lenght of voice coil in the airgap of driver UO Volume velocity at the front port UAB Volume velocity at the internal port UF Volume velocity inside the front box (UF=Us~UAB) UB Volume velocity inside the rear box (UB=-UF) US Volume velocity generated at the source Pg Pressure generator (e~uivalent) Eg Input voltage to the loudspeaker Speaker Parameters f5 (Ts= ~f ) Free Air Resonance frequency QES Electro-Magnetic Q at f5 Qms Mechanical Q at fs Qts Total Q at fSI QesQms Qes+Qms .
.~ .
WO92/19080 2 ~ PCT/US91/02731 G!8696 f~`
. .
Vas Volume of air having sam acoustic compliance as driver suspension Vd Peak displacement volume of diaphragm (=SDXM) SD Effective diaphragm area Xm Peak linear displacement of diaphragm Referring now to Fig. lO, there is shown the general form of the Vented Box Bandpass Loudspeaker (VBBP) configuration., Fig. ll shows the simplified acoustical analagous circuit of the Vented Box Bandpass Loudspeaker (VBBP) configuration. The terms Ro and Pg are determined by the following formulal:
R = ~L)2 p = Eg(BL) RESD RSD
In the following circuit analysis, assumptions are made tha`t there is a lossless enclosure (internal box resistance =
O and leakage resistance =~) and that the voice coil inductance is small (LF%O) The circuit analysis is as follows:
( ) g ¦ (Ro+RAS)+SMAS+ - ¦ Us~ F -~sMApUO
UF-U
(2) = sMAp-Uo sCAp (3) sMAgUAB+ - +sMAPUo~O
s,CAB
W092/19080 ~ i~ a86~6 Pcr/usgl/o273l l in Flgures 10 and 11 and in the calculations are:
LIST OF SYMBOLS
CAB Acoustic compliance of Rear Box CAp Acoustic compliance of Front Box CAs Acoustic compliance of Driver (Loudspeaker VAS=POC2CAs) MAp Acoustic mass of Front Port MAS Acoustic mass of Driver MAB Acoustic mass of Internal Port RAS Acoustic Resistance of Driver RE Electrical Resistance of Driver voice coil SD Driver Diaphragm, M2 VB Volume of Rear Closed Box ~M3) (VB=POC2CAB) Vp Volume of Front Box (M3) (Vp=POC2CAp) Vd Peak displacement volume driver diaphragm (SDXM) PO Mas densily of air (7.18 kg/m3) C Speed of sound in air (345 m/sec) Xm Peak linear displacement of driver diaphragm Sp Area of the front port SB Area of the internal port B Magnetic flux density in driver airgap l lenght of voice coil in the airgap of driver UO Volume velocity at the front port UAB Volume velocity at the internal port UF Volume velocity inside the front box (UF=Us~UAB) UB Volume velocity inside the rear box (UB=-UF) US Volume velocity generated at the source Pg Pressure generator (e~uivalent) Eg Input voltage to the loudspeaker Speaker Parameters f5 (Ts= ~f ) Free Air Resonance frequency QES Electro-Magnetic Q at f5 Qms Mechanical Q at fs Qts Total Q at fSI QesQms Qes+Qms .
.~ .
WO92/19080 2 ~ PCT/US91/02731 G!8696 f~`
. .
Vas Volume of air having sam acoustic compliance as driver suspension Vd Peak displacement volume of diaphragm (=SDXM) SD Effective diaphragm area Xm Peak linear displacement of diaphragm Referring now to Fig. lO, there is shown the general form of the Vented Box Bandpass Loudspeaker (VBBP) configuration., Fig. ll shows the simplified acoustical analagous circuit of the Vented Box Bandpass Loudspeaker (VBBP) configuration. The terms Ro and Pg are determined by the following formulal:
R = ~L)2 p = Eg(BL) RESD RSD
In the following circuit analysis, assumptions are made tha`t there is a lossless enclosure (internal box resistance =
O and leakage resistance =~) and that the voice coil inductance is small (LF%O) The circuit analysis is as follows:
( ) g ¦ (Ro+RAS)+SMAS+ - ¦ Us~ F -~sMApUO
UF-U
(2) = sMAp-Uo sCAp (3) sMAgUAB+ - +sMAPUo~O
s,CAB
(4) From Equation (2) UF=(l+S2MApCAp)Uo Us+UAB=UF
(5) U5=UF-UAB
sM~ ~ sC~
WO ~2/19~0 PC~/US91/0:27~1 1 2 ~ 9 6;
.. . .
S MApCApMABCp~B+s (MABcAB+MApcAp~M~pcAB+l U
sM~ ~ sC~
WO ~2/19~0 PC~/US91/0:27~1 1 2 ~ 9 6;
.. . .
S MApCApMABCp~B+s (MABcAB+MApcAp~M~pcAB+l U
(6) Us= ' -- 1 o S MABCAB
Substitute Equations ( 4 ) and ( 6 ) into the Equation ( 1 ) S2MAScAs + sCAS (Ro + RAS ~ 1 g ~ [ sCAS ¦ x MApcAp~ABcAB + S (MABCAB + MApCAp -~ MApC.~B) + 1 (1 + S MAPCAP) + SMAp ~ Uo sCAs ( 8 ) Pg ( S 3 CAsMABcAB ) = { S MASCASMP~PCAPMABCAB+
3 O s MAscAsMABcAB + S MAscAsMApcAp+s4MAscAsMApc~B
+s2MAscAs-~s5cAsRAtMApcApMABcAB~s CAsRAlMABcAB
+S CASRATMAPCAP+S CASRATMApCAB+SCASRAT
+S4MApCApMABCAB+S2(MABcAB+MApcAp+MApcAB) 1 S MABCAB+S CApMABCABMAp~S4CAsM~ABCAB}uo 45 ~9) Pg(S3CAsMABCAB)={S M~.SCAS~APCAP~ABCAB~
S5CP~SRATCAPMABCAB~ S (MAscAs~lABcAB+MAscA
Mp~scAscAB+~pcApMABcAB~MABcA~3M~7~ pcAp +MARCA~APCA.~) +S CA,~RArr (MAPCAP~k5APCAR+
~' .
" ' ' , WO92/19080 ~1 ~ 8 ~ 9 6 PCT/~S91/0~73 )+s2(MAscAs+2MABcAg+MApcAp+MAp AB) +SCASRAT+l )Uo ASSUMPTIONS
10 (10) TS2=_= MASCAS
wS2 (11) TB2= _ = MABcAB.
WB
(12) Tp2= _ = MApCAp 20 Wp (13) T 2= 1 = M C
25~ Wps t14) TpB2= _ = MAPCAB
WPB
poC2 poC2 (15) RAT=Ro+RAS = WsVASQMS CASWsQts 1 Ts ~(16) CASRAT
WsQts Qts (17) PO(S) = sMApUo SYSTEM TRANSFER FUNCTION
sMAPUo Po ( s ) (18) G(s) = _ =
Pg Pg(s) bs4 (19) G(s) =
S~ + a5S~ + a4S4 + a3S~ + a2S~ + alS + aO
when, TB2Tp2 1 B p s _ s (20) a5= x WsQts TS2TB2Tp2Ts2TR2Tp2QtS TsQtS Qts .. . .
WO 92/1 9080 21~ 8 6 ~ 6 PCT/US91 /02731 5 (21) a4 T ~TB~Tp~ (Ts2TB2+Ts2Tp2-~TS2TpB2+~Tp2TB2+TB2Tp = ~ + + P + + P = Wp2+WB2 +~_ -~ 2Ws + ~ .
Wps Ts ( p pB B ) l 1 TpB2 (22) A3=_ Ts~TB~Tp~ QtSTs l ~ TB~Tp7 Ws ¦ W 2+W~ Wp +W 2 (23) a2 ~- ~T .:! (Ts 2TB +Tp +TpB) s B p = (wB2wp2+2ws2wp2~ws2wB2+ 1~ ~
Ts l WsWB2Wp2 (24) al= x Qts Ts TB2Tp Qts ( 2 5 ) aO = .~ - WS2WB2Wp2 Ts TB Tp MAPCASMABCAB Tps TB Tps2 WS2Wp2 Ts TB Tp Ts~TB~Tp~ Ts~Tp~ Wps~
Substitute Equations ( 4 ) and ( 6 ) into the Equation ( 1 ) S2MAScAs + sCAS (Ro + RAS ~ 1 g ~ [ sCAS ¦ x MApcAp~ABcAB + S (MABCAB + MApCAp -~ MApC.~B) + 1 (1 + S MAPCAP) + SMAp ~ Uo sCAs ( 8 ) Pg ( S 3 CAsMABcAB ) = { S MASCASMP~PCAPMABCAB+
3 O s MAscAsMABcAB + S MAscAsMApcAp+s4MAscAsMApc~B
+s2MAscAs-~s5cAsRAtMApcApMABcAB~s CAsRAlMABcAB
+S CASRATMAPCAP+S CASRATMApCAB+SCASRAT
+S4MApCApMABCAB+S2(MABcAB+MApcAp+MApcAB) 1 S MABCAB+S CApMABCABMAp~S4CAsM~ABCAB}uo 45 ~9) Pg(S3CAsMABCAB)={S M~.SCAS~APCAP~ABCAB~
S5CP~SRATCAPMABCAB~ S (MAscAs~lABcAB+MAscA
Mp~scAscAB+~pcApMABcAB~MABcA~3M~7~ pcAp +MARCA~APCA.~) +S CA,~RArr (MAPCAP~k5APCAR+
~' .
" ' ' , WO92/19080 ~1 ~ 8 ~ 9 6 PCT/~S91/0~73 )+s2(MAscAs+2MABcAg+MApcAp+MAp AB) +SCASRAT+l )Uo ASSUMPTIONS
10 (10) TS2=_= MASCAS
wS2 (11) TB2= _ = MABcAB.
WB
(12) Tp2= _ = MApCAp 20 Wp (13) T 2= 1 = M C
25~ Wps t14) TpB2= _ = MAPCAB
WPB
poC2 poC2 (15) RAT=Ro+RAS = WsVASQMS CASWsQts 1 Ts ~(16) CASRAT
WsQts Qts (17) PO(S) = sMApUo SYSTEM TRANSFER FUNCTION
sMAPUo Po ( s ) (18) G(s) = _ =
Pg Pg(s) bs4 (19) G(s) =
S~ + a5S~ + a4S4 + a3S~ + a2S~ + alS + aO
when, TB2Tp2 1 B p s _ s (20) a5= x WsQts TS2TB2Tp2Ts2TR2Tp2QtS TsQtS Qts .. . .
WO 92/1 9080 21~ 8 6 ~ 6 PCT/US91 /02731 5 (21) a4 T ~TB~Tp~ (Ts2TB2+Ts2Tp2-~TS2TpB2+~Tp2TB2+TB2Tp = ~ + + P + + P = Wp2+WB2 +~_ -~ 2Ws + ~ .
Wps Ts ( p pB B ) l 1 TpB2 (22) A3=_ Ts~TB~Tp~ QtSTs l ~ TB~Tp7 Ws ¦ W 2+W~ Wp +W 2 (23) a2 ~- ~T .:! (Ts 2TB +Tp +TpB) s B p = (wB2wp2+2ws2wp2~ws2wB2+ 1~ ~
Ts l WsWB2Wp2 (24) al= x Qts Ts TB2Tp Qts ( 2 5 ) aO = .~ - WS2WB2Wp2 Ts TB Tp MAPCASMABCAB Tps TB Tps2 WS2Wp2 Ts TB Tp Ts~TB~Tp~ Ts~Tp~ Wps~
Claims (19)
1. Apparatus for achieving improved performance of a transmission line loudspeaker producing a front and back wave comprising one or more electromagnetic driver means mounted in an enclosure means having front and back chamber means connected by a conduit means so that the back wave of the loudspeaker is constructively summed with the front wave in the front chamber means, and a transmission line means attached to the front chamber means comprising the only sound outlet of the system.
2. Apparatus as claimed in claim 1, in which the transmission line means is a short tube means in the enclosure configured to produce a desired band-pass frequency response characteristic.
3. Apparatus as claimed in claim 2, in which a separate pipe means passes through the loudspeaker enclosure means and exits through the short take means for the purpose of noise cancellation.
4. Apparatus as claimed in claim 1, in which a drain means is added between the from and back chamber means to allow trapped liquids to drain from the back chamber.
5. Apparatus as claimed in claim 2, in which a drain tube means is added between the front and back chamber means to allow trapped liquids to drain from the back chamber.
6. Apparatus as claimed in claim 3, in which a drain hole is provided between the front and back chamber means to allow trapped liquids to drain from the back chamber.
7. Apparatus as claimed in claim 2, including a noisy duct means to which the short tube means is connected for the purpose of noise control.
8. Apparatus as claimed in claim 7, in which the short tube means is formed by the area between a plate means in the front chamber means and the connection to the noisy duct or pipe.
9. Apparatus as claimed in claim 7, in which a ventilation tube means is connected between either the front or the back chamber means and the outside air and a venturi-like structure means is in the noisy duct means in order to create a low pressure region to draw outside air through the system.
10. Apparatus as claimed in claim 1 in which said conduit means comprises a hole connecting said front and back chambers.
11. Apparatus for achieving improved performance of a transmission line loudspeaker means producing a front and back wave comprising a driver means, said driver means mounted in an enclosure means, said enclosure means having front and back chamber means connected by a conduit means so that the back wave of the loudspeaker means is constructively summed with the means attached to the from chamber means comprising the sole sound outlet of the system.
12. Apparatus as claimed in claim 11 in which the transmission line means is a short tube means in the enclosure configured to produce a desired band-pass frequency response characteristic.
13. Apparatus as claimed in claim 2, in which a separate pipe means passes through the loudspeaker enclosure means and exits through the short tube means for the purpose of noise cancellation.
14. Apparatus as claimed in claim 1, in which a drain means is added between the front and back chamber means to allow trapped liquids to drain from the back chamber.
15. Apparatus as claimed in claim 2, in which a drain tube means is added between the from and back chamber means to allow trapped liquids to drain from the back chamber.
16. Apparatus as claimed in claim 3, in which a drain hole is provided between the front and back chamber means to allow trapped liquids to drain from the back chamber.
17. Apparatus as claimed in claim 2, including a noisy duct means to which the short tube means is connected for the purpose of noise control.
18. Apparatus as claimed in claim 7, in which the short tube means is formed by the area between a plate means in the front chamber means and the connection to the noisy duct or pipe.
19. Apparatus as claimed in claim 7, in which a ventilation tube means is connected between either the front or the back chamber means and the outside are and a venturi-like structure means is in the noisy duct means in order to create a low pressure region to draw outside air through the system.
Priority Applications (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE69129664T DE69129664T2 (en) | 1991-04-19 | 1991-04-19 | DEVICE FOR NOISE REDUCTION |
| EP91920600A EP0580579B1 (en) | 1991-04-19 | 1991-04-19 | Noise control apparatus |
| JP3518527A JPH06508445A (en) | 1991-04-19 | 1991-04-19 | Improvements regarding transmission pipe loudspeakers |
| ES91920600T ES2118093T3 (en) | 1991-04-19 | 1991-04-19 | NOISE CONTROL DEVICE. |
| DK91920600T DK0580579T3 (en) | 1991-04-19 | 1991-04-19 | Noise Control Device |
| PCT/US1991/002731 WO1992019080A1 (en) | 1991-04-19 | 1991-04-19 | Improvements in and relating to transmission line loudspeakers |
| CA002108696A CA2108696A1 (en) | 1991-04-19 | 1991-04-19 | Improvements in and relating to transmission line loudspeakers |
| HK98112067A HK1011163A1 (en) | 1991-04-19 | 1998-11-17 | Noise controller apparatus |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/US1991/002731 WO1992019080A1 (en) | 1991-04-19 | 1991-04-19 | Improvements in and relating to transmission line loudspeakers |
| CA002108696A CA2108696A1 (en) | 1991-04-19 | 1991-04-19 | Improvements in and relating to transmission line loudspeakers |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2108696A1 true CA2108696A1 (en) | 1992-10-20 |
Family
ID=25676762
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002108696A Abandoned CA2108696A1 (en) | 1991-04-19 | 1991-04-19 | Improvements in and relating to transmission line loudspeakers |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0580579B1 (en) |
| JP (1) | JPH06508445A (en) |
| CA (1) | CA2108696A1 (en) |
| DE (1) | DE69129664T2 (en) |
| DK (1) | DK0580579T3 (en) |
| ES (1) | ES2118093T3 (en) |
| HK (1) | HK1011163A1 (en) |
| WO (1) | WO1992019080A1 (en) |
Families Citing this family (26)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1995030393A1 (en) * | 1994-05-10 | 1995-11-16 | Noise Cancellation Technologies, Inc. | Active noise cancelling muffler |
| US6504938B1 (en) * | 2000-10-06 | 2003-01-07 | Logitech Europe S.A. | Dual-chamber loudspeaker |
| US8284955B2 (en) | 2006-02-07 | 2012-10-09 | Bongiovi Acoustics Llc | System and method for digital signal processing |
| US11431312B2 (en) | 2004-08-10 | 2022-08-30 | Bongiovi Acoustics Llc | System and method for digital signal processing |
| US10158337B2 (en) | 2004-08-10 | 2018-12-18 | Bongiovi Acoustics Llc | System and method for digital signal processing |
| US10848118B2 (en) | 2004-08-10 | 2020-11-24 | Bongiovi Acoustics Llc | System and method for digital signal processing |
| US10069471B2 (en) | 2006-02-07 | 2018-09-04 | Bongiovi Acoustics Llc | System and method for digital signal processing |
| US10701505B2 (en) | 2006-02-07 | 2020-06-30 | Bongiovi Acoustics Llc. | System, method, and apparatus for generating and digitally processing a head related audio transfer function |
| US11202161B2 (en) | 2006-02-07 | 2021-12-14 | Bongiovi Acoustics Llc | System, method, and apparatus for generating and digitally processing a head related audio transfer function |
| US10848867B2 (en) | 2006-02-07 | 2020-11-24 | Bongiovi Acoustics Llc | System and method for digital signal processing |
| CA2645852C (en) * | 2006-03-15 | 2013-12-24 | Thomas J. Danley | Sound reproduction with improved low frequency characteristics |
| DE102011084567C5 (en) * | 2011-10-14 | 2019-08-14 | Eberspächer Exhaust Technology GmbH & Co. KG | Active muffler |
| US9264004B2 (en) | 2013-06-12 | 2016-02-16 | Bongiovi Acoustics Llc | System and method for narrow bandwidth digital signal processing |
| US9883318B2 (en) | 2013-06-12 | 2018-01-30 | Bongiovi Acoustics Llc | System and method for stereo field enhancement in two-channel audio systems |
| US9906858B2 (en) | 2013-10-22 | 2018-02-27 | Bongiovi Acoustics Llc | System and method for digital signal processing |
| US10639000B2 (en) | 2014-04-16 | 2020-05-05 | Bongiovi Acoustics Llc | Device for wide-band auscultation |
| US9615813B2 (en) | 2014-04-16 | 2017-04-11 | Bongiovi Acoustics Llc. | Device for wide-band auscultation |
| US10820883B2 (en) | 2014-04-16 | 2020-11-03 | Bongiovi Acoustics Llc | Noise reduction assembly for auscultation of a body |
| US9479861B2 (en) * | 2014-06-26 | 2016-10-25 | Anthony Allen BISSET | Compact wideband bass and midrange horn-loaded speaker system |
| US9564146B2 (en) | 2014-08-01 | 2017-02-07 | Bongiovi Acoustics Llc | System and method for digital signal processing in deep diving environment |
| US9638672B2 (en) | 2015-03-06 | 2017-05-02 | Bongiovi Acoustics Llc | System and method for acquiring acoustic information from a resonating body |
| US9621994B1 (en) | 2015-11-16 | 2017-04-11 | Bongiovi Acoustics Llc | Surface acoustic transducer |
| WO2017087495A1 (en) | 2015-11-16 | 2017-05-26 | Bongiovi Acoustics Llc | Surface acoustic transducer |
| AU2019252524A1 (en) | 2018-04-11 | 2020-11-05 | Bongiovi Acoustics Llc | Audio enhanced hearing protection system |
| WO2020028833A1 (en) | 2018-08-02 | 2020-02-06 | Bongiovi Acoustics Llc | System, method, and apparatus for generating and digitally processing a head related audio transfer function |
| CN113504663B (en) * | 2021-07-23 | 2023-04-25 | 歌尔科技有限公司 | Sound production module, sound production module silencing method and intelligent glasses |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5031801A (en) * | 1973-07-20 | 1975-03-28 | ||
| JPS5789393A (en) * | 1980-11-17 | 1982-06-03 | Bose Corp | Controller for low end response for loudspeaker system |
| US4473906A (en) * | 1980-12-05 | 1984-09-25 | Lord Corporation | Active acoustic attenuator |
| US4549631A (en) * | 1983-10-24 | 1985-10-29 | Bose Corporation | Multiple porting loudspeaker systems |
| US4616731A (en) * | 1984-03-02 | 1986-10-14 | Robinson James R | Speaker system |
| US4665549A (en) * | 1985-12-18 | 1987-05-12 | Nelson Industries Inc. | Hybrid active silencer |
| US4875546A (en) * | 1988-06-02 | 1989-10-24 | Teledyne Industries, Inc. | Loudspeaker with acoustic band-pass filter |
| JPH0787628B2 (en) * | 1989-02-22 | 1995-09-20 | 株式会社ケンウッド | Speaker system for bass reproduction |
| US5025885A (en) * | 1989-07-14 | 1991-06-25 | Bose Corporation | Multiple chamber loudspeaker system |
| JP4862491B2 (en) * | 2005-05-25 | 2012-01-25 | 東レ株式会社 | Flocking piles and flocking products |
-
1991
- 1991-04-19 DK DK91920600T patent/DK0580579T3/en active
- 1991-04-19 JP JP3518527A patent/JPH06508445A/en active Pending
- 1991-04-19 ES ES91920600T patent/ES2118093T3/en not_active Expired - Lifetime
- 1991-04-19 WO PCT/US1991/002731 patent/WO1992019080A1/en active IP Right Grant
- 1991-04-19 CA CA002108696A patent/CA2108696A1/en not_active Abandoned
- 1991-04-19 EP EP91920600A patent/EP0580579B1/en not_active Expired - Lifetime
- 1991-04-19 DE DE69129664T patent/DE69129664T2/en not_active Expired - Fee Related
-
1998
- 1998-11-17 HK HK98112067A patent/HK1011163A1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06508445A (en) | 1994-09-22 |
| EP0580579A1 (en) | 1994-02-02 |
| DE69129664D1 (en) | 1998-07-30 |
| EP0580579B1 (en) | 1998-06-24 |
| EP0580579A4 (en) | 1994-06-15 |
| DE69129664T2 (en) | 1998-12-03 |
| ES2118093T3 (en) | 1998-09-16 |
| HK1011163A1 (en) | 1999-07-02 |
| WO1992019080A1 (en) | 1992-10-29 |
| DK0580579T3 (en) | 1999-04-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |