EP0266485A2 - Electromechanical horn with excitation of its acoustic diaphragm controlled electronically by sensors which measure its resonance frequency - Google Patents
Electromechanical horn with excitation of its acoustic diaphragm controlled electronically by sensors which measure its resonance frequency Download PDFInfo
- Publication number
- EP0266485A2 EP0266485A2 EP87107567A EP87107567A EP0266485A2 EP 0266485 A2 EP0266485 A2 EP 0266485A2 EP 87107567 A EP87107567 A EP 87107567A EP 87107567 A EP87107567 A EP 87107567A EP 0266485 A2 EP0266485 A2 EP 0266485A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- diaphragm
- electromagnet
- horn
- resonance frequency
- sensor
- 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.)
- Withdrawn
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
- B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
- B06B1/0207—Driving circuits
- B06B1/0223—Driving circuits for generating signals continuous in time
- B06B1/0269—Driving circuits for generating signals continuous in time for generating multiple frequencies
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B2201/00—Indexing scheme associated with B06B1/0207 for details covered by B06B1/0207 but not provided for in any of its subgroups
- B06B2201/50—Application to a particular transducer type
- B06B2201/52—Electrodynamic transducer
- B06B2201/53—Electrodynamic transducer with vibrating magnet or coil
Definitions
- This invention relates to the field of electromechanical resonance devices for sound generation, and particularly to high-sounding horns for vehicles, trains and boats.
- Sound generating devices of the electromechanical excitation type currently consist of: - a resilient steel diaphragm carrying in its centre the mobile part of an electromagnet; - an electric switch with a normally closed contact connected in series with the power feed to the electromagnet; - an adjustment screw which determines the switch contact opening point; - a diffuser which resonates at the same frequency as the metal diaphragm.
- the electromagnet When the electromagnet is electrically fed, it attracts the mobile part rigid with the resilient diaphragm. When the diaphragm has nearly attained its maximum travel, the switch connected in series with the electromagnet coil is opened by a push rod operated by the mobile part of the electromagnet.
- the mobile part of the electromagnet and the diaphragm on which it is fixed continue their travel by inertia until their kinetic energy has been completely absorbed elastically; beyond this point, the elastic energy accumulated by the diaphragm is restituted by reaction with the fixed structure to which it is connected, so that the diaphragm reverses its direction of movement. In this manner it again closes the switch which, again exciting the electromagnet, causes the diaphragm to commence a new oscillation cycle at a frequency equal to the resonance frequency of the electromechanical system.
- the magnetic vibration is obtained by electronic oscillators operating at a vibration frequency approximately equal to the resonance frequency of the electromagnetic system; with this method the oscillator output controls an electronic switch connected in series with the electromagnet coil, thus replacing the mechanically operated switch.
- this method has drawbacks which can be summarized as follows. Firstly, the generated frequency must be stabilised to make it independent of voltage variations; the generated frequency must also be acceptable to the variation in the diaphragm resonance frequency caused by variations in its temperature.
- a further serious drawback of this method is the cost involved in limiting the diaphragm production tolerances so that the resonance frequency of the diaphragms produced does not fall outside the limited tolerance range compatible with the constant frequency emitted by the electronic generator.
- This drawback is eloquently displayed by the reduction in sound output consequent on the variation in the mechanical vibration characteristics of the system, deriving from lengthy operation.
- the mechanical parts of the system have the same resonance frequency as the electronic oscillator, as they age they acquire a different frequency because of the fall-off in mechanical strength, the slack which occurs in the connections, the occurrence of wear and other reasons.
- An object of the present invention is to provide a horn which dispenses with the mechanical switch, so obviating all the aforesaid drawbacks caused by it.
- a further object is to provide a horn the sound of which deives from the generation of a diaphragm vibration induction frequency which is always the frequency creating maximum diaphragm resonance, independently of the variations in this latter deriving from any variation in the diaphragm dimensions, structure or fixing.
- An electromechanical horn provided with an acoustic diaphragm able to undergo movements induced in it by variable magnetic fields generated by an electromagnet, characterised in that the electromagnet which operates the diaphragm is excited by frequencies generated by an electronic oscillator which are based on the value of the maximum diaphragm resonance frequency measured by a specific sensor.
- the metal container 1 forms the fixed part of the electromagnet, and carries fixed to the centre of its closed base 2 a ferromagnetic core 3 with the relative coil 4.
- this container is closed by a diaphragm 5 fixed in a particularly rigid manner about its entire edge, which is usually circular.
- the diaphragm 5 is usually of steel and has fixed to its central region a ferromagnetic core 6 forming the mobile part of the electromagnet.
- the reference numeral 7 indicates a sensor for sensing the pressure variations induced in the air by the vibration of the overlying diaphragm 5.
- This sensor which in a certain sense could be called a "microphone" can obviously be of various types, as can normal microphones. It can thus, with suitable circuit modifications, be in the form of various types of electrical pressure transducers such as piezoresistive transducers, resistive transducers on an alumina substrate, or in the form of diaphragm position sensors such as Hall effect sensors and electromagnetic sensors.
- Another possiblity is to combine sensor elements and circuit elements into a single integrated circuit.
- the senor could be of the piezo-ceramic type or capable of converting the occurring pressure variations into electrical potential variations.
- the reference numeral 8 indicates the position of a power transformer, and 9 indicates the position of a power feed terminal.
- the reference numeral 10 indicates an insulating support for the electronic circuit and sensor.
- the mobile core 6 On feeding the coil 4 from a voltage generator of variable frequency but constant amplitude, the mobile core 6 is caused to oscillate, as is the diaphragm rigid therewith, this having its maximum amplitude when the generated voltage has a frequency equal to the resonance frequency of the mobile resilient part 5, 6 of the device.
- the piezoelectric pressure sensor transforms the pressure variation generated in the air by the rapid movements of the diaphragm into variations in voltage, which is related directly to the amplitude, frequency and phase of its vibrations.
- This sensor therefore assumes the electrical characteristics of a piezoceramic element resonating at the diaphragm frequency.
- it When connected into the reaction circuit of an oscillator circuit, as shown in the schematic diagram of Figure 3, it generates a control signal for the coil 4 having a frequency equal to the resonance frequency of the sound-generating diaphragm 5.
- A indicates a pressure sensor
- B an oscillator circuit
- C an impedance adaptor or a pulse width modifier circuit
- D a pilot amplifier
- E a solid state power switch
- F the control electromagnet for the acoustic diaphragm.
- the electrical schematic diagram of Figure 3 shows the functions of the circuit elements to be used for constructionally optimising the invention.
- the integrated circuit I.C.1 has a typical circuit configuration of a quartz-controlled oscillator. In place of this latter, the sensor 7 (piezoelectric transducer) is connected with the correct polarity for causing the oscillator circuit to resonate at the inherent resonance frequency of the sound-generating electromagnetic system.
- the oscillator ouput is fed to the input of the impedence adaptor and current amplifier I.C.2 (in Figure 2), the output of which controls the final power circuit consisting of the transistors Q1 and Q2, to then control the horn coil 4 or solenoid.
- This particular transistor circuit configuration is provided to reduce the power dissipated by Q2 to a minimum, and at the same time to allow its heat dissipation. This is obtained by connecting the collector (in common with the cooling fin) directly to the metal container 1 of the horn T, which is provided with a resonant diffuser R ( Figure 1).
- I.C.2 can be replaced by a pulse width modulator, so as to obtain sound tone modulation.
Abstract
Description
- This invention relates to the field of electromechanical resonance devices for sound generation, and particularly to high-sounding horns for vehicles, trains and boats.
- Sound generating devices of the electromechanical excitation type currently consist of:
- a resilient steel diaphragm carrying in its centre the mobile part of an electromagnet;
- an electric switch with a normally closed contact connected in series with the power feed to the electromagnet;
- an adjustment screw which determines the switch contact opening point;
- a diffuser which resonates at the same frequency as the metal diaphragm. - When the electromagnet is electrically fed, it attracts the mobile part rigid with the resilient diaphragm. When the diaphragm has nearly attained its maximum travel, the switch connected in series with the electromagnet coil is opened by a push rod operated by the mobile part of the electromagnet.
- At this point, the mobile part of the electromagnet and the diaphragm on which it is fixed continue their travel by inertia until their kinetic energy has been completely absorbed elastically; beyond this point, the elastic energy accumulated by the diaphragm is restituted by reaction with the fixed structure to which it is connected, so that the diaphragm reverses its direction of movement. In this manner it again closes the switch which, again exciting the electromagnet, causes the diaphragm to commence a new oscillation cycle at a frequency equal to the resonance frequency of the electromechanical system.
- These normal switch devices have considerable drawbacks, which can be summarised as follows:
- As the sound output of the horn depends on the time at which the switch operates, it is difficult to obtain maximum sound output because of the difficulty of fixing or adjusting the switch operation point;
- The sound output is subject to considerable fall-off with time due to the mechanical instability of the switch operation points;
- The switch contacts are subject to sparking which causes them to wear and lead to a variation in their time of operation;
- The contact sparking creates electromagnetic waves which can be troublesome to modern electronic systems currently in use, particularly in motor vehicles. - To obviate these drawbacks deriving from the switch, a different method of exciting the electromagnet has recently been conceived. More specifically, the magnetic vibration is obtained by electronic oscillators operating at a vibration frequency approximately equal to the resonance frequency of the electromagnetic system; with this method the oscillator output controls an electronic switch connected in series with the electromagnet coil, thus replacing the mechanically operated switch. However, even the use of this method has drawbacks which can be summarized as follows. Firstly, the generated frequency must be stabilised to make it independent of voltage variations; the generated frequency must also be acceptable to the variation in the diaphragm resonance frequency caused by variations in its temperature. A further serious drawback of this method is the cost involved in limiting the diaphragm production tolerances so that the resonance frequency of the diaphragms produced does not fall outside the limited tolerance range compatible with the constant frequency emitted by the electronic generator. This drawback is eloquently displayed by the reduction in sound output consequent on the variation in the mechanical vibration characteristics of the system, deriving from lengthy operation. Although when new the mechanical parts of the system have the same resonance frequency as the electronic oscillator, as they age they acquire a different frequency because of the fall-off in mechanical strength, the slack which occurs in the connections, the occurrence of wear and other reasons.
- An object of the present invention is to provide a horn which dispenses with the mechanical switch, so obviating all the aforesaid drawbacks caused by it.
- A further object is to provide a horn the sound of which deives from the generation of a diaphragm vibration induction frequency which is always the frequency creating maximum diaphragm resonance, independently of the variations in this latter deriving from any variation in the diaphragm dimensions, structure or fixing.
- These and further objects which will be more apparent to experts of the art from a reading of the description and claims given hereinafter are attained by the following device:
- An electromechanical horn provided with an acoustic diaphragm able to undergo movements induced in it by variable magnetic fields generated by an electromagnet, characterised in that the electromagnet which operates the diaphragm is excited by frequencies generated by an electronic oscillator which are based on the value of the maximum diaphragm resonance frequency measured by a specific sensor.
- The invention is illustrated by way of non-limiting example on the accompanying drawings in which:
- Figure 1 is a diagrammatic section showing the arrangement of the essential parts of the horn;
- Figure 2 is an electrical schematic diagram showing the relationship between the essential parts;
- Figure 3 is a block diagram showing the connection of the various parts.
- With reference to the aforesaid figures, the
metal container 1 forms the fixed part of the electromagnet, and carries fixed to the centre of its closed base 2 aferromagnetic core 3 with therelative coil 4. - At the other end, this container is closed by a
diaphragm 5 fixed in a particularly rigid manner about its entire edge, which is usually circular. - The
diaphragm 5 is usually of steel and has fixed to its central region a ferromagnetic core 6 forming the mobile part of the electromagnet. - The reference numeral 7 indicates a sensor for sensing the pressure variations induced in the air by the vibration of the
overlying diaphragm 5. - This sensor, which in a certain sense could be called a "microphone", can obviously be of various types, as can normal microphones. It can thus, with suitable circuit modifications, be in the form of various types of electrical pressure transducers such as piezoresistive transducers, resistive transducers on an alumina substrate, or in the form of diaphragm position sensors such as Hall effect sensors and electromagnetic sensors.
- Another possiblity is to combine sensor elements and circuit elements into a single integrated circuit.
- By way of example, the sensor could be of the piezo-ceramic type or capable of converting the occurring pressure variations into electrical potential variations.
- The
reference numeral 8 indicates the position of a power transformer, and 9 indicates the position of a power feed terminal. Thereference numeral 10 indicates an insulating support for the electronic circuit and sensor. - On feeding the
coil 4 from a voltage generator of variable frequency but constant amplitude, the mobile core 6 is caused to oscillate, as is the diaphragm rigid therewith, this having its maximum amplitude when the generated voltage has a frequency equal to the resonance frequency of the mobileresilient part 5, 6 of the device. The piezoelectric pressure sensor transforms the pressure variation generated in the air by the rapid movements of the diaphragm into variations in voltage, which is related directly to the amplitude, frequency and phase of its vibrations. - This sensor therefore assumes the electrical characteristics of a piezoceramic element resonating at the diaphragm frequency. When connected into the reaction circuit of an oscillator circuit, as shown in the schematic diagram of Figure 3, it generates a control signal for the
coil 4 having a frequency equal to the resonance frequency of the sound-generatingdiaphragm 5. - If for the already listed reasons the diaphragm resonance frequency undergoes variation, this is automatically reflected in the frequency generated by the sensor 7 which in this manner can continue to cause the diaphragm to vibrate under maximum resonance conditions, ie maximum sound output. This therefore avoids the costly setting operations normally required by conventional horns.
- With reference to the block diagram of Figure 3, A indicates a pressure sensor, B an oscillator circuit, C an impedance adaptor or a pulse width modifier circuit, D a pilot amplifier, E a solid state power switch, and F the control electromagnet for the acoustic diaphragm.
- The electrical schematic diagram of Figure 3 shows the functions of the circuit elements to be used for constructionally optimising the invention.
- The integrated circuit I.C.1 has a typical circuit configuration of a quartz-controlled oscillator. In place of this latter, the sensor 7 (piezoelectric transducer) is connected with the correct polarity for causing the oscillator circuit to resonate at the inherent resonance frequency of the sound-generating electromagnetic system.
- The oscillator ouput is fed to the input of the impedence adaptor and current amplifier I.C.2 (in Figure 2), the output of which controls the final power circuit consisting of the transistors Q1 and Q2, to then control the
horn coil 4 or solenoid. This particular transistor circuit configuration is provided to reduce the power dissipated by Q2 to a minimum, and at the same time to allow its heat dissipation. This is obtained by connecting the collector (in common with the cooling fin) directly to themetal container 1 of the horn T, which is provided with a resonant diffuser R (Figure 1). - In other circuit versions, I.C.2 can be replaced by a pulse width modulator, so as to obtain sound tone modulation.
Claims (3)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IT02932/86A IT1205507B (en) | 1986-11-05 | 1986-11-05 | ELECTROMECHANICAL TRUMPET WITH EXCITATION OF THE SOUND MEMBRANE ELECTRONICALLY PILOTED BY DETECTORS OF ITS FREQUENCY OF RESONANCE |
IT293286 | 1986-11-05 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0266485A2 true EP0266485A2 (en) | 1988-05-11 |
EP0266485A3 EP0266485A3 (en) | 1988-11-02 |
Family
ID=11104011
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP87107567A Withdrawn EP0266485A3 (en) | 1986-11-05 | 1987-05-24 | Electromechanical horn with excitation of its acoustic diaphragm controlled electronically by sensors which measure its resonance frequency |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0266485A3 (en) |
JP (1) | JPS63124095A (en) |
IT (1) | IT1205507B (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1990000093A1 (en) * | 1988-06-29 | 1990-01-11 | Infrasonik Ab | Low frequency sound generator, especially for grills |
US5109212A (en) * | 1989-03-29 | 1992-04-28 | Bruno Cortinovis | Electronically controlled horn for motor vehicles |
EP1008394A1 (en) * | 1998-06-29 | 2000-06-14 | Matsushita Electric Industrial Co., Ltd. | Electrical/mechanical/sound converter and apparatus of electrical/mechanical/sound conversion |
EP1383108A1 (en) * | 2002-07-19 | 2004-01-21 | Mark Thomas Coward | A horn for generating a sound |
WO2005034057A1 (en) * | 2003-10-09 | 2005-04-14 | Fabbrica Italiana Accumulatori Motocarri Montecchio F.I.A.M.M. S.P.A. | Audible warning device and operating method |
EP1710022A2 (en) * | 2005-04-04 | 2006-10-11 | WERMA Signaltechnik GmbH + Co. KG | Signalling device comprising an acoustic signal generator |
DE102013221182B4 (en) * | 2013-10-18 | 2021-05-06 | Volkswagen Aktiengesellschaft | Acoustic signaling system and arrangement and method for operating an acoustic signaling system for a motor vehicle |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2011257685A (en) * | 2010-06-11 | 2011-12-22 | Hamanako Denso Co Ltd | Alarm device |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3771772A (en) * | 1971-05-15 | 1973-11-13 | K Honda | Ultrasonic cleaning device |
DE2448685A1 (en) * | 1974-10-12 | 1976-04-22 | Bosch Gmbh Robert | Electro-magnetic signal horn with armature attached to membrane - ferro-magnetic element on armature in inductive coupling path |
US4395665A (en) * | 1981-06-09 | 1983-07-26 | The Arthur G. Russell Company, Incorporated | Control system for vibrating a member at its resonant frequency |
DE3442483A1 (en) * | 1984-11-22 | 1986-05-22 | Robert Bosch Gmbh, 7000 Stuttgart | Method for solid-state control of the operating frequency of the oscillating armature of an electromagnetic warning horn |
-
1986
- 1986-11-05 IT IT02932/86A patent/IT1205507B/en active
-
1987
- 1987-05-24 EP EP87107567A patent/EP0266485A3/en not_active Withdrawn
- 1987-06-05 JP JP62141318A patent/JPS63124095A/en active Pending
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3771772A (en) * | 1971-05-15 | 1973-11-13 | K Honda | Ultrasonic cleaning device |
DE2448685A1 (en) * | 1974-10-12 | 1976-04-22 | Bosch Gmbh Robert | Electro-magnetic signal horn with armature attached to membrane - ferro-magnetic element on armature in inductive coupling path |
US4395665A (en) * | 1981-06-09 | 1983-07-26 | The Arthur G. Russell Company, Incorporated | Control system for vibrating a member at its resonant frequency |
DE3442483A1 (en) * | 1984-11-22 | 1986-05-22 | Robert Bosch Gmbh, 7000 Stuttgart | Method for solid-state control of the operating frequency of the oscillating armature of an electromagnetic warning horn |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1990000093A1 (en) * | 1988-06-29 | 1990-01-11 | Infrasonik Ab | Low frequency sound generator, especially for grills |
AU626894B2 (en) * | 1988-06-29 | 1992-08-13 | Infrasonik A.B. | Low frequency sound generator, especially for grills |
US5109212A (en) * | 1989-03-29 | 1992-04-28 | Bruno Cortinovis | Electronically controlled horn for motor vehicles |
EP1008394A1 (en) * | 1998-06-29 | 2000-06-14 | Matsushita Electric Industrial Co., Ltd. | Electrical/mechanical/sound converter and apparatus of electrical/mechanical/sound conversion |
EP1008394A4 (en) * | 1998-06-29 | 2005-08-24 | Matsushita Electric Ind Co Ltd | Electrical/mechanical/sound converter and apparatus of electrical/mechanical/sound conversion |
EP1383108A1 (en) * | 2002-07-19 | 2004-01-21 | Mark Thomas Coward | A horn for generating a sound |
WO2005034057A1 (en) * | 2003-10-09 | 2005-04-14 | Fabbrica Italiana Accumulatori Motocarri Montecchio F.I.A.M.M. S.P.A. | Audible warning device and operating method |
EP1710022A2 (en) * | 2005-04-04 | 2006-10-11 | WERMA Signaltechnik GmbH + Co. KG | Signalling device comprising an acoustic signal generator |
EP1710022A3 (en) * | 2005-04-04 | 2008-07-23 | WERMA Signaltechnik GmbH + Co. KG | Signalling device comprising an acoustic signal generator |
DE102013221182B4 (en) * | 2013-10-18 | 2021-05-06 | Volkswagen Aktiengesellschaft | Acoustic signaling system and arrangement and method for operating an acoustic signaling system for a motor vehicle |
Also Published As
Publication number | Publication date |
---|---|
JPS63124095A (en) | 1988-05-27 |
IT1205507B (en) | 1989-03-23 |
EP0266485A3 (en) | 1988-11-02 |
IT8602932A0 (en) | 1986-11-05 |
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Inventor name: CORTINOVIS, BRUNO Inventor name: GIORGIONI, TULLIO |