Abstract: An electromagnetic transducer, such as an audio speaker, includes a return path member which is a pole piece for external magnet geometries or a cup for internal magnet geometries. The magnetic flux return path for the primary drive magnet is through a first portion of the return path member. A first section of a low reluctance magnetic flux return path for a secondary drive magnet is through a second portion of the return path member. A magnetically conductive plate provides a second section of the low reluctance return path from the second portion of the return path member to the secondary drive magnet.

Abstract: An electroacoustic transducer includes a magnetic circuit of a magnetically conductive material with a pair of opposed surfaces defining a gap therebetween. The magnetic circuit includes a magnet inducing a magnetic field in the gap, the magnet having a surface constituting one of the opposed surfaces. The magnetic circuit further includes a diaphragm and a coil having electrically conducting paths secured to the diaphragm. The coil has portions of its paths situated in the gap.

Abstract: The present invention relates to an miniature actuator especially suitable for hearing aid applications. The actuator according to the present invention operates according to the change in reluctance principle. In particular, the actuator according to the present invention operates in a balanced configuration comprising two planar coils, two magnets, a membrane and a spacer chip providing the necessary back chamber volume.

Abstract: In an electro-dynamic loudspeaker, vent holes are optimized to provide improved the magnetic flux characteristics while maintaining sufficient ventilation. In addition, ported and unported enclosures may be utilized with the electro-dynamic loudspeakers to enhance low frequency performance.

Abstract: A loudspeaker comprising at least one magnet 27, a yoke 24 fixed to a bottom surface of the magnet, a flat plate 26 fixed on an upper surface of the magnet, a magnetic circuit 29 having a magnetic gap 28 formed between the plate and the yoke, and a flat diaphragm 23 provided with a coil 21 disposed above the magnetic gap. The magnet has a width greater than that of the plate, and at least a part of the upper surface of the magnet is exposed so that it directly faces the diaphragm. According to the structure of the present invention, a larger volume magnet can be used without increasing the size of the magnetic circuit. Furthermore, as magnetic flux can be concentrated in an upper region of the magnetic gap, the magnetic circuit becomes efficient and compact. Thus a compact and high-efficiency loudspeaker for high frequency sound reproduction can be provided.

Abstract: A speaker has an annular magnet structure. First and second annular magnets are arranged concentrically with each other and connected by a shunt at one end and a pole-defining structure at the other end to concentrate magnetic flux in a cylindrical voice coil gap. The shunt and pole structure are stacked such that the combined magnetic assembly has an opening extending centrally therethrough. A voice coil rides in the cylindrical magnetic flux gap and its leads are brought out through the opening to the other side of the magnet. When used with an enclosure, the diaphragm of the speaker may communicate through the central opening with the volume of a tuned enclosure extending behind the speaker, or the opening may serve as a port of the enclosure, allowing further degrees of control over total acoustics.

Abstract: An electromagnetic transducer such as an audio speaker, having an improved geometry in the positioning of its voice coils relative to its magnetic air gaps, facilitating a greater linear travel. The transducer has a push-pull geometry with at least two voice coils. At all positions throughout the linear travel region, less than 100% of the total voice coil windings are active, and less than 100% of the total available magnetic air gap height is active. As the voice coil assembly moves in one direction, the percentage of active windings or magnetic air gap is seamlessly handed off from the upper voice coil or magnetic air gap to the lower voice coil or magnetic air gap, and vice versa in the opposite direction. Some of the available voice coil windings and some of the available magnetic air gap height are left unused throughout the linear travel region, but, in exchange, the distance of the linear travel is dramatically increased.

Abstract: An electromagnetic transducer such as an audio speaker, having a push-push geometry in which there are two or more air gaps and the magnetic flux across the air gaps is in the same orientation. If there are more than one voice coil, the voice coils may thus be generating the same electromagnetic polarity by being wound in the same direction about the bobbin, or by being wound in opposite directions and having separate, opposite polarity electrical connections. The transducer exhibits high linearity over a long travel.

Abstract: An electromagnetic transducer, such as an audio speaker, includes a return path member which is a pole piece for external magnet geometries or a cup for internal magnet geometries. The magnetic flux return path for the primary drive magnet is through a first portion of the return path member. A first section of a low reluctance magnetic flux return path for a secondary drive magnet is through a second portion of the return path member. A magnetically conductive plate provides a second section of the low reluctance return path from the second portion of the return path member to the secondary drive magnet.

Abstract: An electromagnetic transducer such as an audio speaker exhibiting highly linear performance over a greatly extended excursion. The motor structure includes a stack of two or more magnet and plate pairs, with the magnets polarized in the same orientation such that the magnetic flux flows in the same direction over all of the magnetic air gaps. The voice coil is handed off from gap to gap with a configuration providing a substantially constant BL over an end-to-end distance at least as large as the thickness of one plate plus twice the thickness of one magnet.

Abstract: A speaker arrangement in which a diaphragm does not displace in directions other than a regular oscillating direction. The speaker arrangement includes a magnetic circuit having a magnetic gap, a voice coil located in the magnetic gap, a voice coil bobbin having the voice coil wound thereon, a diaphragm mounted on the voice coil bobbin, a hollow portion extending in a longitudinal direction of the voice coil bobbin and defined inside that portion of the magnetic circuit which is surrounded by the voice coil, an elongated rod inserted in the hollow portion of the magnetic circuit and fixed to the diaphragm, and at least one support member located at a predetermined position in the hollow portion of the magnetic circuit for movably supporting the elongated rod in the magnetic circuit hollow portion.

Abstract: A compound loudspeaker drive unit comprising a first drive unit and a second drive unit arranged co-axial with respect to the center axis of the loudspeaker, and each drive unit comprises permanent magnet means and pole piece means together forming a magnetic circuit with a pole gap for exciting a voice coil assembly, each pole gap providing magnetic field directed radially with respect to a center axis of the loudspeaker. At least one of the permanent magnet means has a radially extending magnetization direction with respect to said center axis of the loudspeaker and the acoustic centers of said drive units substantially coincide.

Abstract: A voice coil actuator is disclosed which provides a proportional solenoid type characteristic and in which first and second magnets are positioned at different ends of a first soft magnetic pole piece and magnetized in opposite directions, the first soft magnetic pole piece having a length greater than the length of the first magnet and the length of the second magnet. A coil having a length less than the lengths of the first soft magnetic pole piece is positioned for travel along an axis common to the first soft magnetic pole piece and first and second magnets, and a structure provides a magnetic path between free ends of the first and second magnets.

Abstract: An electromagnetic transducer such as an audio speaker having at least one of the soft magnetic components of its motor assembly constructed as a laminated structure of electrically insulated magnetically conductive sections. Eddy currents, which would have been induced in a monolithic component in response to an electrical signal applied to the voice coil, are prevented or significantly reduced by the electrical insulation material between the sections of the laminated component. The transducer produces less heat, is less susceptible to flux modulation, and has increased power handling and reduced distortion.

Abstract: An electromagnetic transducer such as an audio speaker, having a tube geometry motor which is not axisymmetric. The tube geometry motor includes a tubular yoke of soft magnetic material. The tube includes an air gap hole through a wall of the tube. A pole piece extends through the air gap hole to define the magnetic air gap between the tube wall and the pole piece. A hard magnet is coupled to the tube. In some embodiments, the pole piece is coupled to a back plate inside the tube, which in turn is coupled to the hard magnet. A diaphragm assembly is coupled to the outer side of the tube. The axis of movement of the diaphragm assembly and the extruded axis of the tube motor are perpendicular. Different models of the transducer motor can be fashioned by increasing the magnetic flux over the magnetic air gap, without having to make the motor wider or deeper, and without requiring new tooling for the tube, simply by making the motor longer and longer along the extruded axis.

Abstract: An electroacoustic transducer 1 includes a base 24 made of a magnetic material; a magnetic core 22 made of a magnetic material and upstanding on the base 24; a diaphragm 20 made of a magnetic material and spaced from a leading end of the magnetic core; a magnetic field generating member 25 cooperating with the base 24, the magnetic core 22 and the diaphragm 20 to constitute a magnetic circuit, for supplying a static magnetic field; a coil 23 placed around the magnetic core, for supplying an oscillating magnetic field to the magnetic circuit. The magnetic field generating member 25 constitutes a multiplex ring structure in which a magnet 25a and a support ring 26 are integrated together, whose faces opposing the diaphragm 20 have respectively magnetic poles of the same polarity.

Abstract: A converter with two coils and two magnetic gaps of which the upper and lower yokes of are two innerwardly concave plates or round plates. 3 set or more than 3 sets of axially magnetized permanent magnets are provided. Said permanent magnets are directly engaged with pole faces of said plates. Two magnetic gaps are formed between the vertical peripheric faces of said plates and the outer peripheric faces of a coaxial mounted annular or cylindrical magnetic body. Coils are inserted into said magnetic gap, while wound direction of two coils and the direction of current are decided to produce an electrodynamic force in the coils to the same direction. Said converter possesses resistance load characteristics by setting the values of the inductance of the two coils equal to each other in case that said converter are provided with two magnetic paths and coil circuits completely symmetric in their magnetic characteristics.

Abstract: An acoustical speaker and planar magnetic transducer therefore wherein the transducer is provided with at least array of spaced magnets which are oriented having their pole faces at an angle with respect to a plane defining a surface of a sound producing diaphragm on which extends an electrical trace circuit.

Abstract: A speaker vibrating plate having a voice coil secured thereto is provided in a frame, a rotor having an annular side yoke is rotatably supported in the frame, and a stator having poles is provided in the frame. A first permanent magnet is provided on the rotor at a central portion thereof, and an annular second permanent magnet is mounted on the rotor outside the side yoke for forming a magnetic circuit passing through the rotor and the stator, and a stator coil is provided in the stator. A driving circuit is provided for energizing the stator coil for rotating the rotor.

Abstract: An electromagnetic transducer, such as an audio speaker, in which magnetic flux is provided to the drive magnetic air gap(s) by both an external permanent magnet (as in conventional pole plate geometry transducers) and an internal permanent magnet (as in conventional neo or cup geometry transducers). Both magnets may have the same polarity orientation, enabling them to be simultaneously charged after assembly of the transducer's motor structure. A lower one of the permanent magnets uses the yoke as its return path. A low reluctance return path is provided for the upper one of the permanent magnets to improve performance.

Abstract: A speaker with enhanced magnetic flux loop includes a core magnet (12) installed inside hollow space of a bottom yoke (11), and a ring-shape magnet (13) with opposing polarity placed on the outer periphery of the core magnet (12). The ring-shape magnet (13) acts as an induction medium in a magnetic flux loop flowing across the core magnet (12), thus bottom yoke the magnetic flux within the boundary of the yoke (11) and preventing loss of magnetic flux. The dual magnet architecture brings about increased sensitivity to sound and output volume for the speaker, whilst the external dimensions of the conventional speaker can be scaled down as a result of smaller yoke (11).

Abstract: A speaker vibrating plate having a voice coil secured thereto is provided in a frame, a rotor having poles is rotatably supported in the frame, and a stator having poles is provided in the frame. A permanent magnet is provided in the rotor for forming a magnetic circuit passing through the rotor and the stator, and a stator coil is provided in the stator. A driving circuit is provided for energizing the stator coil for rotating the rotor.

Abstract: A loudspeaker has first and second diaphragms provided in a case. A first voice coil is provided for vibrating the first diaphragm, and a second voice coil is provided for vibrating the second diaphragm. A first permanent magnet is provided for applying a magnetic flux to the first voice coil, and a second permanent magnet is provided for applying a magnetic flux to the second voice coil.

Abstract: An informing apparatus for a mobile communication apparatus has two magnetic gaps A, B formed in a magnetic circuit, in which voice coils are set respectively. A first vibrant part includes one voice coil connected to a diaphragm, and a second vibrant part includes another voice coil connected, via supporters, to a casing set outside the magnetic circuit, the supporters and the magnetic circuit. A sound receiving function and/or a call-tone receiving function, which is performed with a sound signal and/or a call-tone signal sent to the voice coil 8 in the first vibrant part, and a silent mode call-reception informing function, which is performed with a call-reception signal sent to the voice coil in the second vibrant part whereby the supporters and the magnetic circuit are vibrated thereby making the mobile communication apparatus itself resonate, work independently.

Abstract: A loudspeaker with independent magnetic dampening and excursion control includes at least two magnets for dampening the axial movement of a voice coil. The dampening magnets substantially reduce/prevent fatigue of the component parts of the loudspeaker and detrimental contact between the voice coil and its supporting parts and the remaining component parts of the loudspeaker. A pole yoke supported by a backplate defines the inner diameter of an annular gap within which the voice coil moves and a top plate defines the outer diameter of the gap. A first dampening magnet is statically supported by the pole yoke. A second dampening magnet is supported by and moves in concert with the voice coil. As the voice coil and second magnet move within the gap, the repelling forces of the magnets provide the desired dampening effect, thus limiting or reducing the movement in one direction.

Abstract: An electromagnetic transducer such as an audio speaker, having a push-push geometry in which there are two or more air gaps and the magnetic flux across the air gaps is in the same orientation. If there are more than one voice coil, the voice coils may thus be generating the same electromagnetic polarity by being wound in the same direction about the bobbin, or by being wound in opposite directions and having separate, opposite polarity electrical connections. The transducer exhibits high linearity over a long travel.

Abstract: The invention relates to an electromagnetic driver comprising a soft magnetic core in the form of an E with three legs and a back, an alternating field driver, magnetically coupled to the soft magnetic core, for generating an alternating magnetic field in the soft magnetic core, depending upon a sound signal, a constant field driver magnetically coupled to the soft magnetic core for generation of a constant magnetic field in the soft magnetic core, a soft magnetic element for coupling to the plate of the planar diaphragm loudspeaker, lying opposite the back and magnetically closing the legs across at least one small induction gap, whereby the constant field and the alternating field are asymmetrically superimposed such that a resulting force, or a resulting torque on the soft magnetic element, is proportional to the sound signal.

Abstract: A magnetic core for speaker is constructed to include an annular magnet connectable to the body of the speaker, a center magnet mounted in the center of the annular magnet and connectable to the body of the speaker, an annular magnetically conducting plate mounted on the topmost edge of the annular magnet, and a center magnetically conducting plate mounted on the topmost edge of the center magnet for producing a magnetic loop with the annular magnetically conducting plate.

Abstract: A magnetic core for speaker is constructed to include an annular magnet connectable to the body of the speaker, a center magnet mounted in the center of the annular magnet and connectable to the body of the speaker, an annular magnetically conducting plate mounted on the topmost edge of the annular magnet, and a center magnetically conducting plate mounted on the topmost edge of the center magnet for producing a magnetic loop with the annular magnetically conducting plate.

Abstract: A loudspeaker includes a magnetic circuit comprising a center plate, first and second magnets disposed respectively on a lower surface and an upper surface of the center plate and magnetized to be repulsive to each other, an under plate disposed at a lower surface of the first magnet, and a yoke. The loudspeaker further comprises a voice coil, a diaphragm, an edge coupled with the outer circumferential edge of the diaphragm, and a frame. The above-described magnetic circuit further comprises a top plate disposed on an upper surface of the second magnet. Both of the second magnet and the top plate have a ring shape, the inner and the outer diameters of the second magnet and the top plate being substantially the same. Outer diameters of the second magnet and the top plate are smaller than that of the center plate, and the center plate is provided on its upper surface with a protrusion for positioning of the second magnet.

Abstract: An electroacoustic transducer of small dimensions has a cup-shaped component made of a metallizable plastic material embedded in a housing component having a housing shape and being of a non-metallizable plastic material. The cup-shaped component has an inner surface provided with a metal coating. A magnet is arranged in the cup-shaped component. A diaphragm is connected to the housing component and has an oscillation coil configured to interact with the magnet.

Abstract: A speaker diaphragm having a voice coil secured thereto is provided in a frame, a rotor having a permanent magnet is rotatably supported in the frame, and a stator having poles is provided in the frame. The permanent magnet provided on the rotor is provided for forming a magnetic circuit passing through the rotor and the stator, and a stator coil is provided in the stator. A driving circuit is provided for energizing the stator coil for rotating the rotor.

Abstract: A speaker has an annular magnet structure. First and second annular magnets are arranged concentrically with each other and connected by a shunt at one end and a pole-defining structure at the other end to concentrate magnetic flux in a cylindrical voice coil gap. The shunt and pole structure are stacked such that the combined magnetic assembly has an opening extending centrally therethrough. A voice coil rides in the cylindrical magnetic flux gap and its leads are brought out through the opening to the other side of the magnet. When used with an enclosure, the diaphragm of the speaker may communicate through the central opening with the volume of a tuned enclosure extending behind the speaker, or the opening may serve as a port of the enclosure, allowing further degrees of control over total acoustics. In one embodiment, annular magnets of axial polarity are oppositely poled, and are positioned concentrically with a space between them.

Abstract: Negative stiffness is generated for a vibration system of a speaker unit by using a movable magnet attached to the vibration system of the speaker unit and also a ring-like stationary magnet arranged coaxially at the outer radius thereof in order to increase equivalently internal volume of a cabinet. In addition, an offset in the displacement direction of the vibration system of the speaker unit is detected with a Hall element and fed back to a power amplifier in order to correct the offset in the displacement direction of the vibration system of the speaker unit. As a result, a reliable and practical bass reproduction speaker apparatus can be obtained, and the speaker apparatus is noise-free and excellent in bass reproduction performance even with a cabinet of small capacity.

Abstract: A first magnet is provided in an upper case and a second magnet is provided in a lower case so that these magnets face each other. These magnets are magnetized in opposite directions. A diaphragm having a drive coil is placed between these magnets. Thus, magnetic flux emitted from the respective magnets bends in a direction approximately perpendicular to the initial direction of emission of the flux. In the magnetic field, the component of the magnetic flux in the direction of radiation proportional to the driving force is dominant, and is symmetrical relative to the direction of vibration. Therefore, the sound pressure of the reproduced sound is increased and the secondary harmonic distortion caused by asymmetry of the driving force can be reduced.

Abstract: A loudspeaker includes a magnetic circuit comprising a center plate, first and second magnets disposed respectively on a lower surface and an upper surface of the center plate and magnetized to be repulsive to each other, an under plate disposed at a lower surface of the first magnet, and a yoke. The loudspeaker further comprises a voice coil, a diaphragm, an edge coupled with the outer circumferential edge of the diaphragm, and a frame. The above-described magnetic circuit further comprises a top plate disposed on an upper surface of the second magnet. Both of the second magnet and the top plate have a ring shape, the inner and the outer diameters of the second magnet and the top plate being substantially the same. Outer diameters of the second magnet and the top plate are smaller than that of the center plate, and the center plate is provided on its upper surface with a protrusion for positioning of the second magnet.

Abstract: A rotor having a yoke is rotatably supported in a frame, and a stator provided in the frame at a central portion of the frame. An annular first permanent magnet is provided on the yoke, and an annular second permanent magnet is provided on the yoke. A diaphragm is supported in the frame, and a voice coil is secured to the diaphragm and inserted in a gap formed by the first permanent magnet. At least two coils are provided on the stator for forming magnetic fluxes between the rotor and the stator so as to rotate the rotor.

Abstract: A speaker has an annular magnet structure. First and second annular magnets are arranged concentrically with each other and connected by a shunt at one end and a pole-defining structure at the other end to concentrate magnetic flux in a cylindrical voice coil gap. The shunt and pole structure are stacked such that the combined magnetic assembly has an opening extending centrally therethrough. A voice coil rides in the cylindrical magnetic flux gap and its leads are brought out through the opening to the other side of the magnet. When used with an enclosure, the diaphragm of the speaker may communicate through the central opening with the volume of a tuned enclosure extending behind the speaker, or the opening may serve as a port of the enclosure, allowing further degrees of control over total acoustics. In one embodiment, annular magnets of axial polarity are oppositely poled, and are positioned concentrically with a space between them.

Abstract: In the electric-acoustic transducer, first to third permanent magnets are respectively received in the first to the third recesses of a yoke, so as to generate non-alternating magnetic fields. The first and second magnetic gaps are formed between the yoke and the first and the second plates. The first and the second coils are respectively disposed in the first and the second magnetic gaps, to generate alternating magnetic fields of the same phase, when an electric driving signal is applied from the exterior. The electric-acoustic transducer achieves reproduction of a broad frequency band with high power and high efficiency, even with an ultra slim or small dimension, proper for a small electronic appliance such as a notebook computer, by employing dual voice coil drivers and auxiliary magnetic circuits.

Abstract: Disclosed is an electric-acoustic transducer comprising at least one fixed coil adapted to generate alternating magnetic field upon externally receiving an electrical drive signal, a frame having a recessed structure for centrally receiving and supporting the fixed coil, at least one moving permanent magnet disposed over the fixed coil while being spaced from the fixed coil by a desired vertical distance in such a fashion that it is vertically movable, the moving permanent magnet serving to generate non-alternating magnetic field, and a vibrating diaphragm supported by an upper end of the frame at a peripheral portion thereof, the vibrating diaphragm supporting the permanent magnet by a central portion thereof, whereby the vibrating diaphragm vibrates vertically in accordance with an interaction between the alternating magnetic field generated from the fixed coil and the non-alternating magnetic field generated from the permanent magnet.

Abstract: A signal converter used in various electronic communication products saves power consumption and prolongs the time for usage thereof by its structural characteristics. The signal converter functions as a vibrator, a speaker, and a receiver, etc. together, and generates vibration or sound by magnets installed such that a repulsive force or an attractive force generated from magnets and excitation coils is directed to the same direction so as to remove an inefficient functional operation.

Abstract: A loudspeaker (10) according to the invention is presented, which contains at least one radially magnetized permanent magnet (12), and whose receiving part is made of a paramagnetic or diamagnetic material. Such loudspeakers (10) can be constructed in a very simple and compact manner. With the further development of loudspeakers (10) able to utilize the stray flux from radially magnetized permanent magnets (12), it is possible to produce derivations with two diaphragms (13, 13′) with identical reproduction frequencies, without great cost.

Abstract: A loudspeaker (10) according to the invention is presented, which contains at least one radially magnetized permanent magnet (12), and whose receiving part is made of a paramagnetic or diamagnetic material. Such loudspeakers (10) can be constructed in a very simple and compact manner. With the further development of loudspeakers (10) able to utilize the stray flux from radially magnetized permanent magnets (12), it is possible to produce derivations with two diaphragms (13, 13′) with identical reproduction frequencies, without great cost.

Abstract: An electroacoustic transducer with attenuated effective output irregularities caused by intrinsic normal modes of oscillation. What stands out, as a structural property of a preferred embodiment, is a sandwich assembly, having an oscillating medium of layered components suspended between two rigid baffles, with a hinged baffle extension supporting the device in upright position. An opening, asymmetrically positioned in each of said two rigid baffles, exposes to the ambient medium a driven and asymmetrically positioned antinode belonging to a predetermined mode pattern of the oscillating medium. The resulting asymmetrical and partial coupling of the oscillating medium with the ambient medium limits occurrences of irregularities in effective output. Similarly, the asymmetrical and partial driving of the oscillating medium leads to a relatively high number of normal modes simultaneously excited.

Abstract: A speaker and a speaker apparatus used for acoustic sound reproduction include a magnetic circuit unit having a center plate of a magnetic material and a set of magnets arranged on both sides of the center plate with magnetic poles of repulsive polarities facing each other, a voice coil in which a magnetic field that is formed by the magnetic circuit unit is interlinked with at least a portion of an alternating magnetic field produced, a vibrating plate connected to the voice coil, and a set of resilient supporting members arranged plane-symmetrically with respect to the outer peripheral surface of the vibrating plate for movably supporting the outer periphery of the vibrating plate. The vibrating plate is movably supported by a set of resilient supporting members arranged plane-symmetrically to suppress the rolling of the vibrating plate during vibrations to realize stable vibrations of the vibrating plate.

Abstract: A speaker including a magnetic circuit formed by an annular yoke and an annular magnet which are concentric around a central axis and face each other across a gap. The magnet includes an N pole region and an S pole region successively arranged along the central axis direction and divided by an imaginary boundary line. At rest, a first coil is positioned in the gap in the N pole region, and a second coil is positioned in the gap in the S pole region. When the coils are driven by an excessively large current, a portion of the first coil moves beyond the boundary line to enter the S pole region, thereby causing a gentle first damping force on the first coil to prevent an excessive displacement. Likewise, the excessive current causes the second coil to move beyond the boundary line to enter the N pole region, thereby causing a second damping force which is opposite in direction to the first damping force.

Abstract: A loudspeaker (10) with a magnet system (12) arranged in a space (32) surrounded by a conical diaphragm (14) has a core (20) of the magnet system (12) first connected to the loudspeaker basket (11) and only then is the pot (19) connected to the core 20. It is then possible to manufacture loudspeakers (10) with internally located magnet systems (12) on production lines which can also be used to manufacture loudspeakers with magnet systems (12) that are located on the outside of the basket (11). Because the pot (19) is only installed later in the core (20) a centering bushing (34) can be placed between the core (20) and the voice coil support (18), which leads to a considerable improvement in the production quality of such loudspeakers (10).

Abstract: A speaker apparatus includes a yoke formed of a magnetic material and having a flange portion and a center pole protruded integrally forwards from a mid portion of the flange portion, and a ring-shaped driving magnet into which the center pole is inserted. The speaker apparatus also includes a top plate mounted on the driving magnet. The top plate is formed of a magnetic material and the center pole is inserted through the top plate. The top plate defines a magnetic gap together with the center pole. The speaker apparatus further includes a voice coil mounted on a bobbin secured to a diaphragm in the magnetic gap, and a canceling magnet arranged on the outer periphery of and spaced from the driving magnet at a pre-set spacing for covering the driving magnet. The canceling magnet cancels the magnetic flux leaking to outside a magnetic circuit including the driving magnet.

Abstract: The degree of wire sweep and wire clearance over the buss bars in the 16 Mega Bit LOC package is found to be dependent on the angle of the bond wires. A positive wire angle range of 5 to 15 degrees is recommended for minimum wire sweep and maximum wire clearance over the buss bars. This is so because they offer the least resistance to the flow of the mold compound during transfer molding. A staggered gating system ensures that the wire angles in all cavities are positive with respect to the gate. This invention is also applicable to conventional packages.