Abstract: An audio speaker has a driver unit having a support frame with a central portion forming a magnetic structure defining an annular gap around a central magnetic post, a vibration system having a diaphragm and a voice coil, the voice coil is attached to one side of the diaphragm where the vibration system is fixed to the support frame and where the voice coil is movably mounted in the annular gap, and a magnetic fluid disposed in the annular gap only in a space between one side of the voice coil and a surface of the annular gap having a higher magnetic flux density.

Abstract: An audio speaker includes a driver unit having a magnetic pole case defining a radial gap, a vibration system having a diaphragm and a voice coil where the vibration system is fixed to the drive unit and the voice coil is movably mounted into the radial gap, and a residual magnetic fluid layer disposed on the surfaces of one or more of the magnetic pole case and the voice coil where an air gap exists between the voice coil and the magnetic pole case.

Abstract: An audio speaker has a driver unit having a support frame with a central portion forming a magnetic structure defining an annular gap around a central magnetic post, a vibration system having a diaphragm and a voice coil, the voice coil is attached to one side of the diaphragm where the vibration system is fixed to the support frame and where the voice coil is movably mounted in the annular gap, and a magnetic fluid disposed in the annular gap only in a space between one side of the voice coil and a surface of the annular gap having a higher magnetic flux density.

Abstract: The micro-speaker includes a driver unit having a housing, a magnet disposed within the housing forming a radial gap between the magnet and the circumferential walls of the housing, and a magnetic plate disposed on the magnet, a vibration system having a diaphragm and a voice coil where the vibration system is fixed to the drive unit and the voice coil protrudes into the radial gap, and a volatile magnetic fluid in the radial gap about the voice coil.

Abstract: An element-modified ferrofluid comprising a base oil, a plurality of magnetic particles covered with at least one surfactant, and an elemental modifier. The elemental modifier is a metal, a metal mixture, an alloy, or a nonmetal.

Abstract: An audio speaker includes a driver unit having a magnetic pole case defining a radial gap, a vibration system having a diaphragm and a voice coil where the vibration system is fixed to the drive unit and the voice coil is movably mounted into the radial gap, and a residual magnetic fluid layer disposed on the surfaces of one or more of the magnetic pole case and the voice coil where an air gap exists between the voice coil and the magnetic pole case.

Abstract: The method of assembling a speaker includes disposing a quantity of volatile magnetic fluid containing a pre-determined amount of lubricating oil into a radial gap of a driver unit, aligning a vibration system having a diaphragm and a voice coil to the driver unit such that the voice coil is movably mounted into the radial gap, fixing the vibration system to the driver unit, and removing the volatile component of the volatile magnetic fluid. The speaker includes a driver unit having a magnetic pole case defining a radial gap, a vibration system having a diaphragm and a voice coil where the vibration system is fixed to the drive unit and the voice coil is movably mounted into the radial gap, and a residual magnetic fluid layer disposed on the surfaces of one or more of the magnetic pole case and the voice coil where an air gap exists between the voice coil and the magnetic pole case.

Abstract: The micro-speaker includes a driver unit having a housing, a magnet disposed within the housing forming a radial gap between the magnet and the circumferential walls of the housing, and a magnetic plate disposed on the magnet, a vibration system having a diaphragm and a voice coil where the vibration system is fixed to the drive unit and the voice coil protrudes into the radial gap, and a volatile magnetic fluid in the radial gap about the voice coil.

Abstract: The method of assembling a pick-up actuator includes assembling a lens holder assembly to a base unit creating a magnetic gap between complementary electromagnetic components of the lens holder assembly and the base unit, disposing a quantity of a volatile magnetic fluid or a low viscosity oil-based magnetic fluid into the magnetic gap created between complementary electro-magnetic components of a lens holder assembly and a base unit, fixing resilient support members between the lens holder assembly and the base unit. The optical pick-up actuator includes a lens holder assembly, a base unit, resilient support members connecting the lens holder assembly and the base unit, an electromagnetic drive system, and a volatile magnetic fluid or a low viscosity oil-based magnetic fluid.

Abstract: The method of assembling a micro-speaker includes disposing a quantity of volatile magnetic fluid into a radial gap of a driver unit, aligning a vibration system having a diaphragm and a voice coil to the driver unit such that the voice coil is accommodated into the radial gap, fixing the vibration system to the driver unit, and removing the volatile component of the volatile magnetic fluid. The micro-speaker includes a driver unit having a housing, a magnet disposed within the housing forming a radial gap between the magnet and the circumferential walls of the housing, and a magnetic plate disposed on the magnet, a vibration system having a diaphragm and a voice coil where the vibration system is fixed to the drive unit and the voice coil protrudes into the radial gap, and a volatile magnetic fluid in the radial gap about the voice coil.

Abstract: An element-modified ferrofluid comprising a base oil, a plurality of magnetic particles covered with at least one surfactant, and an elemental modifier. The elemental modifier is a metal, a metal mixture, an alloy, or a nonmetal.

Abstract: The method of assembling a speaker includes disposing a quantity of volatile magnetic fluid containing a pre-determined amount of lubricating oil into a radial gap of a driver unit, aligning a vibration system having a diaphragm and a voice coil to the driver unit such that the voice coil is movably mounted into the radial gap, fixing the vibration system to the driver unit, and removing the volatile component of the volatile magnetic fluid. The speaker includes a driver unit having a magnetic pole case defining a radial gap, a vibration system having a diaphragm and a voice coil where the vibration system is fixed to the drive unit and the voice coil is movably mounted into the radial gap, and a residual magnetic fluid layer disposed on the surfaces of one or more of the magnetic pole case and the voice coil where an air gap exists between the voice coil and the magnetic pole case.

Abstract: The method of assembling a micro-speaker includes disposing a quantity of volatile magnetic fluid into a radial gap of a driver unit, aligning a vibration system having a diaphragm and a voice coil to the driver unit such that the voice coil is accommodated into the radial gap, fixing the vibration system to the driver unit, and removing the volatile component of the volatile magnetic fluid. The micro-speaker includes a driver unit having a housing, a magnet disposed within the housing forming a radial gap between the magnet and the circumferential walls of the housing, and a magnetic plate disposed on the magnet, a vibration system having a diaphragm and a voice coil where the vibration system is fixed to the drive unit and the voice coil protrudes into the radial gap, and a volatile magnetic fluid in the radial gap about the voice coil.

Abstract: The invention relates to a composition and process for producing a chemically stable magnetic fluid comprising a plurality of magnetic particles covered first with a small molecular weight surface modifier, which is a nondispersant and acts as a surfactant-accepting layer, and then with at least one surfactant. The surface modifier/surfactant coated magnetic particles are then suspended in a silicone oil-based, hydrocarbon oil-based or an ester oil-based carrier liquid.

Abstract: The invention relates to a composition and a process for producing a magnetic fluid comprising finely divided magnetic particles covered with at least one surfactant. A fluorocarbon-silane surface modifier is employed which is added to cover the free oxidizable exterior surface of the outer layer of the particles to increase the acid resistance of the colloid.

Abstract: The invention relates to a composition and a process for producing a chemically stable magnetic fluid comprising finely divided magnetic particles covered with surfactants. A surface modifier is also employed which is added to cover thoroughly the free oxidizable exterior surface of the outer layer of the particles to assure better chemical stability of the colloid under different environmental conditions.

Abstract: The present invention relates to a ferrofluid composition having improved oxidation resistance, which contains a carrier liquid, magnetic particles in a stable colloidal suspension, and from more than about 10% to about 400% by weight of an antioxidant based on the weight of the magnetic particles.

Abstract: A novel magnetic colloid composition containing a polar ester carrier liquid, magnetic particles, and an acid terminated poly (12-hydroxystearic acid) dispersant of the Formula I: ##STR1## where "R" is selected from the group consisting of alkyls, aralkyls, and aryls, substituted or unsubstituted, and "n" is an integer from 0 to 4, or mixtures thereof where "R" and "n" may be the same or different.

Abstract: The invention relates to a composition and a process for producing a chemically stable magnetic fluid comprising finely divided magnetic particles covered with surfactants. A surface modifier is also employed which is added to cover thoroughly the free oxidizable exterior surface of the outer layer of the particles to assure better chemical stability of the colloid under different environmental conditions.

Abstract: The present invention relates to a ferrofluid composition having improved oxidation resistance, which contains a carrier liquid, magnetic particles in a stable colloidal suspension, and from about 5% to about 50% by weight of an antioxidant.