Abstract: This invention relates to a process for preparing high-purity aromatic oligomers by effectively separating an organic layer containing aromatic oligomers or the reaction products of a polycyclic aromatic compound with formaldehyde from an aqueous layer containing an acid catalyst in a simplified manner, hitherto regarded difficult to accomplish, and obtaining high-purity aromatic oligomers from the organic layer containing a reduced amount of impurities. In separating the aqueous layer containing the acid catalyst and the organic layer containing the oligomers from the reaction mixture formed by the condensation of a polycyclic aromatic compound and formaldehyde, the emulsion phase is broken by adding a nonionic or cationic surfactant in an effective amount and an alkali in an amount sufficient to neutralize 1-70% of the acid in the acid catalyst, the organic and aqueous layers are separated and the aromatic oligomers are recovered from the organic layer.

Abstract: This invention relates to a resin composition useful as a vibration-damping agent and the like. The resin composition is formulated by adding 1 wt % or more of styrenated phenol obtained by the reaction of a phenol with styrene to a polycyclic aromatic oligomer obtained by condensing a polycyclic aromatic compound containing 2 to 3 rings and formaldehyde. The polycyclic aromatic oligomer is obtained by the reaction of a polycyclic aromatic compound with formaldehyde and, if necessary, further with a phenol in the presence of an acid catalyst and has a number average molecular weight of 300-1000. The styrenated phenol is obtained by the reaction of 1 mole of a phenol with 1-2.5 moles of styrene in the presence of an acid catalyst.

Abstract: A head suspension supporting a head at the tip end is allowed to swing at the tip end of a carriage in a recording disk drive. A microactuator is interposed between the head suspension and the carriage. A resistor is connected to the microactuator in serial. The microactuator is allowed to function as a capacitance. A combination of the microactuator and the resistor enables establishment of a so-called low pass filter. A high frequency noise involuntarily introduced in the driving voltage for the microactuator can be eliminated or removed from the driving voltage. Elimination of the high frequency noise enables a reliable prevention of the mechanical or physical resonance or vibration in the head suspension. A tracking action of the head related to a target recording track can reliably be stabilized.

Abstract: This invention relates to an aromatic oligomer represented by the following formula (1): (A—F)n—A   (1) wherein A is a unit comprising (a) 30-90 wt % of a bicyclic or tricyclic aromatic compound and (b) 10-70 wt % of a phenol, F is methylene or a mixture of methylene and —CH2OCH2— and n is a number of 1-100. The aromatic oligomer is obtained by and reaction of a polycyclic aromatic compound such as naphthalene and benzothiophene, a phenol and formaldehyde compound in the presence of an acid catalyst. The aromatic oligomer is odorless and useful for various applications. In particular, when incorporated in rubber or resin, the aromatic oligomer can perform execellently as a tackifier in a wide temperature range or perform excellently as a vibration damping agent.

Abstract: A magnetoresistive head reproduces information recorded on a recording medium with high recording density, suppressing generation of Barkhausen noise. A magnetoresistive effect element in the head is a flat multi-layer film in which a free magnetic layer is set to a lowest layer. The head also includes a non-magnetic substrate, an insulating layer contacting a center portion of a lower surface of a substrate side of the free magnetic layer, and a pair of electrode layers. The electrode layers are formed with the insulating layer in between, contacting both edge portions of the free magnetic layer. The electrodes are formed with the same surface height as the surface height of the insulating layer. A pair of magnetic wall control layers suppress movement of a magnetic wall of the free magnetic layer.

Abstract: A pair of slits are defined in a slider body of a head slider so as to extend from a trailing end surface to the leading end on the slider body. A movable block is established in the slider body between the slits. The slits ensure the extent of movement for the movable block. Elongated plates enable a relative displacement between the movable block and a stationary block. A head element is mounted on a trailing end surface of the movable block. The thickness of a non-magnetic layer corresponds to the gap length of the head element. The gap length of the head element can easily be controlled based on deposition of the non-magnetic layer. The thickness of the non-magnetic layer can be reduced in a relatively facilitated manner, so that the gap length of the head element can easily be minimized.

Abstract: The hydrogenated aromatic oligomer of this invention is represented by the following formula (1)

Abstract: This invention provides a process for purifying to a high degree of purity aromatic hydrocarbons containing impurities which are difficult to separate by distillation such as sulfur compounds and nitrogen compounds. The process of this invention for purifying aromatic hydrocarbons comprises treating crude aromatic hydrocarbons with a formaldehyde or with a formaldehyde and a phenol in the presence of an acid catalyst to form oligomers, distilling or evaporating the reaction mixture thereby separating the unreacted aromatic hydrocarbons from the oligomers, and crystallizing or washing with an organic solvent the separated aromatic hydrocarbons. In case the target hydrocarbon is naphthalene, it is possible to prepare naphthalene which has a purity of 99.9999 wt % or more, emits little odor, and can be readily flavored by perfumes. Naphthalene of this quality is used to prepare an insecticide of excellent fragrance.

Abstract: A magnetic recording medium inspection method for detecting a small protrusion that constitutes a defect on a surface of a magnetic recording medium, the method comprising the steps of flying a glide inspection head at a predetermined height over a surface of the moving magnetic recording medium; detecting a contact duration time during which the glide head is in contact with the protrusion on the surface of the magnetic recording medium using a contact detection sensor attached to the glide inspection head; and determining the small protrusion based on the contact duration time.

Abstract: A thin film magnetic head has a media opposing surface which is adapted to be opposed to a recording medium, and includes a sacrificial layer, on a substratum that has a surface for forming the media opposing surface having at least one rail. A tracking mechanism or loading/unloading mechanism can be provided on the slider. An electrostatic actuator suitable for driving such a mechanism includes a stationary section having a plurality of teeth parallel to each other, a movable section having a plurality of teeth parallel to the teeth of the stationary section, a support spring for supporting the movable section so that the movable section can be moved with respect to the stationary section in the tooth width direction.

Abstract: An adsorptive tangential force is measured at the moment when a slider has contacted or touched a receiving surface. The adsorptive tangential force is induced solely by the adsorption transmitted from the receiving surface to the slider. An overall tangential force transmitted from the receiving surface to the slider is measured when the slider is kept urged against the receiving surface. The coefficient of dynamic friction is calculated based on the differential between the thus measured overall and adsorptive tangential forces. The effect of the adsorption can be eliminated from the calculated coefficient of dynamic friction. It is possible to derive the coefficient of dynamic friction at a still higher accuracy.

Abstract: A head slider includes a front rail having an air bearing surface and a step surface lower than the air bearing surface, provided on a disk faced surface in the vicinity of an air inflow end, a transducer provided in the vicinity of an air outflow end, and a groove for generating a negative pressure by expanding air once compressed by the front rail. The head slider further includes a piezoelectric actuator mounted on a head slider back surface on the opposite side of the disk faced surface excluding the vicinity of the air outflow end. By the piezoelectric actuator, the front rail and the neighboring portion are deformed in the direction toward the recording medium or away from the recording medium, and the positive pressure generated at the air bearing surface is regulated, whereby the floating amount of the head slider can be regulated.

Abstract: An object of the present invention is to provide a magnetoresistive effect type of head for preferably reproducing information recorded on a recording medium with high recording density suppressing generation of Barkhausen noise. The magnetoresistive effect type of head has a magnetoresistive effect element offering a resistive change according to intensity of an external magnetic field, for detecting a magnitude of a resistance of the magnetoresistive effect element to detect intensity of a magnetic field. The magnetoresistive effect element consists of a flat multi-layer film in which a free magnetic layer changing in a direction of a magnetization in accordance with the external magnetic field is set up to a lowest layer.

Abstract: In a magnetic head slider having a horizontal type head element which floats on or comes into contact with a recording medium, in which a portion 32 of the slider including the head element can be moved in a minute range in the tracking direction and the loading and unloading direction and is supported by a stationary section 31 forming a slider body via a support spring 34, a leading wire 22 drawn out from the head element 43 is formed in the process of manufacturing the slider so that the motions of the movable section 32 of a microactuator with respect to the stationary section 31 are not obstructed. The lead wire 22 drawn out from the head element 43 mounted on the movable section 32 is composed of a flexible lead wire 22, the rigidity of which is lower than that of the support spring 34, and a leading wire (which is a flexible lead wire 22) is drawn from the movable section to the stationary section so that the movement of the movable section with respect to the stationary section is not restricted.

Abstract: A head suspension supporting a head at the tip end is allowed to swing at the tip end of a carriage in a recording disk drive. A microactuator is interposed between the head suspension and the carriage. A resistor is connected to the microactuator in serial. The microactuator is allowed to function as a capacitance. A combination of the microactuator and the resistor enables establishment of a so-called low pass filter. A high frequency noise involuntarily introduced in the driving voltage for the microactuator can be eliminated or removed from the driving voltage. Elimination of the high frequency noise enables a reliable prevention of the mechanical or physical resonance or vibration in the head suspension. A tracking action of the head related to a target recording track can reliably be stabilized.

Abstract: A method of electroplating using a photoresist layer on a conductive seed layer. The photoresist layer defines a column-shaped space. Ridges are formed on the wall surfaces of the photoresist layer surrounding the column-shaped space. The ridges extend from the conductive seed layer to the opening of the column-shaped space. The electrolytic solution drives bubbles out of the column-shaped space, so that the column-shaped space is filled with the electrolytic solution without any cavities. In addition, if hydrogen bubbles are generated in the column-shaped space, the electrolytic solution serves to drive the hydrogen bubbles out of the column-shaped space along the corners of the column-shaped space.

Abstract: An adsorptive tangential force is measured at the moment when a slider has contacted or touched a receiving surface. The adsorptive tangential force is induced solely by the adsorption transmitted from the receiving surface to the slider. An overall tangential force transmitted from the receiving surface to the slider is measured when the slider is kept urged against the receiving surface. The coefficient of dynamic friction is calculated based on the differential between the thus measured overall and adsorptive tangential forces. The effect of the adsorption can be eliminated from the calculated coefficient of dynamic friction. It is possible to derive the coefficient of dynamic friction at a still higher accuracy.

Abstract: A thin film magnetic head slider has a media opposing surface which is adapted to be opposed to a recording medium, and includes a sacrificial layer, on a substratum that has a surface for forming the media opposing surface having at least one rail. A tracking mechanism or loading/unloading mechanism can be provided on the slider. An electrostatic actuator suitable for driving such a mechanism includes a stationary section having a plurality of teeth parallel to each other, a movable section having a plurality of teeth parallel to the teeth of the stationary section, a support spring for supporting the movable section so that the movable section can be moved with respect to the stationary section in the tooth width direction.

Abstract: In a method for forming a horizontal head slider having a media opposing surface flying above or coming into contact with a recording medium, a film-like surface of a head for recording/reproducing information provided in parallel to the media opposing surface, and a rail portion provided on the media opposing surface for generating a pressure for ensuring stable flying or contact. The rail portion has a planar portion and a taper portion, and all of the shaping accuracy of the bottom surface of the slider and the rail, the adhesive property to a sacrificial layer overlaid thereon and the surface smoothness of the rail surface are enhanced. When the rail portion is formed, a part of mold for the planar portion is prepared by a metallic layer 2 and a mold for the taper portion is prepared by a photoresist layer 3, and a sacrificial layer 4, a media opposing surface layer 6 and a slider body layer 6 are formed thereon in this order.

Abstract: A compact and simple lapping apparatus in which, even if projections and depressions are formed in the circumferential direction on the top surface of a lapping plate, a workpiece and a bar are hard to damage and the polished surface of the workpiece is kept in good condition. This apparatus is provided with at least one lapping jig in which a workpiece is placed on the rotating top surface of the lapping plate. Further, a lapping head adapted to be able to rotate only in a direction on the lapping plate is attached to this lapping jig. This lapping head is equipped with a workpiece and at least two dummy work materials (or stock) so that these dummy works compose (as-polished) surfaces, which should be polished, together with the workpiece. Moreover, a device for detecting the remaining part of the workpiece to be lapped is provided on the workpiece.