Hitachi Maxell, Limited

Maxell Holdings, Ltd.

Fujifilm Corporation

Shinji Kawakami

Sadamu Kuse

Toshio Kawakita

Masao Fujita

Kenji Tanaka

Toshio Hiroi

Shinji Tsujimoto

Hisanobu Mikamo

Masanori Yamasaki

Hitoshi Tsukamoto

Hidekazu Kawatoko

Makoto Shiokawa

The magnetic recording medium disclosed in the present application includes a non-magnetic support, an undercoat layer, a magnetic layer containing magnetic particles, and a back coat layer. The coercive force Hc of the magnetic layer in the thickness direction at 25&#xb0; C. is not 4100 oersteds (Oe) or more, and the coercive force Hc of the magnetic layer in the thickness direction at a temperature between 55&#xb0; C. and 80&#xb0; C. inclusive is not less than 1200 oersteds (Oe) and not more than 3700 oersteds (Oe).

Coating-type magnetic recording medium for heat-assisted recording, and heat-assisted magnetic recording apparatus and heat-assisted magnetic recording method using the same

The magnetic recording medium includes a non-magnetic substrate, a non-magnetic layer, and a magnetic layer, wherein the magnetic layer contains a hexagonal strontium ferrite magnetic powder, Mr and t satisfy 0.0020 &#x3bc;T&#xb7;m&#x2264;Mr&#xb7;t&#x2264;0.0150 &#x3bc;T&#xb7;m, where Mr is the residual magnetic flux density of the magnetic layer, and t is the average thickness of the magnetic layer, Lsatisfies 2 nm&#x2264;L&#x2264;6 nm, where Lis the average thickness of a first mixed layer that is formed on the surface of the magnetic layer opposite to the non-magnetic layer, Lsatisfies 0.1&#x2264;L/t&#x2264;0.45, where Lis the average thickness of a second mixed layer that is formed on the surface of the magnetic layer facing the non-magnetic layer.

Magnetic recording medium

A refractive index nL and an attenuation rate kL of a magnetic layer are obtained by irradiating linearly polarized light at an irradiation angle of 70&#xb0; from a lengthwise direction of the magnetic layer to the surface of the magnetic layer, and a vertical reflectance RL during vertical incidence of the linearly polarized light in the lengthwise direction is obtained based on nL and kL. A refractive index nT and an attenuation rate kT of the magnetic layer are obtained by irradiating linearly polarized light at an irradiation angle of 70&#xb0; from a width direction of the magnetic layer to the surface of the magnetic layer, and a vertical reflectance RT during vertical incidence of the linearly polarized light in the width direction is obtained from nT and kT. If a variation rate A (%) of RL and RT is A=|RL/RT&#x2212;1|&#xd7;100, the relationship A&#x2264;10% is established.

High recording density magnetic recording medium and recording/reproduction mechanism for the same

In a magnetic recording medium according to the present invention, if a straight line W having a length of 500 nm and a width of 15 nm is displayed parallel to a width direction of the magnetic layer and a straight line L having a length of 500 nm and a width of 15 nm is displayed parallel to a longitudinal direction of the magnetic layer, the number of magnetic particles that intersect the straight line W is N1, and the number of magnetic particles that intersect the straight line L is N2, then, a relationship of N1/0.5&#x3e;60 and N2/0.5&#x3e;60 is established where N1/0.5 is the number of magnetic particles per micrometer obtained by dividing N1 by 0.5 &#x3bc;m and N2/0.5 is the number of magnetic particles per micrometer obtained by dividing N2 by 0.5 &#x3bc;m.

A magnetic recording medium of the present invention includes a non-magnetic substrate, and a magnetic layer containing a magnetic powder. The magnetic powder is constituted by an &#x3b5;-iron oxide powder. The magnetic layer has a squareness in a thickness direction of 0.65 or more. In a differential curve obtained by differentiating a hysteresis curve in the thickness direction of the magnetic layer, two or more peaks are present. In a case where, out of peaks in the same direction among the above-described peaks, a local maximum of a largest peak in a magnetic field range of +500 oersted [Oe] or more is taken as Pand a local maximum of a largest peak in a magnetic field range of &#x2212;500 oersted [Oe] or more and less than +500 oersted [Oe] is taken as P, a relationship below is satisfied:0.25&#x2264;2/1&#x2264;0.60.

Magnetic recording medium using &#x3f5;-iron oxide particle magnetic powder

The magnetic recording medium of the present invention comprises: a non-magnetic substrate; a non-magnetic layer formed on one of principal surfaces of the non-magnetic substrate; and a magnetic layer formed on a principal surface of the non-magnetic layer opposite to the non-magnetic substrate. Mr and t satisfy 0.0020 &#x3bc;T&#xb7;m&#x2266;Mr&#xb7;t&#x2266;0.0150 &#x3bc;T&#xb7;m, where Mr is the residual magnetic flux density of the magnetic layer, and t is the average thickness of the magnetic layer, Lsatisfies 2 nm&#x2266;L&#x2266;6 nm, where Lis the average thickness of a first mixed layer that is formed on the surface of the magnetic layer opposite to the non-magnetic layer, and Lsatisfies 0.1&#x2266;L/t&#x2266;0.45, where Lis the average thickness of a second mixed layer that is formed on the surface of the magnetic layer facing the non-magnetic layer.

A method for manufacturing a magnetic recording medium of the present invention includes a magnetic layer forming step in which a drying process is performed. The drying process includes: a pre-heating stage in which a magnetic coating film is heated until the surface temperature of the magnetic coating film stops rising and reaches a substantially constant temperature; a constant rate drying stage that is performed after the pre-heating stage in which the surface temperature of the magnetic coating film is held substantially constant; and a falling rate drying stage that is performed after the constant rate drying stage in which the surface temperature of the magnetic coating film is increased to be higher than the surface temperature during the constant rate drying stage to harden the magnetic coating film. The constant rate drying period in which the constant rate drying stage is performed is 0.2 seconds or more. The first solvent is made of one solvent or two or more solvents having different boiling points, and the difference (T&#x2212;T) between the boiling point Tof the solvent having the lowest boiling point among the solvents contained in the first solvent and the surface temperature Tof the magnetic coating film during the constant rate drying period is 1 to 50&#xb0; C.

Magnetic recording medium and method for manufacturing the same

The present invention provides a magnetic head that can sustain favorable head contact even when magnetic tapes having different thicknesses are used. A magnetic head has a sliding surface coming in contact with a moving magnetic tape. An electromagnetic transducing element is disposed in the sliding surface. First edges are formed at each end of the sliding surface in the direction of movement of the magnetic tape. Second edges are formed in positions extended in the direction of movement of the magnetic tape from each end of the sliding surface and come in contact with the magnetic tape.

Magnetic tape head with limited ranges of tape wrap angle and distance between first and second edges

A servo controlling method of the present invention is a servo controlling method for controlling a position of a magnetic head against a magnetic tape that is accommodated in a cartridge and has at least a data track and a servo track, and the method includes the steps of: reading tape variance information from a magnetic tape cartridge () side, the magnetic tape cartridge () being composed of a cartridge () and a magnetic tape (); reading a servo signal recorded in the servo track by the magnetic head and converting the servo signal into head position information; and controlling the position of the magnetic head according to an off-track value based on the tape variance information and an off-track value calculated from the head position information. With this configuration, even in the case where a recording track width is narrowed and a tape speed is increased, the magnetic head can follow a recording track accurately at a high speed.

Servo controlling method, recording/reproducing apparatus, magnetic tape, and magnetic tape cartridge

The present invention provides a recording and reproducing apparatus that can perform high-precision tracking servo control by removing noise from detected servo signals. The recording and reproducing apparatus performs tracking servo control while reading servo signalsthat are formed on a surfaceof a recording mediumso as to produce optical contrast, the apparatus including a modulated irradiatorfor irradiating the servo signalswith a light beam, the intensity of the light beam being modulated by a modulating wave that is frequency-modulated; a photoelectric converterfor converting reflected light from the servo signalsinto electric signals; and a synchronous demodulatorfor subjecting the electrical signal to synchronous demodulation using the modulating wave as a reference wave.

Recording and reproducing apparatus and recording medium

In the apparatus and method of the invention, a servo signal reproduction unit generates a PES from a servo signal reproduced from a magnetic tape, and a frequency conversion unit performs FFT processing of the PES to generate frequency component information. Then, a filter value generation unit generates filter values based on the frequency component information and writes these to a memory. When recording various data signals to the magnetic tape, the filter values are read from the memory and a control filter serving as a notch filter is incorporated into a feedback control for a tracking servo. This enables periodic and narrow-band noise to be removed from a PES, consequently reducing PESs. Accordingly, learning-type optimum notch filter control that allows a magnetic head to follow recording tracks at high speed and with high precision is possible even when the recording track width is reduced and the tape speed is increased.

Servo signal recording apparatus, information recording apparatus, and tracking servo method

A magnetic head assembly of the present invention includes a head rail having a plurality of head element portions each including a MR element and sliding portions that come into contact with a magnetic tape, and a protective film on a magnetic tape sliding surface of the head element portions and the sliding portions, wherein the protective film is formed in a portion other than the vicinity of both ends of the head rail in a traveling direction, and an outermost surface of the protective film, on which a magnetic tape is capable of sliding, is formed flat. Thus, a magnetic head assembly used in a magnetic tape apparatus can be provided, in which an output does not decrease due to the abrasion deformation of the head element portions and the increase in spacing by the adhesion of stain.

Magnetic head assembly and magnetic tape driving apparatus

A servo signal recording apparatus of the present invention is provided with a tape motion measurement unitthat measures the lateral motion of a magnetic tape, and outputs tape motion information, a signal processing unitthat generates a servo signal that includes the tape motion information output from the tape motion measurement unit, and a servo signal recording headthat records the servo signal generated by the signal processing unitto the magnetic tape. The tape motion measurement unitmeasures the tape motion prior to the timing at which a servo signal is recorded to the magnetic tapeby the servo signal recording head, and records a servo signal that includes the tape motion information. This configuration enables a servo signal that can be used to perform tracking servo at high speed and with high accuracy to be written to a magnetic tape.

Growing community of inventors

Osaka, Japan

Shinji Kawakami