Abstract: A polymer clad optical fiber is provided in which, if the diameter of an inner core is taken as a1, and the diameter of an outer core is taken as a2, and if a ratio X (which=a22/a12) between a cross-sectional area of the inner core and a cross-sectional area of the outer core is within a range of 1.8?X?2.2, and if a relative refractive index difference between the inner core and the outer core is taken as ?1, and if a relative refractive index difference between the outer core and a cladding is taken as ?2, then for a parameter Y which is defined as Y=?1/?2, when a high temperature is taken as Ymax and a low temperature is taken as Ymin, a relationship is established in which, when X is within a range of 1.8?X?2.0, then 0.25?Ymin?0.84X?0.68, and Ymax is 0.25?Ymax?0.84X?0.68, and, when X is within a range of 2.0?X?2.2, Ymin is 0.48X?0.71?Ymin??2/9X+13/9, and Ymax is 0.48X?0.71?Ymax??2/9X+13/9.

Abstract: A drawing method for a bare optical fiber, comprises the steps of: melting an optical fiber preform using a heating device and drawing the bare optical fiber; and naturally cooling down the bare optical fiber or forcibly cooling down the bare optical fiber by a cooling device after the heating and melting step, wherein a temperature history during the drawing the optical fiber preform to obtain the bare optical fiber in the heating device satisfies a relational expression: T??0.01X+12 where a time period when the heated and molten portion of the optical fiber preform heated and molten by the heating device reaches 1800° C. or higher is T (min) and a OH group concentration in a cladding layer of the optical fiber preform is X (wtppm).

Abstract: A method of producing an optical fiber preform by heating a glass preform that has a glass rod and a silica glass porous body and includes a valid portion and invalid portions, comprising: heating the glass preform while moving the glass preform along its axial direction relative to a heater; stopping the relative movement or decreasing a speed of the relative movement when an invalid portion positioned at a tail end reaches a vicinity of the heater; heating the invalid portion for a predetermined time while maintaining a temperature at which the silica glass porous body can be vitrified; decreasing the heating temperature to a temperature determined by adding 200° C. to an annealing point of a silica glass; and removing the glass preform to the outside of the heating furnace without increasing the heating temperature to the temperature at which the silica glass porous body is vitrified.

Abstract: A method of producing an optical fiber preform comprising: performing production of a glass preform having a valid portion to be drawn to an optical fiber and invalid portions disposed to both ends of the valid portion by depositing a porous silica glass body on a periphery of a glass rod; and performing vitrification of the porous silica glass body by heat treating the glass preform, wherein, during the vitrification, at least a portion of the porous silica glass body in the invalid portion of at least one end is dislocated relative to the glass rod along the axial direction of the glass rod such that a stress between the glass rod and the porous silica glass body is relaxed.

Abstract: An optical fiber twisting apparatus that prevents line distortion in an optical fiber undergoing a drawing process and provides a consistent coating on a bare optical fiber. This optical fiber twisting apparatus includes a twist roller apparatus that having a twist roller that, by imparting a twist to an optical fiber, imparts a twist to a molten portion of an optical fiber preform positioned on an upstream side of the optical fiber, and a support portion that supports the twist roller. The accuracy of the outer circumference of the twist roller when the twist roller is forming a part of the twist roller apparatus is 15 ?m or less.

Abstract: A file is transferred directly between a parent magnetic-disk device and a child magnetic-disk device. In one embodiment, a parent magnetic-disk device has a host-mode execution program, whereas a child magnetic-disk device is capable operating in a device mode as is the case with an ordinary magnetic-disk device. The parent magnetic-disk device has an operating-mode-setting unit including a special-purpose jumper block. An MPU employed in the parent magnetic-disk device executes the host-mode execution program to put the parent magnetic-disk device in a host mode. At an activation time, the MPU refers to the logic of the special jumper block to start an operation in the host mode. The MPU controls the parent magnetic-disk device to directly transfer a file to the child magnetic-disk device. Thus, the file can be transferred between the parent and child magnetic-disk devices without intervention by a host computer.

Abstract: A rare-earth doped optical fiber that includes a core and one or more clad layers surrounding the core, in which the core has a rare earth dopant, and a relationship of Equation (1) is satisfied: 0 < ? r 0 r c ? D ? ( r ) · P p 2 ? ( r ) · P s 2 ? ( r ) ? r ? ? ? r ? r 0 r c ? D ? ( r ) · P p 2 ? ( r ) ? r ? ? ? r ? 0.35 ( 1 ) where Pp(r) represents an electric field distribution in an exciting wavelength, Ps(r) represents an electric field distribution in wavelengths of spontaneous emission and/or stimulated emission carried in the core, D(r) (mass %) represents a rare-earth dopant distribution, ro represents a core center, and rc represents a core diameter.

Abstract: A polymer clad optical fiber is provided in which, if the diameter of an inner core is taken as a1, and the diameter of an outer core is taken as a2, and if a ratio X (which=a22/a12) between a cross-sectional area of the inner core and a cross-sectional area of the outer core is within a range of 1.8?X?2.2, and if a relative refractive index difference between the inner core and the outer core is taken as ?1, and if a relative refractive index difference between the outer core and a cladding is taken as ?2, then for a parameter Y which is defined as Y=?1/?2, when a high temperature is taken as Ymax and a low temperature is taken as Ymin, a relationship is established in which, when X is within a range of 1.8?X?2.0, then 0.25?Ymin?0.84X?0.68, and Ymax is 0.25?Ymax?0.84X?0.68, and, when X is within a range of 2.0?X?2.2, Ymin is 0.48X?0.71?Ymin??2/9X+13/9, and Ymax is 0.48X?0.71?Ymax??2/9X+13/9.

Abstract: An optical fiber is formed by performing vapor phase deposition of SiO2 on the outside of a glass rod comprising a core section and a first cladding section and drawing a glass preform which formed by a second cladding section. Also, a single mode optical fiber is manufactured so that the ratio of the diameter D of the first cladding section and the diameter d of the core section is in a range of 4.0 to 4.8, and OH concentration is 0.1 ppm or less. Also, an optical fiber is manufactured so that a value of D/d>4.8, and the OH concentration is 0. 1 ppm or less. It is thereby possible to maintain an initial loss in the 1380 nm wavelength range even if hydrogen diffusion occurs.

Abstract: Embodiments of the invention relate to writing servo patterns onto a recording disk with a high degree of accuracy and with correct phases in a servo-pattern-writing process. An In-Drive SSW (TSSW) process is processing to write product servo patterns onto a recording disk on the basis of time aligned patterns. In the processing to write product servo patterns onto a recording disk, time intervals between time aligned patterns already written on an ID-side track are measured, and timings to write the product servo patterns onto the recording disk on the basis of the measured time intervals are determined. Product servo patterns are then written onto an OD-side track with the determined timings relative to detections of the time aligned patterns used as references. In this way, circumferential-direction positions of product servo patterns written on a track may be aligned to the corresponding circumferential-direction positions of product servo patterns written on an adjacent track.

Abstract: Embodiments of the invention relate to measuring characteristics of a head with an actuator put in a state of being pushed against a crush stop. In one embodiment, with a head placed on an innermost ID side or with the current of a VCM sustained at a magnitude I_mid, a burst pattern is written onto a recording disk. At this stage, the gain of a VGA is equal to its maximum value Gmax. Then, while the current of the VCM is being changed gradually, the gain of the VCA is measured. As the current of the VCM becomes equal to a magnitude I_center, a read element of the head is positioned right above the burst pattern. At that time, the gain of a VGA is equal to its minimum value Gmin. As the read element is further moved to the OD side, the gain of the VGA again becomes equal to the maximum value Gmax. A read/write offset of the head is identified by the magnitudes I_center and I_mid.

Abstract: The present invention provides a composition for on-site forming gaskets, which has excellent heat resistance, weather resistance, oil resistance, curability, compression set, and the like, a gasket, and (meth)acrylic acid and a curable composition thereof. Specifically, the present invention provides a composition for on-site forming gaskets containing a vinyl polymer with a (meth)acryloyl group at a molecular end as an essential component, and a gasket, a cured product of the composition exhibiting predetermined compression set. Also, the present invention provides a (meth)acrylic polymer having a (meth)acryloyl group at a molecular end and a curable composition thereof, a cured product exhibiting high oil resistance.

Abstract: Embodiments of the invention provide a disk drive that may perform part of a function assignment process without being connected to a special test apparatus. In one embodiment, servo data is written only into dedicated regions of a disk. A function assignment program is stored within the dedicated regions. When a processor is powered on, the processor refers to a state setter and judges whether the function assignment program is to be executed. The state setter is constituted by a nonvolatile memory or a jumper block. The function assignment program includes data relating to servo data writing based on a self-servo writing scheme, and data relating to parameter setup.

Abstract: Embodiments of the invention provide a hard disk drive that is capable of performing degaussing promptly and properly and a recording method for use with such a hard disk drive. A hard disk drive according to one embodiment of the present invention comprises a current source for supplying a first current, which flows to a write head for writing data onto a magnetic disk; a current source for supplying a second current, which flows to the write head when the polarity of the first current changes; transistors for reversing the polarity of a current flowing to the write head; and a control circuit for exercising control so that the second current I2, which flows from the current source to the write head when the polarity of the first current I1 is reversed, becomes approximately zero before the first current I1 converges to approximately zero during a degauss period.

Abstract: Embodiments of the invention relate to writing servo patterns having aligned phases onto a recording disk in a process to write the servo patterns onto the disk. In one embodiment, time aligned patterns are written onto a magnetic disk on the basis of time intervals between base patterns with timings aligned to each other throughout tracks on the disk. The time aligned patterns are written onto typically servo tracks at time intervals Ts with aligned timings. Then, on the basis of these time aligned patterns, product servo patterns are written onto the disk. A time aligned pattern is written onto the disk after the lapse of a predetermined write time period since detection of a base pattern corresponding to the time aligned pattern. The write time period is determined on the basis of time intervals between base patterns on adjacent tracks.

Abstract: The present invention provides a curable composition comprising: (A) a vinyl polymer (I) comprising, at the molecular terminus, at least one group represented by the general formula (1): CH2?C(Ra)—C(O)O—??(1) wherein Ra represents a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, (B) a polymerization initiator, and (C) a metallic soap. The curable composition comprising a vinyl polymer has superior mold release properties without a substantial decrease in mechanical properties such as compression set.

Abstract: In an electronic switch which includes a pair of terminal portions 14, 14, and self arc-suppressing elements Q21, Q22 having a one-way on and off control construction connected in inverse-series between the pair of terminal portions and which turns on and off the self arc-suppressing elements Q21, Q22 with phase control, shunt resistors R51, R52 provided between the pair of terminal portions 14, 14 and connected in series to the pair of self arc-suppressing elements Q21, Q22 and thyristors S71, S72 for extracting the gate voltages applied to gates of the self arc-suppressing elements Q21, Q22 upon driving are provided. Furthermore, thyristors S71, S72 are driven by the voltages across the shunt resistors R51, R52 generated when overcurrent larger than predetermined current flows through the shunt resistors R51, R52.

Abstract: A curable composition having a low viscosity and providing a satisfactory rubber cured article is provided. A composition curable by radical photo curing and cationic photo curing in combination, comprising the under-mentioned components (A), (B), (C) and (D) as essential components: (A) a vinyl polymer having two or more acryloyl group or the like per molecule, the acryloyl groups or the like being present at one or more molecular ends; (B) an epoxy compound and/or an oxetane compound; (C) a radical photopolymerization initiator; and (D) a cationic photopolymerization initiator.

Abstract: An active energy curing type composition for an in-place shaping gasket is provided which is capable of providing an in-place shaped gasket superior in heat resistance, weather resistance, oil resistance, curability, compression set, and the like. An active energy curing type composition for an in-place shaping gasket, comprising the under-mentioned components (A) and (B) as essential components, wherein the viscosity of the composition is 400 Pa·s or less at 23° C. and the compression set of a cured article which is prescribed in JIS K 6262 is 30% or less: (A) a vinyl polymer having two or more (meth)acryloyl groups per molecule at the molecular ends, and (B) a vinyl polymer having one (meth)acryloyl group per molecule at the molecular end.

Abstract: The purpose of the present invention is to provide a natural evaporation type humidifier which has enough humidifying capability and which is less expensive and portable, and a humidify element thereof and a humidify case thereof. One end of a humidify element 12 which has a plurality of humidify segments 24 connected to be free to extend and contract is fixed to a first case portion 28. One end of another humidify element 12 having the same structure is fixed to a second case portion 30. Each other end of the two humidify elements 12 is connected by a connect member 48. An inner space 42 as a water reservoir is formed at the first case portion 28 and the second case portion 30. At the time of non-usage, the first case portion 28 and the second case portion 30 are closed, and the humidify elements 12 and the connect member 48 are stored in the inner space 42. At the time of usage, the first case portion 28 and the second case portion 30 are opened, and the humidify elements 12 are extended.