Hitachi Global Storage Technologies Netherlands B.v.

Kanto Kagaku Kabushiki Kaisha

Other

Mitsubishi Gas Chemical Company, Inc.

Jiro Abe

Takayoshi Suga

Hiroshi Uchida

Tetsuo Ueda

Gaku Ikedo

Atsuhiro Tokita

Takeru Horino

Nobuhisa Koide

Toyoji Oshima

Iwao Oshimi

Atsushi Kimoto

Hiroaki Tamashita

Yuki Inagaki

Kazuhiko Tsutiya

Hiroto Nagasawa

A problem is presented in that conventional photochromic compounds cannot be considered adequate in terms of the colorizing/decolorizing rate and durability, and the production process therefore has many steps. The present invention provides an industrially applicable photochromic compound that has both a rapid colorizing/decolorizing reaction and high durability and can also be synthesized at a low cost. This compound is characterized in that etheric oxygen atoms are bonded to the carbon atoms at position 1 of a pyranoquinazoline (8H-pyrano[3,2-f]quinazoline) skeleton and position 10 of a naphthopyran (3H-naphtho[2,1-b]pyran) skeleton, said compound having photochromic properties and being a photochromic compound that has both a rapid colorizing/decolorizing reaction and high durability. Also provided is an industrially applicable photochromic compound that can be synthesized at a low cost.

Pyranoquinazoline derivatives and naphthopyran derivatives

In order to address the problems of conventional photochromic compounds, which are the insufficient coloring/discoloring speed and durability exhibited thereby and the large number of production steps, the present invention provides a photochromic compound that exhibits a high speed coloring/discoloring reaction and high durability while it is able to be synthesized in low cost, and that has industrial applicability. The compound of the present invention is characterized by the insertion of a diarylimidazolyl radical into the ortho position of an aryl group. The compound exhibits photochromic properties, and achieves a photochromic compound having both a high speed color switching reaction and high durability. Furthermore low cost synthesis is possible, and the photochromic compound has industrial applicability.

Pentaarylbiimidazole compound and production method for said compound

Provided are: a method for controlling the decoloration reaction rate and color density of a fast light-modulating material to levels suitable for practical use; and a fast light-modulating material having a decoloration reaction rate and a color density which are suitable for practical use. A polymer obtained by polymerizing a paracyclophane-bridged hexaarylbisimidazole compound having a radical-polymerizable group, and a copolymer obtained by copolymerizing the compound with a (meth)acrylic acid compound or a sensitizer having a radical-polymerizable group can achieve controlled decoloration reaction rates, photosensitivity and color tones.

Photochromic material

A hard-disk drive. The hard-disk drive includes a magnetic-recording disk having a plurality of tracks formed thereon. The hard-disk drive also includes a magnetic-recording head configured to be positioned over a target track selected from the plurality of tracks and configured to write data to and to read data from the target track. Moreover, the hard-disk drive includes a range-definer configured to define an allowed range of a position error of the magnetic-recording head corresponding to the target track. In addition, the hard-disk drive includes a write-enabler configured to determine whether writing data by the magnetic-recording head is allowed based on the position error of the magnetic-recording head with respect to the target track and the allowed range that is calculated from data read out by the magnetic-recording head.

Hard-disk drive, method of controlling the hard-disk drive, and method of manufacturing the hard-disk drive

Embodiments of the present invention provide a magnetic disk device including a spindle motor using a fluid dynamic bearing, which can send back READY within a period requested by a host system at the time of starting a magnetic disk device under low temperature and low supply voltage conditions without a particular heating approach. According to one embodiment, the magnetic disk device sets a waiting time in a period from when a spindle motor reaches a rated speed until when an HSA is loaded to a magnetic disk at the time of starting under low temperature and low supply voltage conditions within such a range that the timeout of the host does not occur, and the spindle motor itself is heated by rotation of the spindle motor in the waiting time to lower viscosity of the lubrication fluid to ensure sufficient voltage margin for an SPM driver.

Method of starting the magnetic disk device using fluid dynamic bearing spindle motor

Growing community of inventors

Kanagawa, Japan

Jiro Abe