Hoya Corporation

Avanstrate Inc.

Hoya Precision Inc.

Nikkiso Company Limited

Hoev Company, Limited

Kazuaki Hashimoto

Koichi Sato

Shin-Ichiro Hirota

Yu Oogami

Naomi Matsumoto

Yoshikazu Hirose

Tetsuo Takano

Xuelu Zou

Akihiro Koyama

Satoshi Ami

Naoyuki Higuchi

Masafumi Miura

Mitsugu Imai

Takashi Watanabe

Hiroaki Yanagita

Osamu Sugihara

Masatomo Shibui

Go Chiwata

Dongna Qin

Robert W Johnson

Mikiko Morishita

Tomoyuki Goto

A glass is an amorphous oxide glass. An SiOcontent ranges from 56 mol % to 80 mol %, an LiO content is 2.00 mol % or less, a BOcontent ranges from 0 mol % to 4 mol %, a total content of MgO and CaO (MgO+CaO) ranges from 9 mol % to 40 mol %, and the oxide glass has a specific gravity of 2.75 g/cmor less, and a glass transition temperature of 650° C. or higher.

Glass for magnetic recording medium substrate or for glass spacer for magnetic recording and reproducing apparatus

Provided is a glass for a magnetic recording medium substrate or for a glass spacer for a magnetic recording/reproducing apparatus, in which a mole ratio of the total content of AlOand MgO relative to the total content of SiOand CaO [(AlO+MgO)/(SiO+CaO)] is in a range of 0.417 or more and 0.6 or less, the total content of SiOand AlO(SiO+AlO) is in a range of 64 mol % or more and 85 mol % or less, the total content of SiO, AlO, MgO, and CaO (SiO+AlO+MgO+CaO) is in a range of 87 mol % or more and 98 mol % or less, the NaO content is 0 mol %, and an average linear expansion coefficient of the glass at 100° C. to 300° C. is 68×10/° C. or less.

Glass for magnetic recording medium substrate or for glass spacer to be used in magnetic recording/reproducing device, magnetic recording medium substrate, magnetic recording medium, and magnetic recording/reproducing apparatus

In an amorphous glass, an SiOcontent is in a range of 56 mol % or more. An MgO content is in a range of 15 mol % or more and 28 mol % or less. An LiO content is in a range of 0.2 mol % or more. An NaO content is in a range of 5 mol % or less. A total content of AlO, MgO, and CaO (AlO+MgO+CaO) is 36.50 mol % or less. The total content of SiO, MgO, LiO, AlO, and CaO (SiO+MgO+LiO+AlO+CaO) is 97.5 mol % or more. A mole ratio of the total content of SiOand MgO relative to the LiO content [(SiO+MgO)/LiO] is 13 or more. A mole ratio of a CaO content relative to a total content of AlOand MgO [CaO/(AlO+MgO)] is 0.10 or less.

Glass for magnetic recording medium substrate, magnetic recording medium substrate, magnetic recording medium, glass spacer for magnetic recording and reproducing apparatus, and magnetic recording and reproducing apparatus

A ring-shaped glass spacer is to be arranged in contact with a magnetic disk in a hard disk drive device. A film that contains at least one of tin oxide, zinc oxide, and titanium oxide is formed on each surface of a main surface, and an outer circumferential edge surface, and an inner circumferential edge surface of the glass spacer. The thickness of the film on a center portion of the outer circumferential edge surface of the glass spacer is larger than the thickness of the film on a center portion of the inner circumferential edge surface of the glass spacer.

Glass spacer and hard disk drive device

A glass for magnetic recording medium substrate is an amorphous oxide glass. In terms of mol %, SiOcontent ranges from 45 to 68%, AlOfrom 5 to 20%, total content of SiOand AlO60 to 80%, BOfrom 0 to 5%, MgO from 3 to 28%, CaO from 0 to 18%, total content of BaO and SrO 0 to 2%, total content of alkali earth metal oxides from 12 to 30%, total content of alkali metal oxides from 3.5 to 15%, and at least one kind selected from the group made of Sn oxide and Ce oxide being included, a total content of Sn oxide and Ce oxide ranges from 0.05 to 2.00%, a glass transition temperature ≥625° C., a Young's modulus ≥83 GPa, a specific gravity ≤2.85, and an average linear expansion coefficient at 100 to 300° C.≥48×10/° C.

Glass for magnetic recording medium substrate, magnetic recording medium substrate, magnetic recording medium and glass spacer for magnetic recording and reproducing apparatus

Provided is a glass for a magnetic recording medium substrate or for a glass spacer for a magnetic recording/reproducing apparatus, in which the total content of LiO, NaO, KO, BO, and ZnO (LiO+NaO+KO+BO+ZnO) is in a range of 0 mol % or more and 3 mol % or less, the mole ratio of the total content of AlOand MgO relative to the total content of SiOand CaO [(AlO+MgO)/(SiO+CaO)] is in a range of 0.30 or more and 0.6 or less, the total content of SiOand AlO(SiO+AlO) is in a range of 64 mol % or more and 85 mol % or less, and the total content of SiO, AlO, MgO, and CaO (SiO+AlO+MgO+CaO) is in a range of 87 mol % or more and 98 mol % or less.

Glass for magnetic recording medium substrate or for glass spacer to be used in magnetic recording/reproducing device, magnetic recording medium substrate, magnetic recording medium, glass spacer to be used in magnetic recording/reproducing device, and magnetic recording/reproducing device

A glass, which is a glass for a magnetic recording medium substrate or for a glass spacer for a magnetic recording and reproducing apparatus, is an amorphous oxide glass. An SiOcontent ranges from 56 mol % to 80 mol %, an LiO content ranges from 1 mol % to 10 mol %, a BOcontent ranges from 0 mol % to 4 mol %, a NaO content is 0 mol %, a total content of MgO and CaO (MgO+CaO) ranges from 9 mol % to 40 mol %, and the oxide glass has a specific gravity of 2.75 g/cmor less, a glass transition temperature of 650° C. or higher, and a Young's modulus of 90 GPa or more.

Glass for magnetic recording medium substrate or for glass spacer for magnetic recording and reproducing

A method for manufacturing a ring-shaped glass spacer to be arranged in contact with a magnetic disk in a hard disk drive device includes processing for forming a film on the surface of a glass spacer main body, which is the base of the glass spacer. In the processing, the film is formed by passing the glass spacer main body through a location where the components of the film are in a spray state while an outer circumferential edge surface of the glass spacer main body is being rotated in a circumferential direction thereof.

Method for manufacturing glass spacer, glass spacer, and hard disk drive device

Provided is a glass for a magnetic recording medium substrate, which is an amorphous glass, in which an SiOcontent is in a range of 54 mol % or more and 62 mol % or less, an MgO content is in a range of 15 mol % or more and 28 mol % or less, an LiO content is in a range of 0.2 mol % or more, and an NaO content is in a range of 5 mol % or less.

A glass for magnetic recording medium substrate is an amorphous oxide glass. In terms of mol %, SiOcontent ranges from 45 to 68%, AlOfrom 5 to 20%, total content of SiOand AlO60 to 80%, BOfrom 0 to 5%, MgO from 3 to 28%, CaO from 0 to 18%, total content of BaO and SrO 0 to 2%, total content of alkali earth metal oxides from 12 to 30%, total content of alkali metal oxides from 3.5 to 15%, and at least one kind selected from the group made of Sn oxide and Ce oxide being included, a total content of Sn oxide and Ce oxide ranges from 0.05 to 2.00%, a glass transition temperature &#x2265;625&#xb0; C., a Young's modulus &#x2265;83 GPa, a specific gravity &#x2264;2.85, and an average linear expansion coefficient at 100 to 300&#xb0; C.&#x2265;48&#xd7;10/&#xb0; C.

Provided is a glass for a magnetic recording medium substrate, which is an amorphous oxide glass, in which an SiOcontent ranges from 56 mol % to 80 mol %, an LiO content ranges from 1 mol % to 10 mol %, a BOcontent ranges from 0 mol % to 4 mol %, a total content of MgO and CaO (MgO+CaO) ranges from 9 mol % to 40 mol %, and the oxide glass has a specific gravity of 2.75 g/cmor less, a glass transition temperature of 650&#xb0; C. or higher, and a Young's modulus of 90 GPa or more.

The disclosed cover glass is produced by etching a glass substrate that has been formed by a down-drawing process, and chemically strengthening the glass substrate to provide the glass substrate with a compressive-stress layer on the principal surfaces thereof. The glass substrate contains, as components thereof, 50% to 70% by mass of SiO, 5% to 20% by mass of AlO, 6% to 30% by mass of NaO, and 0% to less than 8% by mass of LiO. The glass substrate may also contain 0% to 2.6% by mass of CaO, if necessary. The glass substrate has an etching characteristic in which the etching rate is at least 3.7 &#x3bc;m/minute in an etching environment having a temperature of 22&#xb0; C. and containing hydrogen fluoride with a concentration of 10% by mass.

Cover glass and method for producing cover glass

A glass substrate chemically strengthened, includes a primary surface that has a compressive stress layer formed in an uppermost surface layer thereof. The compressive stress layer is configured to enhance strength of the glass substrate due to a compressive stress generated in the compressive stress layer. The compressive layer consists of a layer of a potassium ion concentration equal to or less than 5000 parts per million (ppm).

Glass substrate

A cover glass for use in a mobile device such as a touch-panel mobile telephone has a thickness in the range of, for example, 0.3 mm to 1.5 mm. A recess that can be recognized as a character or a figure when watching from the front side of the mobile device or a recess that can be recognized when touching from the front side of the mobile device is formed on at least one of opposite main surfaces of the cover glass. A surface of this recess is an etched surface treated by etching.

Growing community of inventors

Tokyo, Japan

Kazuaki Hashimoto