Abstract: For providing glasses and glass-ceramics having properties suitable for use as a substrate of an information storage medium of next generation such as one for the perpendicular magnetic recording system without employing arsenic and antimony components which adversely affect human beings and the environment, there are provided glass-ceramics comprising SiO2, Li2O and Al2O3 on oxide basis, comprising lithium disilicate as a crystal phase, and comprising one or more elements selected from the group consisting of Sn, Ce, Mn, W, Ta, Bi, Nb, S, Cl and F.

Abstract: In all of an in-plane magnetic recording system and a perpendicular magnetic recording system, there is provided a crystallized glass for a disk substrate for information recording medium, etc., which has satisfactory surface properties capable of sufficiently adapting with a lamp loading system for high-density recording, has high strength such that it is able to withstand high-speed rotation and impact, has heat expansion properties and heat resistance in agreement with respective drive members, has a low melting temperature, has excellent productivity and is reduced in the elution amount of an alkali from the raw material, namely excellent in chemical durability. The crystallized glass of the invention is a crystallized glass containing an SiO2 component and an Li2O component; further containing at least one member selected from an SrO component and a BaO component in a total content of more than 3.

Abstract: An inorganic composition article used in disk substrate for information recording media, with a low melting point and a high productivity, combining superior surface characteristics capable of sufficiently dealing with a ramp load system for high density recording in both an in-plane magnetic recording system and a perpendicular magnetic recording system, having a high mechanical strength capable of enduring high speed rotation and impact, and combining both a heat expansion characteristic and heat resistance corresponding to each drive component. The inorganic composition articles contain a Li2O component and an Al2O3 component, with the percent by mass ratio of Li2O to Al2O3 (Li2O/Al2O3) being at least 0.3, include crystals, and have a compressive stress layer arranged on a surface.

Abstract: Provided are SiO2—Al2O3-based or Li2O—Al2O3—SiO2-based crystallized glass which has various properties intrinsic to the crystallized glass of the type and which contains an arsenic component or an antimony component in an amount as small as possible or does not contain an arsenic component and an antimony component; and a method for producing the crystallized glass. The crystallized glass contains components of SiO2 and Al2O3 (as oxides) and contains an SnO2 component (as oxide) and/or a CeO2 component (as oxide). Preferably, the glass contains from 0.01 to 5.0% (as oxide) of an SnO2 component and/or from 0.01 to 5.0% (as oxide) of a CeO2 component.

Abstract: To provide a substrate for information recording medium having various properties, in particular higher fracture toughness, required for application of the substrate for information recording medium of the next generation such as perpendicular magnetic recording system, etc. and a material with excellent workability for such purpose. A crystallized glass substrate for information recording medium, consisting of a crystallized glass which comprises one or more selected from RAl2O4 and R2TiO4 as a main crystal phase, in which R is one or more selected from Zn, Mg and Fe, and in which the main crystal phase has a crystal grain size in a range of from 0.5 nm to 20 nm, a degree of crystallinity of 15% or less, and a specific gravity of 3.00 or less.

Abstract: For providing glass-ceramics having properties suitable for use as a substrate of an information storage medium of next generation such as one for the perpendicular magnetic recording system without employing arsenic and antimony components which adversely affect human beings and the environment, there are provided glass-ceramics comprising SiO2, Li2O and Al2O3 on oxide basis, comprising lithium disilicate as a crystal phase, and comprising one or more elements selected from the group consisting of Sn, Ce, Mn, W, Ta, Bi, Nb, S, Cl and F.

Abstract: A manufacturing method is provided for manufacturing a substrate for information storage media having various properties that are demanded for a next generation of information storage media substrate purposes exemplified by perpendicular magnetic recording systems, etc., and above all, having high fracture toughness and a smooth surface at low cost. The method of manufacturing a substrate for information storage media includes a step of preparing glass material of a plate shape containing SiO2 component, Al2O3 component, and R?2O component, R? being at least one selected from Li, Na, and K, and the step of lapping includes at least one sub-step of lapping the glass material with a diamond pad.

Abstract: There is provided a glass substrate which has the properties required in the use as a substrate for an information recording medium of the next generation such as a perpendicular magnetic recording system, and can be applied as a substrate for an information recording medium of the next generation particularly on the premise of using the glass substrate in a dynamic environment. More particularly, there is provided a glass substrate for an information recording medium which has sufficiently high surface hardness, has a good balance between specific gravity and mechanical strength, and has high strength to withstand high speed rotation or drop impact, and which can be produced with a high productivity adequate for a direct press method, without the occurrence of bubbles in the glass blank or reboil upon pressing even if arsenic components or antimony components are not substantially used.

Abstract: The present invention provides an inorganic composition for use in information recording medium disc substrate and such, having an excellent surface property capable of sufficiently corresponding with a ramp load system for high density recording, a high degree of tolerability to high speed rotation, and high productivity at a low melting point. Specifically, this invention provides an inorganic composition containing one crystalline phase selected from the group consisting of ?-quartz (?-SiO2), lithium disilicate (Li2Si2O5) and lithium monosilicate (Li2SiO3), or that contain at least a crystalline phase of lithium monosilicate (Li2SiO3), in which a mean particle diameter of a particle showing a crystalline phase contained in the inorganic composition is 1 ?m or less, a ring flexural strength is 300 MPa or more, and a surface roughness (an arithmetic mean roughness) thereof after a polishing process is 10 ? or less.

Abstract: For providing glass-ceramics having properties suitable for use as a substrate of an information storage medium of next generation such as one for the perpendicular magnetic recording system without employing arsenic and antimony components which adversely affect human beings and the environment, there are provided glass-ceramics comprising SiO2, Li2O and Al2O3 on oxide basis, comprising lithium disilicate as a crystal phase, and comprising one or more elements selected from the group consisting of Sn, Ce, Mn, W, Ta, Bi, Nb, S, Cl and F.

Abstract: In all of an in-plane magnetic recording system and a perpendicular magnetic recording system, there is provided a crystallized glass for a disk substrate for information recording medium, etc., which has satisfactory surface properties capable of sufficiently adapting with a lamp loading system for high-density recording, has high strength such that it is able to withstand high-speed rotation and impact, has heat expansion properties and heat resistance in agreement with respective drive members, has a low melting temperature, has excellent productivity and is reduced in the elution amount of an alkali from the raw material, namely excellent in chemical durability. The crystallized glass of the invention is a crystallized glass containing an SiO2 component and an Li2O component; further containing at least one member selected from an SrO component and a BaO component in a total content of more than 3.

Abstract: Glass-ceramics include SiO2, Al2O3 and Li2O on oxide basis. In the glass-ceramics, total amount in mass % of SiO2 and Al2O3 is less than 77% and Li2O/(SiO2+Al2O3) which is the ratio in mass % of the amount of Li2O to the total amount of SiO2 and Al2O3 is 0.064 or over. The glass-ceramics include at least one crystal phase selected from the group consisting of ?-quartz, ?-quartz solid solution, ?-eucryptite, ?-eucryptite solid solution, ?-spodumene and ?-spodumene solid solution.

Abstract: An inorganic composition article used in disk substrate for information recording media, with a low melting point and a high productivity, combining superior surface characteristics capable of sufficiently dealing with a ramp load system for high density recording in both an in-plane magnetic recording system and a perpendicular magnetic recording system, having a high mechanical strength capable of enduring high speed rotation and impact, and combining both a heat expansion characteristic and heat resistance corresponding to each drive component. The inorganic composition articles contain a Li2O component and an Al2O3 component, with the percent by mass ratio of Li2O to Al2O3 (Li2O/Al2O3) being at least 0.3, include crystals, and have a compressive stress layer arranged on a surface.

Abstract: Provided are SiO2—Al2O3-based or Li2O—Al2O3—SiO2-based crystallized glass that solves the cause of cracking and fracture in forming it into large-size shaped articles, that has homogeneous inner quality and that may be produced stably at high efficiency; and a method for producing it. The crystallized glass contains components of SiO2 and Al2O3, wherein the crystal precipitation peak temperature width obtained in differential thermal analysis of amorphous glass, a precursor thereof, is at least 22° C. Preferably, the total amount of the TiO2 component and the ZrO2 component in the crystallized glass is within a range of from 3.0 to less than 4.3%. FIG. 1 is referred to.

Abstract: The present invention provides an inorganic composition for use in information recording medium disc substrate and such, having an excellent surface property capable of sufficiently corresponding with a ramp load system for high density recording, a high degree of tolerability to high speed rotation, and high productivity at a low melting point. Specifically, this invention provides an inorganic composition containing one crystalline phase selected from the group consisting of ?-quartz (?-SiO2), lithium disilicate (Li2Si2O5) and lithium monosilicate (Li2SiO3), or that contain at least a crystalline phase of lithium monosilicate (Li2SiO3), in which a mean particle diameter of a particle showing a crystalline phase contained in the inorganic composition is 1 ?m or less, a ring flexural strength is 300 MPa or more, and a surface roughness (an arithmetic mean roughness) thereof after a polishing process is 10 ? or less.

Abstract: Obtaining previously a relation between a crystallization temperature and a physical property and a relation between a physical property parameter and the physical property of a glass ceramic, measuring the physical property parameter with respect to the glass ceramic sampled from a manufacturing line of the glass ceramic and controlling an actual crystallization temperature based on the relations so that the manufactured glass ceramic has the desired physical property value.

Abstract: An information storage disk holding member for holding an information storage disk in position in an information storage disk drive device, the holding member being made of glass-ceramics in which a crystal phase is dispersed in a glass matrix. The holding member has specific rigidity (Young's modulus/specific gravity) of not greater than 37 GPa, specific gravity of not greater than 3.0, coefficient of thermal expansion within a range from −50° C. to +70° C. which is within a range from +35×10−7/° C. to +130×10−7/° C., Young's modulus within a range from 95 GPa to 130 GPa, specific gravity within a range from 2.40 to 2.60 and bending strength within a range from 400 MPa to 800 MPa.

Abstract: An information storage disk holding member for holding an information storage disk in position in an information storage disk drive device, the holding member being made of glass-ceramics in which a crystal phase is dispersed in a glass matrix. The holding member has specific rigidity (Young's modulus/specific gravity) of not greater than 37 GPa, specific gravity of not greater than 3.0, coefficient of thermal expansion within a range from −50° C. to +70° C. which is within a range from +35×10−7/° C. to +130×10−7/° C., Young's modulus within a range from 95 GPa to 130 GPa, specific gravity within a range from 2.40 to 2.60 and bending strength within a range from 400 MPa to 800 MPa.

Abstract: There are provided glass-ceramics containing, as a predominant crystal phase or phases, at least one selected from the group consisting of &agr;-cristobalite, &agr;-cristobalite solid solution, &agr;-quartz and &agr;-quartz solid solution, containing substantially no lithium disilicate (Li2O·2SiO2), lithium silicate (Li2O·SiO2), &bgr;-spodumene, &bgr;-eucryptite, &agr;-quartz, mica or fluorrichterite, containing substantially no Cr ingredient or Mn ingredient, and having average linear thermal expansion coefficient within a range from +65×10−7/° C. to +140×10−7/° C. within a temperature range from −50° C. to +70° C., said predominant crystal phase or phases having an average crystal grain diameter of less than 0.10 &mgr;m. The glass-ceramics are suitable for use as a substrate for an information storage medium and also for use as a substrate for a light filter.

Abstract: A photographic camera capable of recording additional image comprising: an optical assembly including a lens and a shutter to form an image of a photographed subject on an image recording medium; and an additional image sheet having an additional image comprising a light transmitting part and an opaque part, which is placed in an image forming optical passage between the optical assembly and the image recording medium being closely to or slightly in contact with the image recording medium. The camera is simple, economical and reliable. Any additional image can be easily recorded in desired color and size.