Hitachi Maxell, Limited

Yoji Takeuchi

Kenji Sumiya

Toshio Oshima

Masayuki Yamada

Shigeo Aoyama

Yoshinori Yamamoto

Tsunemi Ohiwa

Ryuzo Fukao

Hisao Kanzaki

Masato Nishida

Taiji Matsumoto

Akihiko Itoh

The present invention provides an infrared fluorescent substance comprising a component represented by general formula AQO.sub.3 :X (A is at least one element selected from the group consisting of Ca, Sr and Ba, Q is Ti or Zr, and X is at least one element selected from the group consisting of Nd and Yb), and optionally comprising component Y (Al, Ga or In) and/or component Z (Sc, Y, Gd, Bi, Lu or La). Said fluorescent substance is free from the faults of phosphate type fluorescent substances, namely high price and deep blue color, and is low in price, light in blue color, and high in durability.

Fluorescent substance

The invention provides a phosphor excited by infrared rays to emit infrared rays which has a nonacicular particle shape and a particle size of 4 .mu.m or smaller after being synthesized. The phosphor preferably comprises an oxoacid salt-containing compound including at least one element selected from the group consisting of Nd, Yb and Er. The invention further provides a material having a latent image pattern comprising said phosphor and an optical reading system which use the material having a latent image pattern.

Infrared phosphor and material having latent images and optical reading

Latent image forming member and method of manufacturing, latent image

A magnetic recording medium comprising a substrate and a magnetic layer coated on the substrate which comprises a magnetic powder and a binder resin, wherein said binder resin comprises a modified polymer selected from the group consisting of a polymer having a backbone chain comprising a vinyl chloride/vinyl acetate/vinyl alcohol terpolymer and a polymer having a backbone chain comprising polyurethane to both of which a phosphoric acid group of the formula: ##STR1## wherein A is a hydrogen atom, an alkali metal atom or a hydrocarbon group, and n is 0 or 1 is bonded, the magnetic layer having improved surface smoothness, improved durability and excellent electromagnetic conversion characteristics particularly in the short wavelength range.

Magnetic recording medium

A magnetic recording medium comprising a substrate, a magnetic layer formed on one surface of the substrate and a back coating layer formed on the other or back surface of the substrate, wherein the back coating layer contains at least one polyfluoropolyether having a polar group at least one molecular end and optionally at least one fluorine-containing solid lubricant, which has a small coefficient of friction and improved jitter characteristics, durability and corrosion resistance.

A magnetic recording medium improved in corrosion resistance and enhanced in running stability, which comprises a non-magnetic support, a magnetic layer provided on one surface (i.e. the major surface) of the support and a back coat layer provided on the other surface (i.e. the back surface) of the support, the magnetic layer comprising magnetic metal and the back coat layer comprising a salt formed between a nitrogen-containing heterocyclic compound and an aliphatic amine.

Growing community of inventors

Toride, Japan

Yoji Takeuchi