Abstract: An information recording medium has a substrate and a recording layer on the substrate, the recording layer is partially transformable between a crystalline state and an amorphous state by being partially heated and cooled so that a signal is recorded in the recording layer by the partial transformation, and the recording layer includes oxygen.

Abstract: A magneto-optical recording head comprises a magnetic coil formed on a lower surface of a transparent substrate opposed to a magneto-optical disk. A heat sink layer is provided at the outside of the magnetic coil on the lower surface. An objective lens is supported on an upper surface of the transparent substrate. The heat, which is generated by the magnetic coil, is released via the heat sink layer to the space between the magneto-optical disk and the substrate. The release of the heat is facilitated by the air stream which is generated by the rotation of the magneto-optical disk. The heat can be effectively released from the magnetic coil without inhibiting optical characteristics of the objective lens.

Abstract: An information recording medium having recording, reproducing, and rewriting characteristics better than those of prior art media. The media has a recording layer made of a material represented by the following formula: Gex−wSbyTezMw, wherein 0.13≦x≦0.22, 0.20≦y≦0.32, 0.53≦z≦0.60, 0≦w≦0.06, x+y+z=1, and M is any one of Na, Mg, Al, P, S, Cl, L, Ca, Sc, Zn, Ga, As, Se, Br, Rb, Sr, Y, Zr, Nb, Ru, Rh, Cd, In, Sn, I, Cs, Ba, La, Hf, Ta, Re, Os, Ir, Hg, Tl, Pb, Th, U, Ag, Cr, W, Mo, Pt, Co, Ni, Pd, Si, Au, Cu, V, Mn, Fe, Ti and Bi.

Abstract: In an optical disk for high density recording as DVD-RAM, for preventing the deformation of recording tracks caused by stress which may develop between the substrate and the recording stacked film formed thereon, a stress-compensation layer which comprises a metal element as Ti or Cr as the main component and has a property to undergo contraction (tensile stress) is provided, thereby to compensate the compression stress which develops in the stacked film owing to contraction of substrate surface during cooling after the thermal expansion of the substrate surface which occurs at the time of film formation and. To impart the property to contract to the layer, the layer is made to have a pillar-like structure which, starting from the lower face, reaches the upper face of the film.

Abstract: A high-density information recording medium free from lowering the reflectance by over-write of a large number of times and exfoliation defect in a structure for suppressing cross-erase. This medium includes, over a substrate having a groove shape, a recording layer, and three-layered thin films of a first interference layer, a second interference layer and an interface layer having mutually different compositions and disposed on a laser beam incidence side of the recording layer in order named from the laser beam incidence side. The first interference layer has a smaller refractive index and a larger thermal conductivity than the second interference layer, the interface layer is interposed between the second interference layer and the recording layer, and a distance between the first interference layer and the recording layer is greater than at least a groove depth.

Abstract: Disclosed is a phase-change optical recording medium which has a reflectance and a signal modulation conformed to the CD standard, and which is usable for recording at the same linear velocity as the reproducing velocity specified in the CD standard. The phase-change optical recording medium comprises a metallic layer, a first protective layer, a recording layer, a second protective layer, and a reflecting layer on a substrate, in which recording is performed through change from a crystalline state to an amorphous state in the recording layer. The recording layer comprises a recording material of a Ge--Te--Sb--Se system, and the recording layer has an average composition in a direction of thickness which satisfies the following relations as represented by atomic %:Ge.gtoreq.40%, and Sb+Se.ltoreq.

Abstract: By using an information recording medium comprising at least a substrate and an information recording film which is mounted on the above substrate and changes the physical property under irradiation of a recording energy beam, wherein the surface of the information recording area of the above substrate is uneven, both surfaces of the above recording film are also uneven, and an inorganic protective layer is provided in contact with the surface of the above recording film opposite to the above substrate, fine recording points can be formed stably without complicated control of the recording power and recording waveform so that an optical disk unit can record data simply in high density.