EP0051283A1 — Optical recording medium and method for its forma…

Claim 1

Independent Claim 113 words

A recording medium for use in a recording apparatus, wherein a writing beam of light having a prescribed intensity that varies in accordance with an information signal to be recorded is directed at the medium as the medium is moved with respect thereto, said medium comprising: a substrate having a smooth upper surface and a thin recording layer overlaying the upper surface of the substrate, said layer including a nitrated dye material; wherein as the medium is moved with respect to the intensity-modulated writing beam, the recording layer is selectively energized by the beam to induce spaced explosions therein, whereby corresponding pits representative of the information signal are formed in the recording layer.

Claim 2

Dependent Claim 113 words

A recording medium for use in a recording apparatus, wherein a writing beam of light having a prescribed intensity that varies in accordance with an information signal to be recorded is directed at the medium as the medium is moved with respect thereto, said medium comprising: a substrate having a smooth upper surface and a thin recording layer overlaying the upper surface of the substrate, said layer including a nitrated dye material; wherein as the medium is moved with respect to the intensity-modulated writing beam, the recording layer is selectively energized by the beam to induce spaced explosions therein, whereby corresponding pits representative of the information signal are formed in the recording layer.

Claim 3

Dependent Claim 19 words

A recording medium as defined in claim 1, wherein the nitrated dye material is derived from an azo dye.

Claim 4

Dependent Claim 38 words

A recording medium as defined in claim 2, wherein: the beam of light has a prescribed wavelength; and the azo dye has a melting point below about 270°C and is relatively highly absorptive of the beam of light.

Claim 5

Dependent Claim 15 words

A recording medium as defined in claim 2, wherein the azo dye is ANAPLAST-SCARLET MM.

Claim 6

Dependent Claim 16 words

A recording medium as defined in claim 1, wherein the nitrated dye material is a polymer.

Claim 7

Dependent Claim 17 words

A recording medium as defined in claim 1, wherein the light-absorbing coating further includes a dye material.

Claim 8

Independent Claim 132 words

A method for producing a recording medium suitable for use in an optical recording apparatus of a type that directs onto the medium a writing beam of light that is modulated in intensity in accordance with information to be recorded, to produce a sequence of spaced indicia representative of the information, the method including steps of: providing a substrate having a smooth, planer upper surface; nitrating a prescribed amount of dye material to produce a nitrated dye material; dissolving the nitrated dye material in a solvent,.to produce a solution having a prescribed viscosity; dispensing the solution onto the upper surface of the substrate; and spinning the substrate at a prescribed angular velocity, to evaporate the solvent and yield a thin, uniform nitrated dye recording layer on the upper surface of the substrate.

Claim 9

Independent Claim 132 words

A method for producing a recording medium suitable for use in an optical recording apparatus of a type that directs onto the medium a writing beam of light that is modulated in intensity in accordance with information to be recorded, to produce a sequence of spaced indicia representative of the information, the method including steps of: providing a substrate having a smooth, planer upper surface; nitrating a prescribed amount of dye material to produce a nitrated dye material; dissolving the nitrated dye material in a solvent,.to produce a solution having a prescribed viscosity; dispensing the solution onto the upper surface of the substrate; and spinning the substrate at a prescribed angular velocity, to evaporate the solvent and yield a thin, uniform nitrated dye recording layer on the upper surface of the substrate.

Claim 10

Dependent Claim 43 words

A method as defined in claim 7, wherein: the dye material used in the step of nitrating is an azo dye; and the step of nitrating includes a preliminary step of dissolving the dye material in an alcohol, to produce a dye slurry.

Claim 11

Dependent Claim 82 words

A method as defined in claim 8, wherein the step of nitrating further includes steps of: preparing an acid solution of nitric acid and sulphuric acid; mixing together the acid solution and the dye slurry, to form an acid slurry mixture; cooling the mixture to prevent localized overheating caused by a chemical reaction between the acid solution and the dye slurry; quenching the chemical reaction by adding water to the mixture, thereby precipitating the nitrated dye; and purifying the precipitated nitrated dye.

Claim 12

Dependent Claim 35 words

A method as defined in claim 7, wherein the nitrated dye produced in the step of nitrating is a polymer, thereby facilitating the formation of a thin, uniform recording layer in the step of spinning.

Claim 13

Dependent Claim 16 words

A recording medium as defined in claim 1, wherein said surface of said substrate is reflective.

Claim 14

Dependent Claim 21 words

A method as defined in claim 7, and further including the step of providing a substrate having a reflective upper surface.

Optical recording medium and method for its formation

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