Optical Recording Medium Thermal Conductivity Layer Design

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Solution Overview

Problem

Conventional optical information recording media face challenges in high-speed data recording due to rapid heat conduction from the light absorbing layer to the reflective layer, leading to recording errors and high manufacturing costs associated with multiple sputtering or spin coating processes.

Innovation Solution

The solution involves forming a recording medium with a recording layer sandwiched between a support substrate and a light transmitting layer, both with lower thermal conductivity than the recording layer, and a track pitch in the range of 0.1 μm to 0.5 μm, allowing for efficient temperature rise and deformation without rapid heat conduction, and using a single layer recording material with Bi and O as main components to reduce manufacturing complexity and cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a reflective layer with high thermal conductivity is used to reflect the laser beam, then the laser beam can be effectively reflected, but heat is rapidly conducted from the light absorbing layer to the reflective layer, preventing sufficient temperature rise for recording marks

Engineering Contradiction:

Improverecording accuracyVSAvoidtemperature rise of light absorbing layer

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent introduces an intermediate layer between the light absorbing layer and the reflective layer. This intermediate layer has lower thermal conductivity than both adjacent layers, acting as a thermal barrier that prevents rapid heat conduction to the reflective layer, thereby allowing the light absorbing layer to reach sufficient temperature for recording marks while still enabling effective laser beam reflection.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a non-uniform thermal conductivity structure by placing layers with different thermal conductivity values at specific positions. The intermediate layer has lower thermal conductivity than the light absorbing layer and reflective layer, creating a localized thermal barrier exactly where needed to prevent heat loss while maintaining overall optical functionality.

Inventive Principle:

Principle #3Local quality

2Reliability

If multiple functional layers are formed by sputtering or spin coating to achieve proper optical and thermal properties, then recording performance is improved, but manufacturing cost increases due to the large number of manufacturing processes

Engineering Contradiction:

Improverecording performanceVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent combines multiple functional requirements into a simplified layered structure. The intermediate layer simultaneously serves as a thermal barrier and an optical interface layer, while the reflective layer maintains both reflection functionality and structural support. This merging reduces the total number of separate manufacturing steps while achieving the same recording performance.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The intermediate layer performs multiple functions: it acts as a thermal insulation layer, an optical interface layer, and a structural component. The reflective layer also serves dual purposes as both a reflection surface and a support structure. This multi-functionality reduces the number of separate layers and manufacturing processes needed.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables high-speed data recording without errors and increases data density, while reducing manufacturing costs by minimizing the number of formation processes and using cost-effective materials.

Implementation Method 1

by irradiating a laser beam from the substrate side, regions of the light absorbing layer irradiated with the laser beam heat up and expand

Methodology Applied

Scientific EffectLaser heating: Laser

Implementation Method 2

a light absorbing layer... by irradiating a laser beam... regions of the light absorbing layer irradiated with the laser beam heat up

Methodology Applied

Scientific EffectAbsorption of electromagnetic radiation: Absorption (EM radiation)

Implementation Method 3

regions of the light absorbing layer irradiated with the laser beam heat up and expand, causing partial deformation of the intermediate layer and/or the substrate

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 4

the reflective layer is formed of a metal film of gold, silver, copper, aluminum, or the like (i.e., a thin film with high thermal conductivity). Here, when the light absorbing layer heats up due to the irradiation of a laser beam during the recording of recording data, such heat is rapidly conducted to the reflective layer

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS7385911B2Optical recording medium having multiple layers of different thermal conductivities

Publication Date: 2008.06.10 TDK CORP

AI summary

In an information recording medium according to the present invention, a recording layer, a first layer, and a second layer are formed so that a thermal conductivity of the first layer that contacts one surface of the recording layer and a thermal conductivity of the second layer that contacts another surface of the recording layer are both lower than a thermal conductivity of the recording layer and a track pitch is in a range of 0.1 μm to 0.5 μm, inclusive.