Magnetic Disk Writing Control for Ternary Recording Density
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Solution Overview
Problem
Existing magnetic disk devices face challenges in increasing storage capacity without increasing the number of digit areas, particularly when using shingled magnetic recording (SMR) methods that lead to data destruction during updates and restrict writing to specific end portions of tracks.
Innovation Solution
Implementing a magnetic disk device that writes ternary information by controlling write currents to achieve different magnetization states in digit areas, allowing for increased storage capacity by using three levels per digit area instead of two, and optimizing write operations to prevent data destruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If binary information is written to magnetic disk using conventional methods, then data storage is achieved, but storage capacity is limited by the number of digit areas
Solution Approach 1:
The patent changes the magnetization state parameter from two levels (positive/negative) to three levels by introducing a specific magnetization state where magnetization is perpendicular to the disk surface. This allows each digit area to store ternary information (0, 1, 2) instead of binary (0, 1), increasing storage capacity without requiring more digit areas
Solution Approach 2:
The patent introduces a new dimension of magnetization orientation by perpendicular to the disk surface, in addition to the conventional in-plane magnetization. This dimensional change enables three distinct magnetization states (positive, negative, and perpendicular) that can represent three different data values, effectively increasing information density per digit area
2Quantity of substance
If shingled magnetic recording is used to increase storage capacity, then recording density improves, but data destruction occurs during updates
Solution Approach 1:
The patent performs preliminary classification of write operations into three types based on the relationship between current and previous data. By pre-determining the appropriate write current magnitude and polarity for each case, the system can update data without destroying adjacent track data, preventing the data loss problem inherent in SMR updates
3Quantity of substance
If ternary information is written by controlling write currents, then storage capacity increases, but write operation complexity increases
Solution Approach 1:
The patent controls write current with three parameters (magnitude and polarity) to achieve three magnetization states. By systematically varying these parameters based on data type classification, the system achieves ternary storage while keeping the control mechanism manageable through predefined write current patterns for different data update scenarios
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
Enhances storage capacity without increasing digit areas by enabling the writing and reading of ternary information, thereby improving recording density and preventing data destruction during updates.
Implementation Method 1
The magnetic head is configured to execute a magnetization operation of magnetizing the magnetic disk to one of a first polarity and a second polarity that is a polarity opposite to the first polarity
Implementation Method 2
The magnetization operation includes a first magnetization operation of magnetizing the magnetic disk with a first recording width and a second magnetization operation of magnetizing the magnetic disk with a second recording width larger than the first recording width
Data Source
AI summary
According to one embodiment, a magnetic head executes a magnetization operation of magnetizing a magnetic disk to one of a first polarity and a second polarity opposite the first polarity. The magnetization operation includes a first magnetization operation of magnetizing the disk with a first recording width and a second magnetization operation of magnetizing the disk with a second recording width larger than the first recording width. The controller magnetizes a first area unit to the first or second polarity in the first or second magnetization operation, and then magnetizes a second area unit to a polarity opposite to that of the first area unit in the second magnetization operation. The second area unit is an area unit, radially adjacent to the first area unit, included in a second track that is a track adjacent to a first track among tracks and to be written after the first track.