Servo Mark Length Matched to Write Head Gap

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Solution Overview

Problem

Magnetic storage media with high perpendicular squareness face challenges in maintaining signal-to-noise ratios due to complex magnetic orientations, leading to data loss during read-out, particularly in servo patterns on magnetic tape.

Innovation Solution

The development of techniques to bias and write servo patterns on magnetic tape with greater perpendicular squareness, utilizing two heads or a single head to create remanence magnetization biases and symmetrical servo marks, ensuring precise magnetic orientations that enhance signal-to-noise ratios.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If perpendicular magnetic storage media with high perpendicular squareness are used to increase storage density, then storage capacity is improved, but signal-to-noise ratio deteriorates leading to data loss during read-out

Engineering Contradiction:

Improvestorage capacityVSAvoidsignal-to-noise ratio

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent changes the magnetic field application parameters by using a bipolar magnetic field waveform with specific positive and negative lobes. The positive lobe creates perpendicular magnetization for high storage density, while the negative lobe compensates for magnetic orientation complexity. This parameter change resolves the contradiction by maintaining both high perpendicular squareness and acceptable signal-to-noise ratio through controlled magnetic field characteristics.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite magnetic field structure combining two distinct field components: a first magnetic field with magnetization vector substantially perpendicular to the tape surface, and a second magnetic field with magnetization vector substantially parallel to the tape surface. This composite approach allows simultaneous achievement of high storage density (from perpendicular component) and reduced data loss (from parallel compensation component).

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If complex magnetic orientations are used in perpendicular media to achieve high storage density, then storage capacity is improved, but data loss during read-out increases

Engineering Contradiction:

Improvestorage capacityVSAvoiddata loss

Core Design Contradiction:

Quantity of substanceVSLoss of information

Solution Approach 1:

The patent converts the harmful effect of complex magnetic orientations (which cause data loss) into a beneficial structure. By deliberately creating a bipolar magnetic field pattern where the negative lobe mirrors the positive lobe, the complex orientations are structured to produce compensating effects. The second magnetic field component specifically addresses and compensates for the data loss caused by the first magnetic field's perpendicular magnetization.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Measurement precision

If servo patterns are written on magnetic tape with high perpendicular squareness, then positioning accuracy is improved, but signal quality deteriorates

Engineering Contradiction:

Improvepositioning accuracyVSAvoidsignal quality

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies parameter changes to the magnetic field waveform used for writing servo patterns. By using a bipolar waveform with controlled positive and negative lobes, the system maintains precise magnetic orientation for positioning accuracy while the compensating negative lobe preserves signal quality. This allows servo patterns to be written with both high positioning accuracy and acceptable signal quality.

Inventive Principle:

Principle #35Parameter changes

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

These techniques improve data storage capacity and signal quality by maintaining high perpendicular squareness while reducing data loss during read-out, allowing for accurate positioning and efficient data retrieval.

Implementation Method 1

A write head of a magnetic drive generates a magnetic field for a short period to create a symmetrical servo mark in the magnetic tape

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The different magnetized regions may encode a series of bits that represent a value of '0' or '1'. The magnetically oriented regions may be aligned on data tracks

Methodology Applied

Scientific EffectMagnetic hysteresis: Magnetic Hysteresis

Data Source

PatentUS8797674B2Servo mark length matched to write head gap for magnetic storage media

Publication Date: 2014.08.05 SONY GROUP CORP

AI summary

Magnetic storage tape and techniques for erasing and writing to magnetic storage tape having a perpendicular squareness greater than 50 percent and a longitudinal squareness less than 50 percent are described. In general, the magnetic tape may be biased with a remanence magnetization, or magnetic orientation, in any direction. One or two head systems may use various magnetic field patterns to create the desired remanence magnetization. Servo marks may have a remanence magnetization in an opposite magnetic orientation than that of the remaining bias on the servo track, e.g., substantially perpendicular to the magnetic tape. In some examples, a write head may alternate the direction of the magnetic field to continuously bias and write servo patterns to the magnetic tape. In addition, a symmetrical servo mark may be created in the magnetic tape with a write head having a gap width approximately equal to the length of the servo mark.