Certify Testing Apparatus Dynamic Gain Control Magnetic Media
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Solution Overview
Problem
Existing certify testing methods for magnetic recording media face difficulties in detecting error locations due to undulations in the substrate and irregularities in film thickness distribution, which affect the accuracy of error detection.
Innovation Solution
A certify testing apparatus and method that dynamically varies the gain of playback signals using an automatic gain control circuit, allowing the output level to stabilize after a specific time period following the detection of signals from error areas, enabling effective error discrimination by comparing the slice level and signal levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional certify testing is conducted without dynamic gain control, then the testing process is simple, but error detection accuracy deteriorates due to substrate undulations and film thickness irregularities
Solution Approach 1:
The patent applies dynamics by introducing time-varying gain control in the signal processing system. The gain is dynamically adjusted based on the elapsed time since the last error detection, allowing the system to adapt to signal level variations caused by substrate undulations and film thickness irregularities. This dynamic adjustment improves error detection accuracy without requiring complex hardware modifications to the magnetic recording medium itself.
Solution Approach 2:
The patent changes the parameter of signal gain over time to compensate for variations in playback signal levels. By controlling the gain rate as a function of time since error detection, the system can distinguish between signal variations caused by medium irregularities and actual error conditions, thereby improving measurement precision while maintaining a relatively simple system architecture.
2Measurement precision
If dynamic gain control is implemented to improve error detection, then error detection accuracy improves, but the processing time and system complexity increase
Solution Approach 1:
The patent implements periodic action through the time-based gain control mechanism, where the gain is adjusted in a systematic manner based on elapsed time intervals since error detection. This periodic adjustment pattern allows the system to process signals efficiently while maintaining improved error detection accuracy, as the gain changes follow a predictable temporal pattern rather than requiring continuous complex calculations.
3Reliability
If the gain is dynamically varied based on time since error detection, then long error bits can be detected accurately, but the control mechanism becomes more complex
Solution Approach 1:
The patent employs feedback through the automatic gain control circuit, which continuously monitors the playback signal and adjusts the gain based on the time elapsed since the last error detection. This feedback mechanism enables reliable detection of long error bits by maintaining appropriate signal levels throughout the detection process, while the automated nature of the control reduces the need for manual intervention and simplifies overall system operation despite the added circuitry.
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 enhances the detection capability of error locations on magnetic recording media, reducing the impact of substrate undulations and film thickness irregularities, and allows for accurate testing of magnetic recording media with improved error detection, particularly for long error bits.
Implementation Method 1
a magnetic head part which plays back signals that are recorded in said magnetic recording medium
Implementation Method 2
an amplification means which amplifies said played back signals at a gain rate controlled according to elapsed time after input of a signal originating in an error area
Data Source
AI summary
An apparatus is provided that can detect error locations in certify testing of a magnetic recording medium without influence from undulation of the substrate or irregularities in film thickness distribution of magnetic film of the magnetic recording medium. Such an apparatus tests playback signals of a magnetic recording medium, the magnetic head 53 conducts playback of signals which are recorded in the magnetic recording medium. The AGC unit 34 amplifies the played back signals at a gain rate controlled according to elapsed time after input of a signal originating in an error area of the magnetic recording medium among the played back signals. The CMP unit 38 compares the slice level and the level of the amplified signals, and discriminates the existence or non-existence of error.