Optical Storage Laser Noise Reduction via Adaptive Equalization
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Solution Overview
Problem
Conventional techniques for reducing laser noise in optical disk reproduction signals face challenges with wide band analog dividing circuits and delay adjusting circuits, which hinder effective noise reduction.
Innovation Solution
An information processing apparatus and method that includes a photodetector, a front monitor, and a data detection processing unit with adaptive equalizers to generate a reproduction signal by reducing laser noise through adaptive equalization processing based on input signals from the photodetector and front monitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional analog dividing circuits and delay adjusting circuits are used for laser noise reduction, then noise reduction effect can be achieved, but device complexity and feasibility problems arise
Solution Approach 1:
The patent replaces complex analog electronic circuits (dividing circuits and delay adjusting circuits) with digital signal processing operations. The adaptive equalizer uses digital algorithms to perform noise reduction functions that were previously requiring complex analog hardware, thereby reducing device complexity while maintaining effectiveness.
Solution Approach 2:
The patent changes the operating parameters from analog domain to digital domain. By digitizing the signal processing operations and using adaptive equalization algorithms, the system achieves noise reduction through parameter adjustments in the digital realm rather than through complex analog circuit configurations.
2Quantity of substance
If high-density data recording is performed by shortening channel bit length, then recording density is increased, but signal quality and noise reduction become more difficult
Solution Approach 1:
The patent applies preliminary equalization processing to the reproduction signal before further signal processing steps. The adaptive equalizer pre-compensates for signal degradation and noise effects that occur during high-density recording, thereby maintaining signal quality even when channel bit length is shortened for increased density.
Solution Approach 2:
The patent employs adaptive equalization with feedback mechanisms that continuously adjust equalization parameters based on the actual signal characteristics. This feedback loop allows the system to compensate for the degraded signal quality inherent in high-density recording by dynamically optimizing the equalization response.
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
The solution effectively reduces laser noise in the reproduction signal, improving the quality of the signal and addressing the limitations of existing technologies.
Implementation Method 1
a photodetector that outputs a signal based on reflected light from a disk with respect to light emitted from a laser diode
Implementation Method 2
light emitted from a laser diode
Data Source
AI summary
An apparatus comprises a photodetector (PD) that irradiates a disk with laser light and outputs a signal based on a reflected light from the disk, a front monitor that outputs a reference signal based on an emitted light of a laser diode, and a data detection processing unit to which an output signal of the PD is input to generate a reproduction signal. The data detection processing unit includes a reproduction signal adaptive equalizer that outputs an equalization signal by adaptive equalization processing based on the PD output signal, and a laser noise adaptive equalizer that outputs the equalization signal by the adaptive equalization processing based on a laser noise signal, and generates the reproduction signal in which the laser noise is reduced on the basis of an arithmetic operation result of the output of the reproduction signal adaptive equalizer and the output of the laser noise adaptive equalizer.