Optical Pickup Dirt Detection and Signal Compensation
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Solution Overview
Problem
Optical disc devices face challenges in accurately recording or reproducing information when dirt is present in the optical pickup, leading to decreased peak levels of received-light signals and subsequent failure in focus and tracking control.
Innovation Solution
The optical disc device includes a light amount signal generator and a dirt determiner that detects dirt presence based on a threshold, controlling the laser light source or light receiving element to increase the peak level of received-light signals, ensuring accurate recording or reproduction even with dirt in the optical pickup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the optical pickup operates normally without compensation, then the device structure remains simple, but the recording and reproduction accuracy deteriorates when dirt is present in the optical pickup
Solution Approach 1:
The patent applies preliminary action by detecting dirt presence in advance through monitoring the peak level of received-light signals. When dirt is detected (peak level below threshold), the system proactively adjusts the laser light source output or light receiving element sensitivity before recording/reproduction operations are affected, ensuring accurate operation despite dirt presence without requiring complex physical cleaning mechanisms
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting operational parameters (laser light source output power or light receiving element sensitivity/gain) based on the detected dirt level. The controller modifies these parameters in real-time to compensate for light attenuation caused by dirt, maintaining signal quality and recording accuracy without changing the physical structure of the optical pickup
2Reliability
If the peak level of received-light signal decreases due to dirt, then the optical pickup is contaminated, but focus and tracking control fail
Solution Approach 1:
The patent applies feedback by continuously monitoring the peak level of received-light signals and using this information to control the laser light source output or light receiving element sensitivity. The controller receives feedback about signal quality and automatically adjusts parameters to maintain focus and tracking control accuracy, ensuring reliable operation even when dirt causes signal attenuation
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 solution enables accurate recording and reproduction of information on optical discs by increasing the peak levels of received-light signals, thereby maintaining focus and tracking control despite dirt presence in the optical pickup.
Implementation Method 1
a light receiving element that receives reflected light from the optical disc, and performs photoelectric conversion on the reflected light received to output a received-light signal
Data Source
AI summary
An optical disc device includes: an optical pickup including a first laser light source that emits laser light, an objective lens that focuses the laser light emitted from the first laser light source onto an optical disc, and a light receiving element that receives reflected light from the optical disc, and performs photoelectric conversion on the reflected light received to output a received-light signal; an FS signal generator that generates an FS signal indicating the light amount of the reflected light from the optical disc, based on the received-light signal from the light receiving element; and a dirt determiner that determines that dirt is present in the optical pickup, when the peak level of the FS signal is less than a dirt determination threshold, and controls the light receiving element to increase the peak level of the received-light signal from the light receiving element.