Servo Control Device for Optical Disk Drive with Emboss Area Detection
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Solution Overview
Problem
Conventional optical disk drives experience seeking errors due to the high reflectivity of emboss areas in DVD-RAM disks, which affects the Tracking Error Zero Crossing (TEZC) signal, leading to incorrect track seeking and increased seeking time.
Innovation Solution
A servo control device with a detection module, signal generation module, and selection module is integrated with the optical pickup head to detect emboss areas and generate a modified TEZC signal by combining the emboss indication signal, pseudo signal, and TEZC signal, ensuring accurate track seeking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the TEZC signal is used as the seeking signal in conventional optical disk drives, then the optical pickup head can obtain the number of data tracks crossed and control moving speed, but seeking errors occur when moving through emboss areas due to high reflectivity affecting the TE signal
Solution Approach 1:
The patent introduces an intermediary signal processing mechanism that detects emboss areas and generates a modified TEZC signal. When an emboss area is detected (indicated by abnormal TE signal amplitude), the system switches from using the original TEZC signal to a generated pseudo TEZC signal, thereby mediating the harmful effect of high reflectivity on seeking accuracy
Solution Approach 2:
The patent changes the parameter of the seeking signal by generating a modified TEZC signal with different characteristics from the original. The modified signal is generated based on the moving speed of the optical pickup head and the detected emboss area position, altering the signal parameters to compensate for the interference caused by high reflectivity in emboss areas
2Loss of time
If the optical pickup head moves through emboss areas with high reflectivity, then the TE signal becomes glitched, but this causes multiple square waves in the TEZC signal leading to increased seeking time
Solution Approach 1:
The patent performs preliminary detection of emboss areas before they cause seeking errors. By monitoring the TE signal amplitude in advance, the system identifies emboss areas ahead of time and prepares to switch to the modified TEZC signal, preventing the occurrence of multiple square waves and the associated time loss
Data Source
AI summary
A servo control device couples with an optical pickup head, which outputs a TEZC (tracking error zero crossing) signal. The servo control device includes a detection module, a signal generation module, and a selection module. In this case, the detection module detects emboss areas in an optical disk to output an emboss indication signal. The signal generation module generates a pseudo signal in accordance with the moving speed of the optical pickup head and the TEZC signal. The selection module generates a modified TEZC signal in accordance with the emboss indication signal, the pseudo signal and the TEZC signal. An optical disk drive including the servo control device and a servo control method thereof are also provided.