| 摘要 |
A DIGITAL VERSATILE DISC (DVD) SYSTEM COMPATIBLE WITH A COMPACT DISC (CD), A SINGLE- LAYERED DVD AND A MULTI-LAYERED DVD HAVING RESPECTIVELY DIFFERENT STRUCTURES. THE DVD SYSTEM DISCRIMINATES A TYPE OF A DISC (1) LOADED ON A TURNTABLE (2) ACCORDING TO THE TIME AND NUMBER REPRESENTED BY REFLECTION CHARACTERISTIC CURVES OF A FOCUS ERROR SIGNAL DETECTED DURING PERFORMING AN INITIAL FOCUS SEARCH OPERATION FOR THE DISC. THE DVD SYSTEM CALCULATES THE SIZE OF A WAVEFORM OF THE FOCUS ERROR SIGNAL HAVING A REFLECTION CHARACTERISTIC CURVE OBTAINED FROM A REFLECTION LAYER (R,RL1,RL2) OF THE DISC IN A FOCUS- UP SECTION, AND DETERMINES THE DISC AS A MULTI-LAYERED DVD HAVING TWO REFLECTION LAYERS (RL1 ,RL2) WHEN TWO REFLECTION CHARACTERISTIC CURVES EXIST AND HAVE A MAGNITUCIE WHICH IS BETWEEN A FIRST REFERENCE VALUE AND A SECOND REFERENCE VALUE. OTHERWISE, THE DVD SYSTEM DETERMINES THE DISC AS A CD BEING RELATIVELY THICKER IF THE DETECTION TIME OF A REFLECTION CHARACTERISTIC CURVE IS LONGER THAN A PREDETERMINED TIME, AND DETERMINES THE DISC AS A SINGLE-LAYERED DVD IF THE DETECTION TIME IS SHORTER THAN THE PREDETERMINED TIME, BASED ON THE COMPARISON RESULT BETWEEN THE DETECTION TIME OF THE REFLECTION CHARACTERISTIC CURVE AND THE PREDETERMINED TIME. THE DVD SYSTEM QUICKLY DISCRIMINATES BETWEEN A CD AND A DVD, THEREBY PROVIDING AN EFFECT THAT ERROR CAUSED DURING PERFORMING A PLAYBACK OPERATION CAN BE REDUCED IN THE DVD SYSTEM COMPATIBLE WITH THE DVD AND THE CD. (FIG .1)
|
