CD/DVD Servo Evaluation System

The research of evaluation methods and test equipment of DVD optical pickup isnot only the key to research, develop and produce DVD optical pickup, but also themain factor to restrict the development and improvement of Chinese pickup industries.The evaluation technologies include the theoretical analysis and evaluation methodsresearch of characteristic parameter, DVD servo system research and engineeringrealization technology research of test equipment. These researches will promote theestablishment of general technical specification of DVD/CD read-only optical pick-up,break the monopolization of oversea companies in pickup evaluation technology andequipment areas, and improve the overall technical level and competitive energy ofChinese pickup industries.This paper explains and classifies parameters of DVD optical pickup accordingto research the adjusting and evaluation of DVD optical pickup. It includescharacteristic parameters of optical, characteristic parameters of laser power,characteristic parameters of PDIC, characteristic parameters of ACT, characteristicparameters of servo, characteristic parameters of HF signal.This paper briefly introduces the basic principle of DVD servo. The DVDoptical pickup evaluator brings more special requires to the servo system, includingspecial servo actions and output of special parameters. Its precision, reliability,stability and repetition more lie on the performance of the servo system.This paper introduces some key technologies to develop DVD optical pickupevaluator. According to the comparison and analysis of various kinds of evaluatorproduced by foreign companies, this paper puts forward the overall scheme based onbus interface technology, and discusses the system structure from hardware systemstructure, software system structure and evaluation system structure.A DVD servo system based on specific ICs and DSP controlling is designed forDVD optical pickup evaluator, and principal sample equipment is finished. The servosystem can not only complete the focusing, tracking, sled, spindle servo, but alsosatisfy the special requires of the DVD optical pickup evaluator. DVD evaluationequipment adopts system of up-down machine. Through A/D conversion, all testingsignals are gave to computer, and showed testing results.This paper shows the circuit board of DVD servo system and the picture of theDVD optical pickup evaluator. At the same time, it provides the debugging result ofDVD servo system. Results indicate it reach the design demand, and applied tocorporation of optical pickup.