Research Of The Position Measurement Technique For Parallelism Detection Of Optical Disk Driver

As a removable storage media,the reading capability of Optical disk is the key factor of the quality of optical disk driver. By study the mechanism of optical disk driver, one of the most important factor of affecting the reading capability that is the parallelism between Optical head and Spindle motor is found. In industry, after the optical disk driver manufactured, the parallelism between Optical head and Spindle motor has to be measured. By study the measurement of parallelism between Optical head and Spindle motor at present, we find that there are expensive and inconvenient. So it needs to design a new convenient method.Position sensitive detector is based on the lateral photoelectric effect. It is able to measure the displacement of laser spot accurately. For this character of PSD, a new measuring parallelism between optical head and spindle motor system is designed. Using the transparence CD, PSD can detect the displacement of laser spot between non-placing and placing the CD, and it can be used to calculate the parallelism between optical head and spindle motor. The key factor of this system is that the PSD measurement must detect the micron-level displacement. But PSD is analog device and easily affected by the surroundings and other analog device, so it should weakening or removing the effect of any factor.When the measuring approach has been brought forward, analyzing the working principle of PSD, the signal processing circuits and removing the effect of background light and dark currents circuits is designed, and the data acquisition program and working interface is wrote. So the key factor of system that is the measuring displacement subsystem by using PSD, is completed. For the experiment results, the measuring displacement based on PSD sub-system is able to measure the parallelism between Optical head and Spindle motor.