Optical storage device made thinner by substituting electrical means for capabilities of sensors

摘要

There is provided an optical storage device that can position a lens carriage and objective lens even when position sensors for the lens carriage and objective lens are excluded in an effort to make an optical disk unit thinner. In an optical storage device according to the first aspect of the present invention, immediately after an optical disk is loaded in a main body, the cutoff frequency of a filter lying on a path of a reproduction signal is temporarily changed to a lower frequency. A spacing of sectors of the optical disk is detected using a signal sent from the filter. A type of an optical storage medium and a position of a current reproduction track are detected on the basis of the detected sector spacing and data stored in a memory. According to the second aspect, a photosensor has incident light thereof intercepted by an interceptive projection formed on part of a carriage only during a period during which the carriage is located in a laser output adjustment area or light beam adjustment area defined in the vicinity of an outer circumference of the optical disk. Based on driving currents used to drive the carriage when the incident light of the photosensor is intercepted and not intercepted, a holding current used to hold the carriage is calculated. Thus, the carriage is held within the laser output adjustment area or light beam adjustment area. According to the third aspect, when a seek of the carriage relative to an optical disk is started, the carriage is accelerated smoothly, decelerated smoothly, and thus positioned on a target track. The vibration of a lens actuator on the carriage occurring during seek can be minimized, and the lens actuator is locked substantially in the center of the carriage. According to the fourth aspect, during a seek operation of the carriage, a false lens signal equivalent to a lens signal used to lock the lens actuator in the center of the carriage is produced using the envelope of a tracking error signal obtained from reflected light of the light beam emanating from the optical disk. With the false lens signal, the lens actuator is locked in the center of the carriage.