Abstract: A method of detecting a crack in a disc loaded on a disc drive and a method of automatically lowering a target speed in response to the detection of a crack in order to stabilize the disc drive. According to the methods, it is automatically determined whether a disc loaded on a disc drive has a crack in a specific mode, and a target speed is automatically changed into a low speed when it is determined that the disc has a crack. Therefore, the crack state of the disc is exactly checked during action of the disc drive, the percentage of error occurrence is decreased, and the probability of damage to the disc is reduced.

Abstract: A method and apparatus accurately measuring the amount of unbalance of a disc, based on the time to reach a target RPM (Rotation Per Minute) regardless of an assembly condition of a disc drive. The method includes: storing a plurality of reference disc unbalance values; measuring an RPM (Rotation Per Minute) of the disc; comparing the measured RPM with a target RPM; and when the measured RPM reaches the target RPM, detecting a reference disc unbalance value among the plurality of reference disc unbalance values based on an elapsed time to reach the target RPM. Accordingly, the amount of disc imbalance of the disc can be constantly measured regardless of an assembly condition of the disc drive and the computer.

Abstract: A method and apparatus accurately measuring the amount of unbalance of a disc, based on the time to reach a target RPM (Rotation Per Minute) regardless of an assembly condition of a disc drive. The method includes: storing a plurality of reference disc unbalance values; measuring an RPM (Rotation Per Minute) of the disc; comparing the measured RPM with a target RPM; and when the measured RPM reaches the target RPM, detecting a reference disc unbalance value among the plurality of reference disc unbalance values based on an elapsed time to reach the target RPM. Accordingly, the amount of disc imbalance of the disc can be constantly measured regardless of an assembly condition of the disc drive and the computer.

Abstract: A method of detecting a crack in a disc loaded on a disc drive and a method of automatically lowering a target speed in response to the detection of a crack in order to stabilize the disc drive. According to the methods, it is automatically determined whether a disc loaded on a disc drive has a crack in a specific mode, and a target speed is automatically changed into a low speed when it is determined that the disc has a crack. Therefore, the crack state of the disc is exactly checked during action of the disc drive, the percentage of error occurrence is decreased, and the probability of damage to the disc is reduced.

Abstract: A method for determining the difference between the sub-Q code and header of a CD-ROM loaded in a CD-ROM drive is provided. The method includes the providing a read-out command to a controller in the CD-ROM drive, searching for a sub-Q code area of a first frame and reading the sub-Q code of the sub-Q code area according to the read-out command and storing the same, by means of the controller, enabling a decoder in the CD-ROM drive and reading header information which is the primary output from the decoder, by means of the controller, calculating the difference between the stored sub-Q code and the stored header information, by means of the controller, and processing the difference and transmitting the result, by means of the controller. Here, the result is processed in a computer and displayed on a monitor connected to the computer.

Abstract: A method is disclosed for measuring the linear velocity of recording of data recorded a CD using a Hall sensor. A Hall sensor is placed in the spindle motor of a CD drive to produce a signal based on alternating magnetic flux in the spindle motor. An amplified and processed version of the signal output from the Hall sensor during operation of the CD drive is monitored to measure the timing of three successive inversions of the signal. Based on this timing measurement, the rotational speed of the spindle motor is determined. The recording linear velocity of the data recorded on the CD presently mounted in the CD drive is obtained based on the rotational speed determined from the Hall signal and on a reference rotational speed. As a result of using this method for obtaining the recording linear velocity of the data recorded on the CD, no errors are generated based on the number of tracks the pickup is moved across, and the time necessary for measuring the recording linear velocity is reduced.

Abstract: A method and apparatus for controlling the moving distance of an optical pick-up includes the steps of taking a first count of the number of pulses of a tracking error signal generated during half a cycle of a photo interrupt signal or a hall effect signal; calculating an aimed distance to move by subtracting the current location of the optical pick-up from the target location thereof; moving the optical pick-up according to the number of pulses of the photo interrupt signal or the hall effect signal indicating the aimed distance to move; taking a second count of the number of pulses of the tracking error signal generated from a moving point to a first inverting point of the photo interrupt signal or the hall effect signal, and further moving the optical pick-up for the number of tracks to compensate for, the number being obtained by subtracting the second number of pulses from the first number of pulses.

Abstract: A method for controlling the gain of a spindle motor in a CD-ROM drive, includes the steps of: calculating a first number of tracks on a disc from a starting point of a program region to a reproduction position of data to be reproduced according to information received from a main controller; calculating a first rotational speed of the spindle motor corresponding to the reproduction position; reading a predetermined code to obtain information representative of a current position of a pickup; calculating a second number of tracks on the disc from the starting point of the program region to the current position of the pickup; calculating a second rotational speed of the spindle motor corresponding to the current position of the pickup; and driving a sled motor to move the pickup to the reproduction position and controlling the spindle motor based on a first quantity defining a difference between the first number of tracks and the second number of tracks, and further based on a second quantity defining a differe

Abstract: A swift deceleration method of a disk system and a circuit thereof such as an Optical Disk Driver, Compact Disk Player, CD-ROM and the like, which can quickly control a vibrating lens support when the optical pickup has been stopped, is disclosed, thus enabling the disk system to switch tracks faster. The method forces the transition of a deceleration circuit from an unlock state to a lock state when the feed motor is stopped, moves the optical pickup in a radial direction and controls the vibration of a lens support during stoppage of the optical pickup by operating the feed motor in a deceleration mode when the feed motor is in transition from the unlocked state to the locked state.

Abstract: There is disclosed a method of searching at high speed an information recorded on a compact disk in an optical recording/reproducing apparatus, by means of detecting the numbers of current tracks and tracks of the target position and converting the detected value of the tracks to a value of time corresponding to velocity. In the compact disk system, the number of track required to be move the target position is obtained by detecting the numbers of the current and target tracks. The number of tracks obtained is converted as the value of time, and the sled motor in pick-up tools is driven according to the obtained value of time, and then the break point is settled at the point of 3/4 of the time driven in the sled motor, and finally the target track is detected at high speed after passing over the point of 1/4.