Abstract: There is provided control system including: movement mechanism configured so that the movement mechanism is driven by motor; detector configured to detect position and speed of the movable member; and controller. The controller is configured to: control the motor so that the movement mechanism reciprocatively moves the movable member; and in a course to move the movable member to a returning point, control the movement of the movable member by controlling the motor based on the speed of the movable member so that the movable member is moved at a constant speed until a deceleration start point of time, and control the movement of the movable member by controlling the motor based on the position of the movable member so that the movable member is decelerated from the deceleration start point of time and stops at the returning point in accordance with a target position locus.

Abstract: In a digital gyroscope, the rate signal (including the quadrature) and the displacement signal of the drive part are sampled with an ADC. This displacement signal has the same frequency and phase as the quadrature signal that gets sampled in the rate channels. The displacement signal is sampled with the same clock as the rate signal resulting in the displacement signal having the same close-in phase noise folded into the signal band as the sampled quadrature in the rate signal. The sampled drive signal is subtracted from the sampled rate signal to eliminate the clock jitter induced noise in the rate signal. This relaxes the close-in phase noise requirement of the PLL and allows for a low power PLL implementation.

Abstract: A touch implementation method and device and an electronic device are provided, and the method includes: displaying N calibration points for user touch by a display screen of an electronic device; acquiring first coordinates of the N calibration points for user touch; acquiring second coordinates of the N calibration points; and calculating a mapping parameter between a first coordinate of a point and a second coordinate of the point according to the first coordinates of the N calibration points and the second coordinates of the N calibration points. The mapping parameter is configured for acquiring a first coordinate of a touch point touched by the user upon a user touching the display screen. Embodiments of present disclosure can reduce the cost of the electronic.

Abstract: In one general embodiment, a tape drive system includes: a read channel; a write channel; logic configured to receiving a request for a write operation to be performed in a tape drive; logic configured to determine an optimum a write procedure in response to receiving the request, the determining being based on expected writing times of each of a plurality of write procedures and an expected transaction size of a next write operation; and logic configured to invoke the determined optimum write procedure in response to determining the optimum write procedure.

Abstract: A servo control apparatus includes a subtractor configured to calculate a difference between a first command value for controlling a servo motor, and a first detection value from the servo motor; an integral term creation unit configured to create an integral term based on an output of the subtractor; an internal division processing unit configured to internally divide the first command value; a subtractor configured to calculate a difference between an output of the internal division processing unit and the first detection value; a proportional term creation unit configured to create a proportional term based on the subtractor; and a adder configured to add an output of the integral term creation unit and an output of the proportional term creation unit, in which a calculation period calculated by the proportional term creation unit is shorter than a calculation period calculated by the integral term creation unit.

Abstract: In one general embodiment, a method includes receiving a request for a write operation to be performed in a tape drive, determining an expected transaction size of a next write operation, comparing the expected transaction size of the next write operation to each of a first transaction size threshold and a second transaction size threshold in response to receiving the request, determining an optimum a write procedure based at least in part on the comparison, and invoking the optimum write procedure in response to determining the optimum write procedure, wherein the first transaction size threshold is greater than the second transaction size threshold, and wherein the optimum write procedure is selected from the group consisting of: a backhitch write procedure, a same wrap backhitchless flush (SWBF) write procedure, and a recursively accumulating backhitchless flush (RABF) write procedure.

Abstract: A power saving method and a power saving system are applied in an optical disk drive. The power saving system comprises a power controlling unit for differentiating the specific sets of circuits not being used at a specific operation rate and powering them down. The sets of circuits not being used will be powered up while the associated operation rate at which they are required to operate is nearly started.

Abstract: An optical disc device includes a pickup, a driving mechanism that drives the pickup, and a driving controlling portion that applies an initial driving voltage to the driving mechanism over a specific time interval up until the pickup arrives at an outermost position on an outer peripheral side, the initial driving voltage causing the pickup to arrive at the outermost position. After the specific time interval has elapsed, the driving controlling portion applies, to the driving mechanism, an adjustment driving voltage of a voltage amplitude less than a voltage amplitude of the initial driving voltage or a driving frequency less than a driving frequency of the initial driving voltage.

Abstract: An exemplary method of controlling an optical storage apparatus includes: driving a first mechanical mechanism of the optical storage apparatus by applying a first control signal to the first mechanical mechanism, wherein a second mechanical mechanism of the optical storage apparatus is inactive while the first mechanical mechanism is operating in response to the first control signal; adjusting the first control signal applied to the first mechanical mechanism when the second mechanical mechanism is requested to be active; and driving the second mechanical mechanism by applying a second control signal to the second mechanical mechanism while the first mechanical mechanism is operating in response to the adjusted first control signal.

Abstract: A system and method for printing a visible image onto an optical disc through tuning a driving signal of an optical pick-up unit are disclosed. The system includes a driving circuit, coupled to the optical pick-up unit, for providing a driving signal to drive the optical pick-up unit; and an adjusting circuit, coupled to the driving circuit, for controlling the driving circuit to adjust the driving signal according to a rotation source signal corresponding to a rotation of the optical disc.

Abstract: An optical disc device capable of preventing a current larger than prescribed in specifications from flowing by measuring amounts of variation in drive signals of the actuator or the spindle motor, and in view of a correlation between those amounts of variation in the drive signals and the amount of current, changing the servo control system characteristics according to measured amounts of variation, and setting a limit to the level of drive signals.

Abstract: In one embodiment the present invention includes a circuit comprising a switch and a switch driver. The switch is configured to provide synchronous rectification switching of a back-EMF voltage. The synchronous rectification switching produces a source voltage. The switch driver is configured to receive the back-EMF voltage and the source voltage. The switch driver provides a control signal to a control terminal of the switch. The control signal has a frequency. The frequency is used to control an amount of the synchronous rectification switching. Accordingly, the frequency reduces a dissipated power associated with the synchronous rectification switching.

Abstract: An HF waveform prevailing during a read operation varies due, for instance, to changes in the ambient temperature of an optical disc drive and variations in the characteristics of a laser. This degrades read performance and decreases the number of rewritable disc read operations. To address the above problems, an optical disc drive and an optical information read method are disclosed. The disclosed optical disc drive and optical information read method vary an HF amplitude in relation to the resistance, differential resistance, or temperature of the laser.

Abstract: A position-error-signal calculation circuit (105) calculates a relative position error between a laser-focused-beam spot (103) and an information recording layer (102), and generates a focus error signal (106). A filter (108) amplifies and passes therethrough a signal component in the vicinity of the natural resonance frequency of at least one mode among the natural vibration modes of the optical disc medium (101). A drive amplifier receives through a stabilizing compensator (109) and a D/A converter (110) the focus error signal (106) passed by the filter (108), to drive an objective lens (113), thereby allowing the laser-focused-beam spot (103) to track the information recording layer (102).

Abstract: A signal processor includes an operational amplifier performing an operation on first and second signals, and amplifying a signal resulting from the operation based on an amplification control signal to remove an offset voltage, a buffer buffering an output signal of the operational amplifier and outputting a result of the buffering as differential signals, an automatic gain amplifier automatic gain amplifying the differential signals output from the buffer and outputting an automatic gain amplified signal as a single ended signal, a level shifter level shifting a level of the single ended signal including the offset voltage and outputting a level shifted signal as level shifted differential signals, and an offset voltage compensation unit converting a difference between the level shifted differential signals to a digital signal, detecting the offset voltage based on the digital signal, and outputting the amplification control signal to compensate for the detected offset voltage.

Abstract: An optical disc recording device according to the present invention is capable of quickly performing the OPC operation for a rewritable optical disc, and is also capable of setting the proper writing power for both an unwritten area and a written area. A microcomputer reads out, from a memory, preliminary writing conditions for the optical disc in question, and then performs preliminary writing so that data is written to a test writing area of the optical disc under the preliminary writing conditions. After that, test writing to the test writing area, which has been subjected to the preliminary writing, is performed with the writing power being changed, and thereby the optimum writing power is determined. Information about the writing power and the erasing power is stored in the memory on an optical disc type basis. The information is used for the preliminary writing.

Abstract: An optical disc drive apparatus (100) of the present invention rotates an optical disc (1) at a predetermined rotation speed using a motor (2). An optical pickup (3) irradiates the optical disc (1) with a laser beam (5) emitted from an internal semiconductor laser (4) included therein, and obtains a reproduction signal (7) based on a laser beam reflected from the optical disc (1). A laser driving unit (8) controls a driving current (9) of the semiconductor laser (4) to a predetermined level, and superimposes a high-frequency current (11) having a predetermined level on the driving current (9). In a high-speed reproduction mode, a control unit (12) sets the rotation speed of the optical disc (1) higher, the power of the laser beam (5) irradiating the optical disc (1) higher, and the level of the high-frequency current (11) lower than in a normal reproduction mode.

Abstract: A device for controlling access to an optical disc includes a control word calculator and a numerically controlled oscillator (NCO). The control word calculator is arranged to calculate a control word corresponding to a radius where the optical disc is accessed. In addition, the NCO is arranged to generate an output frequency according to the control word, wherein the output frequency is utilized for accessing the optical disc. An associated method for controlling access to an optical disc includes: calculating a control word corresponding to a radius where the optical disc is accessed; and generating an output frequency according to the control word, wherein the output frequency is utilized for accessing the optical disc.

Abstract: An optical recording/reproducing system 1 reads a recorded signal written to a recording track of a recording medium 3 by light. The light is modulated by a drive signal on which a frequency signal is superimposed. The light is scanned along the recording track at a predetermined scan velocity. The optical recording/reproducing system 1 includes a computer 13 and an LD driver 17 that control, based on the scan velocity, a superimposed magnitude of the frequency signal on the drive signal.

Abstract: An optical disk apparatus according to the present invention generates a divided clock signal by dividing a recording clock signal, and based on the divided clock signal, determines a test emission pattern for test recording which is used for controlling the power of a light beam that is output from an emission section. When the linear velocity at recording changes, the division ratio is adjusted in a direction of reducing a change in frequency of the divided clock signal. In an optical disk apparatus which performs laser power control by conducting a test emission with multipulses in a test area, a good detection accuracy of a multi-pulse average value can be maintained even at high x-speeds.

Abstract: An optical disk drive capable of reproducing data even when warpage is present in an optical disk. A system controller of the optical disk drive reproduces data by setting a maximum speed in accordance with the type of an optical disk, an amount of side-to-side runout, or the like. In the meantime, when a read error arises as a result of trial reproduction being performed at an outer radius of the disk at startup, warpage is determined to be present in the optical disk, and a limitation on the maximum speed is raised. The rotational speed is set to allowable maximum speed of the optical disk drive, and warpage is corrected by means of centrifugal force. When reproduction becomes impracticable for reasons of meandering of a tack, or the like, during the course of reproduction of data, the rotational speed is decreased, to thus perform a retry.

Abstract: An optical disk processing system having a recording unit and a printing unit is provided. The optical disk processing system comprises a printing unit and a recording unit. A drive controller of the recording unit rotationally drives a loaded optical disk (D) and detects whether or not a rotational speed is reduced during acceleration. When the rotational speed is reduced, it is judged that a stick-slip has occurred and loading of a plurality of the optical disks (D) is detected.

Abstract: A personal security apparatus includes a transmitting device having an event detector initiating different signals which indicate different event types. A transceiver receives the signals from the transmitting device and interprets each signal as corresponding to a particular event type. The transceiver sends respective event type alert signals to a remote monitoring device. The remote monitoring device provides a plurality of respective event type indicators for each of the event type alert signals received.

Abstract: A method is disclosed for performing Beta prediction for high-speed writing on unknown recordable optical discs. Test recordings are performed in the inner (20) and outer test (40) zones of an unknown recordable optical disc, yielding results expressed as measured beta target values. At least one beta target value is computed in a data zone (30) of the unknown recordable optical disc. Beta (power) is predicted as a function of speed for continuous angular velocity (CAV) speed profiles, or equivalently, as a function of disc radius for CAV writing, for high speed writing on said unknown optical disc by constructing a piecewise linear interpolation of beta versus speed or disc radius using the measured target values and the at least one calculated beta target value.

Abstract: An optical disk device of the present invention includes a spindle motor, an optical pick-up, and a rotation control portion. The spindle motor is a rotational drive portion that rotates an optical disk, on an information recording surface of which a plurality of addresses are recorded. The optical pick-up records an information signal onto and plays back the information signal from the information recording surface of the optical disk that is rotated by the spindle motor. The rotation control portion controls the rotation of the optical disk by the spindle motor. In this case, the rotation control portion performs control based on a first reference signal that can be read off the optical disk, such that the optical disk is rotated at a speed that is based on a specified clock count.

Abstract: An optical recording/reproducing system 1 reads, based on a predetermined reproduction clock, information associated with a recording track of a recording medium by irradiating frequency light. The frequency light is scanned at a predetermined scan velocity. The optical recording/reproducing system includes a computer 13, a DSP 49, and a LD driver that modulate light by a drive signal on which a frequency signal is superimposed to thereby output the frequency light, and synchronizes a frequency of the frequency signal with a frequency of the reproduction clock according to the scan velocity.

Abstract: A data recording/reproducing system (1) reads a recording signal written on a recording track of a recording medium (3), by using light, which is modulated by a drive signal wherein a frequency signal is superposed for scanning the signal along the recording track at a prescribed scanning speed. Then, the system reproduces the read signal as data. The data recording/reproducing system is provided with a computer (13) for controlling the superposition frequency of the frequency signal for the drive signal corresponding to the scanning speed, and an LD driver (17).

Abstract: An optical disc apparatus comprises an overcurrent detector and when the overcurrent detector detects an overcurrent during a recording operation or a reproduction operation and during an operation for controlling a focus of an objective lens, a rotation speed of an optical disc is reduced and an actuator is controlled to cause the objective lens to be in a retracted state under the condition that a disc motor exerts brake force. The objective lens is in the retracted state until the rotation speed of the optical disc becomes equal to or smaller than a predetermined value and when the rotation speed of the optical disc is equal to or smaller than the predetermined value, the objective lens is released from the retracted state.

Abstract: A method to balance spindles in a plurality of disk drives is disclosed and claimed. An initial imbalance and initial phase for one of the plurality of disk drives is determined, the determination depending upon an amplitude and phase calibration. One of a plurality of balancing masses is selected based on the initial imbalance and attached at an angular position selected based upon the initial phase. A final imbalance after attachment is similarly determined. These determinations are repeated for each of the plurality of disk drives, with the final imbalance and the initial imbalance recorded for each. The amplitude calibration is adjusted based on a comparison of a measured distribution and a theoretical distribution of the final imbalance versus the initial imbalance.

Abstract: A system for determining groove/land (G/L) switching points of an optical disc is disclosed. The system includes a motor rotating signal generating apparatus, an detection apparatus, and a G/L switching point generating apparatus. The motor rotating signal generating apparatus is for sensing the rotation of a motor to generate a motor rotating signal with a period corresponding to the rotation of the optical disc. Also, the detection apparatus is used for receiving the motor rotating signal and an original G/L switching point signal and utilizing the motor rotating signal and the original G/L switching point signal to determine a location of an reproduced G/L switching point of the optical disc. The G/L switching point generating apparatus is for generating an reproduced G/L switching point signal according to the location of the reproduced G/L switching point determined by the detection apparatus.

Abstract: The object of this invention is to provide an optical disc apparatus and an optical disc reproducing method that can realize an excellent reproducing operation by suppressing noise in the optical disc apparatus using an optical attenuator. In order to solve this object, a control voltage of the optical attenuator is changed according to reproduction power when reproducing the optical disc and an ambient temperature of the optical attenuator. In addition, the amplitude of a high frequency current for driving a laser diode is changed according to an attenuation factor of the optical attenuator.

Abstract: A method and device are disclosed for improving reliability of reading an optical storage medium, such as an optical disc (20). A disc spin speed value (31) of the optical disc (20) is provided and an unnormal value of said disc spin speed value (31), which differs from a disc spin speed value within a range of nominal disc spin speed values, is detected, indicating normal spinning operation of said optical disc (20). By using this method, the spinning loss of an optical disc, e.g. due to insufficient disc clamping force, is detected fastly and reliably, in a manner resulting in a reduced risk of damaging the disc and disc reader during such spinning loss. Further actions may be taken in both cases, including disabling the drive in order to prevent damage of the disc or to thwart such illegal usage.

Abstract: An optical disk drive includes a spindle motor, a power source, a microprocessor, and a comparator. The spindle motor is for supporting a disk. The power source supplies a first voltage to drive the spindle motor to rotate. The microprocessor signals the power source to supply a second voltage to slow down rotational speed of the spindle motor when receiving a power-off signal. The comparator compares the rotational speed with a predetermined value. The microprocessor signals the power source to stop supplying power to the spindle motor when the rotational speed is smaller than the predetermined value. A controlling method for controlling the spindle motor in the optical disk driver is also provided.

Abstract: A write-once read-many information recording medium is provided, which is capable of easily searching for a latest DDS and a latest defect list. At least one disc management working area is sequentially allocated in a predetermined direction on the write-once read-many information recording medium of the present invention. The latest defect list and the latest DDS are provided in a recorded disc management working area neighboring a border between the recorded disc management working area and an unrecorded disc management working area, where the latest defect list precedes the latest DDS in the predetermined direction.

Abstract: A disc apparatus which can judge accurately whether or not a spindle motor is at fault due to a short circuit is provided. A disc apparatus (1) includes a spindle motor (3) which rotates a disc (2), a differential operational amplifier (5) which successively detects output voltages of the spindle motor (3), and a failure judgment unit (10) which calculates an average voltage of the plural output voltages and judges whether or not the spindle motor (3) is at fault in accordance with the average voltage and the output voltages. When counting number of occurrences of a specific state which indicates that one of the two output voltages detected successively is larger than the average voltage and other of the two output voltages is smaller than the average voltage, the failure judgment unit (10) judges that the spindle motor (3) is at fault.

Abstract: A write-once read-many information recording medium is provided, which is capable of easily searching for a latest DDS and a latest defect list. At least one disc management working area is sequentially allocated in a predetermined direction on the write-once read-many information recording medium of the present invention. The latest defect list and the latest DDS are provided in a recorded disc management working area neighboring a border between the recorded disc management working area and an unrecorded disc management working area, where the latest defect list precedes the latest DDS in the predetermined direction.

Abstract: An optical disk drive capable of detecting occurrence of step-out or tooth jump in a mechanism for transferring an optical pickup. The optical pickup is transferred in a radial direction of the optical disk by means of a stepping motor. Upon receipt of a seeking operation command from a host machine, a control section drives the stepping motor by way of a controller, to thus cause the optical pickup to perform seek up to a target address. When logical contradiction has arisen in a stepper pointer showing the amount of rotation of the stepping motor, the control section determines that step-out or tooth jump has arisen. Moreover, even when a difference exists between an address indicated by the value of the stepper pointer and an actual address, step-out or tooth jump is determined to have arisen. When the step-out or tooth jump has arisen in the transfer mechanism, the rotational speed of a spindle motor or the rotational speed of the stepping motor is decreased.

Abstract: A write-once read-many information recording medium is provided, which is capable of easily searching for a latest DDS and a latest defect list. At least one disc management working area is sequentially allocated in a predetermined direction on the write-once read-many information recording medium of the present invention. The latest defect list and the latest DDS are provided in a recorded disc management working area neighboring a border between the recorded disc management working area and an unrecorded disc management working area, where the latest defect list precedes the latest DDS in the predetermined direction.

Abstract: An optical information storage medium and a method of recording thereon. The optical information storage medium has a lead-in area, a user data area and a lead-out area, and data indicating a maximum and/or a minimum writing speed, maximum and minimum writing speeds, or compatible writing speeds is recorded in a recordable region of at least one of the lead-in area and the lead-out area. The optical information storage medium and the method of recording on the media enable a disc drive to reliably record data on a disc which cannot achieve a prescribed recording speed due to manufacturing conditions, at an optimal speed considering the pre-recorded writing speed data.

Abstract: In an optical recording method and apparatus of the present invention, a driving power is applied to a light source to control emission of a light beam to a recording layer of an optical storage medium, the driving power including a sequence of mark and space portions, each mark portion having a pulse width that corresponds to a multiple of a period T of a write clock. A multi-pulse waveform of each mark portion of the driving power includes a front-end portion, a multi-pulse portion and a tail-end portion, the front-end portion having a first pulse width t1 with a high-power write level Pw and starting from a middle-power erase level Pe, the multi-pulse portion including write pulses each having a second pulse width t2 with the write level Pw and a third pulse width t3 with a low-power base level Pb, the multi-pulse portion having a duty ratio z=t2/(t2+t3), and the tail-end portion having a fourth pulse width t4 with the base level Pb and ending at the erase level Pe.

Abstract: A method and apparatus for controlling reproduction speed of an optical disk are provided. The method for controlling reproduction speed of an optical disk includes checking whether a read command has been received, and examining whether the received read command is intended for performance evaluation based on the number of backward track jumps of a laser beam irradiated on the optical disk. The method and apparatus for controlling reproduction speed of an optical disk provide designed read performance when an external host executes a performance test.

Abstract: A recording medium, a method for searching for content data from the recording medium, and a method and apparatus for reproducing data from the recording medium are disclosed. The recording medium includes a stream area for storing content data, and a reproduction management area for storing a search file capable of searching for the content data. The search file divides the content data into a plurality of scenes. If the content data supports a multi-angle, the search file classifies the scenes according to angles, and includes attribute for specifying the angles. Therefore, the recording medium can easily search for a variety of content data recorded in the recording medium, can provide the searched result, and can effectively reproduce/manage data of the recording medium, resulting in the creation of more convenient functions for a user.

Abstract: Conventional reproducing apparatuses used to perform incorrect detection or consume electricity considerably. According to the present invention, the comparator 61 comparing voltages at both ends of the spindle motor 15 and outputting the result is provided, and the control IC 12 judges whether or not the spindle motor 15 is rotating based on the output from the comparator 61. Based on this judgment, brake pulses are repeatedly supplied to the spindle motor 15 until the spindle motor 15 stops. Based on the number of times the brake pulses are supplied until the spindle motor 15 stops, the presence or absence of an optical disk in the disk drive is determined.

Abstract: A method of an embodiment of the invention optically writes a plurality of image data files on an optically writable data side of an optical disc. The method optically marks a plurality of thumbnail images on an optically writable label side of the optical disc. Each thumbnail image corresponds to one of the image data files.

Abstract: A data processing apparatus for outputting a plurality of picture data forming reproduced data to a reproduction apparatus for reproduction, the data processing apparatus having a processing circuit for judging if the reproduction rate of the picture data by the reproduction apparatus is slower than a transfer rate for transferring the picture data to the reproduction apparatus and outputting all of the picture data forming the reproduced data to the reproduction apparatus when judging as a result of the judgment that the reproduction rate is slower than the transfer rate.

Abstract: A method and apparatus to record data on an optical recording medium include generating a recording waveform having an erase pattern comprising a multi-pulse having a high level which is higher than an erase power level and a low level which is lower than the erase power level. A power level of a leading one of the multi-pulse of the erase pattern and a power level between an end of the erase pattern and a start point of a leading pulse of a recording pattern are controlled to be the low level and the high level, respectively, the high level and the high level, respectively, the high level and the low level, respectively, or the low level and the low level, respectively.

Abstract: A signal processor includes an operational amplifier performing an operation on first and second signals, and amplifying a signal resulting from the operation based on an amplification control signal to remove an offset voltage, a buffer buffering an output signal of the operational amplifier and outputting a result of the buffering as differential signals, an automatic gain amplifier automatic gain amplifying the differential signals output from the buffer and outputting an automatic gain amplified signal as a single ended signal, a level shifter level shifting a level of the single ended signal including the offset voltage and outputting a level shifted signal as level shifted differential signals, and an offset voltage compensation unit converting a difference between the level shifted differential signals to a digital signal, detecting the offset voltage based on the digital signal, and outputting the amplification control signal to compensate for the detected offset voltage.

Abstract: There is provided an information recording/reproducing apparatus for recording or reproducing an information to or from an information recording medium having a plurality of recording layers stacked on a substrate which can always perform stable spindle rotation control irrespective of an error of a desired frequency value or the like, and which includes an optical head for recording or reproducing an information to or from the recording layers by use of an optical beam; a spindle motor for rotating the recording medium; and a drive voltage holding circuit for holding a drive voltage of the spindle motor when the optical head performs switching between the recording layers for recording/reproducing.

Abstract: A method and apparatus for writing data to a rewritable ultra-speed disc using an optimum pulse at a write speed of the disc, based on Absolute Time in Pre-groove (ATIP) information. The method includes: reading a disc code from the disc; determining a write speed of the disc from the read disc code; and writing data to the disc. The writing is at the determined write speed and according to a write strategy when the write strategy for the lead-in area is determined to be present, and is according on a default write strategy when the write strategy for the lead-in area is determined not to be present.

Abstract: An optical disk apparatus comprising a reproduced signal detector which digitizes a reproduced signal from an optical disk, a broadband synchronizing clock signal generator for generating a synchronizing clock signal for use in reproducing data, a signal processor for processing signals, and a disk rotation controller for controlling the optical disk by switching control modes according to the reproducing position of the disk, that is, performing CAV control using the constant rotating velocity which is the same as the current rotating velocity in a range where the synchronizing clock signal generator allows a reproduced signal to be subjected to pull-in-synchronization, and performing CLV control so that the linear velocity is constant to minimize the pull-in-enable changes of number of revolutions in a range exceeding the pull-in-synchronization range, by which arrangement the amount of change of number of spindle motor revolutions when the reproducing position of the optical pickup changes is minimized, th