Abstract: Optically detectable marks readable by a wide range of optical systems are included on an optical storage medium. Among other uses, the marks may be used to determine the type of the optical storage medium in an optical device capable of reading multiple types of optical storage media.

Abstract: A super-resolution medium (1) has a medium identification information for specifying a type of medium recorded in a medium information area (3) by use of pre-pits having a length not shorter than a length of a resolution limit of an optical system in a reproducing device (10).

Abstract: An optical disc apparatus includes a light separator configured to separate a light beam emitted from a light source into a main beam and a sub-beam, an objective lens configured to, when the light beam is condensed and irradiated to an optical disc having a uniform recording layer in which a track is formed by record marks, irradiate at least part of the sub-beam to an area where the main beam is not irradiated in a radial direction which is defined as a direction of radius of the optical disc, and a signal generating unit configured to generate a mark layer distance signal, representing a distance between a focus of the light beam and a mark layer to which the track belongs, based on a return light beam resulting from at least one of the main beam and the sub-beam, which has been irradiated to the track.

Abstract: Provided is a digital broadcast receiver capable of displaying a message, a list of titles of contents or the like together with a viewing screen without interrupting viewing of contents. The digital broadcast receiver includes a controller 25 configured to determine whether an optical disc inserted into the receiver is a read-only optical disc or a recordable optical disc and also to control a display screen. Upon insertion of an optical disc, the controller 25 causes a display screen including a first display area and a second display area to be displayed, the first display area displaying digital broadcast or external input contents, the second display area displaying a message indicating that the optical disc is being prepared. In a case where the optical disc is a read-only optical disc, the controller 25 causes only a playback screen of contents recorded in the optical disc to be displayed upon completion of the preparation of the optical disc.

Abstract: The present invention provides a multilayer optical disc and an optical disc drive which can identify recording layers without performing tracking servo control or changing the structure of the disc. In a multilayer optical disc 100, the recording layer includes a layer identification region 101 having a recording pattern for layer identification, the layer identification region 101 including a layer specific region 102 having a specific pattern and a common region 103 having a common pattern different from the specific pattern, the layer specific region 102 being provided at a different radial position in each of the recording layers. The optical disc drive detects the layer specific region 102 having the specific pattern from the layer identification region 101 of the multilayer optical disc 100, and identifies the current layer based on the radial position of the layer specific region.

Abstract: Provided are an optical disc discrimination method, an optical disc device and an integrated circuit that enable to accurately discriminate the type of an optical disc. The optical disc discrimination method comprises a first seeking step (S3) of performing a seek operation to a predetermined reference address in a user data area; a second seeking step (S5) of performing a seek operation from the reference address sought in the first seeking step (S3) to a predetermined target address in a physical information area, an address reading step (S7) of reading a current address at a position sought in the second seeking step (S5), and an optical disc type determination step (S8 through S10) of determining the type of the optical disc loaded in the optical disc device, based on the current address read in the address reading step (S7).

Abstract: A method for recording information which cannot be easily copied on a BCA is provided so as to prevent pirated copies from being made. The BCA recording device for optical discs records, on the BCA on an optical disc, identifying information unique to the optical disc. The BCA recording device is provided with: a BCA data generating section which generates BCA mark signals and BCA code signals which indicate the identifying information; a BCA mark generating section which, based on the BCA mark signals, generates BCA marks by recording marks on the recording film in the BCA on the optical disc, thereby partially changing the reflectance of the recording film; and a BCA code generating section which, based on the BCA code signals, generates BCA codes by partially removing the recording film on the BCA.

Abstract: A configuration for reading out disc management information easily without errors from a disc in which recording is conducted with data recording densities of a plurality of kinds. An optical disc includes a plurality of data recording areas in which information is recorded with data recording densities which are different from each other. Information of the data recording densities in the data recording areas is recorded in a management information recording area (a BCA area or a PIC area) by using a unique format which does not depend upon the data recording densities of the data recording areas. The divided data recording areas are disposed in the same plane of the disc, or disposed over a plurality of recording layers.

Abstract: An apparatus configured to write input data on an optical recording medium using a write pulse waveform including a first pulse, a last pulse and a multi-pulse train is provided.

Abstract: An optical recording medium is provided, the optical recording medium including a plurality of zones configured to store data corresponding to an adaptive write pulse, the adaptive write pulse including a first pulse, a last pulse, and a multi-pulse train, the adaptive write pulse being different for each of the plurality of zones, the plurality of zones being reflected by a grouping table, the grouping table being configured to generate an adaptive write pulse waveform by varying a position of a rising edge of a first pulse of a mark to be written according to a length of the mark to be written and a leading space, the adaptive write pulse waveform being generated without regard for a trailing space of a present mark being written using the adaptive write pulse waveform, the adaptive write pulse being configured to correspond to the adaptive write pulse waveform, and store rising edge data of the first pulse of the adaptive write pulse waveform varying according to corresponding stored values of lengths of m

Abstract: An optical recording medium is provided, the optical recording medium including a plurality of zones respectively corresponding to width data of first and/or last pulses of an adaptive write pulse waveform stored in a grouping table, the grouping table being configured to group a magnitude of a present mark of input data and magnitudes of leading and/or trailing spaces of the present mark into a short pulse group, a middle pulse group, and a long pulse group using grouping pointers, store data configured to calculate a width of a write pulse, an adaptive write pulse being generated in response to the calculated width, generate the adaptive write pulse waveform by varying a position of a rising edge of a first pulse of a mark to be written according to the magnitudes of the present mark and the leading space, the adaptive write pulse waveform being generated without regard for the trailing space of the present mark being written using the adaptive write pulse waveform, the adaptive write pulse being configured

Abstract: An optical disc apparatus includes an optical pickup including: a light source; an objective lens for converging a light flux emitted from the light source and forming an optical spot on an information recording plane of an optical disc; and an optical modulation unit divided into a plurality of areas for modulating an area containing a main beam of the light flux to change a shape of the optical spot, wherein data is reproduced by converting a reproduction signal read from the optical disc with the optical pickup into an NRZI signal of a predetermined modulation rule by a PRML method. An optical spot shape, laser power setting and PRML setting are changed with each optical disc and each drive operation state.

Abstract: An apparatus configured to write input data on an optical recording medium using a write pulse waveform, the write pulse waveform including a first pulse, a last pulse and a multi-pulse train, is provided.

Abstract: A device for detecting wobbles on an optical disc is provided, where the device is utilized for generating a wobble signal according to a plurality of detection signals. The device includes an analog signal processing circuit, a pair of analog-to-digital converters (ADCs), and a digital signal processing circuit. The analog signal processing circuit is arranged to perform analog signal processing on the detection signals to generate a plurality of output signals. In addition, the pair of ADCs are arranged to digitalize the output signals to generate a plurality of digital values. Additionally, the digital signal processing circuit is arranged to perform digital signal processing on the digital values and generate an arithmetic output, where the arithmetic output is utilized for generating the wobble signal or utilized as the wobble signal. An associated method for detecting wobbles on an optical disc is further provided.

Abstract: An environmental load information of an information recording medium is recorded on the information recording medium so as to recycle or dispose properly an information recording medium, which is not necessary any more. The information recording medium comprises a main information area (102) for recording or reproducing information and a recording area (101) for environmental load information, which is recorded with an environmental load information of the information recording medium.

Abstract: An optical medium associated with a first type of optical drive laser, such as a blue laser, embeds identification information readable by a second type of optical drive laser, such as a red laser associated with DVD media or an IR laser associated with CD media, in order to reduce the time used by the optical drive to recognize media. An attempt to read the embedded identification information by the second laser that succeeds provides the optical drive with the information to proceed with use of the optical medium using the first laser. An attempt to read the embedded identification information that fails provides the optical drive with the opportunity to detect whether the optical medium is associated with the second laser so that a single spindle kick of the optical medium by the optical drive determines whether the optical medium is associated with either of two types of lasers.

Abstract: A technique for investigating differences of composition and structural state of a recording layer of an optical disc along with other defects, such as scratches, contamination, warp and distortion, prior to video recording and for setting up appropriate recording conditions in compliance with this result to thereby perform recording is disclosed. In an optical disc recording device capable of recording information on an optical disc, a region to be investigated is defined based on the video recording reservation contents. Then, investigate and evaluate the disc state which can affect the recording quality in a target disc region to be recorded. Next, based on investigation/evaluation results, perform recording setup, recording speed setup, servo control setup and recording position setup to thereby perform the recording. By appropriately modifying the recording setup on a case-by-case basis, it is possible to achieve high-quality recording.

Abstract: An optical disc discriminating method and an optical disc discriminating apparatus which can discriminate a type of optical disc with a simple configuration, causes a drive means to vary an incident angle of a laser light beam with respect to an optical disc while irradiating the optical disc with the laser light beam from a light beam generating section, causes a photodetector to detect a diffraction light of the laser light beam from a recording track of the optical disc, detects a value corresponding to the incident angle when the diffraction light is detected, and discriminates the type of the optical disc on the basis of the detected value.

Abstract: An information storage medium includes an area in which updated disc-related information and recording-related information updated with a change in at least one of a disc version number and a recording speed is recorded along with existing disc-related information and recording-related information. The existing disc-related information and recording-related information are recorded, and the updated disc-related information and recording-related information is recorded in an area in which the existing disc-related information and recording-related information is recorded. Accordingly, data can be recorded/reproduced on/from a new version of information storage medium even using an existing drive.

Abstract: To identify the type of a loaded disc, there is provided an optical disc device, comprising: a light source driven by a drive signal with a high frequency signal superimposed; a detector for detecting return light emitted from the light source; and a controller for controlling the amplitude of the high frequency signal to be superimposed on the drive signal, the optical disc device being configured to read data from an optical disc loaded therein by a signal outputted from the detector, wherein: the controller causes the light source to irradiate the loaded optical disc with light in a condition in which a high frequency signal different from a high frequency signal for data reading is superimposed on the drive signal; and the controller identifies a type of the loaded optical disc based on the return light from the loaded optical disc.

Abstract: A mass-storage device according to an embodiment of the invention is disclosed that includes a laser and an indication mechanism. The laser at least optically writes to an optically writable surface of an optical disc incident to the laser. The indication mechanism indicates whether the optically writable surface incident to the laser is an optically writable label surface or an optically writable data surface of the optical disc.

Abstract: A recording apparatus includes an acquiring unit for acquiring, from an optical disc, disc-state information including at least information of an optical disc type, information of a recording format, and information indicating whether the optical disc has already been finalized, a first determining unit for determining, based on the information of the optical disc type and the information of the recording format in the acquired information, whether the optical disc type and the recording format correspond to one of predetermined combinations, a second determining unit for determining, based on the result of determination by the first determining unit and the acquired information, whether the optical disc needs to be finalized, and a display control unit for controlling, when the second determining unit determines that the optical disc needs to be finalized, display of a message representing the need of the finalization.

Abstract: Proposed is an optical disk device capable of appropriately performing focus control. In an optical disk device, an objective lens is moved in the thickness direction of an optical disk by controlling an actuator and a time interval in which each of the recording layers was detected is measured while moving the objective lens, a first time interval from the first detection of the recording layer to the second detection of the recording layer is compared with a second time interval from the second detection of the recording layer to the third detection of the recording layer, and a focal position of the objective lens is determined based on the comparative result.

Abstract: An optical disc identifying device includes an optical pickup head, a digital signal processor and a radio frequency amplifier. The optical pickup head has a plurality of laser diodes and a lens. During a start-up procedure, a non-blue laser diode of the optical pickup head is turned on to irradiate a loaded optical disc, thereby generating an electronic signal. The digital signal processor outputs a driving signal, thereby controlling a motor driver to move the lens in a focusing direction. The radio frequency amplifier receives the electronic signal during the movement of the lens, thereby generating a first signal. The digital signal processor includes a detecting unit for comparing the first signal with a slicing signal to generate a pulse signal, and determining whether the optical disc is a blue-ray disc or a non-blue-ray disc according to a pulse number of the pulse signal.

Abstract: An optical article for playback in a player includes at least one sector comprising a first control logic configured to set the value of a first register, the first register having a default value before it is set, and a non-default value after it is set, and a first command to be read sequentially after the sector. The first command is configured to direct the player to play a first content on the article if the first register is set to the default value and to direct the player to play a second content on the article if the first register is set to the non-default value. The optical article includes a mark containing an optical state change material disposed on the sector, wherein the mark is in one of a first optical state or a second optical state, and wherein the first control logic can be read only when the mark is in the second optical state.

Abstract: A method for determining a disc format is disclosed. Data from at least one address of the disc is retrieved, wherein the at least one address is selected from a plurality of predetermined addresses related to the disc format. The disc format is determined according to the retrieved data.

Abstract: There is provided an optical information recording/reproducing apparatus having an optical disc drive unit for driving an optical disc mounted, a hologram disc drive unit for driving a hologram disc mounted, a disc discrimination device for discriminating which of an optical disc and a hologram disc was mounted, a selection device of the disc drive unit for selecting an optical disc drive unit, when discriminated to be an optical disc, by the disc discrimination device, while selecting a hologram disc drive unit, when discriminated to be a hologram disc, by the disc discrimination device, and a drive device of the disc drive unit for driving the disc drive unit selected by the selection device of the disc drive unit.

Abstract: A disc-shaped information recording medium includes a first recording layer (L0 layer) having (I) a first trial write area (101P-1) for trial write of first trial write information for calibration of the laser beam along the first track path (TP1) from the inner circumference toward the outer circumference and (II) a first recording area for recording the first recording information along a first track path (TP1), in this order from the inner circumference side. Furthermore, the disc-shaped information recording medium includes a second recording layer (L1 layer) having (I) a second trial write area (101P-2) for trial write of second trial write information for calibration of the laser beam along the second track path (TP2) from the outer circumference toward the inner circumference and (II) a second recording area for recording the second recording information along a second track path (TP2), in this order from the inner circumference side.

Abstract: An optical pickup device includes: a splitting section for splitting a beam; a light-receiving section for receiving the split beams. The light-receiving section includes: a tracking-use main light-receiving region and tracking-use sub light-receiving regions, and auxiliary light-receiving regions. Each of the auxiliary light-receiving regions receives only a light beam reflected off a recording layer other than a recording layer subjected to an information writing/reading process. A light-receiving area of each of the auxiliary light-receiving area is smaller than a light-receiving area of each tracking-use light-receiving region. Further, an optical pickup device includes: a splitting section for splitting a beam; and a light-receiving section for receiving the split beams. The light-receiving section includes a sub light-receiving regions for receiving tracking-use sub beams.

Abstract: In a recording apparatus capable of performing a curing process at high speed by curing a plurality of books at a time during recording and capable of performing recording of a recordable type, when recording is stopped once, the unit of books to be cured at a time is set smaller than that during continuous recording, in order to realize inexpensively both performing a curing process at high speed in hologram recording and realizing recording of a recordable type freely in a book unit. It is therefore possible to terminate recording in the unit of arbitrary books irrespective of the unit of books to be cured, and perform recording of a recordable type without loss.

Abstract: A method of determining a disk type of an optical disk is provided to comprise steps of: using a first light path for forming an incident beam; moving an objective lens system corresponding to the first light path from a start position towards the optical disk; receiving a sensor output signal during the movement of the objective lens system, wherein the sensor output signal includes a central aperture signal; determining the disk type of the optical disk according to the central aperture signal.

Abstract: An optical recording medium having a read-only storage area and a writable storage area and a recording/reproducing apparatus and method therefor. The optical recording medium is a hybrid disc having both the read-only storage area, which is suitable for mass production of information having the same contents, and the writable storage area on which data can be recorded, updated or added at a user's option.

Abstract: A discrimination method of an optical disc. The method includes: focusing a light spot on a rewritable zone of the optical disc; reading an EFM signal of data marks of the optical disc to check if the optical disc is a data disc or a blank disc; when the optical disc is a data disc, utilizing an SBAD signal for discrimination of the optical disc; when the optical disc is a blank disc, utilizing a DPD signal for discrimination of the optical disc; checking if the header signals exist or not; identifying the optical disc as a DVD-RAM disc if the header signals exist; and identifying the optical disc as a DVD-RW disc if there is no header signal. In this way, the accuracy of the optical disc discrimination is enhanced.

Abstract: An evaluation apparatus obtains an evaluation value of a signal read from an optical recording medium includes a reading device reading a signal recorded on the optical recording medium. Edge positions are detected of the read signal acquired by the reading device. A frequency distribution table is generated of the edge positions on the basis of an accumulation result of information of the edge positions detected by the edge position detection device. A first calculation of a T degree value is represented as [{?fi×(xi?A)(2m+1)}/F]{1/(2m+1)}??Formula 1 (wherein m is a natural number excluding zero) The variables xi, fi, F, and A represent the value of each of the classes, the frequency of each of the classes, the sum of the frequencies, and the weighted average value, respectively.

Abstract: An image processing apparatus and data erasing method make it possible to unrecoverably erase encrypted data recorded in an auxiliary storage device at high speed while reducing the load put on the CPU. Upon reception of a data erase request from a data utilizing process, the data requested to be erased is registered in a predetermined storage unit. The data registered in the storage is unrecoverably erased by overwriting, and an area in the auxiliary storage device in which the erased data was stored is released after the overwriting erasure process.

Abstract: An optical article comprising a mark disposed on the optical article; wherein the mark comprises an optical state change material; wherein the optical state change material undergoes a change in its optical state when exposed to an activation signal selected from one or more of a laser, thermal energy, infrared rays, X-rays, gamma rays, microwaves, visible light, ultraviolet light, ultrasound waves, radio frequency waves, electrical energy, chemical energy, magnetic energy, and mechanical energy; wherein the optical article is transformed from a pre-activated state to an activated state when an authorized activation method is used; and wherein the optical article is transformed from a pre-activated state to an incorrectly activated state when an unauthorized activation method is used. A method and a system for changing the functionality of the optical article are also provided.

Abstract: A recording medium, a method for recording control information in the recording medium, and a method and apparatus for recording/reproducing data in/from the recording medium using the same are disclosed. The recording medium includes a data area, and a management area for recording control information capable of identifying write compatibility and read compatibility with a driver for recording or reading data on or from the recording medium. Herein, the control information may include a class number for identifying the read compatibility, and a version number for identifying the write compatibility, and the write compatibility may be determined using the version number within the class number.

Abstract: The present invention provides a method and an apparatus for determining the number of data layers in an optical disc. Firstly, the objective lens of the optical pickup head is controlled so that it moves toward the optical disc. At the same time, a generated SBAD signal is recorded. The number of wave peaks in the SBAD signal is then detected and the number of the data layers in an optical disc is determined according to the detected number of wave peaks in the SBAD signal.

Abstract: An information recording and reproducing apparatus records data on and reproduces data from each of a plurality of recording layers of a recording medium. A controller (7) controls a formatting process to format the recording medium (1) by performing a first formatting process on the data area of a recording layer. The first formatting process comprises formatting the data area in a series of recording increments that progress from the inner side of the data area to the outer side of the data area. Within each recording increment the formatting is performed along a path extending from the outer side of the data area to the inner side of the data area. A second formatting process on the data area of another recording layer once the first formatting process has been completed, the second formatting process being performed along a path extending from the inner side of the data area of the other recording layer to the outer side of the data area of the other recording layer.

Abstract: A highly reliable optical disk apparatus adapted to record and reproduce the information in and from plural types of optical disks is disclosed. An acquisition unit acquires a predetermined signal from the reflected light obtained by radiating a predetermined laser on each of the optical disks. A comparator compares the waveform of the signal acquired by the acquisition unit with the comparative waveform of the signal stored in a memory beforehand and obtained from the radiated laser corresponding to the optical disk. An identification unit identifies the type of the optical disk based on the result of comparison by the comparator.

Abstract: A defect is detected on a storage medium of a disk drive. A location of the defect is determined, within a smallest addressable unit of data stored on the storage medium. An indication of the location is stored in a memory. A location of a sensor of the disk drive relative to the data stored on the storage medium is monitored. A response of at least one of a defect detector of the disk drive, a read channel controller of the disk drive, and a servo controller of the disk drive is changed based on the location of the sensor relative to the data stored on the storage medium and the stored indication of the location of the defect.

Abstract: A method for generating an RFZC signal is provided. The method includes the following steps. First, an RF signal is received and the received RF signal is converted into an RF-ENVLP signal. Next, a DC offset of the RF signal is calibrated according to a variation of the RF-ENVLP signal so as to obtain a calibrated RF-ENVLP signal and obtain a gain according to the calibrated RF-ENVLP signal. Then, an RFZC signal is generated according to the calibrated RF-ENVLP signal and the gain.

Abstract: According to the present invention, there is provided a method of recording a unique ID to a read-only optical disc based on the 17PP modulation. The read-only optical disc (1) has set thereon a specific physical cluster to which a unique ID is to be recorded. With user data to be recorded to the specific physical cluster being made all zero (0), a pit/land pattern is formed, and a molding machine using a molding die is used to form many optical discs in the common manner. Thereafter, an ID unique to each optical disc is generated, and a land in a predetermined position in the specific physical cluster is transited to a pit by irradiating high-power laser light to the land correspondingly to the bit information, so that the pit/land pattern will comply the 17PP modulation rule even after the transition of the land to the pit.

Abstract: A method for discriminating different types of optical discs includes the steps of focusing a beam spot generated by a laser source on an optical disc, and rotating the optical disc; generating a radio frequency signal and a corresponding first signal of the radio frequency signal; comparing a peak-to-peak value of the corresponding first signal with a predetermined value; determining the optical disc as a high density optical disc when the peak-to-peak value of the first signal is smaller than the predetermined value; and, determining the optical disc as a low density optical disc when the peak-to-peak value of the first signal is greater than the predetermined value.

Abstract: There is provided a method of calculating the degradation over time of the quality of data recorded on an optical disk in a short time. In the method, when user data is recorded on a data area, a test signal including a component in which the signal level is smaller than a reference value, is recorded on a test area. Then, the test signal is reproduced from the test area when a predetermined time has passed, to calculate the quality degradation of the user data from the evaluation result. Alternatively, every time when the user data is recorded/reproduced on/from the data area, the test signal is recorded/reproduced repeatedly on/from the test area. Then, the test signal is reproduced from the test area at a predetermined timing, to calculate the quality degradation of the user data from the evaluation result.

Abstract: An optical disc drive according to the present invention is designed to read data from a multilayer optical disc 100, from/on which data can be read or written using a light beam. The drive includes a light source 222 for emitting a light beam, an objective lens 230 for converging the light beam, a photodetector 236 for detecting the light beam that has been reflected from the disc, and a control section 246 for setting a read power for a particular one of the multiple storage layers of the disc by reference to a read power table 501b. The table 501b stores multiple read powers for the respective storage layers in order to make S-curves of a focus error signal obtained from the respective layers have predetermined amplitudes. In this manner, the optical disc drive of the present invention can be loaded with a multilayer optical disc more smoothly by setting the best read powers for the respective storage layers of the disc.

Abstract: There is disclosed a method of permitting recording setup information required to perform a test recording on an optical disk to be obtained from an external device as the need arises. The method comprises the steps of: measuring an evaluation index associated with recording characteristics with which data was recorded on the optical disk by an optical disk drive; making a decision as to whether the measured evaluation index indicates a state in which recording setup information used in data recording by the optical disk drive should be updated; acquiring recording setup information corresponding to at least the machine ID of the optical disk drive and the medium ID of the optical disk when the evaluation index is judged to indicate the state in which the recording setup information should be updated; and setting the acquired recording setup information in the optical disk drive.

Abstract: Payload 0 as a header is recorded to a head of a UDI area. In the case of recording payload 0 and other payloads, each of them is quintuple-recorded in order to take a countermeasure against errors. Other payloads such as payload 1 and the like are recorded after payload 0. In the case of quintuple-recording, the payloads of the same payload number are collectively quintuple-recorded. AUDI is recorded from a position after one second from start time S. The payloads are arranged in positions at 12-frame intervals. Thus, the five data which is multiple-written are not arranged in the radial direction of a disc but widely distributed onto tracks. Error resistance is improved. An interval of data is set to an optimum value in accordance with the number of multiple-writing times, a linear velocity, a recording position on the disc, and the like.

Abstract: An optical disc reproducing device that composes a composite reproducing apparatus in accordance with the present invention includes an optical disc detecting portion which detects inserting and ejecting of an optical disc. The optical disc reproducing device also includes an identification information obtaining portion which obtains identification information to uniquely identify the optical disc from a management information recorded area of the optical disc. The identification information obtaining portion reads out the identification information and outputs it to a display device when inserting of the optical disc is detected by the optical disc detecting portion. An identification information recording portion which is included in the display device stores the identification information in a memory portion when the identification information is output from the optical disc reproducing device.

Abstract: It is highly precisely determined as to whether or not a laser-irradiated position on an optical disk is positioned within an identification area (BCA) in which identification information is recorded, and the position of the identification information area is efficiently determined. An optical disk apparatus includes an optical pickup for detecting reflected light from an optical disk and generating a light amount signal, and a detecting section for outputting a detection signal which is in accordance with a change in the signal level of the light amount signal, the detection signal indicating that the change has continued for a first predetermined time or longer.