Abstract: In a tilt compensation method and an apparatus thereof, an apparatus that compensates for a tilt of a recordable and reproducible optical recording medium includes a tilt detector detecting a tilt of the optical recording medium and a recording compensator. The recording compensator compensates for a recording signal having a predetermined recording pattern by using a predetermined system according to the tilt detected by the tilt detector, in which the tilt detector detects a tilt with respect to an optical recording medium in which a tilt margin is greater than 0 and less than 0.0052 (0<tilt margin<0.0052) and the recording compensator compensates for the detected tilt. Thus, a desired size (length and width) of a mark can be recorded by controlling the power level and the recording time needed for recording according to the detected tilt. Also, the above method and apparatus are suitable for a high density optical disc system.

Abstract: An optical recording medium has a phase-change recording layer containing Sb and Te as essential elements therefor, to which is added at least one element selected from the group consisting of Ag, Au, Cu, Zn, B, Al, Ga, In, Si, Ge, Sn, Pb, N, P, Bi, La, Ce, Cd, and Tb, the recording layer being capable of assuming an amorphous phase changed from a crystalline phase by the application of a laser beam thereto, thereby optically recording information. Recording marks are formed in the recording medium by converting a light emission wave of laser beam into a recording pulse train comprising a plurality of on-pulses and off-pulses, with a recording frequency being continuously changed corresponding to the location of each of the recording marks in the radial direction of said recording medium. A recording apparatus has laser beam driving circuit means, signal generation means, and signal transmission means for achieving the above recording method.

Abstract: A record carrier has substantially parallel tracks, which exhibit first variations of a first physical parameter and second variations of a second physical parameter of the track. The first variations represent information recorded on the record carrier, which information is recoverable by means of a controllable type of data processing. A modulation pattern of the second variations represents a code for controlling the type of data processing. With respect to a code track that includes the modulation pattern, the modulation pattern in the left neighboring track is aligned to the modulation pattern in the right neighboring track. Thereby crosstalk due to the second variations in decreased, and at least two tracks have the same modulation pattern. The playback device has a demodulator and a control unit for retrieving the code from at least two tracks.

Abstract: The information recording apparatus irradiates a laser beam on a recording medium such as an optical disk and forms a recording mark corresponding to a recording signal to record information. A recording pulse signal includes a mark period irradiating the laser beam for forming the recording mark and a space period in which the recording mark is not formed. The mark period has a top pulse period and an intermediate bias period following the top pulse period. The mark period constituted by the top pulse period and the intermediate bias period does not have a continuous part of a plurality of pulses having a small pulse width unlike a pulse train, so that the correct recording mark can be stably formed on the recording medium without an inadequate deformation of a recording pulse shape, even in the case of a high speed recording.

Abstract: A recording medium for recording digital information including a substrate member, a plurality of recording tracks formed on the substrate member, and a plurality of pits formed on the recording tracks. In the recording medium, the pits are arranged in a fixed period, the position of an edge of each pit is changed in accordance with the digital information to be recorded in the recording medium, and the phase of the train of the pits formed on one of the recording tracks and the phase of the train of the pits formed on another one of the recording tracks adjacent to the one of the recording tracks are shifted each other by half of the fixed period.

Abstract: The invention relates to an optical record carrier recording method for forming pits and lands by directing a radiation beam (12) onto a recording surface (21) of an optical record carrier (20). The radiation beam for each pit to be recorded is set to at least one write power level (Pw) capable of forming a pit during a write power irradiation period (31) and, for each land between the pits, to at least one bottom power level (P0) incapable of forming a pit during a bottom power irradiation period (51).

Abstract: A phase change optical recording medium together with methods for optimally initializing and recording feasible for carrying out read/write/erase operations at multiple recording velocities ranging from 4.8 m/sec to 30 m/sec. Preferably, a recording layer included in the recording medium essentially consists of Ag, In, Sb and Te, with the proportion in atom % of a(Ag): b(In): c(Sb): d(Te), with 0.1≦a≦7, 2≦b ≦10, 64≦c≦92 and 5≦d≦26, provided that a+b+c−d≧97. Initializing the recording medium uses a scanning beam spot from a high power semiconductor laser having energy density input equal to, or less than, 1000 J/m20, scanning speed of the beam spot in the range of 3.5 m/sec to 6.5 m/sec0, and intensity of laser emission equal to, or greater than 330 mW.

Abstract: A shortest mark 108 is recorded with a single recording pulse. A long mark 125 is recorded with a two-stage pulse including a first-part pulse and a second-part pulse. In the case where each of positions 115 and 118 of front edges of the recording pulses is determined based on a relationship between a length of a space immediately before a mark and that of the mark itself so as to properly position the front edges of reproduced waveforms of all the mark lengths and each of positions of rear edges of the recording pulses of all the mark lengths is fixed so as to satisfy a prescribed relative relationship with an edge of a recording clock, power 122 of a recording pulse 101 of the shortest mark is determined so as to realize a proper rear edge position 112 of the reproduced waveform of the shortest mark and power 124 of a second-part pulse 104 is determined for each mark length so as to realize a proper rear edge position 123 of the reproduced waveform of the long mark.

Abstract: Provided is a processing method of a master optical disc with an improved jitter and modulating degree of the reproduced signal, and a fine reading accuracy. In an exposure step for forming one pit by laser beam exposure of a plurality of pulse arrays, using the laser beam for exposure to an optical disc as an intermittent beam, the pulse length of the edges of a pit is made longer than the pulse length of the center portion. Moreover, the pulse interval behind the front edge pulse and/or the pulse interval in front of the rear edge pulse is longer than the pulse interval of the center portion.

Abstract: The present invention has enabled to solve various problems associated with the optical recording medium of phase change type when high density recording is conducted by reducing the record marks. Provided is an optical recording method for an optical recording medium having a recording layer of phase change type wherein amorphous record marks are formed in the recording layer by irradiating the medium with a recording beam which is power-modulated between high power and low power. In this method, minimum record marks are formed such that at least a part of the rear end protrudes toward the forward end of the mark.

Abstract: When data is reproduced by an apparatus which is different from an apparatus used for recording the data, the fluctuation of edge positions of the reproducing data increases, making reproduction incompatible, and the present invention solves this problem.

Abstract: Top-power increasing pulse is imparted to part of a top power irradiation period of a recording laser light beam, to temporarily increase the top power level of the light beam. For pits of a same length, control is performed on the top-power increasing pulse, which includes control to decrease a ratio, to a unit pit length, of a width of the top-power increasing pulse as the recording speed increase ratio is raised, control to decrease a ratio, to a difference between the top power level and the bottom power level, of a difference between a peak level of the top-power increasing pulse and the top power level as the recording speed increase ratio is raised, and/or control to increase a ratio, to a unit pit length, of a delay of a rise of the top-power increasing pulse from a start of the top power irradiation period as the recording speed increase ratio is raised.

Abstract: A system and method are disclosed for generating a transition in a laser control signal at a precise point in time. A write strategy processor is configured to input a sequence of data and to determine a transition in a laser control signal from the sequence of data. The transition is specified by a number of pulse clock units and a delay. A write pulse generator is configured to input the number of pulse clock units and the delay and to generate a transition by creating a signal having a transition at the time specified by the number of pulse clock units and delaying the transition by the specified delay.

Abstract: The invention provides a method for improving the yield of a CD recorder, adjusting the current recordable rate and a write delay table using the data of a write radio frequency profile.

Abstract: There are times when an abnormal light emission occurs and damage the medium when updating the setting register of the pulse width or the laser driving current during recording operation in an optical information recording and reproducing device. There are thus provided a plurality of pulse width setting registers for setting the pulse width of the multi-pulse emissions. When updating the pulse width of the multi-pulse, the pulse width setting register is changed and then the recording operation is performed, and at the time to change the pulse width setting register during recording, the generation of recording pulse train is stopped.

Abstract: A laser beam is directed to an optical recording medium such as a DVD-R to successively form thereon marks of a length corresponding to data with a spacing disposed therebetween. A Q value or the amount of reduction in time causes the rise time of laser irradiation to be delayed with respect to the scheduled rise time at least after a spacing equal in length to the mark of the shortest length employed for recording. The Q value satisfies the following equation (1) expressed in terms of the relationship between the recording speed n and an asymmetry.

Abstract: A pulse width control circuit is used to control the pulse with of a modulation signal to be written to a recording medium, such as a CD-R. The circuit controls both the leading and trailing edges of the modulation signal. The circuit includes a first delay circuit including multiple series connected first inverters for delaying the modulation signal and generating multiple first delay signals. The first delay signals are input to a first selector, which selects one of the first delay signals. A first logic circuit receives the selected first delay signal and the modulation signal and performs a first logic operation. The output of the first logic circuit is input to a second delay circuit, which includes multiple series connected second inverters for delaying the first logic circuit output signal, and generating multiple second delay signals. A second selector selects one of the plurality of delayed logic signals in accordance with the second selection signal.

Abstract: An edge detection system for detecting pre-formatted marks on a disk surface using reflected beams of optical signals. The detector include at least two separate sensing areas to analyze the energy distribution of the reflected beam to generate an edge detecting signal.

Abstract: A method of recording information in a phase-change recording medium, including the steps of conducting a test recording, using a laser beam including a plurality of pulse trains, each pulse train including alternately (a) a comb-shaped pulse train portion and (b) a flat pulse-free portion, or using a laser beam including a comb-shaped pulse train pulse train portion without including the flat portion, with a duty ratio of the comb-shaped pulse train portion being changed, thereby recording a plurality of signals or laser-beam applied portions in the recording medium, reproducing the plurality of recorded signals, or measuring the light intensities reflected by the laser-beam applied portions and converting the measured light intensities to voltages and obtaining the relationship between the amplitudes of the signals reproduced from the recorded signals or the voltages and the duty ratios corresponding thereto in order to specify a pulse strategy for recording information in the phase-change recording medium,

Abstract: An optical disk recording apparatus, an optical disk recording method, an optical disk playback apparatus, and an optical disk playback method are provided. For example, the present invention is applied to a high-sound-quality optical disk which can be played back by a conventional compact disk player, and aims at supplying still higher-quality contents which can be played back even by a conventional optical disk apparatus. Second information is recorded by partial changes of optical characteristics, such changes being of such a degree which does not affect detection results of first and second areas which are detected by the irradiation of a laser beam.

Abstract: A method and an apparatus capable of recording optical information at high density are disclosed. A recording pulse which includes a top pulse followed by a multiple pulse set is generated to form a pit, wherein, based on the distance from the top pulse, either pulse widths of pulses within the multiple pulse set are set to be sequentially smaller or pulse intervals of pulses within the multiple pulse set are set to be sequentially larger.

Abstract: An optical recording method for recording mark length-modulated information on a recording medium by using a plurality of recording mark lengths.

Abstract: An optical recording apparatus for writing information on an optical recording medium in which a recording surface is covered with a transparent layer. The information to be written on the optical recording medium is converted into a pulse signal, and spherical aberration occurring due to an error of a thickness of the transparent layer is detected, the pulse signal being controlled in accordance with the detected spherical aberration.

Abstract: An apparatus and method are disclosed for optimizing the writing of data to an optical disc to improve readback characteristics and minimize the effects of errors. An optimization circuit generates an optimized modulation signal which is used to modulate a writing beam of a laser beam recorder, the optimized modulation signal comprising a series of data symbols that correspond to resulting pits and lands on the optical disc. The optimization circuit optimizes the locations of pit and land transitions on the optical disc by individually adjusting leading and trailing edges of the data symbols, as well as amplitudes of the data symbols. In this manner, the particular length of each pit and land on the disc can be individually selected based on nominal symbol length, as well as other factors including radial and angular locations of the pits and lands on the disc.

Abstract: The life of a rewritable information carrier such a CD-E covered by a phase-change recording layer is extended by varying the manner of representing information of an information block, for subsequent recordings, in the same portion of the record carrier. The manner can be changed, for example, by shifting the initial position at which representing information is written along the track over a distance randomly selected within predefined boundaries; or by writing a varying amount of information representing information from the end of the block before the start of information from the beginning of the information block to rotate the information in the track; or by scrambling the information in a varying manner such as using different keys. The manner of representation can be changed, for example, for each subsequent recording on the same portion of the record carrier. This causes different patterns to be recorded in the same portion, even if the same information is recorded in that portion of the track.

Abstract: An optical information recording method including: irradiating a recording medium with laser light, wherein 0 signals having width nT are recorded or rewritten using continuous laser light having a power level Pe, and 1 signals having width nT are recorded or rewritten using a light pulse train having a first pulse portion fp having power Pw and width xT (T: clock time), a multi-pulse portion mp in which a number (n−n′) of high level pulses each having power Pw′ and width yT, and, if (n−n′)>1, a low level pulse which has power Pb and width (1−y)T are applied, and an end pulse portion ep having power Pb′ and width zT, wherein n and n′ are a positive integer (n>n′), and wherein each of Pw and Pw′ is greater than Pe, Pe is greater than each of Pb and Pb′, and at least one of x, y and z is in a range as follows: 0.35≦x≦0.75, 0.30≦y≦0.55, 0.35≦z≦0.70.

Abstract: An information recording method for recording information on an optical disk by a recording pulse train of an optical beam emitted by an optical source includes the steps of (a) changing a recording channel clock period T in accordance with a change of a recording linear velocity so that a recording linear density is kept constant, and (b) updating values of parameters Ttop, Tmp and &rgr; at intervals based on a desired recording linear velocity. A symbol Ttop is a ratio of a width of a top heating pulse in the recording pulse train to the recording channel clock period T. A symbol Tmp is a duty ratio of each heating pulse in a multi-pulse section following the top heating pulse. A symbol &rgr; is a ratio of a recording power Pw at the desired linear velocity to an optimal recording power Pwmin at a minimum recording linear velocity (&rgr;=Pw/Pwmin).

Abstract: An optical information recording device forms a mark, in which the mark indicating record information is formed by irradiating a record light pulse on a record medium, by controlling a strength of the record light pulse according to both of a mark length of the mark and a record density in a mark length direction of the record medium.

Abstract: In a tilt compensation method and an apparatus thereof, an apparatus that compensates for a tilt of a recordable and reproducible optical recording medium includes a tilt detector detecting a tilt of the optical recording medium and a recording compensator. The recording compensator compensates for a recording signal having a predetermined recording pattern by using a predetermined system according to the tilt detected by the tilt detector, in which the tilt detector detects a tilt with respect to an optical recording medium in which a tilt margin is greater than 0 and less than 0.0052 (0<tilt margin<0.0052) and the recording compensator compensates for the detected tilt. Thus, a desired size (length and width) of a mark can be recorded by controlling the power level and the recording time needed for recording according to the detected tilt. Also, the above method and apparatus are suitable for a high density optical disc system.

Abstract: In the recording of an optical recording medium of phase change type according to the present invention, favorable properties are realized even when the recording is effected in a wide range of linear velocity. The optical recording method of the present invention is a method for recording an optical recording medium comprising a substrate and a recording layer of phase change type on the substrate. A pulse train is used as the recording waveform for laser beam modulation during the formation of one recording mark. The pulse train includes at least one unit pulse comprising an upward pulse and a subsequent downward pulse, and the relation (I): 0.25≦(TclH/TclL)×n≦1.25  (I). is satisfied when width of the last downward pulse standardized by the reciprocal of linear velocity is TclH at a linear velocity of V and TclL at a linear velocity of V/n (n is a real number greater than 1).

Abstract: An information recording method for recording information on a rewritable recording medium including recording first synchronizing signal information in a first synchronizing signal portion on the rewritable recording medium, recording second synchronizing signal information in a second synchronizing signal portion following the first synchronizing signal portion on the rewritable recording medium, and recording data information in a data portion of the rewritable recording medium after the second synchronizing signal portion by forming marks in the data portion, wherein the data information corresponds to both ends of each of the record marks. A length of the first synchronizing signal portion changes and a start position of the first synchronizing signal portion changes, and a change of the start position of the first synchronizing signal portion is smaller than a change of the length of the first synchronizing signal portion.

Abstract: An information recording method and an apparatus therefor, wherein a recording compensation controlling unit 1 receives data to be recorded and determines whether a pulse timing adjustment is to be performed or not, and instructs an APC 3 to adjust the timing thereby to advance the pulse start timing of laser light and/or to delay the pulse termination timing when the pulse timing adjustment is to be performed. The recording compensation controlling unit 1 determines the pulse timing adjustment corresponding to the presence or absence of a predetermined “space, record mark”, whereby the positional shift quantity of leading and trailing edges is reduced even for the marks having a fine dimension, and the jitter is reduced.

Abstract: An information recording method which forms marks or spaces based on the predetermined recording modulating method on a recording medium by radiating a light source using a multi-pulse line is disclosed. The information recording method comprises a head heating pulse and a head cooling pulse, followed by plural serial rear heating pulses and serial rear cooling pulses. The width of the rear heating pulse is constant in a view of time, regardless of the recording liner speed of the recording medium. When recording information comprising pulses N times as long as the channel clock cycle T by a laser ray from a laser source, the recording method uses constant angular velocity control comprising a constant recording frequency and a constant rotating angle velocity or zone constant angular velocity control which raises the recording frequency according to moving the laser ray to the outer area of each zone on the recording medium and a constant angle speed.

Abstract: A recording medium having a dummy signal area on at least one side of a recording area is used and information is recorded with a dummy signal added to at least one of the leading and trailing sides in the recorded information signal. The user data area remains unaffected by repeated overwriting so that recorded user data is reproduced correctly. In particular, the wave form distortion caused by fluidization of a recording film remains at the dummy signal area and does not affect the user data area, so that the reproduction of the target information (user data) is assured.

Abstract: A recording medium having a dummy signal area on at least one side of a recording area is used and information is recorded with a dummy signal added to at least one of the leading and trailing sides in the recorded information signal. The user data area remains unaffected by repeated overwriting so that recorded user data is reproduced correctly. In particular, the wave form distortion caused by fluidization of a recording film remains at the dummy signal area and does not affect the user data area, so that the reproduction of the target information (user data) is assured.

Abstract: A recording medium having a dummy signal area on at least one side of a recording area is used and information is recorded with a dummy signal added to at least one of the leading and trailing sides in the recorded information signal. The user data area remains unaffected by repeated overwriting so that recorded user data is reproduced correctly. In particular, the wave form distortion caused by fluidization of a recording film remains at the dummy signal area and does not affect the user data area, so that the reproduction of the target information (user data) is assured.

Abstract: A top-power-increasing additional pulse is imparted to a portion of top power irradiation of a laser light beam, and a bottom-power-off pulse is imparted to a portion of bottom power irradiation of the laser light beam. Fine adjustment amount for the top power irradiation is modified roughly in accordance with a desired length of a pit to be formed, and the duration of the top-power-increasing additional pulse is adjusted finely. Fine adjustment amount for the bottom power irradiation is modified roughly in accordance with a desired length of a land to be formed, and the duration of the bottom-power-off pulse is adjusted finely. Further, timing to start the top power irradiation of the laser light beam is modified according to a desired length of a pit to be next formed; that is, the greater the next pit length, the more is delayed the top power irradiation start timing.

Abstract: The present invention provides digital read channel circuitry for an optical disk reader. An RF signal corresponding to a track on the optical disk is sampled to provide digital samples corresponding to the RF signal. The samples are taken at a rate that may differ from the channel bit rate of the RF signal. The digital samples are then processed to provide data at the channel bit rate. Multiple digital read channels may be used to read multiple tracks of an optical disk simultaneously. The multiple RF signals may be sampled based on a sample clock common to the multiple digital read channels.

Abstract: An optical recording method for recording mark length-modulated information on a recording medium by using a plurality of recording mark lengths. The optical recording method comprises the steps of: when a time length of one recording mark is denoted nT (T is a reference clock period equal to or less than 25 ns, and n is a natural number equal to or more than 2), (i) dividing the time length of the recording mark nT into &eegr;nT,&agr;1T, &bgr;1T, &agr;2T, &bgr;2T, . . . , &agr;1T, &bgr;1T, . . .

Abstract: An encoder converts a binary data word to a binary code word. The encoded bits have first and second binary values at a predetermined clock interval. A pulse generator responds to the encoded bits to generate energizing pulses during each clock interval in which the encoded bits have the first binary value. The energizing pules have a uniform duration less than the clock interval. A laser responds to the energizing pulses for recording on a medium.

Abstract: Method and system for compensating for thermal effects in writing and reading of mark and space characters on a CD-R/RW disk. Character lengths are measured for character triples (preceding mark, preceding space, present mark) on a disk, and a difference &Dgr;L between present mark length and a reference mark length is computed for each of a selected group of combinations of preceding mark lengths and preceding space lengths. Mean values of &Dgr;L are computed for each of these combinations. These mean values are interpreted as estimates of the thermal effects for the disk. Where the number of values of &Dgr;L, for a given combination of preceding mark lengths and preceding space lengths, used to determine a mean value of &Dgr;L is less than a threshold number, a selected algorithm is used to provide an adjusted mean value. Variation of thermal effects with disk write speed is determined and used in accounting for thermal effects. Frequency response effects of mark and space lengths are removed.

Abstract: A device is provided for calculating mutual phase shift of first and second incident signals. The device includes a first pair of blocks associated with the first incident signal, a second pair of blocks associated with the second incident signal, checking circuit, and post-processing circuit. Each of the blocks has storage elements for storing a predetermined set of samples of the corresponding incident signal. In the presence of minimum samples or maximum samples of both incident signals, the checking circuit stores a first set of samples relating to the first incident signal in one of the blocks of the first pair and a first set of samples relating to the second incident signal in the counterpart block of the second pair, and then stores the following sets of samples of each incident signal alternately in the two blocks of each pair. The checking circuit delivers a block validation signal when a set of samples has been completely stored in the storage elements of one of the blocks.

Abstract: There are provided an information storage apparatus and an information reproducing method capable of reading a mark without being disturbed by cross talk even if a track pitch is narrow.

Abstract: An optical recording method for an optical recording medium having a recording layer containing an organic colorant on a transparent substrate, which comprises applying a recording laser beam divided into n−2 (wherein n is an integer of at least 2) pulses (or into 1 pulse when n is 2), to the optical recording medium, to form a mark having a recording data of nT (wherein T is the reference clock period), wherein the length of the forefront pulse is at least 1.7T and at most 2.4T, and the lengths of the second and subsequent pulses (multi-pulses) are at least 0.7T and less than 1.0T.

Abstract: An optical recording apparatus includes: a tilt detecting device for detecting a circumferential direction component of a tilt of a recording medium with respect to a laser beam light axis; a recording pulse signal generating device for generating a recording pulse signal by coding an information signal to be recorded and outputting the generated recording pulse; a modulating device for receiving the recording pulse from the recording pulse signal generating device, and modulating an intensity of a laser beam based on the received recording pulse signal; a laser beam irradiating device for applying the modulated laser beam onto the recording medium; and a recording pulse signal control device for controlling a sending timing at which the recording pulse signal is sent from the recording pulse signal generating device to the modulating device, based on the circumferential direction component detected by the tilt detecting device.

Abstract: Optimum movement of first and last signal pulses based on the data pattern is determined before data recording to record marks in the correct position. A specific pattern signal is read from a disc track and digitized with an appropriate slice level by the digitizing circuit (115). A pulse position offset measuring circuit (120) then measures specific edge intervals in the resulting digital signal. Movement of the first and last pulse by the pulse moving circuit (110) is then set so that the offset between the measured edge interval and a predetermined standard edge interval is ideally zero.

Abstract: An optical disk on which digital data is recorded by a pit edge multi-value recording system includes: a plurality of data areas formed with a plurality of data pits with a predetermined pit period, each of the plurality of data pits including one of a plurality of pit edge positions each corresponding to the digital data; and a plurality of servo areas formed with servo reference pits used for servo control. The data areas and the servo areas are formed alternately with each other in a circumferential direction of the optical disk. The servo area includes synchronization pits functioning as synchronization reference in reproducing the optical disk. A pit period 2L of the data pit and a pit length P of the synchronization pit satisfy the following equation: P=N×L (N is an integer not less than 2).

Abstract: A drive pulse for writing is generated based on a data pulse signal to be recorded, a light source element is driven with this drive pulse to obtain a beam of light, and this beam of light is irradiated onto an optical recording medium to record the data pulse signal on the optical recording medium. When the drive pulse is generated, a write pulse is generated based on the data pulse signal, and compared with a beam intensity signal representing intensity of the beam of light to optimally control a pulse width of the drive pulse.

Abstract: The present invention provides an exposure apparatus of an optical disc master plate for exposing a photoresist master plate and writing-in a DVD-R format, and a method of exposing an optical disc master plate. The exposure apparatus of the optical disc master plate can cause both the wobble signal and the land pre-pit signal to precisely synchronize with each other and to output the synchronized signals by use of a formatter. The formatter can facilitate the design of a separation element for electrically separating an analog circuit and a digital circuit from each other and a circumferential circuit thereof. The formatter of the optical disc exposing apparatus operates on the basis of the predetermined basic clock signal Fclk. The formatter is provided with a wobble signal generating circuit which generates a wobble signal and a land pre-pit signal generating circuit which operates on the basis of the same basic clock signal Fclk and generates a land pre-pit signal.

Abstract: The invention relates to a method and a device for recording an information signal 10 in a phase change layer of a recording medium. A mark is recorded by a sequence 13 of write pulses and previous marks between the marks to be recorded are erased by a sequence of erase pulses 14. De bias power level 191, 192 between the erase pulses is made dependent on the recording speed, thus obtaining low jitter of the recorded marks and at the same time preventing thermal cross write during erase.