MXPA01002267A - Method and device for recording marks in an information layer of an optical record carrier - Google Patents

Abstract

A method and device are described for writing an optical record carrier, in which a mark representing recorded data is written in a phase change layer of a record carrier by a sequence of radiation pulses. A trailing power level (t) having a value higher than the erase power level (e) is introduced after a last write pulse (3) in a sequence. Additionally, the power level of the last write pulse (3) in a sequence may be raised. This results in a reduced jitter of the marks written, especially when writing at high recording speeds.

Description

Method and apparatus for recording marks in an information layer of an optical recording carrier The invention relates to a method for recording marks representing data in an information layer of a recording carrier by irradiating the information layer with a pulsed radiation beam, each mark being written by a sequence of pulses, the markings recorded can be erased by irradiating the information layer with a radiation beam having a level of erasing power (e), said information layer having a phase that is reversibly switchable between a crystal phase and a amorphous phase and said pulse sequence consists of write pulses having a first level of writing power (w1), a polarization power level (B) between the write pulses and a subsequent power level (t) after of the last impulse to write a sequence. The invention also relates to an optical recording apparatus for recording data in the form of marks in an information layer of a recording carrier by irradiating the information layer with a pulsed radiation beam, said layer of information having a phase which is reversibly exchangeable between a crystal phase and an amorphous phase, the apparatus is composed of a radiation source that provides the radiation beam and a control unit to control the power of the radiation beam, the control unit provides a sequence of write pulses for writing a mark and controlling the power of the radiation beam, so that it has a first level of writing power (w1) during the write pulses in a sequence of write pulses, a level of Polarization power (b) between the write pulses in a sequence of write pulses, a subsequent power level (t) after the last write pulse of a writing pulse sequence, and a clearing power level (e) between writing pulse sequences. A method and a recording apparatus as defined in the opening paragraphs are known from the international patent application WO 97/30440 (with publication date of August 21, 1997). A mark is written by a sequence of writing impulses. The previously written marks, if any, between the written marks, are erased by applying a level of erasing power between the sequences of writing pulses. The known sequence has a level of bias power between the write pulses and a return to the bias power level after the last write pulse of a write pulse sequence before going up to an erasing power level. The international patent application WO 98/36411 (with publication date of August 20, 1998) discloses an improved method, which has the characteristic that the sequence of writing pulses has a level of polarization power between the pulses of writing and a cooling power level after the last write pulse of a write pulse sequence before going up to the clear power level, the cooling power level which is in a range between the bias power level and a level of erasing power. A change in the polarization power level in the affections of the known methods both in the irregularity of duration of the initial end and in the irregularity of duration of the posterior end. The irregularity of duration is the standard deviation of the time differences between the level transitions in the digitized reading signal and the corresponding transitions in a clock signal, the time differences are normalized by means of the duration of a period of said clock. The mentioned method, described in WO 98/36411, introduces an additional degree of freedom when performing the cooling power level during the cooling period, that is, the period following the last write pulse in a sequence of writing pulses and the one preceding the rise to the erasing power level, independent of the polarization power level. This allows the irregularity of duration of the rear end to be influenced almost independently of the irregularity of duration of the initial end. The known methods are suitable for writing directly onto a recording bearer, that is, information can be written so that it is recorded in the information layer of the recording bearer and, at the same time, the information previously written in the layer is erased. of information.

A disadvantage of the known methods, especially when the marks are written at high recording speeds, is that they do not allow a sufficient reduction of the irregularity of duration in the reading signal that is obtained from the written reading marks when using the known methods .

An object of the invention is to provide a method for recording marks of the type described in the opening paragraph that have an irregularity of reduced subsequent duration.

This objective is achieved when the preamble method is characterized in that the subsequent power level (t) is greater than the erasing power level (e) and less than the first write power level (w1). The method according to the invention replaces the level of cooling power in the known methods, in which it is lower than the level of erasing power (e), by means of a subsequent power level (t) greater than the level of erasing power (e). Instead of cooling the information layer after a sequence of write pulses, a more or less gradual transition is introduced from the writing power level of the last write pulse to the erasing power level, which results in the irregularity of duration of the posterior end of the marks that are smaller than the irregularity of duration of the posterior end of the marks recorded with the known methods. For those skilled in the art, it may be apparent that the incorporations of the method according to the invention with more than one subsequent power level, such as a progressive decrease from the write power level to the erasing power level, provides a Even more gradual transition from the write power level of the last write pulse to the erase power level.

The method according to the invention has advantages especially when used in combination with a recording carrier consisting of an alloy of AglnSbTe, such as a stack of 4 layers of alloy ZnS: SiO2 AglnSbTeZns: SiO2 / AI. These advantages can also be obtained when using recording carriers that are composed of a GelnSbTe alloy. Experiments indicate that, when these alloys are used, the process of erasing the amorphous marks proceeds by growing the crystalline end that is around the center of the mark, rather than by nucleation and subsequent growth.

As a result, the written marks have a well-defined shape with exact edges, leading to an irregularity of intrinsically shorter duration than that observed in, for example, GeSbTe-based recording carriers, which are currently considered very promising for recording to high speed. In addition, full-time erasure (CET) decreases rapidly with decreasing brand sizes. Due to this, the maximum data rate increases with the decrease in the size of the radiation beam point, which allows high recording speeds when it goes, for example, towards wavelengths of the smaller radiation source, as for example in the case of blue laser diodes with a wavelength of approximately 400 nm. The combination of a recording carrier having an AglnSbTe alloy, or GelnSbTe, with the method according to the invention allows to record marks that are obtained with a low duration irregularity of the marks recorded at high recording speeds.

A preferred embodiment of the method according to the invention is characterized in that the last write pulse in a pulse sequence has a second write power level (w2), the second write power level (w2) is greater than the second write power level (w2). first level of writing power (w1). When the write power level of the last write pulse in a write pulse sequence increases compared to the write power level of the previous write pulses in the write pulse sequence, the unevenness of the write pulse is further reduced. duration of the posterior end.

An embodiment of the method according to the invention is characterized in that the subsequent power level (t) depends on the properties of the recording carrier, and another embodiment of the method according to the invention is characterized in that the second power level of the Writing (w2) depends on the properties of the recording bearer.

At the level of the posterior potency (t) a fixed fixed value can be assigned. Alternatively, at the level of posterior potency (t) can be assigned a value that depends on the properties of the individual engraving bearer where the marks will be recorded. The value of the subsequent power level (t) to be used for an individual recording bearer can be determined, for example, by a test procedure in which pulse sequences are used to record marks, in which each sequence has a different value for the subsequent potency level (t), and the resulting marks are read and analyzed. Other test procedures can be used alternately. Finally, the optimum value for the subsequent power level (t) corresponding to an individual engraving bearer can be recorded on that recording bearer. In that case, the value can be read directly from the engraving bearer with a recording apparatus. In the same way, a fixed value can be assigned to the second level of power (w2) or it can be assigned a value that depends on the properties of the individual engraving bearer in which the marks are going to be recorded.

Another object of the invention is to provide an optical engraving apparatus of the kind described in the second paragraph adapted to use the method according to the invention.

The objective is achieved when the optical engraving apparatus of the preamble is characterized in that the rear power level (t) is greater than the level of erasing power (e) and less than the first level of write power (w1).

A preferred embodiment of the recording apparatus according to the invention is characterized in that the control unit controls the power of the radiation beam, so that it has a second level of writing power (w2) during the last write pulse in a Sequence of write pulses, the second level of write power (2) is greater than the first level of write power (w1).

These and other objectives, characteristics and advantages of the invention will become apparent in the following more specific description of the inventor's incorporations, as illustrated in the attached diagrams, in which Figure 1 shows diagrams illustrating the time-dependent the signal of data and of the control signal that controls the power levels of the radiation beam, Figure 2 shows measures of the irregularity of duradon, demonstrates the result of applying a level of posterior potency (t) according to the invendón , Figure 3 shows measures of durability irregularity, demonstrates the result of applying a level of posterior potency (t) and a second level of writing power (w2) according to the invendón, and Figure 4 shows a diagram of the engraving apparatus according to the invendón.

Figure 1 shows diagrams of two signals, a digital data signal 10 and a control signal, 20 or 25, as used in the method according to the invention. The Figure 1a gives the value of the digital data signal 10 as a function of time, the value of the signal represents information to be recorded. Vertical dotted lines indicate transitions in a clock signal of a data clock belonging to the data signal. The period of the data clock, also called the channel bit period, is indicated by Ti. When recording this data signal, a 'high' period 11 is recorded as a mark with a length corresponding to the duradon of the 'high' period and a 'low' period 12 is recorded as a blank area, a spade located between the marks and that has a length corresponding to the duradon of the 'low' period. In general, the length of a mark is substantially equal to the number of channel bit periods of the data signal that times the write speed. Thus, the length of a mark is expressed as the number of periods of the data clock when the corresponding data signal is 'arta' (for example, 11T is used for a mark with a corresponding data signal that is 'afta' for the data clock periods 11). The data is written to an optical engraving carrier having a layer of information. The marks representing the data are written along a track in the information layer upon irradiating the information layer with a pulsed radiation beam. The marks are areas of the information layer with optical characteristics different to what surrounds them, which makes possible the optical reading of the marks. Figure 1b shows a control signal 20 corresponding to the data signal 10 in a first incorporation of the invention and Figure 1c shows a control signal corresponding to the data signal 10 in a second inventor's incubation. The control signal 20 or 25 is used to modulate the power of the radiated beam with which the marks are written in the information layer, where it is assumed that the power level of the radiated beam is proportional to the level of the signal of control. Figures 1b and 1c show a sequence of writing pulses for writing a mark. The power between the writing impulses, which have a first level of writing power (w1) 16, is at a level of polarization potency (b) 18. The previously written marks, if any, between the marks that are being written can be erased by applying a level of erasing power (e) 17. In the embodiment of the invention described with reference to Figure 1 b, a subsequent power level (t) 1 directly follows the last write pulse 3 in the sequence of write pulses, the subsequent power level (t) 1 that is greater than the power level of erasure (e) 17 and that is less than the first level of power of writing (w1) 16. The Figure 1c refers to an incorporation of the invention where, apart from that the level of posterior potency (t) 1 that is greater than the level of deletion potency (e) 17 and smaller than the first level of writing power (w1) ) 16, the last write pulse 3 in a sequence of pulses of writing has a second level of writing power (w2) 2, and the second level of writing power (w2) 2 is greater than the first level of writing power (w1) 16. The examples given in the Figure 1 show sequences of writing pulses with each write pulse having a working acid of 50%. However, write pulses can also be used with work steps other than 50%.

Figures 2 and 3 show the results of the measures of the length irregularity of the inital end 311 and the irregularity of later duradon 321 as a function of the number of DOW 300 cycles, that is, the number of times the marks representing the data are recorded on a single engraving carrier while the previously written marks are erased. Figure 2a shows the results of the durability irregularity measures when the marks are recorded at a recording speed with a data speed of about 34 Mega bits per second (Mbps) by means of the methods known from before. Figure 2b shows the results of the duration irregularity measures when the marks are recorded at a recording speed with a data rate of around 34 (Mbps) by means of the method according to the invention, wherein the level Subsequent power level (t) has an approximate value of 0.47 times the value of the first level of write power (w1), the value of the first level of write power (w1) is 6.5 mW and the value of the power level of erased (e) is 2.5 mW. A significant decrease in the durability irregularity of the trailing end 321 is obtained over the range of the number of DOWs shown in the graph. Figure 3a shows the results of the measures of irregularity of duration when the marks are recorded by means of the same method according to the invention, as used when recording the marks whose measures of irregularity of duration are shown in Figure 2b, except for an increased recording speed with an approximate data rate of 43 Mbps. Due to this increase in engraving velocity, an increase in the durability irregularity of the trailing end 321 is observed. Figure 3b shows the results of the measurements. of the irregularity of duration when the marks are recorded at a speed of engraving with an approximate data rate of 43 Mbps by means of the method according to the invention, where the level of posterior potency (t) has an approximate value of 0.50 times the value of the first level of writing power (w1), the value of the second level of writing power (w2) has an approximate value of 1.10 times the value of the first level of writing power (w1), the value of the first level of writing power (w1) is 6.5 mW and the value of the level of deletion power (e) is 2.5 mW. Once again, on this increase in the speed of engraving, a significant decrease in the irregularity of the duration of the rear end 321 is obtained over the range of the number of DOW dots shown in the graph.

Figure 4 shows a recording apparatus according to the invention for recording on an optical disc-shaped engraving carrier 50. Alternatively, the recording carrier can be in the form of a dnta. An SD data signal, having the information to be recorded, is applied to a control unit 60. A current source 61 within the control unit 60 has 5 outputs A, B, C, D, and E The output A provides a current that, when fed into a radiator source 51 through a control signal Sc, will result in a radiator beam 52 with a first write power level (w1). In the same way, outputs B, C, D and E provide currents that result in the level of polarization potency (b), the subsequent power level (t), the second level of writing power (w2) and the level of erasure power (e), respectively. The stream of each output A, B, C, D, and E can be selected with a transfer unit 62. The transfer unit 62 operates by means of pattern generator 63 controlled by the SD data signal and the S clock signal. ? The pattern generator 63 transforms the data signal SD into sequences of write pulses having a first level of write power, write pulses having a second power level, a level of potency of polarization, a level of potenda posterior and a power level of erasure according to a desired pattern. The clock signal S? it is obtained from a clock generator 58. When the recording apparatus is used for writing at a single speed, the clock generator 58 is previously set at a fixed frequency. When written at a variable speed, the frequency of the clock generator 58 will vary with the current write speed.

The control signal Sc, which is provided at the output of the control unit 60 and which carries the write pulse sequences, is applied to the radiation source 51. The control signal Sc controls the power of the radiation beam 52 generated by the radiation source 51. The radiation beam 52 is focused on an information layer 501 of the engraving holder 50 by means of a lens 53. The disk-shaped engraving carrier 50 rotates about its center by a motor 54. The incorporation of a gravure apparatus according to the invention is suitable for carrying out the methods according to the invention described with reference to Figures 1b and 1c using a single level of posterior potency (t). However, it may be apparent to those skilled in the art that the intakes of the engraving apparatus according to the invention use more than one level of subsequent power, such as a progressive descent from the level of writing power to the level of deleting power, can be carried out by adding additional outputs to the current source 61 and by extending the transfer unit 62. ^^^

Claims (9)

CHAPTER CLAIMING Having described the invention, it is considered as a novelty and, therefore, what is contained in the following is redacted: CLAIMS

1. A method of engraving marks that represent data in an information layer of a engraving bearer by irradiating the information layer with a pulsed radiation beam, each mark is written by means of a pulse sequence, the engraved marks can be erased at irradiating the information layer with a radiating beam having a level of erasing power (e), said information layer having a phase that can change reversibly between a crystal phase and an amorphous phase and said pulse sequence is It consists of writing pulses having a first level of writing power (w1), a polarizing power level (b), between the write pulses, and a subsequent power level (t) after the last write pulse of a sequence, characterized in that the subsequent power level (t) is greater than the level of erasing power (e) and less than the first level of writing power (w1).

2. A method according to claim 1, wherein the information layer having a fose that can change reversibly between a crystal phase and an amorphous phase consisting of an alloy of AglnSbTe.

3. A method according to reivindicadón 1 or 2, characterized in that the last write pulse in a pulse secuenda has a second level potenda writing (w2), the second level potenda writing (w2) is greater than the first level of writing power (w1). * Í ^ ^^^^^ ^^^^^^^ it Jto ^ ¿^ ^ g ^ £ JA5

4. A method according to claim 1, 2 or 3, characterized in that the rear power level (t) depends on the properties of the engraving bearer.

5. A method according to claim 3, characterized in that the second write power level (w2) depends on the properties of the recording bearer.

6. An optical engraving apparatus for recording data in the form of marks on an information layer of a recording holder by irradiating the information layer with a pulsed radiated beam, said layer of information having a phase that can change in a reversible manner between a crystal phase and an amorphous phase, the apparatus is composed of a radiator source that provides the radiator beam and a control unit for controlling the power of the radiation beam, the control unit provides a sequence of writing pulses for writing a mark and controlling potenda radiation beam so as to have a first level of potenda writing (w1) for cough write pulses in a secuenda write pulse, a level of rear power (t) after the last impulse to write a sequence of writing pulses, and a level of erased (e) between the sequence of writing pulses, characterized in that the level of power Subsequent level (t) is greater than the level of erasing power (e) and less than the first level of writing power (w1).

7. An optical recording apparatus according to reivindicadón 6, characterized in that the control unit controta the potenda radiadón beam so as to have a second level of potenda writing (w2) during et last write pulse in a sequence of writing pulses, the second writing power level (w2) is greater than the first writing power level (w1).

8. An optical engraving apparatus according to Claim 6 or 7, characterized in that the optical recording apparatus comprises means for determining the properties of the engraving bearer and means for assigning a value for the subsequent level of potency (t). , whose value depends on the determined properties of the engraving bearer. An optical engraving apparatus according to claim 7, characterized in that the optical engraving apparatus comprises means for determining the properties of the engraving bearer and means for assigning a value for the second level of writing power ( w2), whose value depends on the determined properties of the engraving bearer.