JP2005093017A - Optical information recording device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical information recording device capable of suppressing the degradation in recording quality by the control of a recording strategy consisting of short pulse groups even under a high-temperature environment having a hindrance in rapid heating and quenching. <P>SOLUTION: The pulse width Tcp of a cooling pulse CP which is a short pulse is changed according to the ambient temperature of an optical disk which is an optical information recording medium of a phase change type, by which the recording strategy consisting of the short pulse groups is controlled. As a result, the degradation in the recording quality can be suppressed even under the high-temperature environment having the hindrance in the rapid heating and quenching. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical information recording apparatus and an optical information recording method.

  In recent years, with the advancement of optical technology, optical information recording media include playback-only optical disks such as music CDs (Compact Disks) and CD-ROMs, write-once optical disks using dye-based media, and phase change recording materials. A phase-change optical disk such as a rewritable CD-RW (Rewritable) has been put into practical use. Further, as a phase change type optical disk, a large-capacity optical disk such as a DVD (Digital Versatile Disk) -RAM or a DVD + RW (Rewritable) has attracted attention.

  When recording information (data) on these optical discs, an optical disc apparatus having an optical pickup using a semiconductor laser as a light source is used. For example, a general recording waveform (light emission waveform) for recording information on a phase change type optical disc is generated based on a modulation recording method such as an EFM (Eight to Fourteen Modulation) modulation code or an 8-16 modulation code. There is a single pulse emission waveform (single pulse recording method). However, when such a single pulse recording method is used, the distortion of the recording mark occurs in a tear-like shape due to heat accumulation, or the formation of the amorphous phase becomes insufficient due to insufficient cooling, and recording with low reflection with respect to laser light There is a problem that the mark cannot be obtained.

  Therefore, when recording information on a phase change optical disk, a multi-pulse waveform method is generally used in which a recording mark is formed by a recording pulse train composed of one or a plurality of short pulse groups. Here, the short pulse group is used to form a recording mark that matches an emission waveform based on a recording modulation method such as an EFM modulation code or an 8-16 modulation code. The pulse emission rule such as the pulse width and amplitude of each pulse constituting the short pulse group is called a recording strategy. This recording strategy follows a leading heating pulse FP (Front Pulse), a trailing heating pulse LP (Last Pulse), and a leading heating pulse FP for preheating the recording layer of the phase change type optical disk sufficiently above the melting point. It is composed of a combination of a plurality of continuous heating pulses MP (Multi Pulse) that continues until immediately before the end heating pulse LP and a cooling pulse CP (Cooling Pulse) that is positioned at the end of the pulse group. Note that LP and MP may not exist depending on the recording mark length.

  According to such a multi-pulse emission waveform, the mark portion of the phase change type optical disk generates an amorphous phase by a rapid cooling condition from heating to cooling (heating → cooling) by the heating pulses FP, MP, LP and the cooling pulse CP. In this case, the space portion is formed by generating a crystal phase under the slow cooling condition only by heating with the erase pulse, so that a sufficient reflectance difference is obtained between the amorphous phase and the crystal phase.

  Reproduction jitter, overwrite characteristics, power margin, etc., which are recording characteristics of a phase change type optical disc, are the pulse widths of the heating pulses FP, MP, LP, the pulse width of the cooling pulse CP, the recording power (light emission power), and the type of the optical disc. It varies depending on conditions such as the linear velocity and the ambient temperature of the optical disk. For example, in Patent Document 1, an appropriate recording pulse waveform is selected and applied to an optical disc such as a DVD-R having an organic dye recording layer in accordance with a change in laser ambient temperature. In Patent Document 1, wavelength fluctuation is cited as a cause of deterioration in recording quality, and the wavelength fluctuation is indirectly measured by measuring the laser ambient temperature, and an optimum recording pulse waveform is obtained as needed based on the measurement result. Selected.

JP 2002-216349 A

  In the case of an optical disk having an organic dye recording layer, a recording mark is formed by the duty of heating by a laser pulse. In the case of a phase change type optical disk, for example, recording is performed by forming an amorphous phase by rapid heating and quenching. In order to form a mark, it is difficult to apply the technique of Patent Document 1 to a phase change optical disc.

  Also, in phase change type optical discs, an amorphous phase is formed under rapid heating and cooling conditions from heating to cooling. However, when the ambient temperature of the optical disc becomes high, overheating occurs in the rapid heating process, and insufficient cooling occurs in the rapid cooling process. As a result, the recording quality deteriorates.

  For example, an optical disk device is often used by being mounted inside a personal computer. However, due to the recent increase in speed and multifunction of personal computers, various devices inside the personal computer generate a large amount of heat. The ambient temperature used tends to be high. Furthermore, in a notebook personal computer integrated with high density, the internal temperature rise becomes more remarkable because there is no sufficient heat removal mechanism. Therefore, when recording is performed using a recording strategy optimized at room temperature in a high temperature environment such as the inside of a personal computer, there is a problem that the recording quality expected at room temperature cannot be obtained.

  An object of the present invention is to provide an optical information recording apparatus and an optical information recording method capable of suppressing deterioration in recording quality by controlling a recording strategy consisting of a short pulse group even in a high temperature environment that hinders rapid heating and cooling. It is.

  The invention according to claim 1 is an optical information recording apparatus for recording data on a phase change type optical information recording medium using a recording pulse train composed of one or a plurality of short pulse groups, the ambient temperature of the optical information recording medium Temperature detection means for detecting the pulse width change means for changing the pulse width of the short pulses constituting the short pulse group according to the ambient temperature of the optical information recording medium detected by the temperature detection means, It is characterized by comprising.

  Therefore, by changing the pulse width of the short pulse according to the ambient temperature of the optical information recording medium, the recording strategy consisting of the short pulse group is controlled, and the recording quality is maintained even in a high temperature environment that hinders rapid heating and cooling. As a result, it is possible to suppress the deterioration of the recording quality. In addition, in order to suppress the deterioration of recording quality, for example, compared to the case where an optical information recording apparatus is provided with an exhaust heat fan or the like for lowering the internal temperature, an exhaust heat fan or the like is not required, thereby reducing costs and weight. Can be realized.

  According to a second aspect of the present invention, in the optical information recording apparatus according to the first aspect, the pulse width changing means changes a pulse width of a cooling pulse that constitutes the short pulse group and is located at the rear end thereof. To do.

  Therefore, by changing the pulse width of the cooling pulse according to the ambient temperature of the optical information recording medium, the cooling pulse that has a large effect on the recording quality is controlled, and the recording quality can be maintained even in a high-temperature environment that hinders rapid thermal quenching. Is maintained, and deterioration of recording quality can be suppressed.

  According to a third aspect of the present invention, in the optical information recording apparatus according to the second aspect, the temperature determination is performed to determine whether or not the ambient temperature of the optical information recording medium detected by the temperature detecting means is equal to or higher than a predetermined temperature. And the pulse width changing means, when the temperature judging means judges that the ambient temperature of the optical information recording medium is equal to or higher than a predetermined temperature, the cooling in the short pulse group optimized at room temperature. The pulse width of the cooling pulse is changed so as to be shorter than the pulse width of the pulse.

  Therefore, if it is determined whether the ambient temperature of the optical information recording medium is higher than a predetermined temperature, for example, a temperature higher than room temperature, and if it is determined that the ambient temperature is higher than the room temperature, it is optimized at room temperature. By changing the pulse width of the cooling pulse so that it is shorter than the pulse width of the cooling pulse in the short pulse group, it is possible to maintain the recording quality even under a high temperature environment higher than room temperature, and to suppress the deterioration of the recording quality Become.

  The invention according to claim 4 is the optical information recording apparatus according to claim 2 or 3, wherein the pulse width of the cooling pulse in the short pulse group optimized at room temperature is Tcp, and the ambient temperature of the optical information recording medium Is T, the predetermined temperature is Tth, and the pulse width of the cooling pulse when T ≧ Tth is TcpH, the pulse width changing means changes the TcppH within the range of 0.8Tcp <TcpH <Tcp. It is characterized by doing.

  Therefore, by changing the Tcp within the range of 0.8 Tcp <TcpH <Tcp, the recording quality can be maintained even in a high temperature environment higher than room temperature, and it is possible to reliably suppress the deterioration of the recording quality.

  According to a fifth aspect of the present invention, in the optical information recording apparatus according to the second, third, or fourth aspect, the temperature detecting unit detects an ambient temperature of the optical information recording medium every predetermined time, and changes the pulse width. The means changes the pulse width of the cooling pulse according to the ambient temperature of the optical information recording medium every predetermined time.

  Therefore, the ambient temperature of the optical information recording medium is detected every predetermined time, and the pulse width of the cooling pulse is changed according to the detected ambient temperature of the optical information recording medium every predetermined time. The pulse width of the cooling pulse is changed every time, and it is possible to reliably suppress the deterioration of the recording quality.

  According to a sixth aspect of the present invention, in the optical information recording apparatus according to the second, third, fourth, or fifth aspect, the pulse width changing means includes a head heating pulse, a continuous heating pulse, and a terminal heating pulse that constitute the short pulse group. Only the cooling pulse is changed without changing each pulse width.

  Therefore, it is not necessary to control each pulse other than the cooling pulse by making the pulse widths of the leading heating pulse, continuous heating pulse, and ending heating pulse constant regardless of the ambient temperature of the optical information recording medium, and recording is easy. It becomes possible to suppress deterioration of quality.

  A seventh aspect of the present invention is the optical information recording apparatus according to the first, second, third, fourth, fifth or sixth aspect, wherein the optical information recording medium has a recording layer made of an AgInSnTe recording material. And

  Therefore, it is possible to realize good recording quality by using an optical information recording medium having a recording layer formed of an AgInSnTe recording material.

  The invention according to claim 8 is an optical information recording method in which data is recorded on a phase change optical information recording medium using a recording pulse train composed of one or a plurality of short pulse groups, and the ambient temperature of the optical information recording medium Detecting a temperature, and a pulse width changing step for changing a pulse width of a short pulse constituting the short pulse group according to an ambient temperature of the optical information recording medium detected by the temperature detecting step. It is characterized by comprising.

  Therefore, the same effect as that of the first aspect of the invention can be achieved.

  The invention according to claim 9 is the optical information recording method according to claim 8, wherein the pulse width changing step changes the pulse width of the cooling pulse that constitutes the short pulse group and is located at the rear end thereof. To do.

  Therefore, the same effect as that of the invention of claim 2 is obtained.

  According to a tenth aspect of the present invention, in the optical information recording method according to the ninth aspect, the temperature determination for determining whether or not the ambient temperature of the optical information recording medium detected by the temperature detection step is equal to or higher than a predetermined temperature. And the pulse width changing step includes the step of cooling the short pulse group optimized at room temperature when the temperature determining step determines that the ambient temperature of the optical information recording medium is equal to or higher than a predetermined temperature. The pulse width of the cooling pulse is changed so as to be shorter than the pulse width of the pulse.

  Therefore, the same effect as that of the third aspect of the invention can be achieved.

  The invention according to claim 11 is the optical information recording method according to claim 9 or 10, wherein the pulse width of the cooling pulse in the short pulse group optimized at room temperature is Tcp, and the ambient temperature of the optical information recording medium Is T, the predetermined temperature is Tth, and the pulse width of the cooling pulse when T ≧ Tth is TcpH, the pulse width changing step changes TcppH within the range of 0.8Tcp <TcpH <Tcp. It is characterized by doing.

  Accordingly, the same effect as that of the fourth aspect of the invention can be attained.

  A twelfth aspect of the present invention is the optical information recording method according to the ninth, tenth or eleventh aspect, wherein the temperature detecting step detects an ambient temperature of the optical information recording medium every predetermined time, and changes the pulse width. The step is characterized in that the pulse width of the cooling pulse is changed according to the ambient temperature of the optical information recording medium every predetermined time.

  Accordingly, the same effect as that of the fifth aspect of the invention can be attained.

  A thirteenth aspect of the present invention is the optical information recording method according to the ninth, tenth, eleventh or twelfth aspect, wherein the pulse width changing step includes a head heating pulse, a continuous heating pulse, and a terminal heating pulse constituting the short pulse group. Only the cooling pulse is changed without changing each pulse width.

  Accordingly, the same effect as that of the sixth aspect of the invention can be attained.

  According to the first aspect of the invention, by changing the pulse width of the short pulse in accordance with the ambient temperature of the phase change type optical information recording medium, the recording strategy consisting of the short pulse group is controlled, and rapid heating and quenching are achieved. The recording quality can be maintained even in a high-temperature environment that hinders the deterioration of the recording quality. In addition, in order to suppress the deterioration of recording quality, for example, compared to the case where an optical information recording apparatus is provided with an exhaust heat fan or the like for lowering the internal temperature, an exhaust heat fan or the like is not required, thereby reducing costs and weight. Can be realized.

  According to the second aspect of the present invention, in the optical information recording apparatus according to the first aspect, the cooling that greatly affects the recording quality by changing the pulse width of the cooling pulse according to the ambient temperature of the optical information recording medium. The recording quality is maintained even in a high temperature environment where the pulse is controlled and the rapid heating and cooling are hindered, and the deterioration of the recording quality can be suppressed.

  According to the invention described in claim 3, in the optical information recording apparatus described in claim 2, it is determined whether or not the ambient temperature of the optical information recording medium is a predetermined temperature, for example, a temperature higher than room temperature or more. If it is determined that the temperature is higher than the room temperature, change the pulse width of the cooling pulse so that it is shorter than the pulse width of the cooling pulse in the short pulse group optimized at room temperature. The recording quality can be maintained even underneath, and the deterioration of the recording quality can be suppressed.

  According to the invention described in claim 4, in the optical information recording apparatus according to claim 2 or 3, recording is performed even in a high temperature environment higher than room temperature by changing Tcp within a range of 0.8 Tcp <TcpH <Tcp. Quality is maintained, and deterioration of recording quality can be reliably suppressed.

  According to the invention described in claim 5, in the optical information recording apparatus described in claim 2, 3 or 4, the ambient temperature of the optical information recording medium is detected every predetermined time, and the detected optical information every predetermined time By changing the pulse width of the cooling pulse in accordance with the ambient temperature of the recording medium, the pulse width of the cooling pulse is changed every predetermined time, and the deterioration of the recording quality can be surely suppressed.

  According to a sixth aspect of the present invention, in the optical information recording apparatus according to the second, third, fourth, or fifth aspect, the pulse widths of the leading heating pulse, the continuous heating pulse, and the trailing heating pulse are determined according to the ambient temperature of the optical information recording medium. Regardless of this, it is not necessary to control each pulse other than the cooling pulse, and the deterioration of the recording quality can be easily suppressed.

  According to the seventh aspect of the present invention, in the optical information recording apparatus according to the first, second, third, fourth, or sixth aspect, an optical information recording medium having a recording layer formed of an AgInSnTe-based recording material is used. As a result, good recording quality can be realized.

  According to invention of Claim 8, there exists an effect similar to the invention of Claim 1.

  According to the ninth aspect of the invention, the optical information recording method of the eighth aspect has the same effect as the second aspect of the invention.

  According to the tenth aspect, the optical information recording method according to the ninth aspect has the same effects as the third aspect.

  According to the eleventh aspect, the optical information recording method according to the ninth or tenth aspect has the same effects as the fourth aspect.

  According to the twelfth aspect, the optical information recording method according to the ninth, tenth or eleventh aspect has the same effect as the fifth aspect.

  According to the thirteenth aspect, the optical information recording method according to the ninth, tenth, eleventh or twelfth aspect has the same effects as the sixth aspect.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram schematically showing the configuration of an optical disc apparatus which is an optical information recording apparatus of the present embodiment.

  As shown in FIG. 1, an optical disk apparatus 1 includes a spindle motor 2, a motor driver 3, servo means 4, an optical pickup 5, a read amplifier 6, and a decoder 7 that rotationally drive an optical disk D that is a phase change type optical information recording medium. , A buffer manager 8, a buffer RAM 9, a host I / F 10, a disk information decoder 11, an encoder 12, an LD driver 13, a control unit 14, and the like. The LD driver 13 includes a register 15, a multi-pulse generation unit 16, a power control unit 17, and the like. Here, in FIG. 1, the arrows indicate the directions in which data mainly flow, and in order to simplify the drawing, the connection between the control unit 14 that controls each block in FIG. 1 and each block is omitted. Has been.

  The optical pickup 5 includes a laser diode (LD) as a light source, an optical system that guides laser light emitted from the laser diode to a recording surface of the optical disc D and guides return light reflected by the recording surface to a predetermined light receiving position, A light receiver such as a light receiving element that is disposed at the light receiving position and receives return light, a focus actuator, a track actuator, a seek motor, a position sensor, and the like (all not shown) are incorporated. The optical system has an objective lens (not shown) for condensing laser light on the recording surface of the optical disk D.

  Further, the optical pickup 5 is provided with a thermometer 18 for measuring the internal temperature. As the thermometer 18, a thermistor is used, and the value of the current flowing through the thermistor changes as the resistance value of the thermistor changes with temperature. This change in current value is detected by the control unit 14. The temperature is obtained by the control unit 14 from the correlation between the current value and the temperature. Here, the thermometer 18 and the control unit 14 function as temperature detection means. The internal temperature of the optical pickup 5 is treated as the ambient temperature of the optical disc D, and is substantially the same as the surface temperature of the optical disc apparatus 1 and the surface temperature of the optical disc D (see FIG. 8). Therefore, in the present embodiment, the internal temperature of the optical pickup 5 is used as equivalent to the surface temperature of the optical disc device 1, and the surface temperature of the optical disc device 1 is also handled as the ambient temperature of the optical disc D.

  Such an optical pickup 5 is provided so as to be movable in the sledge direction, that is, in the radial direction of the optical disc D by a seek motor. The focus actuator, the track actuator, and the seek motor are configured so that the laser light spot is positioned at a target location on the optical disk D by the motor driver 3 and the servo means 4 based on the signals obtained from the light receiver and the position sensor. Controlled.

  The control unit 14 includes a CPU, a ROM, a RAM (all not shown), and the like, and functions as a microcomputer (computer) included in the optical disc apparatus 1. A ROM that also functions as a storage medium stores a program including a control program written in a code decodable by the CPU. The CPU controls the operation of each unit described above according to a program stored in the ROM, and temporarily stores data necessary for control in the RAM. When the optical disk device 1 is turned on, the program stored in the ROM is loaded (installed) into the main memory (not shown) of the CPU.

  The optical disk apparatus 1 drives the optical disk D to rotate by a spindle motor 2. At this time, the spindle motor 2 is controlled by the motor driver 3 and the servo means 4 so that the optical disk D is rotated by the CLV (constant recording linear velocity) method, the CAV (constant recording angular velocity) method, or the like. The optical pickup 5 emits laser light from a laser diode, condenses the laser light on the recording surface of the optical disc D by an objective lens, and performs focus servo and track servo by controlling the actuator by servo means 4. The data recorded on the optical disk D is reproduced to obtain a reproduction signal, and the data is recorded on the optical disk D.

  At the time of data reproduction, the reproduction signal obtained by the optical pickup 5 is amplified by the read amplifier 6 and binarized, and then the decoder 7 performs deinterleaving and error correction processing. The data from the decoder 7 is temporarily stored in the buffer RAM 9 by the buffer manager 8 and transferred to the host, for example, a personal computer or the like through the host I / F (host interface) 10 when it is prepared as sector data. The The host I / F 10 is a bidirectional communication interface with the host and conforms to standard interfaces such as ATAPI and SCSI.

  At the time of data recording, the data sent from the host via the host I / F 10 is temporarily stored in the buffer RAM 9 by the buffer manager 8 and then data recording is started. Before starting data recording, OPC (Optimum Power Calibration) is performed in a test writing area called PCA (Power Calibration Area) of the optical disc D, and an optimum recording power is obtained. Further, before starting the data recording, the laser spot is moved to the writing start position. In DVD + RW or the like, the start position is obtained from a wobble signal that is previously engraved on the optical disc D by meandering tracks. In a DVD-RW or the like, the start position is obtained by a land pre-pit instead of a wobble signal, and in a DVD-RAM or the like, the start position is obtained by a pre-pit.

  The wobble signal includes address information called ADIP (ADress In Pre-groove), and this address information is extracted by the disc information decoder 11. The synchronization signal generated by the disc information decoder 11 is input to the encoder 12 so that data can be written at an accurate position on the optical disc D.

  In the LD driver 13, a recording channel clock and EFM data as recording information are input from the encoder 12 by the control unit 14 and temporarily stored as pulse information in the register 15. A multi-pulse (recording pulse train) is generated from the pulse information stored in the register 15 by the multi-pulse generator 16 of the LD driver 13. The power control unit 17 uses the power information stored in the register 15 to control the irradiation power of the laser light emitted from the optical pickup 5 to generate an LD light emission waveform based on the recording pulse train.

  Next, an example of the optical disk D used in the present embodiment will be described with reference to FIG. FIG. 2 is a longitudinal side view schematically showing the layer structure of the optical disc D of the present embodiment.

  As shown in FIG. 2, the optical disc D is configured by laminating a lower protective layer 21, a recording layer 22, an upper protective layer 23, a heat dissipation layer 24, and a UV protective film 25 on a transparent substrate 20.

The transparent substrate 20 is made of, for example, a polycarbonate resin having a refractive index of 1.58, the lower protective layer 21 is made of, for example, ZnS or SiO ₂ to a film thickness of 17 nm, and the recording layer 22 is made of For example, Ag (2) In (10) Sb (28) Te (60) is used as a material to form a film with a thickness of 20 nm. The upper protective layer 23 is formed to a film thickness of 25 nm using, for example, ZnS or SiO ₂ having a refractive index of 2.1, and the heat dissipation layer 24 is made of, for example, an Al alloy (Al—Ti: 1 wt% alloy). As a material, the UV protection film 25 is formed of, for example, a UV curable resin on the uppermost layer.

  In the present embodiment, for example, DVD + RW is used as the optical disc D, and the recording speed is 2.4X. However, the present invention is not limited to this, and for example, CD-RW, DVD-RW, and DVD-RAM. Etc. may be used. In the phase change type optical disc D, the recording quality generally depends on the number of rewrites, the pulse width of the heating pulse, the pulse width of the cooling pulse, the recording power, the type and linear velocity of the optical disc D, the ambient temperature of the optical disc D, and the like. Change.

  Here, in each case where the surface temperature of the optical disc apparatus 1 is room temperature (in this embodiment, for example, room temperature is 30 ° C.), 40 ° C., and 50 ° C., a recording strategy optimized at room temperature is used. Then, DOW (Direct Over Write) was performed on the optical disc D, which is DVD + RW, and the change in recording quality was examined. Note that data is recorded while changing the write power (write Pw) at DOW = 30 times. The result is shown in FIG. FIG. 3 is a graph showing the relationship between write power (light Pw) and jitter at temperatures of 30 ° C., 40 ° C., and 50 ° C. Here, as an index representing the quality of recording quality, a jitter value, which is a variation in signal, is used. Generally, if the jitter value is less than 9%, it is judged that the recording quality is good.

  As shown in FIG. 3, when the surface temperature of the optical disc apparatus 1 is 30 ° C., the jitter bottom value is minimized, and the jitter bottom value increases as the surface temperature increases to 40 ° C. and 50 ° C. . That is, when the surface temperature of the optical disc apparatus 1 is 30 ° C., the jitter bottom value is about 8.5%, but when the surface temperature of the optical disc apparatus 1 is 50 ° C., the jitter bottom value is about 9%. As a result, it was found that in a high-temperature environment where the surface temperature of the optical disk apparatus 1 is 50 ° C., the recording quality deteriorates when a recording strategy optimized at room temperature is used. Further, as the surface temperature of the optical disc apparatus 1 increases, the write power necessary for the jitter to become the bottom increases. This is due to the fact that the temperature of the optical disc D becomes high and cannot be sufficiently cooled in the rapid cooling process after rapid heating. By increasing the write power and rapidly heating to a higher temperature in the rapid heating process, It shows that the amorphous phase is easily formed by the rapid cooling process.

  In the present embodiment, an example is shown in which mark edge recording is performed using an EFM modulation code as a modulation recording method (record mark length modulation recording method), and the data length of a recording mark and a space is 3 to 14 T (T Is one cycle of the channel clock). In the recording strategy, the number of pulses for each mark is N-2 (N is a data length of an integer of 1 or more).

  FIG. 4 is a schematic diagram schematically showing an example of a short pulse group when the data length is 5T. As shown in FIG. 4, the short pulse group of the present embodiment includes a leading heating pulse FP (Front Pulse) for preheating the recording layer 22 of the optical disc D sufficiently above the melting point, and a trailing heating pulse LP (Last Pulse), a plurality of continuous heating pulses MP (Multi Pulse) following FP and immediately before LP, and a cooling pulse CP (Cooling Pulse) positioned at the end of the short pulse group.

  When N = 3, any one of FP, MP, and LP may not exist. Further, FP, MP, LP, and CP may each have a pulse width of zero. A group of these FP-MP-LP-CPs is called a short pulse group, and one recording mark having a length of 3T to 14T is formed by a combination of FP, MP, LP and CP in the short pulse group. . In the optical disc apparatus 1, data is continuously recorded on the optical disc D by a recording pulse train in which short pulse groups are continuous. In this embodiment, the recording quality is improved by optimizing the recording strategy by controlling the pulse widths of FP, MP, LP, and CP in accordance with the ambient temperature of the optical disc D.

  Here, assuming that the pulse widths of FP, MP, LP, and CP are Tfp, Tmp, Tlp, and Tcp, respectively, the recording strategy that is optimized so that the recording quality is the best at room temperature (30 ° C.) is Tfp = 0. 675T, Tmp = 0.5T, Tlp = 0.5T, Tcp = 0.525T. Based on the recording strategy that provides the best recording quality at room temperature, any of the FP, MP, and CP pulse widths Tfp, Tmp, and Tcp as the surface temperature of the optical disc apparatus 1 is increased by a quality engineering technique. Was investigated as to whether the recording quality in a high-temperature environment would be improved if it was optimized as a control factor affecting the recording quality. Note that LP is excluded from the control factors because the contribution rate to recording quality is lower than other FP, MP, and CP.

  FIG. 5 is an explanatory diagram showing factor assignment. In Level 2, Tfp, Tmp, and Tcp are Tfp = 0.675T, Tmp = 0.5T, and Tcp = 0.525T, which are indicated by 0 in FIG. Level 1 is a case where −0.05 T, that is, a pulse width is shortened with respect to each of Tfp, Tmp and Tcp of level 2, and is shown as −0.05 T in FIG. Level 3 is the case where +0.05 T, ie, the pulse width is increased with respect to each of Tfp, Tmp and Tcp of level 2, and is shown as +0.05 T in FIG. It should be noted that the amount of change in which the pulse width is -0.05T at level 1 and the pulse width is + 0.05T at level 3 is too large to affect the recording signal waveform and cause jitter deterioration. On the contrary, if the change amount is too small, the effect of improving the recording quality by changing the pulse width is small.

  FIG. 6 is a characteristic diagram showing changes in recording quality when the pulse widths Tfp, Tmp, and Tcp of FP, MP, and CP are changed to level 1, level 2, and level 3 according to the explanatory diagram shown in FIG. It is. In FIG. 6, the recording quality becomes better as it goes upward on the Y axis. As shown in FIG. 6, for FP and MP, level 2 has the best recording quality. On the other hand, with regard to CP, level 1 has the best recording quality. Thus, it can be seen that the recording quality at 50 ° C. is improved by shortening the CP pulse width Tcp without changing the FP and MP pulse widths Tfp and Tmp as compared with the recording strategy at room temperature. .

  Therefore, in the present embodiment, two recording strategies, that is, a room temperature recording strategy and a high temperature recording strategy are stored in the ROM of the control unit 14. The recording strategy for room temperature is a recording strategy that is optimized so that the recording quality is best at room temperature (30 ° C.). Tfp = 0.675T, Tmp = 0.5T, Tlp = 0.5T, Tcp = 0.525T. The high temperature recording strategy is a recording strategy in which the CP is shorter than the room temperature recording strategy, and Tfp = 0.675T, Tmp = 0.5T, Tlp = 0.5T, and Tcp = 0.475T. These recording strategies are read from the ROM before the recording operation and set in the register 15 of the LD driver 13. Thereafter, a light emission waveform is formed by the multi-pulse generator 16 based on the recording strategy set in the register 15, and the recording operation is started.

  Here, assuming that the CP pulse width in the room temperature recording strategy is Tcp and the CP pulse width in the high temperature recording strategy is TcpH, Tcp = 0.525T and TcpH = 0.475T, so that TcpH = 0. However, since the optimum Tcp varies depending on the characteristics of the optical disc D, etc., the Tcp is set so as to satisfy the conditional expression of 0.8 Tcp <TcpH <Tcp.

  An information recording process for recording information on the optical disc D by the optical disc apparatus 1 in such a configuration will be described with reference to FIG. Actually, the CPU drives and controls each unit based on a program stored in the ROM of the control unit 14 to execute information recording. FIG. 7 is a flowchart showing the flow of the information recording process.

  First, when information (data) is recorded on the optical disc D, media information such as ADIP information recorded on the optical disc D is read (step S1). Next, based on the read media information, the manufacturer, disc type, disc revision, etc. of the optical disc D are discriminated (S2). Thereafter, the internal temperature of the optical pickup 5, that is, the surface temperature of the optical disc apparatus 1 is measured by the thermometer 18 (S3). Here, functions as a temperature detecting means and a temperature detecting step are executed. The internal temperature of the optical pickup 5 can be used as equivalent to the surface temperature of the optical disc apparatus 1 (see FIG. 8).

  Next, it is determined whether or not the measured temperature T is equal to or higher than a predetermined temperature Tth (for example, 40 ° C. which is higher than room temperature) (S4). Here, functions as a temperature determination means and a temperature determination step are executed. When T ≧ Tth (Y in S4), a high temperature recording strategy, that is, a recording strategy in which the cooling pulse CP is shorter than the room temperature recording strategy is set in the register 15 (S5). Here, the functions as the pulse width changing means and the pulse width changing step are executed. On the other hand, if T <Tth (N in S4), a recording strategy for room temperature is set in the register 15 (S6).

  Thereafter, a light emission waveform is formed by the multi-pulse generator 16 based on the recording strategy set in the register 15, and writing is started (S7). After the light is started, the surface temperature may rise due to heat generated by the optical pickup 5 or LSI accompanying the light. Therefore, a certain time t (for example, 1 minute) elapses from when the temperature is first measured. Every time, temperature measurement is performed (S3), and steps S3 to S7 are repeated (Y in S8). After the temperature measurement, before the fixed time t elapses (N in S8), if the writing is completed (S9), the flow ends.

  As described above, in the present embodiment, the recording strategy including the short pulse group is controlled by changing the pulse width Tcp of the cooling pulse CP according to the surface temperature of the optical disc apparatus 1 handled as the ambient temperature of the optical disc D. Even in a high temperature environment that hinders rapid heating and cooling, the recording quality is maintained, and deterioration of the recording quality can be suppressed. In addition, in order to suppress the deterioration of recording quality, for example, compared with the case where an exhaust heat fan or the like for reducing the internal temperature is provided in the optical disc apparatus, an exhaust heat fan or the like is not required, and cost reduction and weight reduction are realized. Can do.

  In the present embodiment, the pulse width Tcp of the cooling pulse CP is changed in accordance with the ambient temperature of the optical disc D. However, the present invention is not limited to this. For example, the pulse width Tfp of the leading heating pulse FP, the end heating The pulse width Tlp of the pulse LP, the pulse width Tmp of the continuous heating pulse MP, and the like may be changed.

  Here, FIG. 8 is an explanatory diagram showing the temperature measurement results in each part of the optical disc apparatus 1. In FIG. 8, five optical disk devices (drives) 1 having the same structure are prepared, the measured temperature (° C.) at the drive bottom surface, the disk surface and the drive surface in the ambient atmosphere of the optical disk device 1, and the optical pickup. The relationship with the measurement temperature (° C.) by the thermometer 18 in FIG. As shown in FIG. 8, since the temperature measured by the disk surface, the drive surface, and the thermometer 18 are all within about 3 ° C., they are treated as equivalent in this embodiment. Therefore, in the present embodiment, the pulse width is controlled by the temperature measured by the thermometer 18 in the optical pickup 5, that is, the surface temperature of the optical disk apparatus 1, but the present invention is not limited to this. The correlation between the temperature in the ambient atmosphere of 1 and the temperature measured by the thermometer 18 in the optical pickup 5 may be obtained, and the pulse width may be controlled by the temperature in the ambient atmosphere of the optical disc apparatus 1.

  In general, what is important when determining the recording quality is DOW1 and when DOW is repeated. The DOW 1 performs writing with erase power to crystallize the recording layer (recording material) 22 when the optical disc D is produced in a factory. Here, the recording quality is good in DOW0 which performs recording when the recording medium is uniform, but in the optical disk D once written by the optical disk apparatus 1, the part written in the factory and the optical disk apparatus 1 is mixed with the portion in which writing is performed. Since the recording conditions are different between the factory and the optical disc apparatus 1, the recording quality deteriorates in the DOW 1 in which writing is further performed on the optical disc D in such a state. In this embodiment, attention is focused on DOW1 and DOW30.

  A jitter value is used as a parameter indicating the quality of recording. The lower the jitter value, the better the recording quality. Generally, if the jitter value is below 9%, it is judged that the recording quality is sufficiently good. In addition, the optical disc apparatus 1 has a jitter value of 9% because the recording power may vary due to many factors such as variations in elements in the main body or variations in the phase change type optical disc D used. The recording quality is better when the lower write power range (write Pw range) is wider, that is, when the power margin is wider.

  In this embodiment, the recording strategy at 50 ° C. is Tfp = 0.675T, Tmp = 0.5T, Tlp = 0.5T, and Tcp = 0.525T, and Tfp = 0.675T, Tmp = 0.5T. The recording quality was compared between Tlp = 0.5T and Tcp = 0.475T. Note that only Tcp is different.

  FIG. 9 is a graph showing the relationship between write power (light Pw) and jitter in the case of DOW1, and FIG. 10 is a graph showing the relationship between write power and jitter in the case of DOW30. As shown in FIGS. 9 and 10, in both cases, the jitter bottom value is lower when Tcp = 0.475T than when Tcp = 0.525T, that is, the recording quality is improved.

  FIG. 11 is a graph showing the relationship between the write power (write Pw) and I14 / I14H (modulation: the magnitude of the amplitude of the reproduced signal waveform with respect to the peak level of the reproduced signal waveform) in the case of FIG. It is a graph which shows the relationship between the write power in case, and I14 / I14H. As shown in FIGS. 11 and 12, the value of I14 / I14H is larger when Tcp = 0.475T than when Tcp = 0.525T. Here, the larger the value of I14 / I14H, the larger the reproduction signal amplitude, and the smaller the signal amplification at the signal amplifier of the optical disc apparatus 1, the less the application of noise components accompanying the signal amplification. It can be said that the recording quality is high.

  From these results, it is understood that the recording quality is improved by shortening the CP pulse width Tcp at a high temperature (0.525T → 0.475T).

1 is a block diagram schematically showing a configuration of an optical disc apparatus that is an optical information recording apparatus according to an embodiment of the present invention. FIG. It is a vertical side view which shows roughly the layer structure of an optical disk. It is a graph which shows the relationship between the write power and jitter in each temperature of 30 degreeC, 40 degreeC, and 50 degreeC. It is a schematic diagram which shows roughly an example of the short pulse group in case data length is 5T. It is explanatory drawing which shows factor allocation. FIG. 6 is a characteristic diagram showing a change in recording quality when the pulse widths of FP, MP and CP are changed to level 1, level 2 and level 3 according to the explanatory diagram shown in FIG. 5 at 50 ° C. It is a flowchart which shows the flow of an information recording process. It is explanatory drawing which shows the temperature measurement result in each part of an optical disk apparatus. It is a graph which shows the relationship between the write power in the case of DOW1, and jitter. It is a graph which shows the relationship between the write power in the case of DOW30, and jitter. 10 is a graph showing the relationship between write power and I14 / I14H in the case of FIG. 11 is a graph showing a relationship between write power and I14 / I14H in the case of FIG.

Explanation of symbols

1 Optical information recording device (optical disk device)
14, 18 Temperature detection means (control unit, thermometer)
22 Recording layer D Optical information recording medium (optical disk)
CP Cooling pulse FP First heating pulse LP Last heating pulse MP Continuous heating pulse

Claims (13)

In an optical information recording apparatus for recording data on a phase change optical information recording medium using a recording pulse train composed of one or a plurality of short pulse groups,
Temperature detecting means for detecting the ambient temperature of the optical information recording medium;
Pulse width changing means for changing the pulse width of the short pulses constituting the short pulse group according to the ambient temperature of the optical information recording medium detected by the temperature detecting means;
An optical information recording apparatus comprising:   2. The optical information recording apparatus according to claim 1, wherein the pulse width changing means changes a pulse width of a cooling pulse that constitutes the short pulse group and is located at the rear end thereof. Temperature judging means for judging whether or not the ambient temperature of the optical information recording medium detected by the temperature detecting means is equal to or higher than a predetermined temperature;
The pulse width changing means, when the temperature judging means judges that the ambient temperature of the optical information recording medium is equal to or higher than a predetermined temperature, from the pulse width of the cooling pulse in the short pulse group optimized at room temperature 3. The optical information recording apparatus according to claim 2, wherein a pulse width of the cooling pulse is changed so as to be shortened. The cooling pulse when the pulse width of the cooling pulse in the short pulse group optimized at room temperature is Tcp, the ambient temperature of the optical information recording medium is T, the predetermined temperature is Tth, and T ≧ Tth is satisfied Let TcpH be the pulse width of
4. The optical information recording apparatus according to claim 2, wherein the pulse width changing unit changes TcpH within a range of 0.8Tcp <TcpH <Tcp. The temperature detecting means detects an ambient temperature of the optical information recording medium every predetermined time;
5. The optical information recording according to claim 2, wherein the pulse width changing unit changes a pulse width of the cooling pulse according to an ambient temperature of the optical information recording medium every predetermined time. apparatus.   The pulse width changing means changes only the cooling pulse without changing each pulse width of the leading heating pulse, the continuous heating pulse, and the terminal heating pulse constituting the short pulse group. The optical information recording apparatus according to 3, 4, or 5.   7. The optical information recording apparatus according to claim 1, wherein the optical information recording medium has a recording layer made of an AgInSnTe-based recording material. In an optical information recording method for recording data on a phase change optical information recording medium using a recording pulse train composed of one or a plurality of short pulse groups,
A temperature detecting step for detecting an ambient temperature of the optical information recording medium;
A pulse width changing step of changing a pulse width of a short pulse constituting the short pulse group according to an ambient temperature of the optical information recording medium detected by the temperature detecting step;
An optical information recording method comprising:   9. The optical information recording method according to claim 8, wherein the pulse width changing step changes a pulse width of a cooling pulse that constitutes the short pulse group and is located at the rear end thereof. A temperature determination step of determining whether or not the ambient temperature of the optical information recording medium detected by the temperature detection step is equal to or higher than a predetermined temperature;
In the pulse width changing step, when the ambient temperature of the optical information recording medium is determined to be equal to or higher than a predetermined temperature in the temperature determining step, the pulse width of the cooling pulse in the short pulse group optimized at room temperature The optical information recording method according to claim 9, wherein the pulse width of the cooling pulse is changed so as to be shortened. The cooling pulse when the pulse width of the cooling pulse in the short pulse group optimized at room temperature is Tcp, the ambient temperature of the optical information recording medium is T, the predetermined temperature is Tth, and T ≧ Tth is satisfied Let TcpH be the pulse width of
The optical information recording method according to claim 9 or 10, wherein the pulse width changing step changes TcpH within a range of 0.8Tcp <TcpH <Tcp. The temperature detecting step detects the ambient temperature of the optical information recording medium every predetermined time,
12. The optical information recording according to claim 9, wherein the pulse width changing step changes a pulse width of the cooling pulse according to an ambient temperature of the optical information recording medium every predetermined time. Method. The pulse width changing step is characterized in that only the cooling pulse is changed without changing each pulse width of the head heating pulse, the continuous heating pulse and the terminal heating pulse constituting the short pulse group. The optical information recording method according to 10, 11 or 12.

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