JP2005158257A - Information reproducing and recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for recording and reproducing phase transition media by a DVD drive. <P>SOLUTION: This method is an information reproducing and recording method performing record and reproduction of information from phase transition media, a land and a groove are formed on a substrate, the groove has track pitch of 0.74 μm as an information track, when tracking control is performed for the phase transition media by a DPD system, a DPD signal is obtained from phase difference between a mark after recording information and a crystallization state indicating a higher reflection property than the mark, Also, when tracking control is performed for the phase transition media by a push-pull system, it is formed so that a push-pull value standardized by a mirror part is made 0.2 or more, when information is recorded in the groove, tracking control is performed by obtaining a tracking error signal from the push-pull signal, when information recorded in the groove is reproduced, tracking control is performed by obtaining the tracking error signal from the DPD signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides an information reproducing / recording method, and more particularly, a method for reproducing and recording a phase change recording disk with a DVD drive in the same manner as a DVD (Digital video Disk) -ROM (Read Only Memory) disk. is there.

  In an optical disc apparatus capable of recording and reproducing information signals such as video signals or audio signals, a guide groove is formed in advance on a substrate of the optical disc to form a track. Information signals are recorded or reproduced by condensing the laser light on the concave portion (groove) or the flat portion of the convex portion (land) in the track. In a general optical disk device currently on the market, an information signal is usually recorded only in one of the concave portion or the convex portion, and the other is a guard band that separates adjacent tracks. There have also been proposed recording information signals in both of the recesses.

  FIG. 5 is an enlarged perspective view of an optical disc used in a conventional optical disc apparatus. In FIG. 5, reference numeral 1 denotes a recording layer, which is made of, for example, a phase change material. Reference numeral 2 is a recording pit, 3 is a laser beam focusing spot, 4 is a recess, 5 is a protrusion, and 6 is an address pit representing position information on the disk. Further, in the same figure, a transparent disk substrate through which incident light is transmitted is omitted.

  FIG. 6 is a diagram for explaining an example of a conventional optical disk apparatus using an optical disk as described above. In the figure, 10 is an optical disk, 11 is a recording track, 12 is a semiconductor laser, and 13 is emitted from a semiconductor laser 12. A collimating lens that converts the laser light into parallel light, 14 is a beam splitter placed on the light beam, and 15 is an objective lens that condenses the parallel light that has passed through the beam splitter 14 onto the recording surface of the optical disk 10. Reference numeral 16 denotes a photodetector that receives the reflected light from the optical disk 10 that has passed through the objective lens 15 and the beam splitter 14, and is divided into two in parallel with the track direction of the optical disk 10 in order to obtain a tracking error (TE) signal. It consists of two light receiving parts 16a and 16b. Reference numeral 17 denotes an actuator that supports the objective lens 15, and the semiconductor laser 12 to the actuator 17 described above are attached to a head base (not shown) and constitute an optical head 18.

  Reference numeral 21 denotes a differential amplifier to which detection signals output from the light receiving units (photodetectors) 16a and 16b are input, and 22 denotes a low-pass filter (LPF) to which a difference signal output from the differential amplifier 21 is input. Reference numeral 23 denotes a tracking control circuit that receives the output signal of the LPF 22 and the control signal L1 from the system controller 30 and outputs a tracking control signal to the drive circuit 24. The drive circuit 24 outputs a drive current to the actuator 17, and the actuator 17 Drive.

  25 is an addition amplifier that outputs detection signals output from the light receiving units 16a and 16b, and outputs a sum signal thereof. 26 is a sum signal that is input from the addition amplifier 25, and outputs the high-frequency component to the reproduction signal processing circuit 27. The reproduction signal processing circuit 27 receives the high-frequency component of the sum signal from the HPF 26 and outputs an information signal such as audio to the output terminal OUT. Reference numeral 28 denotes an address reproduction circuit which receives the high frequency component of the sum signal from the HPF 26 and reproduces the address signal and outputs it to the system controller 30. A traverse control circuit 31 outputs a drive current to the traverse motor in response to a control signal L2 from the system controller 30. The traverse motor 32 moves the optical head 18 in the radial direction of the optical disc 10. Reference numeral 9 denotes a spindle motor that rotates the optical disk 10.

  Reference numeral 33 denotes a recording signal processing circuit which receives an information signal such as a sound input from the external input terminal IN and outputs a recording signal to an LD (laser diode) driving circuit 34. The LD driving circuit 34 receives a control signal L3 from the system controller 30. Then, a recording signal from the recording signal processing circuit 33 is input, and a driving current is input to the laser diode 12. The system controller 30 receives an address signal from the address reproduction circuit 28 and outputs control signals L1, L2, and L3 to the tracking control circuit 23, the traverse control circuit 31, and the LD drive circuit 34.

Next, the operation of the conventional optical disc apparatus will be described.
The laser beam emitted from the semiconductor laser 12 is collimated by the collimator lens 13 and converged on the optical disc 10 by the objective lens 15 through the beam splitter 14. The light beam reflected by the optical disk 10 has information of the recording track 11 by diffraction, and is guided by the beam splitter 14 onto the photodetectors 16a and 16b, which are light receiving parts, through the objective lens 15. The light receiving units 16a and 16b convert the distribution change of the incident light beam into an electrical signal, and output it to the differential amplifier 21 and the addition amplifier 25, respectively. The differential amplifier 21 converts each input current into a voltage by converting it into a voltage, takes the difference, and outputs it as a push-pull signal. The LPF 22 extracts a low frequency component from this push-pull signal and outputs it to the tracking control circuit 23 as a tracking error signal. The tracking control circuit 23 outputs a tracking control signal to the driving circuit 24 according to the level of the input tracking error signal, and the driving circuit 24 sends a driving current to the actuator 17 according to this signal, and records the objective lens 15. The position is controlled in the direction crossing the track 11. As a result, the focused spot correctly scans the recording track (the convex portion 5 in FIG. 1). The objective lens 15 is position-controlled in a direction perpendicular to the disk surface by a focus control circuit (not shown) so that the focused spot is correctly focused on the disk.

  On the other hand, the addition amplifier 25 performs an IV conversion on the output currents of the light receiving units 16a and 16b, adds the currents, and outputs the result to the HPF 26 as a sum signal. The HPF 26 cuts unnecessary low-frequency components from the sum signal, passes the reproduction signal and the address signal as the main information signal, and outputs them to the reproduction signal processing circuit 27 and the address reproduction circuit 28. The reproduction signal processing circuit 27 demodulates the inputted reproduction signal, and thereafter, undergoes processing such as error correction and is output to the output terminal OUT as an audio signal or the like. The address reproduction circuit 28 demodulates the input address signal and outputs it to the system controller 30 as position information on the optical disk 10. That is, as a result of the focused spot 3 shown in FIG. 1 scanning the recording pit 2, a reproduction signal is input to the reproduction signal processing circuit 27, and as a result of scanning the address pit 6, an address signal is input to the address reproduction circuit 28. Entered. Based on this address signal, the system controller 30 determines whether the light beam is currently at a desired address.

  The traverse control circuit 31 outputs a drive current to the traverse motor 32 in accordance with the control signal L2 from the system controller 30 when the optical head is moved, and moves the optical head 18 to the target track. At this time, the tracking control circuit 23 temporarily suspends the tracking servo by the control signal L1 from the system controller 30 as well. Further, during normal reproduction, the traverse motor 32 is driven according to the low frequency component of the tracking error signal input from the tracking control circuit 23, and the optical head 18 is gradually moved in the radial direction along with the progress of reproduction.

  At the time of recording, the recording signal processing circuit 33 adds an error correction code or the like to the audio signal input from the external input terminal IN, and outputs the encoded recording signal to the LD driving circuit 34. When the LD driving circuit 34 is set to the recording mode by the control signal L3 from the system controller 30, the LD driving circuit 34 modulates the driving current applied to the semiconductor laser 12 according to the recording signal. As a result, the intensity of the light spot irradiated onto the optical disc 10 changes according to the recording signal, and the recording pit 2 is formed. On the other hand, at the time of reproduction, the LD drive circuit 34 is set to the reproduction mode by the control signal L3 from the system controller 30, and controls the drive current so that the semiconductor laser 12 emits light with a constant intensity. As a result, the recording pits and address pits on the recording track can be detected. While the above operations are performed, the spindle motor 9 rotates the optical disk 10 at a constant linear velocity or angular velocity.

FIG. 7 is a diagram for explaining an example in which a tracking error signal is obtained by differential phase detection (DPD) (for example, refer to Japanese Patent Publication No. 3-18255). Is a light receiving element, and the light receiving element 35 is composed of four photoelectric conversion elements (S1, S2, S3, S4). The output signals of the photoelectric conversion elements S1 and S3 are added by an adder 36, and the photoelectric conversion elements S2 and S4 are added. Are added by an adder 37, and the output signals of the adders 36 and 37 are added by an adder 38 to obtain a sum signal H _F and subtracted by a subtractor 39 to obtain a difference signal D _L. Yes.

8, (a) shows the output signal (D _L ) of the subtractor 39, (b) shows the output signal (H _F ) of the adder 38, and the output signal (D _L signal) of the subtracter 39 is sampled and held. is applied to the circuits 43 and 44 to obtain a sampling pulse shown in (c) during the increase of applied to HF signal the output signal of the adder 38 (H _F signal) to zero cross detection circuit 41, the sampling and samples and holds the output signal of the subtracter 39 by the sample hold circuit 44 a pulse give a signal (e), H _F is applied the output signal of the adder 38 (H _F signal) to zero cross detection circuit 42 While the signal is decreasing, the sampling pulse shown in (d) is obtained, and with this sampling pulse, the output signal of the subtractor 39 is sampled and held by the sample hold circuit 43 to obtain the signal shown in (f). , Since the output signal waveform shown in f) is reversed phase, so as to obtain the tracking error signal without disturbance such as offset by the differential amplifier to both the signal by the differential amplifier 45.

  The phase difference tracking method as described above is also described in Patent Document 1, Patent Document 2, and the like. However, these methods irradiate an information track composed of pit rows composed of uneven reflective pits with a reproduction laser light spot. Scan to modulate the optical phase of the reflected light, detect changes in the light intensity distribution on the light receiving element that receives the reflected light, detect deviation from the center of the pit row, and minimize this deviation signal Thus, the reproduction laser beam spot is tracked by servo control.

In addition, a laser beam spot is irradiated while scanning along the information track, and the crystal phase of the recording film is changed by heating / cooling control to change the crystallized state exhibiting high reflection characteristics (hereinafter referred to as a high reflection phase). And so-called phase change recording discs in which information is optically recorded by alternately forming crystallized states exhibiting low reflection characteristics (hereinafter referred to as low reflection phases) are generally known. An optical recording disk that has the same storage capacity as a disk and can be reproduced by a DVD-ROM drive is not yet known.
Japanese Patent Publication No.56-30610 Japanese Examined Patent Publication No. 2-56734

  Conventional conventional phase change recording discs as described above generally have lower reflectivity and amplitude modulation as physical signal characteristics and lack signal strength than DVD-ROM discs, and thus are similar to DVD-ROM discs. However, it is difficult to reproduce with a DVD-ROM drive. In particular, a phase difference tracking signal (DPD signal) used for pit row tracking cannot be obtained sufficiently, and thus tracking control cannot be stabilized.

As described above, conventionally, phase change media have a small phase difference signal and have not been tracked by the phase difference tracking method, so recording and reproduction are performed by the push-pull method.
The present invention has been made in view of the above circumstances, and after recording, the groove shape and layer structure of the phase change disk (media) substrate are formed so that phase difference tracking can be performed, and the phase change medium is a DVD. An object of the present invention is to provide an information reproducing / recording method for reproducing and recording with a drive.

  According to the first aspect of the present invention, there is provided a DVD-ROM for a phase change optical information recording disk having a multilayer structure having a transparent substrate, at least one recording layer formed on the transparent substrate, and a protective layer. Information reproduction recording in which information is reproduced from the phase change optical information recording disk by irradiating a laser beam used for the disk, and information is recorded on the phase change optical information recording disk A land and a groove are formed on the substrate, and the groove has a track pitch of 0.74 μm as an information track, and a DPD (Differential Phase Detection) method with respect to the phase change optical information recording disk. When tracking control is performed, the mark after information recording and the crystallization state exhibiting higher reflection characteristics than the mark In the case where a DPD signal is obtained from the phase difference and tracking control is performed on the phase change optical information recording disk by the push-pull method, the push-pull value normalized by the mirror unit is set to 0.2. When recording information in the groove, tracking control is performed by obtaining a tracking error signal from the push-pull signal. When reproducing information recorded in the groove, the DPD signal is used. The tracking control is performed by obtaining a tracking error signal.

  The invention of claim 2 is characterized in that, in the invention of claim 1, dummy data is recorded on the outer side of the outermost track of the phase change optical information recording disk, and an extra one round is recorded. .

According to the present invention, since it is a phase change optical information recording disk that enables DPD tracking, tracking can be performed even with a push-pull method, and the DPD signal is large, the RF signal is large, and the jitter is improved. The phase change disk can be reproduced and recorded by a DVD drive.
In addition, since the phase-change optical information recording disk has an extra track of dummy data recorded in the data recording end portion, the dummy data is recorded in an extra track so that tracking can be stabilized.

  As described above, conventionally, phase change media have a small phase difference signal, and the phase difference tracking method does not require tracking. Therefore, recording / reproduction is performed by the bush pull method. On the other hand, in the present invention, the groove shape of the substrate and the layer structure of the phase change media are formed so that DPD tracking is applied so that the phase difference between the mark after recording and the crystal can be taken.

FIG. 4 is an enlarged cross-sectional view for explaining an example of a recording medium (medium) used in the practice of the present invention. In the figure, reference numeral 10 denotes a recording medium (optical disk), and the recording medium 10 includes a substrate 10a and a lower part. It is composed of a protective groove layer 10b, a recording layer 10c, an upper protective layer 10d, a heat dissipation layer 10e, a UV protective layer 10f, etc., and PC (polycarbonate) is used for the substrate 10a, and a lower protective layer (as a material, ZnS.SiO ₂ , SiNx or the like) 10b is formed, and a recording layer (using material such as AgInSbTe, GeSbTe or the like) 10c is formed thereon, and an upper protective layer (on top thereof) is further formed. the material uses ZnS.SiO _2, SiNx or the like) 10d is formed, thereon, as the heat dissipation layer (material, using Al, Al alloy, Au, an Ag) 10e formed , UV protective layer on top (as a material, using UV-curable resin) 10f is obtained by the formation. Thus, although such a configuration improves recording / reproduction and DPD tracking, the present invention is not limited to this configuration.

  FIG. 1 is a diagram showing the relationship between the amplitude of a DPD output signal and the amplitude of a push-pull output signal with respect to the groove width, and FIG. 1 (A) shows the amplitude of the DPD output signal with respect to the groove width when recorded in a groove. FIG. 1B is a diagram showing the relationship between the amplitude of the DPD output signal and the amplitude of the push-pull output signal with respect to the groove width when recorded on the groove and land. In both figures, the track pitch Tp is 0.74 μm and the groove depth is 0.145λ. Table 1 shows measured values for FIG. 1A and Table 2 shows measured values for FIG. Show.

  As apparent from FIGS. 1A and 1 and FIGS. 1B and 2, in the groove recording or the groove and land recording, the track pitch Tp is set to 0.74 μm so that at least the groove width is 0. In the range of 0.5 to 0.8 μm, even if the phase change medium DPD tracking is performed, the same accuracy as that of the DVD-ROM can be obtained, so that the phase change medium can be applied to the DVD-ROM player.

  FIG. 2A and Table 3 are a diagram showing a relationship between the groove width (μm) and the jitter (σ / Tw (%)) and a table showing the actual measurement values. Shows that the groove width may be in the range of 0.4 to 0.5 μm.

  FIG. 2B and Table 4 show the relationship between the groove depth (nm), T / C (track cross: a value normalized by the mirror part) and push-pull (push pull: a value normalized by the mirror part). And a table showing the measured values thereof, and the push-pull in the range of the groove depth 45 nm (0.11λ) to 75 nm (0.18λ) and the 1 / 4λ period 0.36λ to 0.43λ. It turns out that it becomes 0.2 or more. Therefore, by setting the groove width to 0.4 to 0.5 [mu] m, the groove depth to 0.11 [lambda] to 0.18 [lambda], and 1/4 [lambda] to 0.36 [lambda] to 0.43 [lambda], tracking can be performed even with the push-pull method. In addition, the DPD signal is large, the RF signal is large, and the jitter can be improved.

  FIG. 3 is a diagram showing the relationship between the recording pitch (μm) and the crosstalk (dB) with the groove depth as a parameter, and Table 5 shows the measured values. From these FIGS. Recording pitch is 0.6 μm to 0.8 μm (track density applied to a DVD player), groove depth is 0.11λ to 0.18λ, 1 / 4λ is 0.36λ to 0.43λ, and crosstalk is −26 dB or less. Thus, tracking can be performed even with the push-pull method, and the DPD signal is large, the RF signal is large, the crosstalk is reduced, and the jitter can be improved.

  As described above, the present invention can increase the DPD signal in a phase change optical recording medium recorded in a groove, or a groove and a land, and apply the phase change optical recording medium to a DVD player. However, since the data for the last round of data recording is usually not recorded outside, the last round of data recording should be reproduced accurately on the recording medium described above. I can't. Therefore, in the present invention, dummy data is recorded on the outer side of the last recording track for an extra round, thereby enabling accurate tracking to the end.

It is a figure which shows the relationship between the amplitude of a DPD output signal with respect to groove width, and the amplitude of a push-pull output signal. It is a figure which shows the relationship of the jitter with respect to a groove width, and the relationship of T / C and a push-pull normalization output with respect to a groove depth. It is a figure which shows the relationship between a recording pitch and crosstalk. It is sectional drawing for demonstrating an example of the phase change type optical recording medium used for implementation of this invention. It is an expansion perspective view of the optical information recording disk used for the conventional optical disk apparatus. It is a figure for demonstrating an example of the conventional optical disk apparatus. It is a figure for demonstrating the example of the conventional phase difference tracking signal generation circuit. FIG. 8 is a waveform diagram for explaining the operation of FIG. 7.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Recording layer, 2 ... Recording pit, 3 ... Condensing spot of laser beam, 4 ... Concave part (groove), 5 ... Convex part (land), 6 ... Address pit, 9 ... Spindle motor, 10 ... Optical disk, 10a ... Substrate, 10b ... lower protective groove layer, 10c ... recording layer, 10d ... upper protective layer, 10e ... heat dissipation layer, 10f ... UV protective layer, 11 ... recording track, 12 ... semiconductor laser, 13 ... collimating lens, 14 ... beam splitter , 15 ... objective lens, 16 ... photodetector, 17 ... actuator, 18 ... optical head, 21 ... differential amplifier, 22 ... low pass filter (LPF), 23 ... tracking control circuit, 24 ... drive circuit, 25 ... summing amplifier , 26 ... high pass filter (HPF), 27 ... reproduction signal processing circuit, 28 ... address reproduction circuit, 30 ... system controller, 31 ... traverse Control circuit, 32... Traverse motor, 33... Recording signal processing circuit, 34... LD drive circuit, 35... Light receiving element, 36, 37, 38 ... adder, 39 ... subtractor, 41, 42. , 44... Sample hold circuit, 45.

Claims (2)

Laser light used for a DVD-ROM disc with respect to a phase change optical information recording disc having a multilayer structure having a transparent substrate, at least one recording layer formed on the transparent substrate, and a protective layer Is an information reproduction recording method for reproducing information from the phase change optical information recording disk by irradiating and recording information on the phase change optical information recording disk,
Lands and grooves are formed on the substrate,
The groove has a track pitch of 0.74 μm as an information track, and when tracking control is performed by the DPD (Differential Phase Detection) method on the phase-change optical information recording disk, a mark after information recording and a height higher than the mark are recorded. When a DPD signal is obtained from the phase difference from the crystallized state showing the reflection characteristics and tracking control is performed by the push-pull method on the phase change optical information recording disk, the push normalized by the mirror unit -Pull value is 0.2 or more,
When recording information in the groove, tracking control is performed by obtaining a tracking error signal from the push-pull signal,
An information reproducing / recording method, wherein when reproducing information recorded in the groove, tracking control is performed by obtaining a tracking error signal from a DPD signal.   2. The information reproducing / recording method according to claim 1, wherein dummy data is recorded on the outside of the outermost track of the phase change type optical information recording disk for an extra round.