JPS6015831A - Recording method by tracing tracking - Google Patents

Abstract

PURPOSE:To attain high-density recording by using the 1st track at the start of recording as a reference track, recording a signal to each predetermined n-th track by means of the mechanical accuray only successively and using them as the reference tracks equal to the 1st track to correct the disturbance or track due to external disturbance. CONSTITUTION:A caption 23 indicates the outermost track, i.e., the 1st track at the start of recording, captions 24A-24C are trackes recording a signal while performing tracing tracking, and if a recording disturbance due to an external disturbance (d) occurs in a track recorded by the tracing tracking, the disturbance is amplifid by the succeed tracks, but since the n-th track is set to the reference track 25 recorded with no control, the state is restored to the initial state by this reference track 25. Thus, the crossing of track failure is prevented. In this case, the track pitch of the reference track 25 is set to a sum of the maximum tracking amount of the track just before and an original track pitch P. The track crossing failure is prevented comletely in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a recording method using profile tracking, and in particular to profile tracking in an optical information file device or the like that uses a light beam to record and reproduce information on a recording medium carrying a heat mode material. Concerning improvements in recording methods.

Prior Art As this type of optical information file device, a magneto-optical 7” (
, a two-way device, or a magneto-optical drum device.

In magneto-optical disk devices, Gd is used as a recording medium.

A disk is used in which a ferromagnetic thin film made of an alloy such as Tb or Fe is provided on the surface of a non-magnetic disk.

This disk records information as a change in the magnetization direction on a ferromagnetic thin film on the surface of the disk while rotating the disk.

That is, recording is performed by the following procedure.

The magnetization direction of the ferromagnetic thin film of the disk is aligned in advance in a direction perpendicular to the disk surface. Next, while rotating the disk and applying an external magnetic field in the opposite direction to the magnetization direction, a light beam modulated according to the information is focused onto the ferromagnetic thin film to a diameter of about 1 μm.

The portion of the ferromagnetic thin film that is irradiated with the light beam spot (recorded bit) is heated by the light energy, reaching more than the Curie point (approximately 160° C.), and the magnetization direction becomes disordered.

Next, as the irradiation position of the beam spot moves as the disk rotates, the temperature of the portion where the temperature has started to rise decreases, and at this time, the direction of the magnetic field is reversed by the external magnetic field. In this way, information is recorded as a reversal of the magnetization direction.

Note that the reproduction is performed according to the following procedure.

A rotating disk is irradiated with an unmodulated, linearly polarized light beam without applying an external magnetic field. A portion of the light beam is reflected on the disk (the surface of the ferromagnetic thin film) and returns on its outward path. This reflected light is separated from the incident light by a beam filter or the like provided in the optical path, and is received by a photoelectric conversion element. When the reflected light is reflected on the disk, the plane of polarization is rotated in different directions depending on the recorded signal, that is, the direction of magnetization.

Therefore, by receiving the reflected light while determining its polarization direction with an analyzer installed just before the photoelectric conversion element, the code can be reproduced. Optical information file devices such as magneto-optical disk drive R etc. According to this method, high-density recording is possible. For example, the diameter is about 1
p by recording using a μm light beam spot,
The size of the recording area for 1 bit (1 bit) is 1μ
With a size of more than m, the signal sequence interval, ie, the track pitch, can be reduced to several μm or less.

On the other hand, in order to fully exploit the potential of such high-density recording, it is required to record signal sequences with submicron precision.

For this reason, a precision ball screw or the like has conventionally been used as a means for moving the optical system in the radial direction of the disk. However, such means have the disadvantage that high-precision components must be used in proportion to the guarantee of accuracy, and therefore manufacturing costs become extremely high. Furthermore, due to mechanical errors of the disk such as disk axis wobbling, the accuracy of the recording position is limited to ±0.2 μm, and there is a drawback that the accuracy of the signal train cannot be sufficiently improved.

On the other hand, as a method to improve the precision of the signal train, a pre-group method is used that forms grooves in advance on the disk and uses the grooves as a guide (as a detection target for tracking signals) to record information. Proposed. This method has the advantage of being able to ensure high recording position accuracy using inexpensive equipment, but if grooves are formed on the disk, thickness unevenness is likely to occur when the ferromagnetic thin film is deposited, and the characteristics cannot be maintained constant. Therefore, magneto-optical disks have the disadvantage of being difficult to put into practical use.

Therefore, a recording method using pattern tracking can be considered as an inexpensive means with high recording position accuracy. This tracing tracking method records with only mechanical precision on the first track, and records at regular intervals on subsequent tracks while tracking the track that was recorded immediately ahead. .

This profile tracking method does not require a particularly high-precision optical system drive means and records with tracking precision, making it possible to ensure high precision (for example, ±0.1 μm). However, on the other hand, if a disturbance occurs during recording and the track is disturbed even once, each subsequent track will be recorded using the disturbed track as a reference, and in this case, the disturbed track will not be collected. The drawback is that high-density anti-recordability cannot be ensured.

The present invention relates to an improvement of the recording method using tracing tracking, and an object of the present invention is to solve the drawbacks of the prior art as described above and to provide a tracing recording method that is inexpensive and capable of high-density recording. shall be.

A feature of the present invention is that the first track at the start of recording is used as a reference track, and thereafter, recording is performed only with mechanical precision on every n-th track determined, and these tracks are set to the same standard as the first track. The purpose of this is to correct track disturbances caused by disturbances, thereby enabling high-density recording.

DESCRIPTION OF EMBODIMENTS The present invention will be specifically described below with reference to FIGS. 1 to 5.

FIG. 1 is a diagram illustrating the configuration of a magneto-optical disk device for implementing the method of the present invention.

In FIG. 1, a disk 1 carrying a ferromagnetic thin film on its surface is rotated in the direction of the arrow by a drive motor (not shown).

On the other hand, on the base 3, which is moved in the radial direction of the disk 10 by the feed screw 2, are a light emitting source (semiconductor laser) 4 for recording and reproduction, a light emitting source (semiconductor laser) 5 for tracking error detection, and a wavelength selective half mirror. -6. Beam splitter (half mirror, etc.) that separates incident light and reflected light 7
, total reflection mirror 8, rotatable movable mirror (tracking mirror) 9, objective lens lO1 condenser lens 11. A cylindrical lens 12, an analyzer plate 13, and a photoelectric conversion element 14 are attached. Furthermore, a current-carrying coil 15 is arranged below the disk 1 to form a magnetic field in the direction of the recording bit.

The photoelectric conversion element 14 is a semiconductor laser 4 for recording and reproduction.
and a light receiving element section configured to separately receive two light beams from the semiconductor laser 5 for tracking error detection, and a light receiving element for receiving the light beam from the semiconductor laser 5 for tracking error detection. In the element section, a four-part sensor is used to perform tracking detection and focus detection.

Next, the operation of the magneto-optical disk device shown in FIG. 1 will be explained.

During recording, the semiconductor laser 4 emits a light beam modulated according to information. On the other hand, the semiconductor laser 5 for tracking error detection emits an unmodulated light beam. These 2
The two light beams are combined at a half mirror 6. At this time, since the semiconductor laser 5 for tracking error detection is located above the semiconductor laser 4, the two light beams are emitted as two parallel beams in the vertical direction.

Each of the semiconductor lasers 4 and 5 is formed into a unit and includes a collimator lens therein, so that the respective emitted light becomes parallel light.

The two light beams emitted from the wavelength-selective half mirror 6 pass through a beam splitter 7, a total reflection mirror 8, and a tracking mirror 9 in this order, and are focused onto a disk by an objective lens 10 as a spot with a diameter of about 1 μm. be done.

A part of the original beam that has reached the disk l is reflected and redirected to the objective lens 10, the tracking mirror 9, and the total reflection mirror 8.
The light enters the beam splitter 7 with a diameter t), is separated from the incident light by the beam splitter, passes through the condenser lens 11, the cylindrical lens 10, and the analyzer 13, and is received by the photoelectric conversion element 14. In this photoelectric conversion element 14,
The two light beams, that is, the two light beams from each of the semiconductor laser 4 for recording and reproduction and the semiconductor laser 5 for tracking error detection are received separately.

During reproduction, the current-carrying coil 15 is not applied, the semiconductor laser 4 is also set to emit an unmodulated beam, and the optical change in the reflected light from the semiconductor laser 4 is judged by the analyzer 13. Information is played back.

By rotating the optical disc 1 at a predetermined speed and moving the base 3 in the radial direction of the disc 1 through the feed screw 2, recording and reproduction are performed over the entire surface of the disc 1.

Next, a second
This will be explained with reference to the figure.

In FIG. 2, numerals 16A, 16B, and 16c indicate recorded information bits, and numeral 17 indicates a bit to be recorded (or reproduced) from scratch. Also, the code 18 is l.
A non-modulated light beam emitted from the semiconductor laser 5 for racking error detection is shown, and numeral 19 indicates a modulated light beam for recording (or a non-modulated light beam for reproduction) emitted from the semiconductor laser 4. The reflected light passes through an astigmatism optical system consisting of a condensing lens 11 and a cylindrical lens 12 as shown in FIG.
The light is received by the light-receiving section of the disc, and focus detection is performed based on this, and the position of the objective lens 10 is changed to correct out-of-focus caused by the disc 10 being tilted. At the same time, when a tracking signal is detected, a tracking error is detected, and the angle of the tracking mirror 9 is changed so that the light beam spot 18 is always aligned with the pitch 16A.

16B and 16C. In this case, tracking error detection by the focus detection method and tracking signal detection method and control of the light beam irradiation position are already known methods.

According to such a light beam irradiation position control method, the two light beams (18 and 19) always move at a constant interval (P in Figure 2), so the signal string being recorded always follows the previous track. It is recorded with high accuracy at equal intervals. The same goes for playback, and reliable and stable playback can be performed.

However, as mentioned above, in the conventional recording method using tracing tracking, it is possible to record with high accuracy when the track is not disturbed by external disturbances, etc.; When this happens, all the tracks recorded thereafter are also disturbed, and there is a problem in that accidents such as adjacent tracks eventually crossing each other occur.

The situation in which an accident occurs according to such a conventional technique will be explained below with reference to FIG.

In FIG. 3, reference numeral 2o indicates the first track at the start of recording, that is, the track recorded without control while keeping the light beam irradiation position constant, and serves as a reference track. The next track 21 is recorded concentrically with respect to the track 20. However, if a disturbance such as an impact occurs while recording the track 22 and the position of the recording beam is disturbed, the recording will be disturbed in response to the disturbance as shown by a. When the next track 23 is recorded in this state, the portion corresponding to the disturbance a is recorded with track disturbance as shown by b. This disturbance b is
The tracking mirror rapidly vibrates to follow the change in the previous disturbance a, and as the inertia of this mirror is added, the disturbance is amplified and a becomes larger. Continuing to record further,
If the turbulence becomes larger and larger, it will eventually lead to an accident where adjacent trucks cross each other as shown at C.

In the present invention, in order to prevent such an accident where the tracks intersect, the first track is used as the reference track, and the light beam irradiation is performed when recording on every predetermined n-th (for example, 10th) track thereafter. It is configured to maintain a constant position. That is, a track (reference track) on which recording is performed with the tracking mirror fixed (uncontrolled state) is set for each nth track. In this case, it is preferable that the track pitch with respect to the track immediately before the reference track is set to an amount equal to the maximum tracking amount of the immediately preceding track plus the original reference track pitch. Crossing accidents can be completely prevented. By detecting and recording the maximum tracking amount of the immediately preceding track, the track pitch of the reference track can be controlled. Hereinafter, an example of the reference track setting method according to the present invention will be explained in detail with reference to FIG. 4.

In FIG. 4, the reference numeral 23 indicates the outermost track, that is, the first track at which recording starts, and the reference numerals 24A, 24B
, 24C indicate tracks on which recording is performed while tracking. If a recording disturbance occurs due to a disturbance as shown by the symbol d in a track recorded by tracing tracking, the disturbance will be amplified and become larger in the following tracks, but according to the present invention, the nth (
For example, the 10th track) is set as the reference track 25 for uncontrolled recording, so the reference track 25
Since the vehicle returns to the initial state at the time, the truck crossing accident in the prior art explained in FIG. 3 can be prevented.

In this case, the track pitch of the reference track 25, that is, the distance between it and the immediately preceding truck, is set to a value that is the sum of the maximum tracking view T of the immediately preceding truck and the original track pitch P, thereby completely preventing truck crossing accidents. can be prevented. Incidentally, the interval between the reference tracks 25, that is, the value of n of the reference track provided every nth is as follows:
As mentioned above, it can be set to 10, for example, but if the disturbance is small, it can also be set to several 100, and tracking can be performed on several 100 consecutive tracks.

Next, referring to FIG. 5, an example of the operation procedure of the recording method using profile tracking of the present invention will be explained.
In step 01, it is determined whether the track to be recorded is the first track, that is, the first track, and if it is the first track, in step 102, the tracking mirror 9 is separated from the control circuit and recording is performed while being held fixed with a fixed bias. 0
Thereafter, in step 103, recording is performed on the second and subsequent tracks while tracking without detecting tracking errors. In this way, in step 104, it is determined whether or not the n-1th track has been reached, and if it is the n-1st track, the tracking error is detected while recording with the Stellar F105 by tracing tracking, and the maximum tracking amount is Record T. In the subsequent n-th track, in step 106, a tracking pitch amount obtained by adding the maximum tracking amount T and the reference track pitch P is sent to the optical system, and based on this amount, the pitch of the n-th reference track is sent. On the n-th reference track, recording is performed by leaving the tracking mirror 9 out of control and holding it at a fixed bias as in step 102 above. Thereafter, recording is performed again on a predetermined number of tracks (for example, up to the 2n-1th track) while tracking without detecting a tracking error. Again the next nth (i.e. 2 from the beginning)
When the track n@th) is reached, it is sent at a pitch equal to the maximum tracking amount of the previous track as described above, and the tracking mirror 9 is separated from the control m11 and held fixed with a fixed bias to perform recording, and this is repeated again. Use as a reference track. I will refrain from any further actions. The Stella f107 determines whether all data has been recorded, and if recording has been completed, the process ends here.

In the embodiment, the first track after the start of recording is the first reference track, but such a first reference track may be provided on the recording medium in advance.

According to the embodiment described above, by preventing an increase in track disturbance caused by disturbances that occur during recording using the profile tracking method and returning to the initial state every predetermined number of tracks, accidents such as track crossing can be prevented. It is possible to implement a recording method using tracing tracking that can prevent this problem and also enable high-density recording. Moreover, tracking recording can be performed using a simple method of recording every predetermined number of tracks with a tracking mirror fixed (in an uncontrolled state). High-density recording can be performed at low cost without increasing the manufacturing cost of the device.

Effects As is clear from the above description, according to the present invention, accidents such as track crossing can be prevented in an extremely simple manner, and a recording method using contour tracking that enables high-density recording can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory perspective view illustrating the overall configuration of a magneto-optical 7' disk device suitable for carrying out the recording method using profile tracking of the present invention, and FIG. 2 is a recording/reproducing light beam in the device shown in FIG. FIG. 3 is an explanatory diagram illustrating the positional relationship of the beam spot of a light beam for tracking error detection; FIG.
The figure is an explanatory diagram illustrating a state in which truck crossing accidents due to disturbance are prevented by the recording method using profile tracking of the present invention, and FIG. 5 is an operational procedure when implementing the recording method using profile tracking of the present invention. This is a flowchart illustrating the following. 1...Disk (recording medium), 2...Sine feed screw, 3
... Base, 4... Semiconductor laser for recording and reproduction (light beam emitting source), 5... Semiconductor laser for tracking error detection (light beam emitting source), 6... Wavelength selectivity/.
-7 mirror, 7... Beam splitter, 8... Total reflection mirror, 9... Tracking mirror, lO... Objective lens, 11... Condensing lens, 12... Cylindrical lens, 13... ... Analyzing plate, 14... Photoelectric conversion element, l5... Current-carrying coil for forming an external magnetic field, 18... Unmodulated light beam spot for tracking signal detection, 19... For recording and reproducing light beam slit. Figure 2 1ρ 1/19 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] (1) At least two light beam emission sources are used to irradiate the recording medium with at least one light beam to scan the previously recorded signal sequence. In a recording method using tracing tracking, in which a signal train is formed by modulating one light beam according to information and irradiating it onto a recording medium, the first track is used as a reference track, and thereafter every nth track determined in advance is recorded. Recording method 0 by tracing tracking characterized in that the light beam irradiation position is kept constant when recording on another track, and the irradiation position is controlled according to a tracking error detection signal when recording on another track.