JPH02165421A - Erasing system and erasing optical system for rewritable type optical disk - Google Patents

Abstract

PURPOSE:To extremely shorten the time for erasing by forming an erasing spot to a sectional shape to cover plural tracks and simultaneously erasing the information data to be rewritten. CONSTITUTION:The erasing optical system 12 is mounted to an erasing head 3 and the major axis of the elliptic spot Se is aligned to the radial direction of the disk to be inspected. The spot Se simultaneously covers the track flux 1c. A spot intensity control signal is formed in a microprocessor 7 by the beginning end and terminal signals of the ID part detected by a reading out head 2 and an ID detector 6 and is applied via a power controller 5 to the erasing optical system 12 so that the ID part is lowered or stopped in the spot intensity and the data part is switched to the intensity necessary for erasing. The microprocessor 7 moves the erasing head 3 to the track flux of the next position and executes erasing upon ending of the erasing of the track flux 1c. The time for erasing is extremely shortened in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an erasing method and erasing optical system for a rewritable optical disc.

[Prior Art] Optical disks or magneto-optical disks, which have been recently developed, record information data at extremely high density.
There are various methods depending on the type of recording film and recording and reading methods. Among these, there are rewritable types of optical disks applied to the information processing field, and magneto-optical disks are originally rewritable types.

Figure 3 (a) and (b) show the ID recorded on the optical disc.
It explains data and information data, and it describes optical discs (
(or magneto-optical disk) 1 is provided with a large number of tracks 1a concentrically or spirally, and each track is equally divided into a plurality of sectors S, -S- with the same phase starting from an index (INDX). At the front of any sector Sn there is a ``Di'' for recording ID data such as a sector number and a control signal, followed by a data section for information data.

The recording of each data differs depending on the method, and in the case of rewritable optical discs, the reflectance changes when the part corresponding to the data is heated and rapidly cooled with a laser spot to change the phase state of the medium. The data is recorded. 1b indicates recorded data. Data reading is performed by detecting this change in reflectance. In order to rewrite, it is necessary to erase the previous data, and in erasing, a spot of appropriate intensity is used to return the phase state of the medium to its original state to enable rewriting (phase change method). It is. In the above, writing and erasing are performed on a track-by-track basis using a laser spot Sp having a short-peak intensity distribution as shown in FIG.

In the above, since the rewriting is performed on the information data, it is necessary to erase only this part and not erase the data in the ID part. For this purpose, during erasing, the spot is controlled by an appropriate method to dim or stop the light relative to the ID area.

FIGS. 4(a) and 4(b) show an example of the configuration of a control circuit for erasing, and to explain its operation, the spot Sp of the readout radar 2 is placed on the optical disc 1 rotating in the direction of arrow C. The track 1a to be erased is scanned by the microprocessor (M
PC) 7 to create a spot intensity control signal and a focus control signal. The spot intensity control signal is applied to the erasing head 3 via the power controller 5, and the spot SP for the data area is controlled to an intensity suitable for erasing. When the erasing of the track is completed, the microprocessor 7 moves the carriage mechanism 4 to the next track based on an index signal indicating the starting point of the track obtained by a separate detector, and the same erasing as above is performed.
Moving and erasing are repeated to erase information data on all tracks.

In magneto-optical disks, the ID data in the ID section is made by drilling bits, making it impossible to erase, and for the data section, the phenomenon of rotation of the plane of polarization of reflected light due to the magneto-optical effect is used. This is a method to do so. To erase information data, a method is used in which the magnetization direction is returned to its original direction by heating with a spot of appropriate intensity. In this case, the intensity of the erase spot does not change the pits in the ID portion and the data is not erased.

Therefore, the spot intensity is kept constant, the entire circumference of the track is scanned, and the spot is moved to the next track based on the index signal.

[Problem to be Solved] In the above-described erasing of the optical disk or magneto-optical disk, it is necessary to erase each track, so it takes a considerable amount of time to erase all the tracks. Writing and erasing are performed multiple times in disc drivers for practical use as well as in disc evaluation tests, but the disadvantage is that efficiency is low due to the long erasing time. Therefore, it is desirable to shorten the erasing time by improving the optical system of the erasing head. For this purpose, instead of erasing one track at a time, it is important to erase a large number of tracks at the same time.

This invention was made in order to eliminate the drawbacks of the conventional erasing method described above, and it is a method for collectively erasing a large number of tracks (track bundle) on a rewritable optical disk or magneto-optical disk. The object of the present invention is to provide an erasing method and an erasing optical system that can dramatically shorten erasing time.

[Means for Solving the Problems] The present invention is a method and an optical system for erasing tn information data recorded in the data portion of each sector set on each track of a rewritable optical disk or magneto-optical disk.

In the erasing method, the cross-sectional shape of the laser spot for erasing is an ellipse that has a long axis in the radial direction of the optical disk or magneto-optical disk and covers a plurality of tracks (track bundle). Delete the track east data section all at once. After erasing, the spot is moved in the radial direction of the disk by a distance corresponding to the long axis in response to an index signal indicating the starting point of the track, and batch erasing of the next and subsequent track bundles is performed one after another, thereby erasing all tracks. .

In the case of an optical disc, the reading head reads out the ID data of a sector of any one track of the track bundle, detects the start and end of the ID data, and switches the spot intensity based on the detection signal. To erase only information data without erasing ID data.

In the case of a magneto-optical disk, information data is erased by scanning the entire circumference of the track bundle while keeping the intensity of the elliptical spot constant.

Next, the erasing optical system uses a laser beam that uses a gas laser tube as a light source.
An elliptical spot is formed by focusing a multi-beam laser or a diffuse beam laser using a semiconductor laser element as a light source using a cylindrical lens or a prism-type ellipse shaper, respectively.

[Function] In the erasing method of the rewritable optical disc of the present invention having the above configuration, the cross-sectional shape of the erasing spot is an ellipse with the long axis in the radial direction of the disc, and the information data of five trough bundles are collectively erased. to delete. In the case of an optical disk, the start and end of the ID section are detected from the ID data obtained by the read head, and the spot intensity is controlled by the detection signal; the ID section is not erased, but the data section is erased. only is done. In the case of magneto-optical disks, the ID data is a non-erasable bit, so by scanning the entire circumference of the track with a spot of a certain intensity suitable for the information data, the information data of the trunk bundle can be collected all at once. will be deleted.

The erasing optical system uses a cylindrical lens or a prism-type ellipse shaper to erase the multi-beam from the gas laser tube or the diffused beam from the semiconductor laser element, respectively.
An elliptical spot is formed that covers the track bundle.

[Embodiment] FIGS. 1(a) and 1(b) show an erasing optical system in an embodiment of the erasing method and erasing optical system for a rewritable optical disc according to the present invention. Figure (a) shows the case where a multi-beam (multi-time type) gas laser tube 8 is used as the light source.
The intensity of laser beam B is greater than this! takes a substantially constant value in a certain range of radius r centered on the optical axis like a curve, and gradually attenuates outside the range. This beam is focused by a cylindrical lens 9 not in the direction of the radius R of the disk but in the direction of rotation θ of the disk to form an elliptical spot S.
form e. In addition, figure (b) shows the semiconductor laser element type 0.
When B is used as a light source, the beam B' from this is diffused over a considerable angular range and forms the intensity distribution of curve E. This is made into a parallel beam using an appropriate collimator lens LEA, and formed into a prism-type ellipse V! All by oval spora) S
Form into p. The long axis of the ellipse is used for erasing as the direction of the radius R of the disk, as described above.

In the above, the intensity of the spot decreases in inverse proportion to the cross-sectional area when the power of the light source is the same, so it goes without saying that in order to erase with an elliptical spot, a light source with a corresponding power is required. In addition, a light source whose power can be controlled as described above shall be selected.

In addition, in the formation of the above-mentioned elliptical spora) SP, the semiconductor laser element! Of course, it is possible to use the cylindrical lens 9 for O or the prism type ellipse shaper II for the gas laser tube 8.

FIG. 2 shows a circuit configuration diagram of an embodiment of an erasing device to which the rewritable optical disc erasing method and erasing optical system according to the present invention is applied. The above-mentioned FIG. 1(a).

The erasing optical system 12 shown in (b) is attached to the erasing head 3, and the long axis of the elliptical spot Se is made to coincide with the radial direction of the disk to be inspected. Spot Se is track bundle 1
Cover c all at once.

In the case of a rewritable optical disc, the above-mentioned FIG. 4(a).

(b), the read head 2, I
Based on the start and end signals of the ID section detected by the D detector 6, a spot intensity control signal is created in the microprocessor 7, passed through the power controller 5, and given to the erasing optical system +2 to control the spot intensity for the ID section. is reduced or stopped, and for the data portion, the strength is switched to the level required for erasing. When erasing of the track bundle 1c is completed, an index signal is input to the microprocessor 7, the carriage mechanism 4 is operated, and the erasing head 3 moves to the next track bundle to erase it. In the case of a magneto-optical disk, there is no need to detect the ID section, and a spot Se with a constant intensity is used.
The entire circumference of the track bundle is scanned, and the information data is erased all at once except for the ID section which cannot be erased. The spot Se moves to the next track bundle based on the index signal.

[Effects of the Invention] As is clear from the above explanation, the rewritable optical disc erasing method and erasing optical system according to the present invention have the following advantages:
By using a cross-sectional wand that covers multiple tracks as an erase spot, the information data to be rewritten is erased all at once, dramatically shortening the erasing time compared to the conventional erasing method for each track. Ru. During erasing, the I
D data is not erased, only the target information data is erased, and for magneto-optical disks, the spot intensity is kept constant and the entire circumference of the track is scanned so that only the information data is erased. There are many things that contribute greatly to the efficiency of evaluation tests for rewritable optical disks or magneto-optical disks.

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are block diagrams of an embodiment of the erasing optical system in the erasing system and erasing optical system for a rewritable optical disc according to the present invention, and FIG. 2 is an erasing system for a rewritable optical disc according to the present invention. 3(a), (b), and (C) are a data configuration diagram of a rewritable optical disk and an intensity distribution curve diagram of a laser spot for reading and erasing. , FIGS. 4(a) and 4(b) are block diagrams of conventional erasing circuits for rewritable optical discs. ■...Optical (magnetic) disk, 1a...Track, 1
b...Record data, 1c...Track bundle, 2.
...read head, 3...erase head, 4...
Carriage mechanism, 5...power controller 6...
-IDM output J, 7... microprocessor, 8...
・Gas laser tube, 9... Cylindrical lens, 10
... Semiconductor laser element, I (la ... collimator,
II... Prism type ellipse shaper, 12... Erasing optical system.

Claims (4)

[Claims] (1) When erasing information data recorded in the data portion of each sector set on each track of a rewritable optical disk or magneto-optical disk, the cross-sectional shape of the erasing laser spot is set on the optical disk or magneto-optical disk. As an ellipse having a long axis in the radial direction and covering a plurality of tracks (hereinafter simply referred to as a track bundle), the data portion of the track bundle covered by the spot is erased all at once, and the starting point of the track is An erasing method for a rewritable optical disk, characterized in that the spot is moved in the radial direction by a distance corresponding to the long axis in response to an index signal indicating the above, and sequential erasing of subsequent track bundles is performed at once. (2) In the optical disc, the reading head reads ID data recorded in a sector of any one track of the track bundle, and the read ID data is
Detecting the start and end of data, switching and controlling the intensity of the spot using the detection signal, and erasing only the information data without erasing the ID data.
The erasing method for a rewritable optical disc according to claim 1. (3) A method for erasing a rewritable optical disk according to claim 1, wherein, in the magneto-optical disk, the entire circumference of the bundle of tracks is scanned with the intensity of the elliptical spot constant, and information data on the track is erased. . (4) A multi-beam laser using a gas laser tube as a light source or a diffuse beam laser using a semiconductor laser element as a light source is focused by a cylindrical lens or a prism-type ellipse shaper, respectively, to the elliptical spot that covers the track bundle. What is claimed is: 1. An erasing optical system for a rewritable optical disk, characterized by forming a rewritable optical disk.