JPH06282844A - Optical recorder - Google Patents

Abstract

PURPOSE:To achieve a narrowing of a track by suppressing a crosstalk with a sufficient S/N ratio of a signal by erasing a specified part of a mark to record information on an optical recording medium with the irradiation of another light beam after the formation of the mark. CONSTITUTION:A physical change. herein a change from an amorphous to crystalline state, is caused on a recording medium and a focusing spot 21 is controlled to be position so that the center 24a of an area to be erased with the irradiation of a second beam is located at a position in the center between one track and an adjacent track, for example, at the central part between 23a and 23b. Here, a quantity of light of the spot 21 is always suppressed to a level at which an optical recording medium changes to an amorphous to crystalline sate, namely, at which a mark recorded is erased. If so, the state is always crystalline (shaded part) after the passage of the spot 21. Thus, after the formation of the mark 22 by a first beam, the mark 22 is erased partly by a second beam to form a substantial information mark 22a. In the amorphous area, reflection factor and refractive index are different from the crystalline area thereby enabling the reading of a record from this difference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording method for recording information by irradiating an optical recording medium with a beam emitted from a light source, and more particularly to an optical recording method for recording information at a high track density. The present invention relates to an optical recording device that achieves

[0002]

2. Description of the Related Art A high-density optical recording method with a narrowed track pitch is disclosed in Japanese Patent Laid-Open No. 183024/1993.
An optical recording method for recording information on a phase change medium disclosed in JP-A-3-183024 will be described with reference to the drawings.

Here, an area given a physical change based on the information to be recorded is used as a mark, and a row in which a plurality of marks are arranged linearly or arcuately is used as a track (hereinafter, this expression will be used). In FIG. 13, a shaded portion 121 is an amorphous portion, 122 is a mark (here, a region given a change from crystalline to amorphous based on the information to be recorded), 12
Reference numeral 3 is a crystal region. The optical recording medium whose entire surface is in a crystalline state is irradiated with a beam to form a uniform recording state (amorphous portion 121) in the track direction in advance, and then the amorphous portion 121.
A light beam is irradiated to the crystal part in between, and the mark 122 is formed based on the information. When such recording is performed, a uniform recording state is provided next to the mark, so that a signal with small crosstalk can be obtained during reading, and information can be accurately read.

[0004]

However, in the above-mentioned recording method, since the recording area 121 adjacent to the information-recorded area 122 is the uniform recording area 121, the signal contrast is lowered and the S / N ratio of the signal is reduced. Will not be enough. Further, there is a problem that a region of the crystalline material 123 is formed in the peripheral portion of the region 122 in which the information is recorded due to the thermal effect of the light beam during recording, which causes crosstalk and hinders narrowing of the track.

The present invention takes into consideration the above problems of the conventional optical recording method, and does not reduce the signal contrast, so that the signal S /
The present invention provides an optical recording apparatus that achieves an optical recording method in which N is sufficiently good, and the occurrence of crosstalk is suppressed to narrow the track.

[0006]

In order to solve the above-mentioned problems, the optical recording apparatus of the present invention controls the light quantity of the light beam emitted from the light source according to the information to be recorded when the number of the light source is one. A light quantity control device, an optical recording medium in which wobbling pits or guide grooves for obtaining a track error signal are formed in advance, a condensing optical system for guiding a light beam emitted from the light source to the optical recording medium, A light separating means for separating a light beam emitted from a light source, a focus error detecting means for detecting a focus error, a photodetector for converting the reflected light from the optical recording medium into an electric signal, and the photodetector A focus control circuit and a tracking control circuit for outputting a control signal based on a focus error signal and a track error signal generated from the obtained electric signal, and the focus and track. And a driving device for irradiating a light beam emitted from the light source based on a signal output from the grayed control circuit in place of the optical recording medium. In addition, it has one of the following:

(A) A polarity inverting circuit that inverts or non-inverts the polarity of the track error signal or the control signal. (B) Offset circuit that gives an offset to the signal output from the tracking control circuit. In the recording device, information is recorded by forming a mark by changing the state of a predetermined area on the optical recording medium using a light beam emitted from the light source, and then on a straight line or an arc of the mark. The mark row is used as a track, and the light beam emitted from the light source irradiates a position different from the track by using the polarity reversing circuit or the offset circuit to erase a predetermined part of the mark.

Further, when there are two light sources, in order to solve the above problem, the optical recording apparatus of the present invention controls the light quantity of the light beam emitted from the first light source according to the information to be recorded. A light amount control device, a second light amount control device for controlling the light amount of the second light source so as to erase information, and an optical recording medium in which wobbling pits or guide grooves for obtaining a track error signal are formed in advance. A condensing optical system for guiding the two light beams emitted from the two light sources to the optical recording medium, a light separation means for separating the light beams emitted from the two light sources, and a focus for detecting a focus error. Error detection means, a photodetector for converting the reflected light from the optical recording medium into an electric signal, and a control signal based on a focus error signal and a track error signal generated from the electric signal obtained from the photodetector. A focus control circuit and a tracking control circuit for outputting, to operate on the basis of a signal output from the focusing and tracking control circuit, the light beam driving the converging optical system that allowed to condensing, the 2
A drive device for irradiating a predetermined position of the optical recording medium with light beams emitted from two light sources, and using a light beam emitted from the first light source, a predetermined region on the optical recording medium. The state is changed to form a mark, and a predetermined part of the mark is erased by the light beam emitted from the second light source.

Further, in an optical recording apparatus having a phase grating which divides the light beam into two in the vicinity of the second light source of the above-mentioned optical recording apparatus, the light beam emitted from the first light source is used to emit the light. A mark is formed by changing the state of a predetermined area on the recording medium, and a predetermined part of the mark is erased by a light beam emitted from the second light source.

[0010]

According to the present invention, the width of the mark recorded on the optical recording medium can be narrowed by erasing a predetermined part of the mark formed by the above structure.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing its embodiments.

FIG. 1 shows an optical recording apparatus for realizing the optical recording method of the first embodiment according to the present invention. In FIG. 1, 1 is a light source, 2 is a light quantity control device, 3 is a collimator lens, 4 is an objective lens, 5 is an optical recording medium, 6 is a polarization beam splitter, 7 is a λ / 4 plate, 8 is a detection lens, and 9 is a detection lens.
Is an optical element, 10 is a photodetector, 11 is an objective lens driving device, 12 is a divergent beam emitted from the light source 1, 13 is a focus control circuit, 14 is a tracking control circuit, and 15
Is a polarity inversion circuit. Here, a phase change medium is used as the optical recording medium 5, and a guide groove is formed in advance. Further, in this embodiment, the condensing optical system is composed of the collimator lens 3 and the objective lens 4, and the light splitting means is composed of the polarization beam splitter 6 and the λ / 4 plate 7.
The focus error detection means is composed of a detection lens 8 and an optical element 9.

First, the divergent beam 12 of linearly polarized light emitted from the light source 1 is collimated by the collimator lens 3, passes through the polarization beam splitter 6, and then passes through the λ / 4 plate 7 to become circularly polarized light. , Is focused on the optical recording medium 5 by the objective lens 4. The reflected light from the optical recording medium 5 is transmitted through the objective lens 4 and again through the λ / 4 plate 7 to become linearly polarized light having a 90 ° polarization direction different from that of the outward path, reflected by the polarization beam splitter 6, and detected. The light is collected by the lens 8 and received by the photodetector 10. The photodetector 10 converts the reflected light from the optical recording medium 5 into an electric signal, and obtains a focus error signal and a track error signal by a method similar to the conventional one. For example, if the optical element 9 is a cylindrical lens, a focus error signal can be obtained by the astigmatism method and a track error signal can be obtained by the push-pull method. Based on these signals, the focus control circuit 13 and the tracking control circuit 14 output signals for controlling the position of the objective lens 4. The tracking control signal is supplied to the polarity reversing circuit 15
However, the polarity is not inverted here and is transmitted to the objective lens driving device 11, and the objective lens driving device 11 operates in response to this signal and the beam 12 emitted from the light source 1 is input.
Controls the position of the objective lens 4 so that the laser beam accurately illuminates the track. The light quantity of the beam 12 emitted from the light source 1 is controlled by the light quantity control device 2 based on the information to be recorded. The beam 12 whose light amount is controlled is focused on the optical recording medium 5 and information is recorded through the process similar to the above process. After recording all the information, the control signals output from the focus control circuit 13 and the tracking control circuit 14 through the same process as described above are the objective lens drive device 11.
The polarity of the signal output from the tracking control circuit 14 is inverted by the polarity reversing circuit 15 and then transmitted to the objective lens driving device 11. In this way, the position of the objective lens 4 is controlled so that the beam 12 emitted from the light source 1 irradiates adjacent tracks and the center of the tracks. At this time, the light amount of the beam 12 emitted from the light source 1 is controlled by the light amount control device 2 so that the mark can be erased, and an operation of erasing a part of the recording track is performed.

Next, the optical recording method of this embodiment will be described in more detail with reference to FIG. Here, the beam used for recording is called the first beam, and the beam used for erasing is called the second beam.

FIG. 2 is a schematic view showing the relationship between the marks on the track recorded on the optical recording medium 5 and the first and second beams, and a sectional view of the optical recording medium 5. In FIG. 2, reference numeral 20 denotes a focused spot of the first beam on the optical recording medium 5
Is the focused spot of the second beam on the optical recording medium 5,
Reference numeral 22 denotes an amorphous portion (mark) of the optical recording medium, dashed-dotted lines 23a, 23b and 23c indicate the center of the track, and dashed-dotted lines 24a and 24b indicate the center of the area to be erased by irradiating the second beam. Is a recording film, 26 is a substrate, and 27 is a guide groove.

Now, the intensity of the first beam emitted from the light source 1 is controlled so that the region on the optical recording medium 5 where the focused spot 20 hits reaches the crystallization temperature and the melting point. The optical recording medium 5 after passing the light spot 20 is in a crystalline state or an amorphous state according to the recorded information. The elliptical or circular stippled area is the focused spot 20
The amorphous portion 22 is made amorphous by the above. In the present embodiment, it is assumed that the entire recording surface of the optical recording medium 5 is initially in a crystalline state, and "1" or "0".
The optical recording medium 5 is irradiated with the first beam modulated at the level corresponding to the binary value of, and as a result, the region corresponding to “0” remains in the crystalline state and the region corresponding to “1” remains. The mark changes to an amorphous state.

Next, after all the information is recorded by giving a physical change, here, a change from crystalline to amorphous, on the optical recording medium 5, the adjacent tracks and the center of the tracks,
For example, at the center positions of the track centers 23a and 23b, the center 2 of the area to be erased by irradiating the second beam is used.
The position of the focused spot 21 is controlled so that 4a comes. At this time, if the light amount of the focused spot 21 is controlled to a level at which the optical recording medium 5 constantly changes from an amorphous state to a crystalline state, that is, a level at which a recorded mark is erased, the focused spot 21 passes. After that, it always becomes a crystalline state. This portion is indicated by the shaded portion. The portion of the second beam after passing through the focused spot 21 becomes a crystalline state, which is equivalent to an unrecorded state. In this way, after the mark 22 is formed by the first beam, the mark 22 is formed by the second beam.
By partially erasing the information mark 2
2a is formed. The region in the amorphous state is different from the region in which the reflectance and the refractive index are in the crystalline state, and it is possible to record and read information by utilizing this difference.

As described above, according to this embodiment, after the information is recorded on the track by the first beam, the polarity reversing circuit is used to irradiate the second beam between the adjacent tracks, and Since the information mark having a narrow recording width can be formed by erasing a part of the area recorded by one beam, crosstalk is small at the time of reading, and S
A signal having a good / N ratio can be obtained, information can be accurately read, and the density can be increased by narrowing the track.
Further, since the information mark and the track on which the adjacent information mark is recorded are equivalent to the unrecorded state, the signal contrast is not lowered. Further, in the present embodiment, the second beam is irradiated to the center between the tracks, so that the two adjacent beams are adjacent at a time.
Part of the amorphous portion 22 of one track can be erased at the same time, and the erase time may be short.

FIG. 3 is a schematic view showing an optical recording method of the second embodiment according to the present invention and a sectional view of the optical recording medium 5.

The optical recording apparatus used in the second embodiment is similar to that shown in FIG. 1, and the position control of the objective lens 4 is as described in the first embodiment. here,
The beam used for recording is called the first beam, and the beam used for erasing is called the second beam.

In FIG. 3, the stippled portion 30 indicates the mark (width d1) made by the first beam and is indicated by alternate long and short dash lines 31a, 31b, 3
1c is the center of the track, the shaded portion of the solid line is the region (width d2, hereinafter referred to as the second beam region) where the second beam is irradiated to return to the crystalline state, and the dashed lines 32a and 32b are the second beam region. In the center, 33 is a recording film, 34 is a substrate,
Reference numeral 5 denotes a guide groove, which has a track pitch (for example, 31a
And 31b) is Tp, and the center of the track and the second
The distance from the center of the beam area is x, and the mark 30 and the second
The width of the overlapping portion of the beam region is a, and the width of the substantial information mark 30a recorded by the method of this embodiment is w. Here, in the present embodiment, the width d2 of the second beam region is
The second beam is obtained by defocusing and condensing the beam from the light source that emits the first beam onto the optical recording medium, and is always larger than d1 and smaller than the track pitch Tp. The irradiation position of the second beam is x
= Tp / 2.

Here, the light amount of the first beam is controlled so that the optical recording medium 5 has the crystallization temperature and the melting point of the optical recording medium 5 according to the information to be recorded, and the light amount of the first beam is controlled. The recording medium 5 is in a crystalline state or an amorphous state depending on the recorded information. In this embodiment, the optical recording medium 5
It is assumed that the entire recording surface is initially in a crystalline state, and the optical recording medium 5 is irradiated with a first beam modulated at a level corresponding to a binary value of "1" or "0", As a result, the region corresponding to “0” remains in the crystalline state,
The area corresponding to 1 ″ changes to an amorphous state as a mark. After all the information is recorded by giving a physical change on the optical recording medium, here, a change from crystalline to amorphous, they are adjacent to each other. Center of track, eg center of track 3
The center of the second beam area 3 at the central position of 1a and 31b
The irradiation position of the second beam is controlled so that 2a comes.
At this time, if the light amount of the second beam is controlled to a level at which the optical recording medium 5 constantly changes from the amorphous state to the crystalline state, the area irradiated with the second beam is always in the crystalline state. This portion is indicated by the shaded portion. The area after the passage of the second beam becomes a crystalline state, which is equivalent to the unrecorded state. In this way, the mark 30 is formed by the first beam.
Then, the mark 30 is partially erased by the second beam to form a substantial information mark 30a. The region in the amorphous state is different from the region in which the reflectance and the refractive index are in the crystalline state, and it is possible to record and read information by utilizing this difference.

As described above, according to the present embodiment, after the information is recorded with the first beam, the second beam is focused on the optical recording medium with a width larger than the width of the area recorded with the first beam. By using the polarity reversing circuit, the beam is irradiated to the center between adjacent tracks to erase a part of the region recorded by the first beam, thereby recording a substantial information mark with an arbitrary narrow width. Therefore, it is possible to obtain a signal with a good S / N ratio with less crosstalk during reading, to accurately read information, and to achieve high density by narrowing the track. Further, since the information mark and the track on which the adjacent information mark is recorded are equivalent to the unrecorded state, the signal contrast is not lowered. Further, in this embodiment, since the width of the area irradiated with the second beam is increased by defocusing, even if the track pitch is comparatively large, the main recording can be efficiently performed with one light source.

FIG. 4 shows an optical recording apparatus for realizing the optical recording method of the third embodiment according to the present invention. The same components as those in FIG. 1 are designated by the same reference numerals. In FIG. 4, reference numeral 41 is an offset circuit. Here, the light source 1
The operation of irradiating a predetermined place on the optical recording medium 5 with the beam 12 emitted from the device to form a mark and record information is the same as the operation described in the first embodiment. After recording all the information, the offset circuit 41 offsets the signal output from the tracking control circuit 14 and transmits the tracking control signal to the objective lens driving device 11, so that the beam 12 emitted from the light source 1 is tracked. The position of the objective lens 4 is controlled so as to irradiate the position slightly displaced. At this time, the light amount of the beam 12 emitted from the light source 1 is controlled by the light amount control device 2 so that the mark can be erased, and an operation of erasing a part of the recording track is performed.

Next, the optical recording method of this embodiment will be described with reference to FIG.
Will be described in more detail with reference to. Here, the beam used for recording is called the first beam, and the beam used for erasing is called the second beam.

FIG. 5 is a schematic diagram showing a sectional view of an optical recording method and an optical recording medium 5 according to a third embodiment of the present invention.
In FIG. 5, the stippled portion 50 is the mark (width d1) made by the first beam, the dashed-dotted lines 51a, 51b, 51c are the center of the track, and the solid shaded portion 52 and the dotted shaded portion 53 are the second. A region (width d2, hereinafter, which is irradiated with a beam (here, the beam is irradiated twice) and returns to a crystalline state,
(Referred to as the second beam region), the dashed-dotted lines 52a and 52b indicate the center of the second beam region 52 and the dashed-dotted lines 53a and 53b.
Indicates the center of the other second beam area 53, 54 indicates the recording film, 55 indicates the substrate, and 56 indicates the guide groove. Also, the track pitch (for example, the distance between 51a and 51b)
Is Tp, the distance between the center of the track and the center of the second beam region is x, and the mark 50 and one of the second beam regions 5 are
2 is a1, the width of the overlapping portion between the mark 50 and the second beam region 53 on the other side is a2, and the substantial information mark 50a recorded by the method of this embodiment is
Be w.

Here, the light amount of the first beam is controlled so that the optical recording medium 5 has the crystallization temperature and the melting point of the optical recording medium 5 according to the information to be recorded, and the light amount is controlled by the first beam. The recording medium 5 is in a crystalline state or an amorphous state depending on the recorded information. In this embodiment, the optical recording medium 5
It is assumed that the entire recording surface is initially in a crystalline state, and the optical recording medium 5 is irradiated with a first beam modulated at a level corresponding to a binary value of "1" or "0", As a result, the region corresponding to “0” remains in the crystalline state,
The region corresponding to 1 ″ changes to an amorphous state as a mark. After all information is recorded by giving a physical change on the optical recording medium 5, here, a change from crystalline to amorphous, the track is changed. The second beam is irradiated by controlling the position so that the distance x between the center of the second beam area and the center of the second beam area is not Tp / 2 (intermediate position between the tracks). During this period, the second beam will be emitted by changing the position twice.
The light amount of the second beam is always controlled to a level at which the optical recording medium 5 changes to a crystalline state. For example, consider between the center 51a and 51b of the truck. First, the position is controlled so that a position away from the center 51a of the track by x is the center of one of the second beam regions, and the second beam is emitted. The region 52 irradiated with the second beam becomes a crystalline state, which is equivalent to the unrecorded state, so that the mark 50
Is reduced by the width a1. Then in the middle 51 of the truck
The position is controlled so that the position away from b by x is the center of the other second beam region, and the second beam is irradiated once again. The region 53 irradiated with the second beam is also in the crystalline state, which is also equivalent to the unrecorded state, so that the mark 50 is reduced by the width a2. As described above, after the mark 50 is formed by the first beam, the mark 5 is formed by the second beam.
By partially erasing 0 twice, the substantial information mark becomes 50a. The region in the amorphous state is different from the region in which the reflectance and the refractive index are in the crystalline state, and it is possible to record and read information by utilizing this difference.

As described above, according to this embodiment, after the information is recorded by the first beam, the tracking offset circuit gives an offset to the track error signal so that the second beam is moved twice between the adjacent tracks. By irradiating at different positions and erasing a part of the area recorded by the first beam, it is possible to record a substantial information mark with an arbitrary narrow width, so that there is little crosstalk during reading. , A signal having a good S / N ratio can be obtained, information can be accurately read, and the density can be increased by narrowing the track. Further, since the information mark and the track on which the adjacent information mark is recorded are equivalent to the unrecorded state, the signal contrast is not lowered.

FIG. 6 is a block diagram of an optical recording apparatus for realizing the optical recording method of the fourth embodiment according to the present invention.
The same components as those in FIG. 1 are designated by the same reference numerals. In FIG. 6, 60 and 61 are polarization beam splitters, 62 and 63 are detection lenses, 64 and 65 are photodetectors,
Reference numeral 66 is an electromagnetic coil, 67 is a controller for controlling the current flowing through the electromagnetic coil, and 68 is a Wollaston prism.

The operation of the optical recording device configured as described above will be described. Here, a magneto-optical medium is used as the optical recording medium 5, and a guide groove is formed in advance. Also,
In this embodiment, the condensing optical system is composed of the collimator lens 3 and the objective lens 4, the light separating means is composed of the polarization beam splitters 60 and 61, and the focus error detecting means is the detecting lens 62 and optical. It is composed of the element 9. . First, the linearly polarized divergent beam 12 emitted from the light source 1 is collimated by the collimator lens 3 and transmitted through the polarization beam splitter 60. In the polarization beam splitter 60, about 70 of the beam emitted from the light source 1 is
% Of light is transmitted. The beam 12 transmitted through the polarization beam splitter 60 is condensed on the optical recording medium 5 by the objective lens 4. At this time, the information is recorded by controlling the direction of the current flowing through the electromagnetic coil 66 by the current control device 67 according to the information to be recorded.

Next, the reflected light from the optical recording medium 5 passes through the objective lens 4 and is reflected by the polarization beam splitter 60. At this time, the polarization beam splitter 60 reflects about 30% of the light having the same polarization as the beam emitted from the light source,
The polarized light orthogonal to the beam emitted from the light source is 100
% It is designed to reflect. The light reflected by the polarization beam splitter 60 is reflected by the polarization beam splitter 61.
Causes a part to be reflected and the rest to be transmitted. At this time, the light reflected by the polarization beam splitter 61 is converted into a focus error signal and a track error signal by the detection lens 62, the optical element 9, and the photodetector 64 by using the same method as described in the first embodiment. Then, based on these signals, the focus control circuit 13 and the tracking control circuit 14 output signals for controlling the position of the objective lens 4. The tracking control signal is input to the polarity reversing circuit 15, but the polarity is not inverted here and is transmitted to the objective lens driving device 11. The objective lens driving device 11 operates according to this signal and is emitted from the light source 1. The position of the objective lens 4 is controlled so that the beam 12 accurately illuminates the track. After recording all the information, the control signal output from the focus control circuit 13 and the tracking control circuit 14 through the same process as above is transmitted to the objective lens driving device 11, but the signal output from the tracking control circuit 14 Is transmitted to the objective lens driving device 11 after the polarity is inverted by the polarity inversion circuit 15. In this way
The position of the objective lens 4 is controlled so that the beam 12 emitted from the light source 1 irradiates adjacent tracks and the center of the tracks. At this time, the current control device 67 makes the direction of the current flowing through the electromagnetic coil 66 constant and erases a part of the recorded track. For information reproduction, the light transmitted through the polarization beam splitter 61 is converted into the Wollaston prism 68.
After the light is separated into two according to the polarization direction, the light is condensed by the detection lens 63, received by the photodetector 65, and a reproduction signal is obtained by the differential detection method.

Next, the fifth embodiment will be described in more detail with reference to FIG. Here, the beam involved in recording information is referred to as a first beam, and the beam involved in erasing information is referred to as a second beam.

FIG. 7 is a schematic view showing the relationship between the marks on the track recorded on the optical recording medium 5 and the first and second beams, and a sectional view of the optical recording medium 5. In FIG. 7, reference numeral 70 designates a focused spot of the first beam on the optical recording medium 5.
Reference numeral 1 denotes the focused spot of the second beam on the optical recording medium 5, and the stippled portion 72 changes the magnetization direction of the optical recording medium 5 to a state different from the unrecorded area by the first beam spot 70. Area (mark) is indicated by the alternate long and short dash lines 73a, 73
b and 73c are the center of the track, the shaded area is the area that is erased by irradiation with the second beam (hereinafter referred to as the second beam area), and the chain lines 74a and 74b are the center of the second beam area. 75 is a recording film, 76 is a substrate, and 77 is a guide groove. Here, the light quantity of the beam forming the focused spot 70 of the first beam is controlled by the light quantity control device 2 so that the area of the focused spot 70 on the optical recording medium 5 is always at the Curie temperature. Has been done,
The current control device 67 changes the direction of the current flowing through the electromagnetic coil 66 according to the information. In this way, information is recorded by changing the magnetization direction of the optical recording medium 5. The stippled portion 72 is a portion whose magnetization direction is, for example, vertically upward. In the present embodiment, it is assumed that the entire recording surface of the optical recording medium 5 is initially downward in the magnetization direction, and "1" or "
In order to create a magnetization direction corresponding to a binary value of 0 ″, the electromagnetic coil 6 is applied while the first beam is applied to the optical recording medium 5.
Change the direction of the current flowing to 6. As a result, the magnetization direction of the region corresponding to "0" remains downward, and the magnetization direction of the region corresponding to "1" changes upward as a mark.
After all the information is recorded by changing the magnetization direction of the optical recording medium 5 in this way, the center of the second beam area 74a is formed at the center of the track and the tracks adjacent thereto, for example, the centers of the track centers 73a and 73b. The position of the focused spot 71 of the second beam is controlled so that At this time, the light quantity of the focused spot 71 of the second beam is controlled by the light quantity control device 2 to a level at which the optical recording medium is always at the Curie temperature. At this time, the direction of the current flowing through the electromagnetic coil 66 is kept constant, and the magnetization of the region where the focused spot 71 of the second beam hits is, for example, always vertically downward. As a result, the magnetization of the portion after passing the focused spot 71 of the second beam is always downward. This part is indicated by the shaded part. In this way, a portion 72a having a magnetization direction that is narrower than the magnetization direction that has been formed by the conventional method is formed, and this serves as a substantial information mark. Information can be read from this portion by utilizing a magneto-optical phenomenon called the Kerr effect.

As described above, according to this embodiment, even when the magneto-optical medium is used as the optical recording medium 5, the track is recorded by using the first beam and then the second beam is used for recording. Since it is possible to form an information mark having a narrow recording width by erasing a part of the region that is formed, a signal with a good S / N ratio can be obtained with little crosstalk during reading.
Information can be accurately read out, and the density can be increased by narrowing the track. Further, since the information mark and the track on which the adjacent information mark is recorded are equivalent to the unrecorded state, the signal contrast is not lowered.

Needless to say, the same effect can be obtained by using the magneto-optical medium as the optical recording medium and carrying out the recording method described in the second and third embodiments. In addition, in each of the above-described examples, an example in which a phase change medium exhibiting a change in refractive index or reflectance and a magneto-optical medium exhibiting a change in polarization direction are used as an optical recording medium is shown, but the present invention is not limited thereto. It goes without saying that narrow marks can be formed on the optical recording medium for recording by utilizing the transmittance and other physical changes, by using the optical recording apparatus of the present invention.

FIG. 8 shows an optical recording apparatus for realizing the optical recording method of the fifth embodiment according to the present invention. The same components as those in FIG. 1 are designated by the same reference numerals. In FIG. 8, 81 is a first light source, 82 is a second light source, 83 is a first light amount control device, 84 is a second light amount control device, 8
Reference numerals 5 and 86 are divergent beams emitted from the first light source 81 and the second light source 82, respectively.

First, the linearly polarized divergent beam 85 emitted from the first light source 81 is the same as that described in the first embodiment, and the beam 85 emitted from the first light source 81 travels on the track. Accurately irradiate. The light amount of the beam 85 emitted from the first light source 81 is controlled based on the information recorded by the first light amount control device 83, and the information is recorded by converging the beam 85 on the optical recording medium 5. It

The beam 86 emitted from the second light source 82 is also focused on the optical recording medium 5 through the same process as the beam 85 emitted from the first light source 81. here,
The light amount of the beam 86 emitted from the second light source 82 is always controlled by the second light amount control device 84 to a light amount capable of erasing the mark. With such a configuration, the positional relationship between the focused spots of the beams 85 and 86 emitted from the first light source 81 and the second light source 82 on the optical recording medium 5 can be set as shown in FIG. . In FIG. 9, 90 is a focused spot of the beam 85, 91 is a focused spot of the beam 86, and the center of the focused spot 90 coincides with the track center, but the center of the focused spot 91 is deviated from the track center by α. It will be in the place. Therefore, a mark is formed in the area where the focused spot 90 hits in accordance with the information, and the focused spot 91 immediately corresponds to a part of the mark. Therefore, when the mark is formed, a part of the mark is immediately erased, Substantially narrow information marks are formed.

As described above, according to the present embodiment, since two light sources are used, one light source records information, and the other light source erases information. Therefore, a substantial information mark is recorded with a narrow width. Therefore, at the time of reading, a crosstalk is small, a signal having a good S / N ratio can be obtained, information can be read accurately, and the density can be increased by narrowing the track. Further, since the information mark and the track on which the adjacent information mark is recorded are equivalent to the unrecorded state, the signal contrast is not lowered. Further, by changing the arrangement of the light source used for erasing, the position of the focused spot of the beam used for erasing can be arbitrarily changed, that is, from the track center of the center of the focused spot 91 of the beam used for erasing. Since the shift amount α can be freely changed, the width of the substantially formed information mark can be arbitrarily set. Furthermore, since recording and erasing of information are performed almost at the same time, the time required for recording may be shorter than that in any of the above embodiments.

FIG. 10 shows an optical recording apparatus for realizing the optical recording method of the sixth embodiment according to the present invention. In addition,
The same components as those in FIG. 1 are designated by the same reference numerals. Figure 1
At 0, 101 is a first light source, 102 is a second light source, 103 is a first light amount control device, 104 is a second light amount control device, and 105 and 106 are the first light source 10 respectively.
1, divergent beams emitted from the second light source 102, 10
Reference numeral 7 is a phase grating which divides the beam into two.

First, the linearly polarized divergent beam 105 emitted from the first light source 101 is the same as the beam 1 emitted from the first light source 101 in the same manner as described in the first embodiment.
05 illuminates the track accurately. First light source 101
The light amount of the beam 105 emitted from the optical disc is controlled by the first light amount control device 103 based on the information recorded, and the information is recorded by converging the beam 105 on the optical recording medium 5.

The linearly polarized divergent beam 106 emitted from the second light source 102 first passes through the phase grating 107. Here, the phase grating 107 has a shape as shown in FIG. 11A, and the phase of the beam 106 passing through the portion a of the phase grating 107 and the phase of the beam 106 passing through the portion b of the phase grating 107 are shifted by just π. Become. That is, the phase grating 107 is shaped so that an optical path difference of half the wavelength is optically generated between the beam passing through the portion a of the phase grating 107 and the beam passing through the portion b of the phase grating 107. The beam transmitted through the phase grating 107 is diffracted, and when condensed, forms a beam spot of ± first-order light at a position symmetrical with respect to the optical axis, but passes through the zero-order light passing through the a part and the b part. Since the phase of the 0th-order light is deviated by π, the 0th-order light that has passed through the portion a and the 0th-order light that has passed through the portion b are canceled out, and a focused spot of the 0th-order light is not formed. That is, when the beam transmitted through the phase grating 107 is focused, it forms two focused spots. If the shape of the phase grating 107 is as shown in FIG.
As in the case of 1, the transmitted beam can be divided into two, and the positions of the focused spots when focused can be separated from the phase grating shown in FIG. 11a. In this way, the position of the focused spot of the beam divided into two is determined by the phase grating 107.
It can be moved closer or farther by changing the lattice period of. Beam 106 transmitted through phase grating 107
Is condensed on the optical recording medium through the same process as described above. Here, the light amount of the beam 106 emitted from the second light source 102 is controlled by the second light amount control device 104 to a light amount that can erase the mark. With such a configuration, the positional relationship between the focused spots of the beams 105 and 106 emitted from the first light source 101 and the second light source 102 on the optical recording medium 5 can be set as shown in FIG. . In FIG. 13, 110 is a focused spot of the beam 105 and 111 is a focused spot of the beam 106. The center of the focused spot 110 coincides with the track center, but the center of the focused spot 111 is deviated from the track center by α. It will be in the place. Therefore, a mark is formed in the area where the focused spot 110 hits in accordance with the information, and since the focused spot 111 corresponds to a part of the mark immediately, a part of the mark is immediately erased when the mark is formed, Substantially narrow information marks are formed.

As described above, according to the present embodiment, two light sources are used, information is recorded by the first light source, and information is erased by the second light source. Since the data can be recorded, a crosstalk is small at the time of reading, a signal having a good S / N ratio can be obtained, information can be accurately read, and the density can be increased by narrowing the track. Further, since the information mark and the track on which the adjacent information mark is recorded are equivalent to the unrecorded state, the signal contrast is not lowered. Further, by changing the grating period of the phase grating 107 used, the position of the focused spot of the beam used for erasing can be arbitrarily changed, that is, the focused spot 111 of the beam used for erasing.
Since the shift amount α of the center of the from the track center can be freely changed, the width of the substantial information mark can be arbitrarily set. Furthermore, since recording and erasing of information are performed almost at the same time, the time required for recording may be shorter than that in any of the above embodiments.

In the third, fourth, fifth and sixth embodiments, the beam spot used for erasing is set to be equal to the beam spot diameter used for recording. The condensed light spot diameter may be different from the condensed light spot diameter used for recording, which does not limit the present invention.

In each of the above embodiments, the astigmatism method is used as the method for obtaining the focus error signal.
Not limited to this, a knife edge method or another method may be used, and the push-pull method is used as a method for obtaining a track error signal. However, the method is not limited to this. For example, a three-beam method or another method of obtaining a track error signal by using three beams may be used. Further, although the optical recording medium in which the guide groove is formed in advance is used, an optical recording medium in which wobbling pits are formed in advance may of course be used and does not pose any problem to the present invention.

[0046]

As is apparent from the above description, according to the present invention, after the mark is formed, the second light beam is irradiated to erase a predetermined part of the mark and record the information on the optical recording medium. Therefore, there are advantages that the signal contrast does not decrease, the S / N of the signal is sufficiently good, and the occurrence of crosstalk can be suppressed to narrow the track.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an optical recording apparatus for realizing an optical recording method according to a first embodiment of the present invention.

FIG. 2 is a schematic view showing a recording method in the first embodiment and a sectional view of an optical recording medium 5.

FIG. 3 is a schematic view showing a recording method in the second embodiment and a sectional view of an optical recording medium 5.

FIG. 4 is a configuration diagram of an optical recording device for realizing the optical recording method of the third embodiment.

FIG. 5 is a schematic view showing a recording method in the embodiment and a sectional view of an optical recording medium 5.

FIG. 6 is a configuration diagram of an optical recording device for realizing the optical recording method of the fourth embodiment.

FIG. 7 is a schematic view showing a recording method in the embodiment and a sectional view of an optical recording medium 5.

FIG. 8 is a configuration diagram of an optical recording device for realizing the optical recording method of the fifth embodiment.

FIG. 9 is a diagram showing the arrangement of focused spots on the optical recording medium 5 of the example.

FIG. 10 is a configuration diagram of an optical recording device for realizing the optical recording method of the sixth embodiment.

11A is a diagram showing the shape of the grating film 107, and FIG. 11B is a diagram showing the shape of the grating film 107.

FIG. 12 is a diagram showing the arrangement of focused spots on the optical recording medium 5 of the same Example.

FIG. 13 is a schematic diagram showing a conventional optical recording method.

[Explanation of symbols]

 1 light source 2 light quantity control device 3 collimator lens 4 objective lens 5 optical recording medium 6 deflection beam splitter 7 λ / 4 plate 8 detection lens 9 optical element 10 photodetector 11 objective lens drive device 12 divergent light emitted from the light source 1 13 focus control circuit 14 tracking control circuit 15 polarity reversing circuit

Claims (8)

[Claims] 1. A light source, a light amount control device for controlling the light amount of a light beam emitted from the light source according to information to be recorded, and a wobbling pit or a guide groove for obtaining a track error signal are formed in advance. A focusing optical system that guides a light beam emitted from the light source to the optical recording medium to the optical recording medium, a light separating unit that separates the light beam emitted from the light source, and a focus error detecting unit that detects a focus error. A photodetector for converting the reflected light from the optical recording medium into an electric signal; and a focus control for outputting a control signal based on a focus error signal and a track error signal generated from the electric signal obtained from the photodetector. Circuit and tracking control circuit, a polarity inversion circuit that inverts or does not invert the polarity of the track error signal or the control signal, and the focus and A drive device for irradiating a predetermined position of the optical recording medium with a light beam emitted from the light source based on a signal output from a tracking control circuit, and the optical recording using the light beam emitted from the light source. After recording information by changing the state of a predetermined area on the medium to form a mark, the mark sequence on the straight line or arc of the mark is used as a track, and the polarity of the signal output from the polarity inversion circuit is set. The optical recording device is characterized in that a predetermined part of the mark is erased by irradiating a light beam emitted from the light source between the adjacent tracks by switching between. 2. A light source, a light amount control device for controlling the light amount of a light beam emitted from the light source according to information to be recorded, and a wobbling pit or a guide groove for obtaining a track error signal are formed in advance. A focusing optical system that guides a light beam emitted from the light source to the optical recording medium to the optical recording medium, a light separating unit that separates the light beam emitted from the light source, and a focus error detecting unit that detects a focus error. A photodetector for converting the reflected light from the optical recording medium into an electric signal; and a focus control for outputting a control signal based on a focus error signal and a track error signal generated from the electric signal obtained from the photodetector. A circuit and a tracking control circuit, an offset circuit that gives an offset to the signal output from the tracking control circuit, and the focus and tracking circuit. A drive device for irradiating a predetermined position of the optical recording medium with a light beam emitted from the light source based on a signal output from a king control circuit, and the optical recording using the light beam emitted from the light source. After recording information by changing the state of a predetermined area on the medium to form a mark, a mark row on the straight line or arc of the mark is used as a track, and the signal output from the offset circuit is used for the tracking. Optical recording characterized by erasing a predetermined part of the mark by applying a signal output from a control circuit so that a light beam emitted from the light source irradiates a position slightly displaced from the track. apparatus. 3. A first light source, a first light amount control device for controlling a light amount of a light beam emitted from the first light source according to information to be recorded, a second light source, and information erasing. A second light amount control device for controlling the light amount of the second light source and an optical recording medium in which wobbling pits or guide grooves for obtaining a track error signal are formed in advance are emitted from the two light sources. Focusing optical system for guiding two light beams to the optical recording medium, light separating means for separating the light beams emitted from the two light sources, focus error detecting means for detecting a focus error, and the optical recording A photodetector for converting the reflected light from the medium into an electric signal, and a focus control circuit and a transistor for outputting a control signal based on the focus error signal and the track error signal generated from the electric signal obtained from the photodetector. A first control circuit for irradiating a predetermined position on the optical recording medium with light beams emitted from the two light sources based on signals output from the focus and tracking control circuit; A mark is formed by changing the state of a predetermined area on the optical recording medium using a light beam emitted from a light source,
An optical recording apparatus, wherein a predetermined part of the mark is erased by a light beam emitted from the second light source. 4. A first light source, a first light amount control device for controlling a light amount of a light beam emitted from the first light source according to information to be recorded, a second light source, and information erasing. A second light amount control device for controlling the light amount of the second light source, an optical recording medium in which wobbling pits or guide grooves for obtaining a track error signal are formed in advance, and light emitted from the two light sources. Focusing optical system for guiding two light beams to the optical recording medium, light separating means for separating the light beams emitted from the two light sources, focus error detecting means for detecting a focus error, and the optical recording A photodetector for converting the reflected light from the medium into an electric signal, and a focus control circuit and a track for outputting a control signal based on the focus error signal and the track error signal generated from the electric signal obtained from the photodetector. And a drive device for irradiating a predetermined position of the optical recording medium with the light beams emitted from the two light sources based on the signals output from the focus and tracking control circuit. A phase grating that divides the light beam into two is provided in the vicinity of the light source, and the state of a predetermined area on the optical recording medium is changed by using the light beam emitted from the first light source to form a mark. An optical recording device, wherein a predetermined part of the mark is erased by a light beam emitted from the second light source. 5. The optical recording according to claim 1, wherein the type of change of the state of the optical recording medium is any one of reflectance, transmittance, refractive index and polarization direction. apparatus. 6. A light spot used on the optical recording medium for forming a mark has a focused spot diameter on the optical recording medium, and a light beam used for erasing a part of the mark is collected on the optical recording medium. 6. The optical recording device according to claim 1, wherein the light spot diameters are the same. 7. A light spot used on the optical recording medium for forming a mark has a focused spot diameter on the optical recording medium, and a light beam used for erasing a part of the mark is collected on the optical recording medium. 6. The optical recording device according to claim 1, wherein the light spot diameters are not the same. 8. A light beam used to form a mark is focused on the optical recording medium in an in-focus state, and a light beam used to erase the mark is defocused to the light beam. The optical recording device according to claim 7, wherein the optical recording device collects the light on a recording medium.