JP2838469B2 - Optical disc playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical disk reproducing apparatus, more particularly, a light spot is irradiated to the optical disk recording medium rotating record mark is formed, reflected light or transmitted from the irradiated portion The present invention relates to an optical disk reproducing device that generates reproduction data based on light.

[0002]

2. Description of the Related Art In general, a magneto-optical disk recording apparatus uses an optical disk recording medium which is magnetized in one direction, and first applies a weak magnetic field to a portion to be recorded in the opposite direction. Next, the part is irradiated with laser light, and the temperature of the part is raised. As a result, the direction of magnetization is reversed only at that portion, and data is recorded.

On the other hand, in a magneto-optical disk reproducing device, first, an optical disk recording medium is irradiated with linearly polarized laser light. Since the plane of polarization of the reflected light from the irradiated portion is rotated by the Kerr effect, data is reproduced by detecting a difference in the rotation angle.

[Conventional Example 1] A conventional optical recording apparatus is disclosed, for example, in Japanese Patent Application Laid-Open No. 58-182134.
In this conventional example, data is recorded by irradiating a rotating optical disc recording medium with a light spot a number of times corresponding to the length of the recording data, and forming a recording mark having a length proportional to the number of times.

However, as shown in FIG. 17, since the optical disk recording medium moves at a certain linear velocity in the x direction with respect to the light spot d, the shape of the recording mark m is not a perfect circle but a tear shape. There was a problem of becoming. Recording mark m
Are recorded in the order of the head of the recording mark m shown in FIG. 17A, the center of the recording mark shown in FIG. 17B, and the tail of the recording mark m shown in FIG. Therefore, as (a), (b), and (c) progress, the heat accumulation increases, and more or less heat remains at the tail of the recording mark m. For this reason, the temperature distribution Ta has a shape that spreads before and after the recording mark m as shown in FIG. 17D, and the head distribution tends to be asymmetric at the head and tail. As a result, only the portion where the temperature distribution Ta exceeds the threshold value Tsh becomes the recording mark m, and its shape becomes a tear shape. As described above, in the optical disk recording apparatus in which the recording medium moves at a linear velocity proportional to the data transfer rate, the temperature distribution T
The adjustment of a was very difficult, and it was difficult to form a uniform recording mark.

[Conventional Example 2] On the other hand, a conventional optical disk reproducing apparatus is disclosed in, for example, Japanese Patent Publication No. 63-56612. In this conventional example, a light spot is scanned in a direction along a track by driving a galvanomirror to absorb rotation unevenness of an optical disk recording medium.
Thus, the relative speed between the light spot and the recording mark is made constant.

However, in this optical disk reproducing apparatus, as in the case of the above-mentioned recording apparatus, the recording medium moves at a certain linear velocity with respect to the light spot g as shown in FIG. Becomes dull, S / N (signal to noise ratio)
However, there was a problem that was reduced. That is, since the light spot d continuously moves in the order of the head of the recording mark m shown in FIG. 19A, the center shown in FIG. 19B, and the tail shown in FIG. Read signal g gradually changes to (a), (b), and (c), and its waveform becomes dull. As described above, in the optical disk reproducing apparatus including the optical disk recording medium that rotates at a linear speed proportional to the data transfer speed, there is a problem that the reliability of the reproduced data is reduced.

Further, as shown in FIG. 18D, even if a recording mark having a uniform shape can be formed with a symmetrical temperature distribution, the leading and trailing ends of the recording mark m are recorded at the time of recording. Since the temperature of the portion is lower than that of the central portion and the threshold value required for reversing the magnetization is almost the threshold, the reversal of the magnetization is not clear, and the contour of the recording mark m becomes irregular. Since this portion is a region where the S / N ratio is low, there is a problem that the rising portion and the falling portion of the read signal g corresponding to this region have a low S / N ratio and further reduce the reliability of reproduced data. Was.

[Conventional Example 3] To solve these problems, an optical spot is vibrated in a direction along a track so as to reduce the relative speed between the optical spot and a recording medium to perform recording and reproduction on an optical disk. The device is disclosed in Japanese Patent Application Laid-Open No. Hei 2-26333.

According to this recording / reproducing apparatus, when an optical disk recording medium rotates at a constant linear velocity or when an optical card has parallel tracks, a recording mark having a uniform shape can be formed and accurate reproduction data can be formed. Obtainable.

[0011]

However, when the optical disk recording medium rotates at a constant angular velocity, no measure can be taken despite the fact that the linear velocity of the recording medium varies greatly depending on the position of the track being recorded or reproduced. Had not been applied.

Further, in this recording / reproducing apparatus, since the light spot is vibrated in the direction along the track, the light spot reciprocates, and does not follow the recording mark on the outward path but on the return path. For this reason, the return scan time is required as much as the forward scan time, and high-speed scanning is difficult. Further, at the moment of switching from the forward path to the return path or from the return path to the forward path, it is necessary to reduce the scanning speed to zero once and then accelerate in the reverse direction, so that it is difficult to always perform scanning at a constant speed.

[0013] Here, the recording time has been described, but the reproducing time also has the same problem, and a detailed description in this case will be omitted.

[0014] The present invention has been made in order to solve such problems, the main object is to provide a always enables accurate playback apparatus regardless of the position of the track.

[0015]

[0016]

This invention SUMMARY OF] is a light spot is irradiated to the optical disk recording medium rotating recording mark is formed, the reproduction data based on the reflected light or transmitted light from the irradiated portion An optical disk reproducing apparatus for generating a light spot includes a light spot irradiation unit, a light spot scanning unit, and a scanning speed switching unit. The light spot irradiating means irradiates the optical spot on the optical disk recording medium. The light spot scanning means repeatedly scans the light spot irradiated by the light spot irradiation means in a direction along a track of the optical disc recording medium within a certain range while making the light spot coincide with the recording mark. The scanning speed switching means switches the scanning speed of the light spot by the light spot scanning means according to the linear velocity of the portion of the optical disk recording medium to which the light spot is irradiated by the light spot irradiation means.

[0017]

Further, the present invention irradiates a light spot on a rotating optical disk recording medium on which a recording mark is formed,
An optical disc reproducing apparatus that generates reproduction data based on reflected light or transmitted light from the irradiated portion,
It includes a light spot irradiation means, a light spot scanning means, and a scanning speed control means. The light spot irradiating means irradiates the optical spot on the optical disk recording medium. The light spot scanning means repeatedly scans the light spot irradiated by the light spot irradiation means in a direction along a track of the optical disc recording medium within a certain range while making the light spot coincide with the recording mark. The scanning speed control means makes the speed at which the light spot is scanned by the light spot scanning means coincide with the average linear velocity from the innermost peripheral part to the outermost peripheral part of the recording area on the optical disk recording medium.

[0019]

Further, the present invention irradiates a light spot on a rotating optical disk recording medium on which recording marks are formed,
An optical disc reproducing apparatus that generates reproduction data based on reflected light or transmitted light from the irradiated portion,
The recording area on the optical disc recording medium includes a plurality of zones composed of a plurality of tracks, and the optical disc reproducing device includes a light spot irradiation unit, a light spot scanning unit,
Scanning speed switching means. The light spot irradiating means irradiates the optical spot on the optical disk recording medium. The light spot scanning means repeatedly scans the light spot irradiated by the light spot irradiation means in a direction along a track of the optical disc recording medium within a certain range while making the light spot coincide with the recording mark. The scanning speed switching means scans the light spot by the light spot scanning means according to the average linear velocity from the innermost part to the outermost part of the zone where the light spot is irradiated by the light spot irradiating means. Switch speed.

[0021]

[0022]

SUMMARY OF] According to the optical disc reproducing apparatus according to this invention, since the scanning speed of the light spot in accordance with the linear velocity of the portion where the light spot is irradiated is switched, in any of the tracks of the optical disc recording medium The light spot is scanned while following the linear velocity. Therefore, the relative speed between the light spot and the recording medium is reduced in any track of the optical disk recording medium. For this reason, it is possible to read only the center without reading the head or tail of the recording mark from the innermost part to the outermost part of the optical disk. Therefore, the read signal of the recording mark becomes large, and the waveform becomes steep.
The N ratio can be improved.

[0023]

According to another optical disk reproducing apparatus according to the present invention, the scanning speed of the light spot is made to match the average linear velocity from the innermost peripheral part to the outermost peripheral part of the recording area on the optical disk recording medium. Therefore, the relative speed between the light spot and the recording medium is reduced on average from the outermost periphery to the innermost periphery. Therefore, only the center can be read without reading the head or tail of the recording mark. Therefore, the read signal of the recording mark is increased on average from the innermost part to the outermost part of the optical disk recording medium, and its waveform becomes steep, so that the S / N ratio can be improved.

[0025]

According to still another optical disk reproducing apparatus according to the present invention, the scanning speed of the light spot is switched according to the average linear velocity from the innermost peripheral portion to the outermost peripheral portion of the zone. The light spot is scanned while following the linear velocity of the recording medium. Therefore, the relative speed between the light spot and the recording medium is reduced on average for each zone. Therefore, only the center can be read without reading the head or tail of the recording mark. Therefore, the read signal of the recording mark increases from the innermost part to the outermost part of the optical disk recording medium, and its waveform becomes steep, so that the S / N ratio can be improved.

[0027]

Next, an embodiment of an optical disk recording apparatus and an optical disk reproducing apparatus according to the present invention will be described in detail with reference to the drawings.

[First Embodiment] FIG. 1 is a block diagram showing a configuration of a magneto-optical disk recording / reproducing apparatus according to a first embodiment of the present invention.

As shown in FIG. 1, this magneto-optical disk recording / reproducing apparatus includes a semiconductor laser 10, a semiconductor laser driving circuit 11, a beam splitter 12, a polygon mirror 13, a motor 14, and a motor driving circuit 15. including.
The magneto-optical disk recording / reproducing apparatus further includes a photodetector 1
6 and a reproduction circuit 17. The magneto-optical disk recording / reproducing apparatus further includes a recording clock generation circuit 18, a clock frequency switching circuit 19, and a recording data generation circuit 20.
And a reproduction clock generation circuit 21 and a changeover switch 22.

The semiconductor laser 10 includes a beam splitter 1
The optical spot d is applied to the optical disc recording medium 23 via the polygon mirror 2 and the polygon mirror 13. The semiconductor laser drive circuit 11 drives the semiconductor laser 10. The beam splitter 12 transmits the laser beam emitted from the semiconductor laser 10 straight and guides it to the polygon mirror 13, and reflects the laser beam reflected by the optical disk recording medium 23 at right angles to guide it to the photodetector 16. The polygon mirror 13 is formed by depositing aluminum or the like on each side surface of a regular polygonal prism, and rotates the laser beam emitted from the semiconductor laser 10 through the beam splitter 12 in one direction within a certain range by being rotated at a high speed. Is repeatedly scanned. The motor 14 rotates the polygon mirror 13 at high speed. The motor drive circuit 15 drives the motor 14,
It is controlled to a predetermined rotation speed.

In this embodiment, the semiconductor laser 10 and the semiconductor laser drive circuit 11 constitute the light spot irradiation means 24. The polygon mirror 13, the motor 14, and the motor drive circuit 15 constitute a light spot scanning unit 25.

First, the recording operation of the magneto-optical disk recording / reproducing apparatus will be described. In response to the recording clock 1 from the recording clock generation circuit 18, the recording data a is output by the recording data generation circuit 20. This recording data a is input to the semiconductor laser drive circuit 11 and also to the changeover switch 22. At the time of recording,
The changeover switch 22 selects the recording data a and inputs it to the motor drive circuit 15.

Recording data a to the semiconductor laser drive circuit 11
Is input, the semiconductor laser 10 emits a laser beam in response to a control signal b from the semiconductor laser drive circuit 11.

On the other hand, the recording data a from the recording data generating circuit 20 is supplied to the motor driving circuit 1 via the changeover switch 22.
5 is input. The motor drive circuit 15 inputs a control signal c to the motor 14 in response to the recording data a.

Here, the recording area on the optical disk recording medium 23 includes a plurality of zones composed of a plurality of tracks. Therefore, the frequency of the recording clock 1 generated by the recording clock generating circuit 18 is
9 is switched according to each zone. That is, as shown in FIG. 2, the average linear velocities V1, V2, V3, V4 from the innermost peripheral portion Rin to the outermost peripheral portion Rout of each zone.
The frequency is increased in proportion to. FIG. 2 exemplifies a case where the image is divided into four zones for simplicity.

Therefore, since the linear velocity at the center position in each zone is the average linear velocity of the zone, the scanning speed of the light spot d by the polygon mirror 13 is equal to the average linear velocity V1, V2, V3, V4. Matched. That is, the motor drive circuit 1 that drives the polygon mirror 13
5 drives the motor 14 according to the average linear velocities V1, V2, V3, V4, and the motor 14 rotates the polygon mirror 13. Thereby, the scanning speed of the light spot d is switched for each zone.

FIG. 3 shows that the laser beam is
FIG. 4 is a diagram showing a state where the light spot is reflected by 3 and thereby a light spot is scanned. As shown in FIG. 3, (a),
When the polygon mirror 13 is rotated as in (b) and (c), the laser beam is incident from the same direction, but the reflection direction changes.

FIG. 4 shows (a), (b), and (b) shown in FIG.
(C) At each moment, the light spot d is
FIG. 4 is a diagram showing a state in which the same spot P on the recording medium 23 is always irradiated with the light spot d following the linear velocity of FIG.

As shown in FIG. 4, the recording medium 23 moves in the x direction shown by the upper arrow in FIG. 4, and the light spot d is called (a), (b), and (c) while being synchronized with the recording data a. It is scanned sequentially in order. Thereby, the light spot d
Is always irradiated to the same location P on the recording medium 23.

Therefore, as shown by the solid line in FIG. 4D, the temperature distribution T of the recording medium 23 has a steep characteristic that becomes maximum at the center of the light spot d. By the way, as shown by the broken line in (d), the temperature distribution Ta generated by the conventional recording method has a duller characteristic than the temperature distribution T generated by the method of the present invention.

Since the portion where the temperature distribution T exceeds the threshold temperature Tsh becomes the recording mark m, the recording mark m having a uniform shape can be formed. Further, since there is no forward scanning of the light spot d, it is possible to start scanning for forming the next recording mark immediately after forming the recording mark m.

As described above, according to the magneto-optical disk recording / reproducing apparatus according to the present invention, it is possible to form the recording mark m having a substantially uniform shape on any track.

Next, the reproducing operation of the magneto-optical disk recording / reproducing apparatus will be described. First, in the reproduction operation, the changeover switch 22 is switched to the reproduction clock generation circuit 21 side, and the reproduction clock k is input to the motor drive circuit 15. In this state, the semiconductor laser 10 is driven by the semiconductor laser drive circuit 11, and the semiconductor laser 10
A weak laser beam having a constant intensity is emitted. This laser beam enters a rotating polygon mirror 13 via a beam splitter 12, and is reflected by the polygon mirror 13 toward an optical disk recording medium 23. Therefore, this laser beam is applied to the optical disc recording medium 23 as a light spot d, and this light spot d is repeatedly scanned within a certain range in a direction along the track of the optical disc recording medium 23.

In this magneto-optical disk recording / reproducing apparatus, the optical disk recording medium 23 rotates at a constant angular velocity, so that the track on the outer peripheral portion has a higher linear velocity. Therefore, the reproduction clock k has a higher frequency in the zone at the outer peripheral portion, like the recording clock l. Motor drive circuit 15
Drives the motor 14 based on such a reproduction clock k, so that the polygon mirror 13 rotates in synchronization with the reproduction clock k. Therefore, the light spot d is scanned according to the average linear velocities V1, V2, V3, V4 of each zone.

Further, the reflected light f from the optical disk recording medium 23 is reflected / separated at right angles by the beam splitter 12 and then guided to the photodetector 16. The reflected light f is converted into a read signal g by the photodetector 16, and the reproducing circuit 17 generates reproduced data h based on the read signal g.

FIG. 5 shows that the light spot d is scanned in the order of (a), (b) and (c) of FIG.
FIG. 3 is a diagram showing a state of irradiation of No. 3; FIG. 5 (a),
As shown in (b) and (c), the light spot d is scanned according to the linear velocity of the optical disk recording medium 23, and is always irradiated on the same position on the optical disk recording medium 23. That is, while the optical disk recording medium 23 moves in the x direction in the figure, the light spot d is continuously scanned in the order of (a), (b), and (c) in synchronization with the reproduction clock k, and The linear velocity of the recording medium 23 is made to follow. As a result, the light spot d is always applied to the center of the same recording mark m on the optical disk recording medium 23 at the moment of reading. Therefore, the head portion or the tail portion of the recording mark m is not read out by the light spot d, and only the central portion is always read out. For this reason, as shown in FIG. 5D, the magnitude of the read signal g is the same in any of (a), (b), and (c). Therefore, the waveform of the read signal g becomes steeper than before, and the S / N ratio is improved.

Here, a case has been described in which a recording mark m having a uniform shape with clear magnetization reversal is read. However, when a recording mark m with unclear magnetization reversal is read, the central portion thereof is mainly read. Therefore, noise from the head or tail of the recording mark m is removed.
That is, the light amount of the light spot is larger at the center and smaller at the periphery. Therefore, since the leading and trailing portions of the recording mark m are read by the peripheral portion of the light spot, the amount of reflected light is small and the noise is small. Therefore, also in this case, the S / N ratio can be similarly improved, and the reliability of the reproduced data can be further improved.

As described above, according to the magneto-optical disk recording / reproducing apparatus, since the light spot always follows the linear velocity from the outermost peripheral portion to the innermost peripheral portion of the optical disk recording medium 23, accurate recording and reproduction can be performed. Reproduction can be performed. Moreover, since the light spot d is scanned in only one direction by the polygon mirror 13, recording and reproduction can be performed at a higher speed than in the third conventional example in which the light spot d is vibrated.

In the above embodiment, an example in which the scanning speed is switched in four steps has been described. However, the present invention is not limited to this.
You may switch between three or less steps or five or more steps.

[Embodiment 2] FIG. 6 is a block diagram showing a configuration of a magneto-optical disk recording / reproducing apparatus according to a second embodiment of the present invention.

As shown in FIG. 6, this magneto-optical disk recording / reproducing apparatus includes a semiconductor laser 10, a semiconductor laser driving circuit 11, a beam splitter 12, and a polygon mirror 1.
3, a motor 14, and a motor drive circuit 15. The magneto-optical disk recording / reproducing apparatus further includes a photodetector 16
And a reproduction circuit 17. The magneto-optical disk recording / reproducing apparatus further includes a recording clock generating circuit 18, a clock frequency switching circuit 19, a recording data generating circuit 20, a reproducing clock generating circuit 21, and a switch 22.

The magneto-optical disk recording / reproducing apparatus according to the first embodiment forms a recording mark by a so-called mark position recording method. The magneto-optical disk recording / reproducing apparatus according to the second embodiment employs a so-called mark edge. A recording mark is formed by a recording method. The difference between the magneto-optical disk recording / reproducing apparatus according to the second embodiment and the magneto-optical disk recording / reproducing apparatus according to the first embodiment is that a recording clock 1 is input to the motor drive circuit 15 at the time of recording instead of the recording data a. It is. In the drawings, portions denoted by the same reference numerals indicate the same or corresponding portions.

First, the case where a recording mark is formed by this mark edge recording method will be described.

According to this method, as shown in FIG. 7, the light spot d is synchronized with the recording clock 1 instead of the recording data a, and the light spot m is irradiated from the innermost peripheral portion to the outermost peripheral portion of the zone irradiated with the light spot m. The average linear velocity up to the part is made to follow.

Therefore, the light spot d is P (n), P
(N + 1),..., P (n + m) in order, with a certain interval S, while jumping one after another. Since the light spot p is synchronized with the recording clock l, this fixed interval S corresponds to the period Sa of the recording clock l.

Here, when a strong light spot d is irradiated when the recording data a is “1”, the temperature of the recording medium 23 rises only in the irradiated portion. Temperature distribution T in this case
Has a steep characteristic as shown in FIG. 7, and the temperature distribution T at the head and tail of the recording mark m can be made uniform. Incidentally, the temperature distribution Ta generated by the conventional mark edge recording method is, as shown in FIG. 7, compared with the temperature distribution T generated by the mark edge method of the present invention.
The characteristics become dull, and the temperature distribution at the head and tail of the recording mark is not uniform.

Next, a method of reproducing the recorded mark m by the mark edge recording method will be described with reference to FIG.

As shown in FIG. 8, the light spot d is synchronized with the reproduction clock k while the optical disk d.
Is irradiated. Thereby, the light spot d is scanned according to the linear velocity of the irradiated portion,
Irradiation is performed at regular intervals S in the order of (n), P (n + 1),... P (n + m). This constant interval S corresponds to the period Sa of the reproduction clock k.

As described above, in the case of the mark edge recording system, similarly to the case of the mark position recording system, the light spot d is always irradiated to the center of the same recording mark m on the optical disk recording medium 23 at the moment of reading. The head and tail of the recording mark m are not read out, and only the center part is always read out. Therefore, the read signal g becomes large and its waveform becomes steep, so that S
/ N ratio can be improved. Further, since the reproduction data h is generated in synchronization with the reproduction clock k based on the read signal g, its reliability can be further improved.

Also, when reading a recording mark m whose magnetization reversal is unclear, it is possible to remove noise from the head and tail of the recording mark m. Therefore, also in this case, the S / N ratio can be similarly improved, and the reliability of the reproduced data can be improved.

In the first and second embodiments, the recording data a may be synchronized with the recording clock l, and conversely, the recording data a may be synchronized with the recording clock l.

[Third Embodiment] FIG. 9 is a block diagram showing a third embodiment of the magneto-optical disk recording / reproducing apparatus according to the present invention.

In the above-described first or second embodiment, the drive speed of the motor 14 is switched in accordance with the recording data a or the recording clock l. However, as shown in FIG. , By directly inputting the switching signal n to the motor drive circuit 15,
4 may be switched. The drive speed switching circuit 26 detects the linear velocity of the optical disk recording medium 23 in the portion where the light spot d is currently irradiated, and generates a switching signal n accordingly. In order to detect the linear velocity of the optical disc recording medium 23, for example, the current position of the pickup device is specified by address information from a sensor or a read signal, and the rotation speed of a spindle motor for rotating the optical disc recording medium 23 is specified. Further, the linear velocity may be calculated by the CPU based on these.

[Embodiment 4] In the above embodiment, the recording area of the optical disk recording medium is divided into four zones, and the scanning speed of the light spot is switched stepwise according to the average linear velocity in each zone. As shown in FIG. 10, the innermost peripheral portion Rin
The scanning speed of the light spot may be made to coincide with the average linear speed Vmean of the linear speed Vmin of the outermost portion Rout and the linear speed Vmax of the outermost peripheral portion Rout. In this case, the average linear velocity Vmean
, The motor 14 may be driven to rotate the polygon mirror 13.

As compared with the above embodiment, the relative speed between the light spot d and the recording mark m increases as the position is closer to the innermost peripheral portion or the outermost peripheral portion. Can be performed.

[Embodiment 5] FIG. 11 is a block diagram showing a fifth embodiment of the magneto-optical disk recording / reproducing apparatus according to the present invention. As shown in FIG.
Is replaced with a hologram disk 27, and the number of rotations of the hologram disk 27 is switched according to the linear velocity of the portion irradiated with the light spot d. The light spot d may follow the linear velocity over the portion.

The hologram disk 27 is a disk in which linear grids at regular intervals are arranged concentrically. For example, “Electronic Photographic Society of Japan, Sep., Imaging, Part 3, pp. 28-35,“ Printer Output Device and Recording Materials Topics "December 20, 1988".

[Embodiment 6] FIG. 12 is a block diagram showing a sixth embodiment of the magneto-optical disk recording / reproducing apparatus according to the present invention.

As shown in FIG. 12, this magneto-optical disk recording / reproducing apparatus is a semiconductor laser 1 according to the first embodiment.
0, the polygon mirror 13, the motor 14, and the motor drive circuit 15 are replaced by three semiconductor lasers 28, 29, and 30, a semiconductor switch circuit 31, and a switch control circuit 32.

The semiconductor switch circuit 31 switches the drive current from the semiconductor laser drive circuit 11 by the switch control circuit 32 and sequentially switches the semiconductor lasers 28, 29 and 3.
It is sent to 0.

When data is recorded on the optical disk recording medium 23 by this magneto-optical disk recording / reproducing apparatus, first, the changeover switch 22 is switched to the recording data generating circuit 20 side. Therefore, the recording data a from the recording data generation circuit 20 is guided to the semiconductor laser drive circuit 11 and the switch control circuit 32. The drive current is sent from the semiconductor laser drive circuit 11 to the three semiconductor lasers 28, 29, and 30 via the semiconductor switch circuit 31. In the semiconductor switch circuit 31, the drive current is switched by the switch control circuit 32. Are sequentially sent to the semiconductor lasers 28, 29, 30.

On the other hand, the frequency of the recording clock 1 from the recording clock generating circuit 18 is
Is switched according to the linear velocity of the portion where the light spots d1, d2, and d3 are currently irradiated.
As described above, the switch control circuit 32 outputs the recording clock l
Since the semiconductor switch circuit 31 is controlled in synchronization with the recording data a generated based on the above, the light spots d1, d2, and d3 emitted from the semiconductor lasers 28, 29, and 30 to the optical disk recording medium 23 are: The linear velocity of the optical disc recording medium 23 in the irradiated portion is made to follow. Accordingly, the relative speed between the light spots d1, d2, and d3 and the optical disk recording medium 23 becomes zero, and a recording mark having a uniform shape can be formed.

FIG. 13 shows the light spot d shown in FIG.
1, d2 and d3 are always the optical disk recording medium 2
It is a figure which shows a mode that the same location P on 3 is irradiated.

As shown in FIG. 13, the optical disk recording medium 23 is moving in the x direction in FIG.
2 and d3 are intermittently followed in the order of (a), (b) and (c). This makes the light spot d
1, d2, and d3 are always irradiated to the same location P on the optical disk recording medium 23, so that a steep temperature distribution T as shown in FIG. be able to. Note that the temperature distribution Ta indicated by a broken line in FIG.

As described above, in this embodiment, since the three semiconductor lasers 28, 29, and 30 are sequentially driven in synchronization with the recording data a, the semiconductor lasers 28, 29, and 3 are driven.
Since the light spots d1, d2, and d3 emitted from 0 follow the linear velocity of the area where they are irradiated, and the temperature distributions at the head and rear of the recording mark can be made uniform. It is possible to form a recording mark m having an arbitrary shape. Next, when data is reproduced by the magneto-optical disk recording / reproducing apparatus, first, the changeover switch 22 is switched to the reproduction clock generation circuit 21 side. For this reason, the switch control circuit 32 outputs the reproduction clock k
And switches the three semiconductor lasers 28, 29, 30 sequentially. Moreover,
The frequency of the reproduced clock k is currently determined by the clock frequency switching circuit 19 at the light spots d1, d2, and d.
Since the light spots d1, d2, and d3 are switched in accordance with the linear velocity of the portion irradiated with 3, the light spots d1, d2, and d3 follow the linear speed of the optical disk recording medium 23 in the irradiated portion. Thus, the semiconductor lasers 28, 29,
Light spots d1 and d of weak constant intensity emitted from 30
2 and d3 are reflected by the optical disk recording medium 23, and the reflected lights f1, f2 and f3 are reflected / separated at right angles by the beam splitter 12, and then guided to the photodetector 16. The reflected lights f1, f2, and f3 are converted into read signals g in the photodetector 16, and reproduced data h is generated in the reproduction circuit 17.

FIG. 14 shows the light spot d shown in FIG.
1, d2 and d3 are always the optical disk recording medium 2
FIG. 4 is a diagram showing a state where the same recording mark m on the third is irradiated.

As shown in FIG. 14, the optical disk recording medium 23 moves in the x direction in FIG.
d2 and d3 are synchronized with the reproduction clock k (a),
Scanning is performed in the order of (b) and (c), and the linear velocity of the optical disk recording medium 23 is made to follow. Thus, the light spots d1, d2, and d3 can be applied to the same recording mark m on the optical disk recording medium 23 at the moment of reading. Therefore, the heads and tails of the recording mark m are not read out by the light spots d1, d2, and d3, and only the center part is always read out. Therefore, the read signal g from the recording mark m is read in the order of (a), (b) and (c) as shown in FIG. , Its waveform becomes steep. Therefore, the S / N ratio can be improved.

Also, when reading from a recording mark m whose magnetization reversal is unclear, noise from the head and tail can be removed, so that the S / N ratio can be further improved and the reproduction can be performed. The reliability of the data h can be further improved.

Here, three semiconductor lasers 28, 29,
Although an example using 30 has been shown, the present invention is not limited to this, and two or four or more semiconductor lasers may be used. As the number of semiconductor lasers increases, the scanning of the intermittent light spot can be made closer to the continuous scanning. Although the mark position recording method has been described here, the mark edge recording method can be applied in the same manner as in the first embodiment.

In the first to sixth embodiments, since the light spot is scanned only in the forward path and not scanned in the backward path, the light spot must sufficiently follow the linear velocity of the irradiated portion. Can be. Therefore, the power of the light spot can be concentrated at one place, and energy can be used efficiently. Therefore, the power of the light spot required for recording can be reduced as compared with the related art, and the power consumption can be reduced. Further, in general, it is difficult to increase the output as the wavelength of the semiconductor laser is shorter, and this has hindered the increase in the density. However, according to the present invention, the energy can be used efficiently even at a low output,
Recording and reproduction of the recording mark are facilitated, and the density can be increased.

[Embodiment 7] FIG. 15 shows a seventh embodiment of the magneto-optical disk recording / reproducing apparatus according to the present invention.

As shown in FIG. 15, a galvano mirror 33 may be provided instead of the polygon mirror 13 in the first embodiment. In the present embodiment, the light spot d is changed by oscillating the galvanometer mirror 33 so that the optical disk recording medium 2
Scanning is performed in the direction along the track No. 3 and the oscillation period is switched according to the linear velocity of the portion irradiated with the light spot d. Therefore, it is difficult to make the scanning speed constant from the start to the end of scanning, but the relative speed between the light spot d and the optical disk recording medium 23 is reduced in any track, so that it is lower than before. Recording and reproduction can be performed accurately.

[Eighth Embodiment] FIG. 16 is a block diagram showing an eighth embodiment of a magneto-optical disk recording / reproducing apparatus according to the present invention.

As shown in FIG. 16, the magneto-optical disk recording / reproducing apparatus is similar to the polygon mirror 1 of the first embodiment.
In place of 3, an objective lens 34 capable of vibrating in parallel to the surface of the optical disk recording medium 23 is provided. The magneto-optical disk recording / reproducing apparatus further includes an objective lens driving circuit 35 for driving an objective lens 34. The objective lens driving circuit 35 receives recording data a during recording, and receives a reproduction clock k during reproduction. Is done. Therefore, the oscillation cycle of the objective lens 34 is switched in synchronization with the recording data a or the reproduction clock k, whereby the light spot d is made to follow the linear velocity of a portion irradiated with the light spot d.
Therefore, recording and reproduction can be accurately performed from the innermost periphery to the outermost periphery of the optical disc recording medium 23.

[Others] In the above embodiment, the recording area of the optical disk recording medium 23 is divided into a plurality of zones composed of a plurality of tracks, and the scanning speed of the light spot d is switched according to the average linear velocity in each zone. However, it goes without saying that switching the scanning speed for each track allows the light spot d to more accurately follow the linear velocity of the portion irradiated with the light spot d.

Further, an objective lens for appropriately condensing the light spot d may be provided between the polygon mirror 13, the hologram disk 27 or the galvano mirror 33 and the optical disk recording medium 23 in the above-described embodiment.

In the above-described embodiment, the reproduction is performed using the reflected light from the recording mark. However, the light spot is irradiated from the back of the optical disk recording medium, and the rotation angle of the polarization plane due to the Faraday effect of the transmitted light. , The reproduction may be performed. Further, the light once transmitted through the optical disk recording medium may be reflected again and detected.

In the above embodiment, the so-called light modulation system in which the light spot is modulated in accordance with the recording data has been described. However, the present invention is not limited to this. A similar effect is achieved.

Further, if the optical disk recording medium 23 on which the recording mark is formed by the magneto-optical disk recording / reproducing apparatus according to the above-described embodiment is reproduced by the conventional optical disk reproducing apparatus, it is possible to obtain reproduced data with higher reliability than before. it can.

It is also possible that the optical disk recording / reproducing apparatus according to the present invention performs the photoresist of the master disk of the magneto-optical disk recording medium, thereby forming a master disk. By duplicating the optical disk recording medium by injection molding or close contact exposure using this master disk, it is also possible to provide an optical disk recording medium capable of obtaining highly reliable reproduced data.

In the above embodiment, the optical disk device is described as an example. However, the present invention is not limited to this, and the present invention can be applied to any device having a non-constant linear velocity.

In addition, the same effect can be obtained by switching the following speed or following the average linear speed in the same manner as in the above-described embodiment using the AO module or the EO module device of the third conventional example. can get.

[0093]

[0094]

According to the optical disc reproducing apparatus according to claim 1 in accordance with the invention of this, according to the present invention, according to the linear velocity of the portion on which the light spot is irradiated, since the switching operation speed of the light spot, At the moment of reproduction, the light spot can follow the linear velocity of the irradiated portion from the outermost peripheral portion to the innermost peripheral portion of the optical disk recording medium. For this reason, the relative speed between the light spot and the optical disc recording medium can be constantly reduced, and reproduced data can be accurately generated from all the recording marks formed on the optical disc recording medium.

[0095]

According to the optical disk reproducing apparatus of the second aspect of the present invention, the scanning speed of the light spot is set to the average linear velocity from the innermost part to the outermost part of the recording area on the optical disk recording medium. Since they match, at the moment of reproduction, the light spot from the outermost peripheral portion to the innermost peripheral portion of the optical disk recording medium can approximately follow the linear velocity of the irradiated portion on average. For this reason,
The relative speed between the light spot and the optical disk recording medium can be reduced, and on average, almost accurate reproduction data can be obtained from all the recording marks formed on the optical disk recording medium.

[0097]

Further, according to the optical disk reproducing apparatus according to the third aspect of the present invention, the light spot is adjusted in accordance with the average linear velocity from the innermost periphery to the outermost periphery of the zone irradiated with the light spot. Switching the scanning speed of
At the moment of reproduction, the light spot from the innermost peripheral part to the outermost peripheral part of the optical disk recording medium can be made to substantially follow the linear velocity of the irradiated part. For this reason, the relative speed between the light spot and the optical disk recording medium can be substantially reduced, and almost accurate reproduction data can be obtained from all the recording marks formed on the optical disk recording medium.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a magneto-optical disk recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing how the scanning speed of a light spot is switched in the magneto-optical disk recording / reproducing apparatus shown in FIG.

FIG. 3 is an explanatory diagram showing a manner in which a light spot is scanned by a polygon mirror in the magneto-optical disk recording / reproducing apparatus shown in FIG.

FIG. 4 is an explanatory diagram showing how a light spot follows a recording medium when recording is performed by the magneto-optical disk recording / reproducing apparatus shown in FIG.

FIG. 5 is an explanatory diagram showing a state in which a light spot follows a recording mark when reproduction is performed by the magneto-optical disk recording / reproducing apparatus shown in FIG. 1;

FIG. 6 is a block diagram showing an overall configuration of a magneto-optical disk recording / reproducing apparatus according to a second embodiment of the present invention.

7 is a diagram for explaining a recording operation by the magneto-optical disk recording / reproducing device shown in FIG. 6;

FIG. 8 is a diagram for explaining a reproducing operation by the magneto-optical disk recording / reproducing device shown in FIG. 6;

FIG. 9 is a block diagram showing an overall configuration of an optical disc recording / reproducing apparatus according to a third embodiment of the present invention.

FIG. 10 is an explanatory diagram showing a scanning speed of a light spot in a magneto-optical disk recording / reproducing apparatus according to a fourth embodiment of the present invention.

FIG. 11 is a block diagram showing an overall configuration of an optical disk recording / reproducing apparatus according to a fifth embodiment of the present invention.

FIG. 12 is a block diagram showing an overall configuration of an optical disc recording / reproducing apparatus according to a sixth embodiment of the present invention.

FIG. 13 is an explanatory diagram showing how a light spot follows the linear velocity of an optical disk recording medium when recording is performed by the magneto-optical disk recording / reproducing apparatus shown in FIG.

FIG. 14 is an explanatory diagram showing a state in which a light spot follows a recording mark when reproduction is performed by the magneto-optical disk recording / reproducing apparatus shown in FIG.

FIG. 15 is a diagram showing a main part of an optical disk recording / reproducing apparatus according to a seventh embodiment of the present invention.

FIG. 16 is a block diagram showing an overall configuration of a magneto-optical disk recording / reproducing apparatus according to an eighth embodiment of the present invention.

FIG. 17 is an explanatory diagram showing how recording is performed by a conventional optical disk recording device.

FIG. 18 is an explanatory diagram showing a state of reproducing by a conventional optical disk reproducing device.

[Explanation of symbols]

 10, 28, 29, 30 Semiconductor laser 11 Semiconductor laser drive circuit 12 Beam splitter 13 Polygon mirror 14 Motor 15 Motor drive circuit 16 Photodetector 17 Reproduction circuit 18 Recording clock generation circuit 19 Clock frequency switching circuit 20 Recording data generation circuit 21 Reproduction Clock generation circuit 22 Changeover switch 23 Optical disk recording medium 26 Drive speed switching circuit 27 Hologram disk 31 Semiconductor switch circuit 32 Switch control circuit 33 Galvano mirror 34 Objective lens 35 Objective lens drive circuit

Claims (3)

(57) [Claims] 1. An optical disk reproducing apparatus for irradiating a rotating optical disk recording medium on which a recording mark is formed with a light spot and generating reproduction data based on reflected light or transmitted light from the irradiated part, A light spot irradiating unit for irradiating the optical spot on the optical disc recording medium; and a light spot irradiated by the light spot irradiating unit is aligned with the recording mark within a predetermined range in a direction along a track of the optical disc recording medium. A light spot scanning unit that repeatedly scans at, according to a linear velocity of a portion of the optical disc recording medium that is irradiated with a light spot by the light spot irradiation unit,
An optical disk reproducing apparatus, comprising: a scanning speed switching unit that switches a speed at which the light spot is scanned by the light spot scanning unit. 2. An optical disc reproducing apparatus that irradiates a light spot on a rotating optical disc recording medium on which recording marks are formed, and generates reproduction data based on reflected light or transmitted light from the irradiated part, A light spot irradiating means for irradiating the optical spot on the optical disc recording medium; and a light spot irradiated by the light spot irradiating means being aligned with the recording mark within a predetermined range in a direction along a track of the optical disc recording medium. A light spot scanning means for repetitively scanning in the optical disk recording medium; An optical disk reproducing device including a speed control unit. 3. An optical disc reproducing apparatus that irradiates a light spot on a rotating optical disc recording medium on which a recording mark is formed, and generates reproduction data based on reflected light or transmitted light from the irradiated portion, The recording area in the optical disk recording medium includes a plurality of concentric zones each including a plurality of tracks, the optical disk reproducing device includes: a light spot irradiating unit configured to irradiate the optical spot with the light spot; Light spot scanning means for causing a light spot irradiated by the means to coincide with the recording mark and repeatedly scanning within a certain range in a direction along a track of the optical disc recording medium; and a light spot irradiated by the light spot irradiation means. The optical scanning is performed according to the average linear velocity from the innermost peripheral part to the outermost peripheral part of the zone. The Tsu preparative scanning means comprises a scanning speed switching means for switching the speed at which the light spot is scanned, the optical disk reproducing apparatus.