JPH10241202A - Optical storage and playback device - Google Patents

Abstract

(57) [Summary] [Problem] If the track width and the spot diameter of a light beam do not match, for example, data cannot be securely erased, resulting in unerased data, which adversely affects the recording of the next data. There was a problem. SOLUTION: A track width measuring means 9 for measuring a track width of an optical storage medium 1, and a spot diameter change for changing a beam spot diameter of a light beam 2 so as to conform to the track width measured by the track width measuring means 9. Means 10 is provided. In addition, an optical power compensating means 8 for compensating for a change in the light beam power to the optical storage medium 1 due to the change of the beam spot diameter by the spot diameter changing means 10 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical storage / reproducing apparatus, and more particularly to an apparatus using a system for recording / reproducing data by irradiating a light beam along a track of a storage medium.

[0002]

2. Description of the Related Art As a means for increasing the capacity of an optical storage medium for storing information, there is a case where a method of increasing the storage capacity while maintaining compatibility in external shape is used. In an optical storage medium that operates data along a track, one of means for improving the storage capacity in the same shape is to reduce the track width.

On the other hand, in general, data recording / erasing / reproduction on an optical storage medium using a light beam is performed by focusing a light beam focused on a recording surface by a lens on the storage surface of the medium. Will be

That is, all operations such as recording / erasing / reproducing are executed with the minimum spot diameter of the light beam (hereinafter referred to as focal spot diameter). Usually, the device is designed such that the focal spot diameter is adapted to the track width of the intended storage medium.

If the track width is wider than the focal spot diameter, data on the track can be read and written. However, conversely, if the track width is smaller than the focal spot diameter, a problem occurs in that information on an adjacent track is read and written.

[0006] For the above reasons, an apparatus corresponding to a storage medium having a different storage capacity, that is, a storage medium having a different track width is designed so as to have a focal spot diameter suitable for a storage medium having the narrowest track width, and has another wide spot diameter. Data is read and written using the focal spot diameter for a storage medium having a track width.

[0007]

By the way, an apparatus designed to fit a certain track width can be said to be actually suitable only for an optical storage medium having that track width.
FIGS. 5 and 6 are diagrams for explaining recording and erasing of data having a track width matching the focal spot diameter and a track width wider than the focal spot diameter, respectively.

Here, (a), (b) and (c) of FIG.
FIGS. 3A and 3B respectively show a state in which data is recorded, a state in which a light beam for erasing data has passed over (a) (a locus of passage of the light beam is indicated by a dotted line), and a state after erasing. . Note that, in the figures of (a) and (b), the S portion is a portion where data is written and the magnetic field is reversed.

As shown in FIG. 5A, the focal spot diameter D ₀
When the track W and the width W _{0 of the} track T match, FIG.
By the passage of the light beam as shown in FIG. 5B (indicated by the dotted line in the figure), the written data is almost completely erased as shown in the V section of FIG. 5C.

[0010] In contrast, if the track width W ₁ is large relative to the focal spot diameter D ₁ as shown in FIG. 6 (a), for shaking the tracking servo is large, as shown in FIG. 6 (b) Due to the passage of a light beam (indicated by a dotted line in the figure), data is left behind as shown by the R portion in FIG. 6C. This adversely affects subsequent data recording.

An object of the present invention is to provide a method for reading and writing data accurately even on such storage media having different track widths.

[0012]

According to the present invention, there is provided an optical pickup unit for irradiating an optical storage medium with a light beam, and the optical pickup unit is mounted on a track of the optical storage medium. Pickup drive means for moving in the vertical direction, focus servo drive means for controlling the focal position of the light beam to follow the track,
In an optical storage / reproducing apparatus having a tracking servo drive unit for controlling an irradiation position of the light beam and an optical power drive unit for controlling an irradiation power of the light beam, a track width measurement for measuring a track width of the optical storage medium Means, and a spot diameter changing means for changing a beam spot diameter of the light beam so as to be adapted to the track width measured by the track width measuring means.

By adopting the above configuration, first, a light beam is radiated from the optical pickup to the target optical storage medium, and the light is emitted along the track of the optical storage medium by the focus servo drive means and the tracking servo drive means. Make the pickup follow.

Subsequently, in order to determine an appropriate spot diameter of the light beam in recording / erasing, the track width of the optical storage medium is measured by the track width measuring means to obtain the track width. Here, if the measured track width is not suitable for the focal spot diameter, the spot diameter for recording / erasing is corrected to an appropriate value by the spot diameter changing means.

Further, the present invention is characterized in that there is provided an optical power compensating means for compensating a change in light beam power to the optical storage medium due to a change in a beam spot diameter by the spot diameter changing means. .

In the case of an apparatus for recording and erasing data by utilizing heat generated by condensing a light beam, which is a target of the present invention, if the spot diameter of the light beam is changed, the spot in the spot is changed. Since the amount of heat also changes, it is necessary to compensate for the change. This can be compensated for by the optical power compensation means as described above.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG.
This will be described with reference to FIG. FIG. 1 is a functional block diagram of the optical storage / reproduction device according to the present embodiment. As shown in FIG. 1, an optical pickup 3 that emits a light beam 2 to an optical storage medium 1 includes a pickup driving unit 4, an optical power driving unit 5, a tracking servo driving unit 6, and a focus servo driving unit 7. It is connected. The optical power driving means 5 is connected to the optical power compensating means 8, the tracking servo driving means 6 is connected to the track width measuring means 9, and the focus servo driving means 7 is connected to the spot diameter changing means 10.

Each of the above units is connected to a main bus 12 extending from the control unit 11. In the figure, reference numeral 13 denotes a memory.

The operation of the optical storage / reproduction device having the above configuration will be described below. First, automatic measurement is performed by the track width measuring means 9 for measuring the track width of the optical storage medium 1. This measuring method follows the following algorithm.

While the focus servo is driven by the focus servo driving means 7, the tracking servo driving means 6 stops driving the tracking servo.

The pickup driving means 4 moves the optical pickup 3 in one direction at a constant speed.

The track width measuring means 9 counts the number of tracks based on a tracking error signal obtained by processing the output signal from the optical pickup 3 by the tracking servo driving means 6.

After a certain time has elapsed, the pickup driving means 4 stops the movement of the optical pickup 3.

The track width is calculated. The calculation formula of the track width at this time is calculated as follows.

Track width = (moving time × pickup moving speed) / track number The tracking error signal is as shown in FIG. 2 when the focus servo is driven and the tracking servo is not driven.
One amplitude (for example, C in the figure) corresponds to one track.
As described above, it is possible to obtain a track width for an arbitrary medium.

Next, the spot diameter is adapted to the above-described measured track width. Of course, when the track width is smaller than the focal spot diameter, no access is required. Holds.

Track width ≦ reproduction diameter (focal spot diameter) ≦ recording / erasing diameter To change the light beam to a recording / erasing light beam spot diameter suitable for the measured track width while satisfying the above relationship, This is realized by shifting the focus by the diameter changing means 10. At this time, the amount of change in the focus focal position for obtaining the target spot diameter is calculated as follows.

Focus position change amount = target spot diameter × (focal length / lens diameter) The spot diameter changing means 10 shifts the focus position of the focus by inputting the calculated focus position change amount to the focus servo drive means 7. Set the target spot diameter.

As a simpler method of changing the spot diameter, the following means can be used. When the difference between the spot diameter D and the track width W is large as shown in FIG. 3 in a state where the servo is driven by the focus servo driving means 7 and the tracking servo driving means 6,
The servo is driven in a state where the light beam spot is largely shaken. If the focus is gradually shifted from this state, the amplitude of the servo gradually decreases, and an appropriate recording / erasing spot diameter can be obtained at the position where the amplitude is smallest as shown in FIG.

Also, at the time of reproduction, as in the case of storing / erasing, there are cases where the reliability of reproduced data is higher when a reproduction diameter suitable for the track width is used. In this case, there is no problem if the data is reproduced only by the intensity of the reflected light, but if the data is reproduced using the rotation of the light deflection surface as in the magneto-optical method of the present example. In the method of shifting the focus, there is a possibility that data cannot be correctly reproduced due to a phase mismatch or the like.

Therefore, in this case, it is necessary to use a method that does not affect the reproduction of data by using an aperture as the spot diameter changing means 10 or the like.

Incidentally, in the case of the magneto-optical method, in recording / erasing data, the perpendicular magnetization film is partially heated to a Curie point or higher by irradiating a light beam, and the magnetic field in that portion is inverted to perform bit recording.

Therefore, the apparatus is designed to obtain a temperature higher than the Curie point at the focal spot diameter, and the temperature changes when the spot diameter is changed by recording / erasing. In the present embodiment, this temperature change is compensated for by the optical power compensating means 8. When the spot diameter is changed by such a method, the compensation power P is obtained by the following equation.

Compensation power P = power p of focal spot diameter
× (changed spot radius D ′ / focal spot radius D) ⁻² The compensation power P is input to the optical power driving means 5 and adjusted to an optical power suitable for the spot diameter.

Of course, it is not possible to change the recording / erasing spot diameter so as to exceed the upper limit of the output power of the optical pickup 3.

As described above, according to the present invention, the recording / erasing spot diameter corresponding to each optical storage medium having an arbitrary track width is selected, and more accurate data recording / reproducing becomes possible.

[0037]

As described above, the optical storage / reproduction apparatus of the present invention first measures the track width of the optical storage medium,
By comparing the focal spot diameter with the track width,
Judgment is made as to whether or not the storage medium is suitable for the performance of the apparatus. If not, the spot diameter of the light beam is changed to record data at an appropriate spot diameter for an arbitrary track width.・ Can be erased. As a result, data can be recorded / reproduced more accurately.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of an optical storage / reproduction device according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a tracking error signal in FIG. 1;

FIG. 3 is a diagram illustrating a spot trajectory when a track width is wider than a spot diameter of a light beam.

FIG. 4 is a diagram showing a spot trajectory when a spot diameter of a light beam and a track width are matched.

FIGS. 5A, 5B, and 5C are diagrams for explaining a process of erasing data on a track; FIGS.

FIGS. 6A, 6B, and 6C are diagrams for explaining a process of erasing data on a track; FIGS.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical storage medium 2 Light beam 3 Optical pickup 4 Pickup driving means 5 Optical power driving means 6 Tracking servo driving means 7 Focus servo driving means 8 Optical power compensating means 9 Track width measuring means 10 Spot diameter changing means

Claims (2)

[Claims] An optical pickup unit for irradiating the optical storage medium with a light beam; a pickup driving unit for moving the optical pickup unit in a direction perpendicular to a track of the optical storage medium; and a focus of the light beam. An optical storage / reproducing system comprising: focus servo drive means for controlling a position to follow the track; tracking servo drive means for controlling an irradiation position of the light beam; and optical power drive means for controlling an irradiation power of the light beam. In the apparatus, a track width measuring unit that measures a track width of the optical storage medium, and a spot diameter changing unit that changes a beam spot diameter of the light beam so as to match a track width measured by the track width measuring unit. An optical storage / reproduction device characterized by comprising: 2. The apparatus according to claim 1, further comprising an optical power compensator for compensating a change in a light beam power to the optical storage medium when the beam spot diameter is changed by the spot diameter changer. The optical storage / reproducing device according to claim 1.