JPS59117743A - Optical storage device - Google Patents

Abstract

PURPOSE:To improve the error margin by providing a means detecting the relative speed between a recording head and a recording medium and a means changing optical power, and controlling the circuit so as to change optical power in response to the change in the relative speed for attaining recording. CONSTITUTION:The optical storage device has a circuit 3 domulating recording information, current switch circuit 4 operated based on the information from the circuit 3, D-A converting circuit 5 converting a relative speed signal into an analog signal, and a current supply circuit 6 or the like whose current is controlled by the analog signal and in which the current is applied to the current switching circuit 4. The difference in the duty ratio on the medium is corrected and the error margin at reproduction is improved by controlling the recording power and attaining recording with the constitution above.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical storage device for recording and reproducing digital information on a small recording medium by optical means, and particularly to an optical disk device using a disk-shaped recording medium.

In optical storage devices such as optical disk devices, a laser light source such as a semiconductor laser is used as the light source. After modulating the laser light, it is focused into a very small spot using an optical lens, and the light energy is used to write the light onto the recording medium. Information is recorded by forming bits. In this recording, in the case of the MFM recording modulation method, as shown in FIG. 1, information is located at the boundary between the presence and absence of each bit, so it is important to form the bits in accurate positions. However, even if recorded data now has a duty ratio of 50, which corresponds to a 1:1 focus interval, when this data is recorded, the formation of bits depends on the recording energy as well as the characteristics of the recording medium. Therefore, the actual duty ratio on the medium changes due to changes in the relative speed between the recording head and the recording medium and the recording power.

Particularly in optical disk devices, a mechanism that rotates a disk-shaped recording medium at a constant rotational speed is widely used.In this case, the relative speed varies depending on the recording area called a track provided concentrically in the radial direction of the disk. Therefore, as shown in the experimental example shown in FIG. 2, the shift in the track position causes a shift in the duty ratio. Such a shift in duty ratio results in a shift in the data bit position during reproduction, that is, a bit shift, and becomes a factor that reduces the phase margin. However, since most of the conventional Kaba devices recorded image information, the required error rate was relatively low, and the FM method, which has a large data discrimination margin, was widely used as the recording modulation method. The above-mentioned deviation in the tutee ratio did not pose a particularly important problem in terms of error margin. However, in recent years, as it has come to be used as a file device for digital information processing, a high error rate is required, and there is a trend toward using the M and FM systems, which have high recording efficiency, as recording modulation systems. Compared to the F iM method, the M P''M method has the advantage of being able to record twice as much information when the binocular length is the same, but the data discrimination window during playback is halved, so the data Bit shifts due to deviations in the tee ratio play a large role in the margin.

Therefore, it has been difficult to obtain a sufficient error rate using conventional methods that do not particularly correct the shift in duty ratio.

An object of the present invention is to provide an optical storage device that reduces bit shifts and obtains a high error rate by correcting data ratio deviations caused by changes in relative speed between a recording head and a recording medium in conventional devices. Our goal is to provide the following.

According to the present invention, an optical storage device for recording digital information on a recording medium using optical power includes means for detecting the relative speed of the recording head and the recording medium, and means for changing the optical power, By controlling the optical power to increase as the speed increases, it is possible to obtain an optical storage device that corrects and records a discrepancy in the data ratio on the medium due to a change in relative speed.

Further, according to the present invention, an optical storage device is obtained in which the relative speed detection means obtains the speed in the radial direction of the disk from the given track position information.

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 3 shows an embodiment of the invention. In FIG. 3, this embodiment includes a circuit 3 that modulates recorded information, a current switcher circuit 4 that operates based on information from the modulation circuit 3,
A DA converter circuit 5 that converts the relative speed W<y into an analog signal; and a current supply circuit 6 in which current is controlled based on the signal from the DA converter circuit 5 and is supplied to the current switch circuit 4. , the current from the current switch circuit 4 is supplied,
A recording head 7 that writes on a recording medium 9 by light emission from a laser diode 8, a disk rotation drive circuit 10 that rotates the recording medium 9, a rotation speed detection circuit 11 that detects the rotation speed of the disk, and a rotation speed detection circuit 11 that detects the rotation speed of the disk. and a relative speed calculation circuit 1 that calculates the relative speed based on the track position signal.
2.

FIG. 4 is a waveform diagram for the embodiment shown in FIG.
)) shows the waveform corresponding to that in FIG. The recording information is first supplied to the recording modulation circuit 3, where it is converted into a waveform suitable for the layout format of the medium-H, and becomes a recording signal (a). As shown in FIG. 4, the waveform of this recording signal ta) indicates that the recording modulation method is the MFM method, but it is not particularly limited to this method.

Next, the recording signal (a) is input to the current switch circuit 4, where the current In from the current supply circuit 6 is switched to produce the drive current (b). This drive current (bl) is supplied to the laser diode 8 in the recording head 7 to cause the laser diode 8 to emit light. This optical output is focused by the optical lens of the recording head 7 and then irradiated onto the recording disk medium 9. At this time, since the recording disk medium 9 is being rotated by the drive of the disk rotation drive circuit 10, the optical power of the recording disk medium 9 forms bits 2 on the medium surface as shown in FIG. Recording is done.

On the other hand, the rotation speed of the recording disk medium 9 is detected by the rotation speed detection circuit 11, and the relative speed calculation circuit 12 calculates the product of the disk rotation speed and the disk radius obtained from the track position signal (Cl, that is, the relative speed). This relative speed signal (d) is manually input to the D-A converter circuit 5, where it is converted into an analog voltage proportional to the relative speed.Then, in the flow supply circuit 6, this analog voltage is It operates in such a way that the voltage determines the #)ft current value II).

"Turbulence value ID 1-frame flow (bl is laser diode 8
The recording energy on the medium surface is kept constant as the relative velocity changes. This is the second
The shift in duty ratio shown in the figure does not occur, and pits with the correct duty ratio can be formed on the medium surface.

In this embodiment described above, the relative speed is detected as the product of the disk rotation speed and the disk radius obtained from the track 1 upright signal, since the rotation speed of the disk is variable. If the disk is rotating at a known constant rotational speed, the relative speed can be determined only from the disk radius obtained from the trunk position signal, so the track position signal can also be used as the relative speed signal.

As explained above, the present invention detects the relative speed between the recording medium and the recording head, and controls the recording driver based on this to correct the duty ratio deviation on the medium. , which has the effect of improving the error margin during playback.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between recorded data and pits on the medium.
Figure 2 is a diagram showing the shift in duty ratio due to relative speed.
FIG. 3 is a block diagram showing one embodiment of the present invention, and FIG. 4 is a diagram showing operating waveforms related to FIG. 3. 1...Record data, 2...Pit, 3
... Recording modulation circuit, 4 ... Current switch circuit, 5 ... D-A conversion circuit, 6 ...
・Current supply circuit, 7... Recording head, 8...
. . . Laser diode, 9 . . . Recording disk medium, 10 . . . Disk rotation drive circuit, II.
... Rotation speed detection circuit, 12 ... Relative speed calculation circuit. /-~ Figure 1, mostly 2 figures, 3 figures

Claims (2)

[Claims] (1) An optical storage device that records digital information on a recording medium using optical power, which includes means for detecting the relative speed of the recording head and the recording medium, and means for changing the optical power, and is configured to respond to changes in the relative speed. An optical storage device characterized in that recording is performed by controlling optical power so as to change accordingly. (2) The relative speed detection means applies force in the radial direction of the disk.