JPS59117739A - Optical storage device - Google Patents

Abstract

PURPOSE:To correct the difference in the duty ratio on a medium and to improve the error margin at reproduction by detecting the relative speed between a recording medium and a recording head, and controlling the duty ratio of a recording data and performing recording. CONSTITUTION:A delay signal (b) having an optimum delay time TDI is selected corresponding to a relative speed from n-set of delay signals by a relative speed signal in a selecting circuit 5. On the other hand, the turning speed of a recording medium 11 is detected by a turning speed detecting circuit 13, and a relative speed calculating circuit 14 calculates a product between this turning speed and a radius of a disc obtained from a track position signal, i.e., relative speed, which becomes the relative speed signal and is inputted to the selecting circuit 5. If the delay time TDI is set so as to correct the difference in the duty ratio by this relative speed signal, the error margin at reproduction is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical storage device that records or reproduces digital information onto or from a recording medium by optical means, and particularly relates to an optical disk device that uses 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 source, it is focused on an extreme spot using an optical lens and the light energy is used to generate a recording medium. Information is recorded by forming bits thereon.

During this recording, in the case of the MF'M recording modulation method, the first
As shown in the figure, since the information lies at the boundary between the presence and absence of each bit, it is important to form hits at precise positions.

However, now the interval between the presence or absence of bits in the recorded data is 1:I.
Even with a duty ratio of 50, which corresponds to The actual duty ratio on the medium is subject to change due to changes in power.

Particularly in optical disk devices, a mechanism that rotates a disk-shaped medium at a constant rotation speed is widely used. Since the speeds are different, as shown in the experimental example of FIG. 2, a shift in the siddy ratio occurs due to movement of the track position.

Such a shift in the duty ratio causes a shift in the data position during reproduction, that is, a focus shift and a decrease in the phase margin. However, since conventional devices of this type often target image information as recorded information, the required error rate is relatively low, and FfV, which has a large data discrimination margin, is used as a recording modulation method.
Since the I method was widely used, the above-described shift in duty ratio did not pose a particular problem in terms of error margin.

However, in recent years, it has come to be used as a file device for digital information processing, and a high error rate is required.
There is a tendency for the FM method to be used. In the MFM method, F
Compared to the M method, it has the advantage of being able to record twice as much information when the minimum bit length is the same, but since the data discrimination window during playback is halved, the bit shift due to the above-mentioned duty ratio difference is large in terms of margin. I'm sorry for taking up the weight. Therefore, it has been difficult to obtain a sufficient error rate using the conventional method that does not particularly correct the deviation in the data ratio.

An object of the present invention is to provide an optical storage device that reduces focus shift and obtains a high error rate by correcting data ratio deviations caused by changes in the 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, in an optical storage device that records digital information on a recording medium using optical power, means for detecting the relative speed of the recording head and the recording medium, and means for changing the recording timing of recorded data. An optical storage device that controls the recording timing to change the duty ratio of recorded data according to changes in relative speed, and corrects and records shifts in duty ratio on a medium caused by changes in relative speed. can get.

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

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 delay circuit that delays information from the modulation circuit 3, a select circuit 5 that selects and selects the delayed information, and a circuit 5 that selects and selects information from the modulation circuit 3. An OR circuit 6 that passes information from the circuit 5, a constant current supply circuit 8, a current switch circuit 7 that controls a constant current by a signal from the OR circuit 6, a recording head 9 including a laser diode 10, and the recording head. 9, a disk rotation drive circuit 12 that rotates the medium 11, a rotation speed detection circuit 3 that detects the rotation speed, and a relative speed based on the track position signal and the rotation speed. and a relative speed calculation circuit 14 that calculates the relative speed.

Figure 4 is an operational waveform diagram of the embodiment in Figure 3 (a).
-(d) show waveforms corresponding to those in FIG. In FIG. 4, recording information is first supplied to the recording modulation circuit 3, where it is converted into a waveform suitable for the recording format on the medium and becomes a recording signal (a). Although the waveform of this recording signal (a) indicates that the recording modulation method is the MFM method, it is not particularly limited to this method.

Next, the recording signal (a) is input to the delay circuit 4, where it becomes a signal having n different delay times. In the select circuit 5, the delay signal (bl) having the optimum delay time TDI corresponding to the relative speed is selected from among the n delay signals corresponding to the relative speed signal.Next, the recording signal fa) and the delay signal ( b) is logically summed by the OR circuit 6 and becomes the recording drive signal (
C). The recording drive signal (C) has a pulse width on the positive polarity side greater than that of the recording signal (a) by 'l' DI.
It is a waveform in which the pulse width on the negative polarity side is smaller by TDI, that is, the duty ratio changes by TDI between positive and negative polarities.

Based on this recording drive signal (C), the current switch circuit 7 switches the current LD from the constant current supply circuit 8, and the switching current output (d) is supplied to the laser diode 10 in the recording throat 9. Ru. The laser diode emits light due to this current, and the optical output of the laser diode is focused by the optical lens of the recording head and irradiated onto the recording disk medium 11. At this time, recording disk medium 1
Since the disk 1 is rotated by the drive of the disk rotation drive circuit 12, bits 2 as shown in FIG. 1 are formed on the medium by optical output, and information is recorded. On the other hand, the rotation speed of the recording disk medium 11 is detected by the rotation speed detection circuit 13, and the relative speed calculation circuit 14 calculates the product of this rotation speed and the disk radius obtained from the track position signal, that is, the relative speed, and generates a relative speed signal. This is manually input to the aforementioned select circuit 5. Therefore, if the delay time TD is set so that the deviation in the duty ratio shown in Fig. 2 is corrected using this relative speed signal, the deviation in the duty ratio due to the relative speed can be corrected by the recording drive signal. This is canceled out by the duty ratio shift in (C), and bits with the correct duty ratio are formed on the medium.

In the above embodiment, the relative speed is detected as the product of the disk rotation speed and the disk radius obtained from the track position signal, since the disk rotation speed ty is applicable to the case where the disk rotation speed ty can change. When the disk is rotating at a constant rotational speed, the relative speed is determined only by the disk radius obtained from the track position signal, so the track position signal can be used as the relative speed signal.

As explained above, the present invention detects the relative speed between the recording medium and the self-recording head [-1]. −
This has the effect of correcting the deviation in the tee ratio and improving the error margin during initialization.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the +E relationship between recorded data and bits on the medium, FIG. 2 is a diagram showing the shift in data ratio due to relative speed, and FIG. 3 is a block diagram showing an embodiment of the present invention. FIG. 4 is an operational waveform diagram according to FIG. 3. 1...Record data, 2...Bit, 3...
...Recording modulation circuit, 4P/delay circuit, 5...
...Select circuit, 6...OR circuit, 7...
... Current switch circuit, 8 ... Constant current supply circuit, 9 ... Recording head, 10 ... Laser diode, 11 ... Recording disk medium, 12
... Disk rotation drive circuit, 13 ... rotation speed detection circuit, 14 ... relative speed meter output circuit.

Claims (2)

[Claims] (1) An optical storage device that records digital information on a recording medium using optical power, which has means for detecting the relative speed of the recording head and the recording medium, and means for changing the recording timing of recorded data. An optical storage device that performs recording while controlling recording timing to change the duty ratio of recorded data in accordance with changes in speed. (2) The relative speed detection means is arranged in the radial direction of the disk.