JPH03241550A - Magneto-optical information device - Google Patents

Abstract

PURPOSE:To improve reliability by performing a phase comparison with a leading edge or a trailing edge of a binarized regenerative signal and generating a synchronous clock for detecting the regenerative signal synchronized with the leading edge or the trailing edge. CONSTITUTION:The synchronous clock (c) in synchronization with the leading edge is obtained by a PLL circuit 2 for performing the phase comparison of the leading edge of the regenerative signal (b). Thus, the clock having a period of 0.5 times as much as a edge shift amt. is obtained. Then, by utilizing the clock (c), the signal (b) is latched in using a D-FF 3, and a latch signal (d) having one period of the synchronous clock as equivanent to the edge shift amt. is obtained. Then, a shift register output (e) delayed by one period of the clock (c) is obtained by a one-bit shift register 4 fromthe signal (d). By logically multiplying this output (e) and the signal (d) with an AND circuit 5, the edge shift amt. is offset, and a reproducing data (f) is obtained to be faithful to the recording signal. By this method, an error rate in reproducing data can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magneto-optical information device using magneto-optic effect, and in particular to a magneto-optical information device that uses a high-frequency magnetic field of a single frequency to record information on a magneto-optical recording medium. The present invention relates to a technique for correcting edge shift of a reproduced signal during reproduction.

[Prior Art] Magneto-optical information devices are expected to be used as large-capacity external storage devices for information processing devices. FIG. 3 is a diagram showing the configuration of an overridable device of this magneto-optical information device,
In the figure, numeral 31 indicates a magneto-optical disk, and the magneto-optical disk 31 is rotationally driven by a spindle motor 32. Information is recorded and reproduced on the magneto-optical disk 31 by an optical pickup 33. The optical pickup 33 has a built-in semiconductor laser diode 34 as a light source, and the light emitted from the semiconductor laser diode 34 is transmitted through a collimator lens 35 and a beam splitter 6a.
, and is focused on the magneto-optical disk 31 by the objective lens 7. On the other hand, the light reflected by the magneto-optical disk 31 passes through the objective lens 7 again, is separated from the incident light by the beam splitter 6a, and is further split into two by the beam splitter 6b, one of which is sent through the sensor lens 8a. light sensor 9
The light is received at a. Then, based on the output of the optical sensor 9a, A
The T/AF control circuit 10 detects focus and tracking error signals, inputs the error signals to the actuator 11, and drives the objective lens 7, thereby performing auto-tracking and auto-tracking. The other light that was split into two by the beam splitter 6a is further split into two by the beam splitter 6C.
Each light passes through the sensor lenses 8b and 8c to the optical sensor 9.
The light is received by the optical sensors 9b and 9c, and a difference signal between the signals from the optical sensors 9b and 9c is taken, and a reproduced signal is obtained by the binarization circuit 1. Also, the magnetic field H applied to the magneto-optical disk 31 during recording
e is connected to the reference oscillation circuit 1 by the magnetic head drive circuit 14.
A high-frequency magnetic field with a single frequency is applied by the magnetic head 15 which is driven in synchronization with a constant frequency reference signal generated in step 3. Also, at this time, the laser drive circuit 1
6 is the polarity of the magnetic field generated by the magnetic head 15 that corresponds to the bit information of the recording signal in synchronization with a reference signal of a constant frequency generated by the reference oscillation circuit 13, and by causing the laser to emit light in a pulsed manner. Desired data can be recorded on the magneto-optical disk 31.

[Problems to be Solved by the Invention] Figure 4 shows that in a conventional device, as a recording signal, the period of the reference signal (a) is T, and the bit information of the recording signal (c) is repeating information of a 3T pattern. FIG. 3 is an explanatory diagram of a recording/reproduction signal at the time of the recording and reproduction, and will be explained below with reference to FIGS. 4 and 3. FIG.

An alternating current magnetic field (b) is applied to the magneto-optical recording medium 31 by the magnetic head 15 in synchronization with the reference signal (a) output by the reference oscillation circuit 13. At this time, the recording signal (c)
With the polarity of the AC magnetic field (bl) corresponding to the bit information, the semiconductor laser diode 34 is
Since the pulse lighting is performed as shown in FIG. 2, the laser pulse irradiation interval is not constant, and the phase of the pulse timing shifts when the recording signal (c) changes. Therefore, the pattern recorded on the magneto-optical recording medium is as shown in Fig. 4(e).
It becomes as shown in . As shown in (f), when the information of this recording pattern (e) is read out, the reproduction signal (f) has a duty ratio even though the recording signal (c) has a single frequency. It will shift.

In other words, in the conventional device, the edges of the reproduced signal (f) are 0,
This results in a 5T shift, which poses a problem in that the error rate of the reproduced signal increases and the reliability of the recording/reproducing apparatus is significantly reduced.

Furthermore, since the edge shift amount e1 differs depending on the device, there is also a problem that data compatibility between devices cannot be guaranteed.

[Means and effects for solving the problems] The present invention, as a means for solving the above-mentioned problems, applies a high-frequency alternating current magnetic field of a single frequency to a magneto-optical recording medium, and also applies a high-frequency AC magnetic field corresponding to a recording signal. A laser beam modulated in synchronization with the alternating current magnetic field is irradiated onto the magneto-optical recording medium, thereby performing a phase comparison of a rising edge or a falling edge of a reproduced signal in a magneto-optical information device that performs recording; means for generating a synchronized clock for detecting the reproduced signal with an edge shift amount of 0.5 cycles; means for latching the reproduced signal using the synchronizing clock; It is characterized by comprising means for delaying by one period of a clock, and means for calculating an AND of a delay signal outputted from the delaying means and the latch signal, and correcting an edge shift of the reproduced signal. The present invention provides a magneto-optical information device.

According to the present invention, phase comparison is performed at the rising edge or falling edge of the binarized reproduced signal, and a synchronization clock for detecting the reproduced signal synchronized at the rising edge or falling edge is generated. amount to 0
．． A synchronous clock with 5 cycles can be obtained. By latching the reproduced signal using this synchronization clock, it is possible to obtain a latch signal whose edge shift amount corresponds to one period of the synchronization clock. Therefore, by obtaining a delay signal delayed by one period of the synchronization clock from this latch signal and performing a logical product of the latch signal and the delay signal, it is possible to obtain a reproduced signal that cancels out the edge shift amount.

[Embodiment] FIG. 1 is a block diagram showing the configuration of an embodiment of a magneto-optical information device of the present invention. Further, FIG. 2 shows a timing diagram of the apparatus shown in FIG. 1. In addition, in FIG. 1, an optical pickup 33 inputs a signal to the binarization circuit l.
etc. are the same as those of the conventional example shown in FIG. 3, so the same numbers are given and explanations are omitted. Hereinafter, a detailed explanation of the present invention will be given with reference to FIGS. 1 and 2.

A reproduction signal of the information recorded on the magneto-optical recording medium 31 can be obtained by the binarization circuit shown in FIG. 1 in the same manner as in the conventional apparatus shown in FIG. 3 described above (FIG. 2(b)). In the reproduced signal shown in FIG. 2(b) obtained at this time, the falling edge is shifted by el compared to the original recorded signal (FIG. 2(a)), as in the conventional example.

In this embodiment, a synchronization clock (c) which is synchronized at the rising edge of the reproduced signal (bl) is obtained by a rising PLL circuit 2 which performs phase comparison at the rising edge of the reproduced signal (bl).

As a result, a clock with an edge shift amount e1 of 0.5 period is obtained.

Next, using this synchronization clock (c), the D-flip-flop 3 is used to latch the reproduced signal (b), and the latch signal ( d).

In addition, the 1-bit shift register 4 outputs the latch signal (d
) to obtain a shift register output (el) delayed by one period of the synchronization clock (C).

This shift register output (e) and the latch signal (d)
By performing a logical product with the AND circuit 5, the edge shift amount e1 is canceled, and reproduced data ff) faithful to the recording signal (a) can be obtained.

In this embodiment, phase comparison is performed at the rising edge of the reproduced signal (b), and the synchronization clock (c) is synchronized at the rising edge.
However, even if we obtain a synchronized clock that synchronizes at the falling edge, the edge shift amount e1
A clock having a period of 0.5 can be obtained.

[Effects of the Invention] As explained above, according to the magneto-optical information device according to the present invention, it is possible to correct the edge shift of the reproduced signal, so the error rate of the reproduced data can be improved, and the magneto-optical information device according to the present invention This has the effect of greatly increasing the reliability of information devices.

In addition, regarding device compatibility of magneto-optical information devices, even if the edge shift amount differs depending on the device, data compatibility is guaranteed because it is equipped with a means to generate synchronized clocks with respective edge shift amounts of 0 and 5T. It has the effect of being

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a magneto-optical information device according to the present invention. FIG. 2 is a waveform diagram illustrating the operation of FIG. 1. FIG. 3 and FIG. 4 are a block diagram of a conventional magneto-optical information device and a waveform diagram illustrating its operation, respectively. 1... Binarization circuit 2... Rising PLL circuit 3.
...D-flip-flop 4...1-bit shift register 5...AND circuit 31...magneto-optical disk 32
...Spindle motor 33...Optical pickup 34...Semiconductor laser diode

Claims (1)

[Scope of Claims] A high-frequency alternating current magnetic field with a single frequency is applied to the magneto-optical recording medium, and a laser beam corresponding to a recording signal is modulated in synchronization with the alternating magnetic field to affect the magneto-optical recording medium. In a magneto-optical information device that performs recording by irradiation, a phase comparison is performed between a rising edge or a falling edge of a reproduced signal, and a synchronization clock for detecting the reproduced signal with an edge shift amount of 0.5 cycle is generated. means for latching the reproduction signal with the synchronization clock; means for delaying the latch signal output from the latching means by one period of the synchronization clock; and a delay output from the delay means. What is claimed is: 1. A magneto-optical information device comprising means for calculating an AND of a signal and the latch signal, and correcting an edge shift of the reproduced signal.