JPH06195786A - Magneto-optic disk reproducer - Google Patents

Abstract

PURPOSE:To detect an ID signal without being subject to the effect of the saturation of a circuit system regarding a magneto-optic disk reproducer reproducing information edge-recorded in a magneto-optic disk. CONSTITUTION:An ID signal is detected by a first detecting section 34 in a circuit band proper to ID while an MO signal is detected by a second detecting section 35 in a circuit band smaller than the circuit band from the first detecting section 34 regarding a regenerative waveform read by an optical head 33 from a magneto-optic disk 32, in which ID and MO are recorded in mark length recording. The ID signal and the MO signal are changed over and reproduced and demodulated respectively by a reproducing demodulating section 36.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical disk reproducing apparatus for reproducing information edge-recorded on a magneto-optical disk.

In recent years, magneto-optical disk devices have been increased in capacity.
Due to variability and high reliability, it has been widely spread from recording / reproducing image information to recording / reproducing computer code information. Therefore, it is necessary to reliably reproduce even in different signal systems.

[0003]

2. Description of the Related Art FIG. 3 is a block diagram of a conventional magneto-optical disk reproducing apparatus. In FIG. 3, information is recorded on the magneto-optical disk 12 used in the magneto-optical disk reproducing apparatus 11 at the position intervals of the edges of magnetic domains having different magnetization directions corresponding to the recording data.

From the magneto-optical disk 12, the optical head 1
The detector 3 reads the ID signal such as address data and the MO signal of user data, and converts the reproduced waveform of current into a voltage waveform.

The ID signal is adjusted in gain by the summing amplifier 14 and sent to the multiplexer 16. The MO signal is adjusted in gain by the differential amplifier 15 and sent to the multiplexer 16.

In the multiplexer 16, the GA from the higher order
ID and MO are selected by the TE signal, and the selected signal (ID or MO) is output to the AGC (auto gain controller) 17, the equalizer 18, and the low-pass filter 19.
, Pulsed by the pulse detector 20 and shaped by the pulse shaver 21, and VFO (variable frequency oscillator)
Decoder 2 extracts data synchronized with the clock at 22
3 is demodulated.

By the way, no problem occurs when recording is performed between the marks (short holes) on the magneto-optical disk 12 by the above-described recording method, but the mark length (long hole) is improved to improve the recording density.
When recorded, since the edge portion of the recording pit has a meaning, if the baseline shift in which the reference voltage for slice level detection fluctuates occurs, the edge position cannot be accurately reproduced.

FIG. 4 shows a diagram for explaining the conventional baseline shift. FIG. 4A shows a recording pattern of MO, which is 2/7 RLCC (Run Length Limitte).
d Code) is coded by a method in which the number of "1" s or "0" s is limited. The long recording pulse length L ₁ (short recording pulse interval T ₁ ) and the short recording pulse length L ₂ (long recording pulse And the interval T ₂ ) are mixed. When reproducing this, the baseline B ₁ does not shift in low frequency coupling as shown in FIG. 4B, but the duty ratio is not 50% in high frequency coupling as shown in FIG. 4C. Shift from baseline B ₁ to B ₂ .

In order to prevent this baseline shift, the circuit band is required up to a low band (ideally DC), and the circuit capacitance Cc in FIG. 3 is increased to lower the cutoff frequency. ing.

[0010]

However, lowering the cut-off frequency is effective for recording the mark length of the MO signal, but when erasing or recording a certain sector and reading the next ID signal, the erasing or recording is performed. Since the power at the time is large, the reflected light also becomes large, and a large signal is sent from the detector of the optical head, and the circuit system is saturated. That is, since the circuit capacitance Cc is increased, the saturation of the circuit system remains until the next ID signal is read, and the ID signal cannot be read after all.

The present invention has been made in view of the above problems, and an object thereof is to provide a magneto-optical disk reproducing apparatus for detecting an ID signal without being affected by the saturation of the circuit system.

[0012]

FIG. 1 is a block diagram showing the principle of the present invention. In the magneto-optical disc reproducing apparatus 31 of FIG. 1, reference numeral 32 denotes a magneto-optical disc, in which information data necessary in the data reproducing process are recorded at irregular pit position intervals or edge intervals, and the magnetization corresponding to the recorded data is recorded. Information is recorded at the position intervals of the edges of magnetic domains having different directions.

Reference numeral 34 is a first detector, which is the optical head 3
The information data is detected in the predetermined circuit band from the reproduced waveform from 3. A second detector 35 detects the recorded data from the reproduced waveform from the optical head in a circuit band different from that of the first detector 34. A reproduction / demodulation unit 36 switches the information data and the recording data from the first and second detection units 34 and 35 and demodulates them.

[0014]

As shown in FIG. 1, the first and second detectors 3
4 and 35, the information data detection and the recording data detection are separated, and a circuit band suitable for each signal is provided. This makes it possible to accurately read information data immediately after erasing or recording without interfering with each other's signals without being affected by the saturation of the circuit system, and also to perform a baseline shift when reading the recording data. Can be removed.

[0015]

FIG. 2 shows a block diagram of an embodiment of the present invention.
In FIG. 2, the magneto-optical disk reproducing device 31 is composed of a magneto-optical disk 32, an optical head 33, first and second detecting units 34 and 35, and a reproducing / demodulating unit 36, as in FIG.

In the magneto-optical disk 32, information data (ID) such as an address necessary for the data reproducing process is previously stored in the ID portion.
Is recorded, and the recording data (MO) is recorded in the MO section at any time.
Erased. This MO recording is performed by mark length recording in which marks are formed between data at the position intervals of the edges of magnetic domains having different magnetization directions corresponding to respective data. It is also possible to perform mark-to-mark recording in which the same mark is formed for data.

The optical head 33 irradiates the magneto-optical disk 32 with a light beam, receives the reflected light corresponding to the data by the detector, and converts the current waveform into the voltage waveform to detect the reproduced waveform as the first and second detections. It is sent to the units 34 and 35.

The first detector 34 detects an ID, and includes a summing amplifier 41, an AGC 43a and an equalizer 44.
a, a filter 45a, a pulse detector 46a, and a pulse shaper 47a. In this case, the circuit capacitance Cc is set so that the circuit band has a cutoff frequency in a high band (several KHz).

The second detector 35 detects MO, and includes a differential amplifier 42, an AGC 43b, and an equalizer 44.
b, a filter 45b, a pulse detector 46b, and a pulse shaper 47b. In this case, the circuit band is configured to have a band up to DC.

That is, the high-frequency cutoff frequency of the first detection section 34 is higher than the low-frequency cutoff frequency of the second detection section 35, so that the first detection section 34 is in the high frequency range and the second detection section 35 is in the high frequency range. The detection unit 35 of is set to the low frequency range.

The reproducing / demodulating section 36 is composed of a multiplexer 48 for switching by a gate signal from the outside, a VFO 49, and a decoder 50.

Next, the above-mentioned magneto-optical disk reproducing device 31.
The reproduction operation of will be described.

First, the reproduced waveform from the optical head 33 is
It is amplified by the summing amplifier 41 of the first detector 34 and
D signal is detected. The ID signal is gain-controlled by the AGC 43a at a cutoff frequency determined by the circuit capacitance Cc and is equalized by the equalizer 44a. This is taken out at a predetermined frequency by a filter (low-pass filter) 45a, a pulse waveform is formed by a pulse detector 46a, shaped into a rectangular pulse by a pulse shaper 47a, digitized, and sent to a multiplexer 48 of the reproduction / demodulation unit 36. On the other hand, the reproduced waveform from the optical head 33 is amplified by the differential amplifier 42 of the second detector to detect the MO signal. This MO signal is transmitted to the AGC 43 similarly to the first detector 34.
b, equalizer 44b, filter (low-pass filter)
45b, pulse detector 46b, pulse shaper 47
It is digitized by b and sent to the multiplexer 48.

The multiplexer 48 uses the pulse shaper 4
The ID signal sent from 7a and the MO signal sent from the pulse shaper 47b are selected according to the gate signal, and V
The data supplied to the FO 49 and synchronized with the clock is sent to the decoder 50 for demodulation.

By separately handling the ID signal and the MO signal in this way, it is possible to match the bands suitable for the respective detection systems, and thereby the baseline shift can be removed in the MO signal detection system. The ID signal detection system can avoid an ID signal undetectable state due to saturation of the detection circuit.

In the above embodiment, the multiplexer 4
Although 8 is provided in the latter stage of the pulse shapers 47a and 47b, the multiplexer 48 is provided in the latter stage of the pulse detectors 46a and 46b and the pulse shapers 47a and 47b are provided in the latter stage. It plays.

[0027]

As described above, according to the present invention, the first and second detectors separate the information data detection and the recording data detection and provide a circuit band suitable for each signal. , It is possible to accurately read the information data immediately after erasing or recording without interfering with each other's signals without being affected by the saturation of the circuit system, and to eliminate the baseline shift at the time of reading the recording data. Is something that can be done.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is a configuration diagram of an embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional magneto-optical disk reproducing apparatus.

FIG. 4 is a diagram for explaining a conventional baseline shift.

[Explanation of symbols]

 31 magneto-optical disk reproducing device 32 magneto-optical disk 33 optical head 34 first detecting section 35 second detecting section 36 reproduction demodulating section 41 summing amplifier 42 differential amplifier 43a, 43b AGC 44a, 44b equalizer 45a, 45b filter 46a , 46b Pulse detector 47a, 47b Pulse shaper 48 Multiplexer 49 VFO 50 Decoder

Claims (4)

[Claims] 1. A necessary direction data (ID) recorded on a magneto-optical disk (32) at uneven pit position intervals or edge intervals in a data reproducing process is read, and a magnetization direction corresponding to the recorded data (MO) is read. Information is recorded at the edge position intervals of different magnetic domains, and at the time of reproduction, the edge position intervals are detected from the reproduced waveform to detect the recorded data (M
In a magneto-optical disk reproducing apparatus for reading out O), a first detection unit (34) for detecting the information data (ID) from the reproduced waveform in a predetermined circuit band, and the recorded data (MO) from the reproduced waveform. A second detection section (35) for detecting in a circuit band different from that of the first detection section
And a reproduction demodulation unit (36) for switching the information data (ID) and the recording data (MO) from the first and second detection units (34, 35) and demodulating each of them. Magneto-optical disk reproducing device. 2. The high cutoff frequency of the circuit of the first detector (34) is set to be higher than the low cutoff frequency of the circuit of the second detector (35). The magneto-optical disk reproducing apparatus according to claim 1. 3. The light according to claim 1, wherein the circuit band of the first detector (34) is set to a high band and the circuit band of the second detector (35) is set to a low band. Magnetic disk player. 4. The information recorded on the magneto-optical disk (32) is recorded by at least one of mark interval recording in which marks are the same for data and mark length recording in which marks are formed between data. The magneto-optical disk reproducing apparatus according to claim 1, wherein