JPH08147707A - Precoded data recording device - Google Patents

Abstract

PURPOSE: To select the amplitude and phase characteristic of a data signal to be recorded in a disk so as to improve the opening of an eye pattern. CONSTITUTION: Address section recording data in a preformatted state is supplied to a wave form equalizer 34 to acquire a cosine descending characteristic, and the wave form equalized recording data is supplied to a low-pass phase compensation filter 36 to form a filter output advanced in the low frequency phase and the wave form shaped filter output is recorded as recorded data in a master disk (MO disk). The amplitude phase characteristic of the preformatted data signal recorded in the master disk is selected so as to cancel an amplitude phase characteristic during reproducing and recorded in the disk. Thus, since the phase fluctuation of the low-pas component of a reproducing signal is canceled even when a high-pass filter is provided in a reproducing signal processing system, the eye pattern of the reproducing signal is widened and errors are accordingly reduced when the wave form of the reproducing signal is shaped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precode data recording apparatus suitable for application to a magneto-optical recording medium in which an address portion is recorded as precode data in advance.

[0002]

2. Description of the Related Art In a magneto-optical disk, as shown in FIG. 5A, it is divided into an inner recording area (channel 1) and an outer recording area (channel 2), and one track formed in each recording area. It is composed of a plurality of sectors, for example, 42 sectors. As shown in FIG. 5B, one sector is composed of a precoded address portion (address area) ADD and a recording data write area (data recording portion MO).

In the address part ADD, as shown in FIG. 1B, the sector marker SM is followed by three pieces of address data of the same content.
It is formed repeatedly. The reason for repeating three times is to ensure that the address data can be read even when there is a read error. This address data is composed of VFO data, address marker AM, and identification data ID. A VFO (variable frequency osillator) is a single-frequency signal used for pulling in the operation of the PLL oscillator for clock generation because it generates a reference signal (reference clock). Postamble data PA is recorded following the address data.

All of these address data are precoded data and are formed by pits.
There is a data recording unit MO following the address unit ADD, and a test area is provided at the beginning of this data recording unit MO. ALPC data is recorded in the test area for controlling the power level of the laser diode, and subsequently, VFO data is recorded.

A buffer area (non-recording portion) is provided at the end of the data recording portion MO to clarify the boundary with the address portion ADD. The number of sectors and the number of bytes constituting one sector shown in the figure are merely examples.

To record data on the MO disk 1 and reproduce the recorded data or address data, the MO disk 1 is irradiated with a laser. As is well known, the address data recorded on the MO disk 1 and the laser power for reproducing the recorded data are relatively low, about 1.2 mW, but the laser power required for recording or erasing is about 8-9 mW. And a large value.

When such a laser power is applied, the output current (RO
The reproduction signal) is supplied to the reproduction signal processing circuit 10 shown in FIG. 6 to demodulate recorded data and the like.

In the reproduction signal processing circuit 10, reference numeral 12 is an optical pickup circuit, which has a built-in laser diode (not shown) in addition to the photodiode PD as described above. The reproduction signal is amplified by the preamplifier 14 and then supplied to a waveform equalizer (equalizer) 16 to add a cosine descending characteristic.

This is to reduce intersymbol interference of the reproduced signal within the transmission band and increase the aperture ratio of the eye pattern of the reproduced signal. This is because when the aperture ratio of the eye pattern increases, the waveform shaping error of the reproduction signal decreases and the reproduction signal can be correctly demodulated (decoded). Figure 7 Curve L
a is an example of this cosine descending characteristic La. The horizontal axis of FIG. 7 represents the reproduction frequency f.

A high-pass filter 17 extracts a high-frequency signal from the waveform-equalized reproduction signal, and the high-frequency signal is supplied to a waveform shaper 18. The waveform shaper 18 converts it into a pulse signal according to the data. The waveform-shaped reproduction signal is supplied to the discriminator 22 and also to the PLL circuit 20 to generate a synchronization signal for discrimination. This P
The LL circuit 20 generates a synchronization signal which is synchronized with the basic period of the pulse signal described above, and the synchronization signal becomes a window pulse to discriminate the reproduction signal (pulse signal).

The discriminator 22 forms a detection code string according to the presence or absence of data, and this is supplied to the decoder 24 at the subsequent stage and decoded into a data bit string, that is, a data bit string at the time of recording.

[0012]

However, transients may occur in the reproduced signal depending on the selected operation mode. This is because the laser power applied to the disc greatly differs depending on the operation mode. Incidentally, in the read mode, as described above, the address portion A
In both the DD and the data recording unit MO, the laser power is a constant small power (about 1.2 mW). In the erase mode and the recording mode, the laser power in the data recording section is several times (8 to 9 mW) the laser power in the address section.

In many cases, the above-mentioned high-pass filter 17 is provided in order to reduce the influence of the transient of this operation mode on the demodulation processing. High pass filter 1
When 7 is inserted, the reproduced signal has a group delay characteristic as shown by the curve Lb in FIG. Due to this group delay characteristic, especially the phase of the low frequency component in the reproduced signal is delayed. Due to this phase delay, the aperture ratio of the eye pattern of the reproduction signal deteriorates, which has an effect when converting the reproduction signal into a pulse signal. This is because there is a risk that the original signal may not be pulsed.

FIG. 9A shows an eye pattern of a reproduction signal provided with a cosine descending characteristic. When this passes through the high pass filter 17 and a phase delay of a low frequency component occurs, as shown in FIG. 9B, the aperture ratio of the eye pattern. Is markedly deteriorated. Therefore, it may be difficult to obtain a correct pulse signal with this eye pattern reproduction signal.

Such an eye pattern is generated by recording data (precode data) for the address portion with a normal NRZ or NRZI data string (unmodulated data string) corresponding to "1" or "0". This is because it is used and recorded.

Therefore, for example, such a problem can be solved if the precode data itself to be recorded on the disc is appropriately modulated and recorded in advance. Specifically, if the precode data itself is subjected to signal processing for advancing the phase of the low-frequency component and then recorded on the master disk, the phase delay due to the high-pass filter 17 during reproduction can be canceled. Because.

In view of the above, the present invention has solved the above-mentioned conventional problems, and the precoding data is recorded on the master disk by performing signal processing that does not adversely affect the waveform shaping processing. It proposes a device.

[0018]

In order to solve the above-mentioned problems, in the invention described in claim 1, the data of the address part is set for a magneto-optical recording medium composed of an address part and a data recording part. In pre-coding, the pre-formatted address portion recording data is supplied to the waveform equalizer to provide a cosine descending characteristic, and this waveform equalized recording data is supplied to the low-pass phase compensation filter. Thus, a filter output in which the low-pass phase is advanced is formed, and a waveform of this filter output is shaped and used as precoded data.

[0019]

The operation will be described with reference to FIG.
The pre-format data used as the DD pre-code data (recording data) is given the same cosine descending characteristic as that of the data reproducing system in the waveform equalizer 34. Then, it is supplied to a low-pass phase compensation filter (low-pass filter) 36. The phase of the low-frequency component of the preformatted data signal is advanced by this filter 36 (see the curve Lc in FIG. 8). This pre-formatted data signal is converted into a binary circuit 3
After waveform shaping in 8, the data recording driver 40
And is recorded on a predetermined position of a disc (master disc) (not shown). A replica MO disk is produced from this master disk.

FIG. 2A shows an eye pattern of a precoded data signal, and when a cosine descending characteristic is added to this, an eye pattern as shown in FIG. 2B is obtained. If this is further filtered, the phase of the low-frequency component advances, and the eye pattern at that time becomes as shown in FIG. The aperture ratio of the eye pattern in FIG.

At the time of data reproduction, the phase of the low frequency component is delayed by the high pass filter 17 described above. Therefore, if the phase of the low frequency component of the precode data signal is advanced in advance so as to cancel this phase delay, The eye pattern of the data signal that has passed through the high pass filter 17 is as shown in FIG. 3, and the aperture ratio of the eye pattern is greatly improved. Therefore, if the waveform is shaped using this, it can be converted into a pulse signal according to the reproduction signal.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a case where the precode data recording apparatus according to the present invention is applied to the above-mentioned recording medium for a magneto-optical recording / reproducing apparatus will be described in detail with reference to the drawings.

Also in the present invention, the MO disk 1 having the recording format as shown in FIG. 5A is targeted. Therefore, the structure of the address portion to be precoded is as shown in FIG. 9B, and a data string (precoded data signal) preformatted to be such a data string is supplied to the master disk recording device 30 shown in FIG. It

The pre-formatted data signal (data string) supplied to the input terminal 32 shown in FIG. 1 is first supplied to the waveform equalizer 34 and is given a cosine descending characteristic similar to the curve La of FIG. Therefore, the waveform equalizer 34 is a Nyquist low pass filter, and a well-known transversal filter can be used.

The preformatted data signal provided with the cosine descending characteristic is a low-pass filter 36 for low-frequency phase compensation.
Is supplied to the low frequency component (500 kHz in the figure).
The following phase is advanced by a predetermined amount. By this phase compensation processing, the filter output has characteristics as shown by the curve Lc in FIG. The amount of phase shift (the amount of phase compensation) is selected so that the phase delay generated in the reproducing system can be canceled. A normal RC filter can be used as the low-pass filter 36 for such a phase advance purpose.

The preformatted data signal whose low-frequency phase is compensated has a binarizing circuit 38 in order to keep its amplitude constant.
Are waveform-shaped so as to be signals of "1" and "0". As is well known, the waveform-shaped preformatted data signal is supplied to the data recording driver 40 and precoded in a predetermined area of the master disk. This master disc is used in the disc manufacturing factory as shown in FIG.
A large number of MO discs such as those shown in are produced.

FIG. 2 shows the state of the eye pattern in the data signal of each part in the disk recording device 30 shown in FIG. 1. FIG. 2A shows the eye pattern by the unmodulated preformatted data signal supplied to the input terminal 32. It is a pattern.

When a cosine descending characteristic is added to this, B in FIG.
The eye pattern is as shown in. At this stage, the aperture ratio of the eye pattern does not decrease (deteriorate). However, when the low-frequency phase compensation filter processing is performed on this waveform-equalized data signal, phase distortion occurs particularly in the low-frequency component, and the phase becomes a lead phase. Due to this lead phase, the aperture ratio of the eye pattern of the data signal is deteriorated, and the aperture of the eye pattern is narrowed as shown in FIG. A data signal with the eye pattern opening narrowed is recorded on the master disk as a precode data signal.

On the other hand, the data reproduction signal processing circuit 10 may have the same configuration as that of the conventional example shown in FIG.
A circuit configuration excluding 6 may be used. FIG. 4 shows the configuration of the reproduction signal processing circuit 10 excluding the waveform equalizer. Therefore, the other structure is the same as that of the conventional example shown in FIG.

The reproduced signal which is the precoded data signal is the same as that shown in FIG. 2C. When this reproduction signal is supplied to the high-pass filter 17 shown in FIG. 4, a phase delay occurs with respect to its low-frequency component, but this low-frequency component has been advanced in advance by the amount corresponding to the phase delay. , Late phase is offset.

As a result, the eye pattern of the output signal of the high-pass filter 17 is as shown in FIG. 3 and the aperture ratio is the same as in FIG. 2B. The larger the aperture ratio of the eye pattern, the easier the waveform shaping process using the zero-cross points in the waveform shaper 18, and the correct the reproduced signal can be converted into the pulse signal.

[0032]

As described above, in the recording apparatus according to the present invention, the amplitude / phase characteristic of the pre-formatted data signal recorded on the magneto-optical disk is selected so as to cancel the amplitude / phase characteristic during reproduction. It is something that is done.

According to this, even if a high-pass filter is interposed in the reproduction signal processing system, it becomes possible to cancel the phase fluctuation of the low frequency component of the reproduction signal, so that the eye pattern of the reproduction signal is widened, and the reproduction signal is increased accordingly. You can reduce the error when shaping the waveform.

Therefore, the present invention is suitable for application to a magneto-optical disk in which the address portion is precoded to obtain a light intensity signal as described above, and magneto-optical recording using such a magneto-optical disk. It is extremely suitable when applied to a reproducing device.

[Brief description of drawings]

FIG. 1 is a system diagram showing an example of a recording apparatus according to the present invention for recording a preformatted data signal.

FIG. 2 is a diagram of an eye pattern.

FIG. 3 is a diagram of an eye pattern similarly after filtering.

FIG. 4 is a system diagram showing an example of a reproduction signal processing circuit to which the present invention can be applied.

FIG. 5 is a diagram showing an example of a recording format of a magneto-optical disk.

FIG. 6 is a system diagram showing a conventional example of a reproduction signal processing circuit.

FIG. 7 is a diagram showing waveform equalization characteristics.

FIG. 8 is a characteristic diagram showing a phase characteristic by a filter process.

FIG. 9 is a diagram of a conventional eye pattern.

[Explanation of symbols]

 16, 34 Waveform equalizer 17 High-pass filter 18 Waveform shaper 20 PLL circuit 22 Discriminator 24 Decoder 36 Low-pass phase compensation low-pass filter 38 Binarization circuit

Claims (2)

[Claims] 1. In a magneto-optical recording medium comprising an address section and a data recording section, when pre-formatting the data of the address section, the pre-formatted address section recording data is stored in a waveform equalizer. The waveform equalized recording data is supplied to the low-pass phase compensation filter to form a filter output with the low-pass phase advanced, and the waveform of this filter output is shaped. A recording device for precoded data, characterized in that the object is used as precoded data. 2. The recording of precoded data according to claim 1, wherein the cosine descending characteristic for waveform equalization is selected to be the same as the cosine descending characteristic of the waveform equalizer provided in the data reproducing system. apparatus.