JP3016404B2 - Digital data recording and playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital data recording and reproducing apparatus suitable for use in, for example, a magneto-optical disk drive.

[0002]

2. Description of the Related Art In a magneto-optical disk, when data is recorded digitally, a partial response system is sometimes used. When recorded by the partial response method, the reproduced signal is a ternary signal of, for example, 1, 0 or -1. When reading the reproduced signal, a threshold level is set between -1 and 0 and between 0 and 1, and the logic is determined based on the threshold level.

[0003]

However, information is not always continuously recorded on a magneto-optical disk.
After recording predetermined information, recording of other information is performed several days later. Therefore, the recording conditions are not always constant. For example, when the power of the laser beam at the time of recording information changes, the size of a mark (pit) formed on the magneto-optical disk also changes. In addition, since a magneto-optical disk once recorded is not always reproduced by the same apparatus, its reproduction conditions (for example, frequency characteristics) may vary during reproduction.

As described above, when the condition at the time of recording or reproduction changes, the level of the reproduction signal changes.
If the threshold level for determining the logic is fixed, the logic may be erroneously determined.

[0005] The present invention has been made in view of such a situation, and it is an object of the present invention to accurately determine the logic.

[0006]

According to the present invention, there is provided a digital data recording apparatus which records data by a partial response system.
Means for generating reference data for setting a plurality of threshold levels for determining the logic of digital data to be read, and recording means for arranging the reference data at the beginning of a predetermined block and recording the reference data on a recording medium And characterized in that:

In this embodiment, the generating means is constituted by a reference generating circuit 51, and the recording means is constituted by a write encoder 37, a drive circuit 36 and a magnetic head 35.

[0008] The digital data reproducing apparatus of the present invention includes a first setting means for setting a reading means reads the reference data, the first <br/> threshold level, the
Setting means for setting a threshold level of 2
And a first threshold level and a second threshold level.
Characterized in that the Yorudo level and a determination means for determining logic of digital data. Digital data playback
The device uses the clock generated from the reference data
The first setting means and the second setting means;
The setting means of (2) uses the clock inverted by the inversion means.
Synchronously, the data obtained by reading the reference data
Data based on the first threshold level or the second threshold
The threshold level can be set as
You.

In the embodiment, the reading means is constituted by a reference reading circuit 68, the setting means is constituted by averaging circuits 63 and 64, and the judging means is a comparison circuit 61,
62, inverters 65 and 66, and an AND gate 67.

[0010]

[Action] In the digital data recording apparatus of the above configuration, persistent generated by the reference generating circuit 51
Of digital data recorded by the
Set multiple threshold levels to determine logic
Reference data is supplied to the write encoding 37 for, it is placed at the beginning portion of the digital data blocks (e.g., sectors). Then, digital data is recorded on a recording medium such as a magneto-optical disk in units of blocks. Therefore, without being affected by the recording conditions at the time of recording,
A recording medium capable of accurately determining logic can be realized.

In the digital data reproducing apparatus having the above configuration, reference data recorded therein is read from a recording medium such as a magneto-optical disk. The first <br/> threshold level is set to correspond to the reference data, the reference de
A second threshold level corresponding to the
It is, the first threshold level and a second thread
The logic of the digital data is determined based on the threshold level . Therefore, it is possible to determine an accurate logic without being affected by a change in the reproduction condition.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a digital data recording and reproducing apparatus according to the present invention, digital data is recorded and reproduced by a partial response system. Therefore, first, the principle of the recording and reproduction of the partial response system will be described.

FIG. 2 is a block diagram for explaining the principle of recording and reproduction by the partial response system. The encoder 1 encodes write data input from a circuit (not shown). The data encoded by the encoder 1 is supplied to the magneto-optical disk 2 and recorded. Then, the data reproduced from the magneto-optical disk 2 is supplied to the decoder 3 and decoded, and the data output from the decoder 3 is input to the multi-valued identification circuit 4 where the logic 1,
It is determined whether the value is 0 or -1, and output as demodulated data.

Now, for example, the NRZI method (PR (1, −
Assuming that the digital data is modulated according to 1)), the encoder 1 can be configured as shown in FIG. That is, the encoder 1 includes an adder 11 for performing modulo-2 addition and a delay circuit 12 for delaying input data by one bit and outputting the delayed data. The adder 11 modulo 2 adds the input data and the data supplied from the delay circuit 12 and outputs the result. The delay circuit 12 delays the output of the adder 11 and outputs it to the adder 11 again. In this way, for example, 0100110 as shown in FIG.
The input digital data consisting of 01000 is 01110
The data is supplied to the magneto-optical disk 2 as 110000 and recorded.

On the other hand, the decoder 3 comprises a subtracter 21 and a delay circuit 22, as shown in FIG. The data reproduced from the magneto-optical disk 2 is supplied to the subtracter 21 and is also supplied to the subtracter 21 after being delayed by one bit by the delay circuit 22. The subtracter 21 calculates the difference between the two inputs and outputs the result to the multi-value identification circuit 4.

As a result, for example, 0111 shown in FIG.
The data recorded on the magneto-optical disk 2 comprising the data of 01110000 is processed by the decoder 3 and
Multi-valued identification circuit 4 as ternary data of 100-1000
Will be supplied.

The eye pattern of the data input to the multi-value identification circuit 4 is as shown in FIG. Multi-value identification circuit 4
Determines whether the data is −1 or 0 based on the threshold level TH1 in FIG. 6, and determines whether the data is based on the threshold level TH2.
It is determined whether it is 0 or 1.

The decoder 3 shown in FIG. 4 can be omitted when it is substantially formed by a magnetic head, an amplifier, a high frequency band compensation circuit and the like in the reproducing system.

Next, an embodiment of a digital data recording and reproducing apparatus according to the present invention will be described with reference to FIG.
In the figure, for example, a magneto-optical disk 31 of a sample servo system (corresponding to the magneto-optical disk 2 in FIG. 2)
Is rotated by a spindle motor 32 controlled by a spindle servo circuit 33, and data is recorded by an optical head 34 and a magnetic head 35.

The drive circuit 36 includes a write encoder 37
The magnetic head 35 is driven in accordance with the output of. The write encoder 37 drives a laser drive circuit 39 via a laser power control circuit 38, and drives a laser diode (not shown) built in the optical head 34.

The signal reproduced from the magneto-optical disk 31 by the optical head 34 is input to the matrix amplifier 40, and is reproduced from the sum signal (PRF signal) obtained from the servo byte section of the magneto-optical disk 31 and the magneto-optical area. Signal (MORF signal) and a focus error signal. The PRF signal is input to the PLL circuit 41 and the A / D converter 43. The servo clock generated by the PLL circuit 41 is supplied to a timing generator 42, an A / D converter 43, an address decoder 44, a tracking error signal generation circuit 45, a tracking and focus servo circuit 46, and a gray code decoder 47. The data clock generated by the PLL circuit 41 is supplied to the write encoder 37, timing generator 42, A / D converter 48, MO decoder 49, reference generation circuit 51, and the like.

The output of the A / D converter 43 is supplied to an address decoder 44, a tracking error signal generation circuit 45, and a gray code decoder 47. Various timing signals generated by the timing generator 42 are supplied to the write encoder 37, the laser power control circuit 38, the SCSI / ECC circuit 50, the reference generation circuit 51, and the like.

The MORF signal is supplied to an MO decoder 49 via an A / D converter 48. The output of the MO decoder 49 is supplied to the SCSI / ECC circuit 50. The SCSI / ECC circuit 50 exchanges data with a host interface (not shown).

Next, the operation will be described. In the recording mode, recording data is input to the SCSI / ECC circuit 50 via a host interface (not shown). The SCSI / ECC circuit 50 performs processing such as addition of an error detection code and interleaving on the input digital data, and outputs the processed data to the write encoder 37. The write encoder 37 performs the above-described partial response processing (the processing of the encoder 1 in FIG. 2) on the input data, and then drives the drive circuit 3 in accordance with the data.
6, the magnetic head 35 is driven. Magnetic head 35
Applies an N-pole (eg, logic 1) or S-pole (logic 0) magnetic field to the magneto-optical disk 31 in accordance with recording data.

On the other hand, the laser power control circuit 38
When a write command is input from the write encoder 37, the optical head 34
Is emitted at the level in the recording mode. Thus, the laser light emitted from the optical head 34 is irradiated onto the magneto-optical disk 31. Thus, digital data is recorded on the magneto-optical disk 31 by the so-called magnetic field modulation method.

Next, in the reproduction mode, the laser power control circuit 38 drives the laser diode of the optical head 34 via the laser drive circuit 39 and changes the level of the emitted laser light to the reproduction level (the level at the time of recording). Weaker level). Then, the optical head 34 receives the reflected light of the laser light irradiated on the magneto-optical disk 31, and outputs the matrix amplifier 40 from the received light output.
Output a MORF signal. This MORF signal is a signal reproduced from the magneto-optical recording layer on the magneto-optical disk 31. This MORF signal is converted by the A / D converter 48 into A
After being subjected to / D conversion, it is input to the MO decoder 49.

The MO decoder 49 performs the operations of the decoder 3 and the multi-level identification circuit 4 shown in FIG. The MO decoder 49 further decodes the data demodulated into three values of 1, 0, -1 into original 1 and 0 digital data. Then, the output of the MO decoder 49 is input to the SCSI / ECC circuit 50 and subjected to processing such as deinterleaving and error detection and correction, and then output to a device (not shown) via the host interface.

In the above recording mode and reproducing mode, the servo circuit 46 controls the optical head 34 based on the focus error signal output from the matrix amplifier 40.
Drives the objective lens incorporated therein to perform focus control. Further, the tracking error signal generation circuit 45 outputs a PR corresponding to the wobbled pit in the servo byte section.
Generate a tracking error signal from the level of the F signal,
Output to the servo circuit 46. The servo circuit 46 controls the tracking of the optical head 34 according to the tracking error signal. The address decoder 44 reads the address data in the servo byte section, and outputs the read result to the timing generator 42. The timing generator 42 supplies a timing signal to each unit at a predetermined timing corresponding to the input address data.

Further, the gray code decoder 47 detects a gray code in a servo byte section and outputs the detection result to the servo circuit 46. The servo circuit 46
The position of the optical head 34 is determined from the output of the gray code decoder 47, and the optical head 34 is moved to a desired track.

The PLL circuit 41 extracts from the output of the matrix amplifier 40 a signal from a clock pit, which is a reference for executing the various operations described above, and generates a clock signal in synchronization with the extracted signal. The clock signal is supplied to various circuits.

Next, a method of setting the threshold level in the above embodiment will be described. For example, when the eye pattern of the reproduced signal is as shown in FIG. 8, the threshold level TH1 between -1 and 0 is set on a line connecting points A1 and A2. The threshold level TH2 between 0 and 1 is set on a line connecting the points B1 and B2.
When the threshold level is set at this position, even if the clock is shifted before and after the clock due to jitter, the margin is maximized and the jitter is strong. For example-
It is possible to set each threshold level to 1 and 0, or to an intermediate level between 0 and 1, but in such a case, the width in the horizontal direction at the threshold level is narrowed, and the margin for jitter is accordingly narrowed. .
Therefore, it is preferable to set the threshold level on the line connecting the points A1 and A2 and between the points B1 and B2 as in the embodiment.

In the present invention, reference data (FIG. 8) for setting the threshold level is used.
Data that can provide an eye pattern as shown in
Is recorded on the magneto-optical disk 31 in advance.

The magneto-optical disk 31 is divided into a plurality of sectors, and data is recorded in each sector according to a format as shown in FIG. That is, 1
A sector is composed of 152 rows, and one row is composed of 5-byte data. Of the 10 bytes of two consecutive rows, the first 2 bytes are servo bytes, and the next 8 bytes are data bytes in which various data are recorded. An ID code including an address and the like is arranged in the data bytes of the first two rows. The second two rows of data bytes include an ALPC for controlling the intensity of the preamble and the laser power.
The data is located. The third two-row data byte is used as a reference area, in which reference data for setting a threshold level is recorded.

The data bytes of the following 130 rows include:
Data (video data, audio data, etc.) to be recorded and reproduced is recorded. The data bytes of the last 16 rows include an error detection and correction code (ECC).
Is recorded.

The above-mentioned ID code is formed in advance on the magneto-optical disk 31 as pre-pits, and various data of the second and subsequent two rows are stored in the magneto-optical recording layer of the magneto-optical disk 31 as needed. Will be recorded above.

The reference generation circuit 51 shown in FIG.
Generates, for example, reference data as shown in FIG. 10 in synchronization with a clock generated by the PLL circuit 41.
Output to the write encoder 37. Write encoder 37
Locates this reference data in the reference area of the format shown in FIG. 9 and supplies it to the magnetic head 35 via the drive circuit 36 to be recorded on the magneto-optical disk 31. That is, reference data is recorded at the beginning of each sector.

At the time of reproduction, in order to set a threshold level with reference to the reference data, the MO decoder 49 incorporates, for example, a multi-value identification circuit 4 having a configuration as shown in FIG. In this embodiment, the decoder 3
The output data is supplied to comparison circuits 61 and 62 and a reference reading circuit 68.
The outputs of the reference reading circuit 68 are equalized by averaging circuits 63 and 6
4 and the outputs of the averaging circuits 63 and 64 are set as threshold levels TH1 and TH2, respectively.
1 and 62. Then, the output of the comparison circuit 61 and the output of the comparison circuit 62 are output as logic 1 or logic -1 determination signals, respectively, and the result calculated by the logic circuit including the inverters 65 and 66 and the AND gate 67 is The signal is output as a determination signal. Clock inverting circuit 69
Output the reference reading circuit 68 after inverting the phase of the clock supplied from the PLL circuit 41.

Next, the operation will be described. The reference reading circuit 68 separates and reads reference data from the data supplied from the decoder 3. At this time, the clock whose phase has been inverted is supplied to the reference reading circuit 68 via the clock inverting circuit 69.
Therefore, as shown in FIG.
Reference numeral 8 reads the level of the reference data at a timing synchronized with the rising edge of the clock whose phase is inverted. As shown in FIG. 8, points A1, A2, B1, and B2 as reference points for setting the threshold level are located at positions synchronized with the falling edge of the clock. Therefore, in the present embodiment, the phase of this clock is inverted by the clock inverting circuit 69, and the read reference data is read in synchronization with the rising edge thereof, whereby the level of the reference signal at points A1 and B2 shown in FIG. Has been detected.

The averaging circuit 63 averages low-level read data among the read data output from the reference read circuit 68. As a result, the threshold level TH1 set between -1 and 0 is set. Then, the threshold level TH1 is supplied to the comparison circuit 61. Similarly, the averaging circuit 64
Performs an averaging of the high-level read data among the read data output by the reference read circuit 68, and outputs the average value to the comparison circuit 62 as a threshold level TH2.

The comparing circuit 61 compares the reproduced data supplied from the decoder 3 with the threshold level TH1 supplied from the averaging circuit 63, and outputs a logical 1 when the reproduced data is smaller than the threshold level TH1. When it is larger, a logical 0 is output. The comparison circuit 62
Compares the reproduced data with the threshold level TH2 supplied from the averaging circuit 64, and outputs a logical 1 when the reproduced data is larger than the threshold level TH2, and outputs a logical 0 when the reproduced data is smaller than the threshold level TH2.

The outputs of the comparison circuits 61 and 62 are inverted by inverters 65 and 66, respectively, and then input to an AND gate 67, where the logical product is calculated. Thus, when the outputs of the comparison circuits 61 and 62 are both logic 0, the logic 1 is output from the AND gate 67. When at least one of the comparison circuits 61 and 62 is the logic 1, the AND gate 67 outputs The output becomes logic 0. Therefore, a decision output of -1, 0 or 1 is obtained from the outputs of the comparison circuit 61, the AND gate 67 and the comparison circuit 62.

In the above description, when digital data is recorded, the reference data for setting the threshold level is simultaneously recorded. However, the reference data for read-only ROM data must be recorded in advance. Can be. Further, in the above embodiment, the case where data is recorded by the magnetic field modulation method is described as an example. However, the present invention can be applied to the case of recording data by the light modulation method.

In the above embodiment, reference data is recorded in units of sectors.
Not only in the sector but also in the beginning of a predetermined block.

[0044]

As described above, according to the digital data recording apparatus of the present invention, data is recorded by the partial response method.
The reference data for setting a plurality of threshold levels for determining the logic of digital data to be read is recorded on a recording medium, so that accurate reading can be performed even if the recording conditions vary. A possible recording medium can be realized.

According to the digital data reproducing apparatus of the present invention, the first threshold level and the second threshold level correspond to the reference data reproduced from the recording medium.
Since the threshold level is set, it is possible to accurately determine the logic of the digital data even when the reproduction conditions fluctuate.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a multi-level identification circuit 4 in an MO decoder 49 of the embodiment in FIG.

FIG. 2 is a block diagram illustrating the principle of recording and reproduction in a partial response system.

FIG. 3 is a block diagram showing a configuration example of an encoder 1 in the embodiment of FIG.

FIG. 4 is a block diagram illustrating a configuration example of a decoder 3 in the embodiment of FIG. 2;

FIG. 5 is a timing chart for explaining the operation of the embodiment in FIG. 2;

FIG. 6 is an eye pattern diagram for explaining the operation of the embodiment in FIG. 2;

FIG. 7 is a block diagram showing a configuration of one embodiment of a digital data recording / reproducing apparatus of the present invention.

8 is a diagram for explaining a phase relationship between an eye pattern of reference data and a clock in the embodiment of FIG. 7;

9 is a diagram illustrating a format of a sector of the magneto-optical disk 31 in the embodiment of FIG.

FIG. 10 is a waveform diagram illustrating phases of a write reference data and a clock.

FIG. 11 is a diagram illustrating phases of a reproduction reference signal and an inverted clock.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Encoder 2 Magneto-optical disk 3 Decoder 4 Multi-value discriminating circuit 11 Adder 12 Delay circuit 21 Subtractor 22 Delay circuit 31 Magneto-optical disk 34 Optical head 35 Magnetic head 36 Drive circuit 37 Write encoder 40 Matrix amplifier 41 PLL circuit 45 Tracking Error signal generation circuit 46 Servo circuit 49 MO decoder 51 Reference generation circuit 61, 62 Comparison circuit 63, 64 Averaging circuit 68 Reference reading circuit 69 Clock inversion circuit

Claims (3)

(57) [Claims] 1. A recording method using a partial response method.
Generating means for generating reference data for setting a plurality of threshold levels for determining the logic of digital data to be read; and arranging the reference data at the beginning of a predetermined block and recording on a recording medium. Means for digital data recording. 2. A reading means for reading reference data arranged at the beginning of each block of a recording medium, and a first thread for determining a logic of digital data from the reference data read by the reading means. first setting means for setting a threshold level, and reference data read by the reading means.
A second thread for determining the logic of digital data from
Second setting means for setting a threshold level , the first threshold level set by the first setting means , and setting by the second setting means
A digital data reproducing device comprising: a determination unit configured to determine a logic of digital data from the second threshold level . 3. The method according to claim 1, wherein the reference data is generated from the reference data.
Further comprising inverting means for inverting the clock, The first setting means and the second setting means may include
In synchronization with the clock inverted by the inversion means,
Based on the data obtained by reading the reference data,
The first threshold level or the second threshold level;
Set the threshold level 3. The method according to claim 2, wherein
A digital data reproducing device according to claim 1.