JP3752139B2 - Recording method and recording apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a recording method and a recording apparatus for modulating and recording a digital signal.
[0002]
[Prior art]
In recent years, optical disks have been put to practical use as large-capacity data files, music and video storage media, but the capacity has been increased for more applications. In order to efficiently access a large-capacity optical disk, the recording data is divided into sectors with a fixed data length, this sector is modulated as a basic recording unit, and the low frequency component of the modulation signal is sufficiently suppressed. Then, a recording method is used. The recording method of the modulation signal is described in, for example, Japanese Patent Application Laid-Open No. 07-211005 called “optical disc and optical disc recording / reproducing apparatus”.
[0003]
Hereinafter, a conventional recording apparatus will be described with reference to FIGS. 4, 5, and 6.
[0004]
FIG. 4 is a block diagram showing the configuration of a conventional recording apparatus for recording on an optical disk using the sample servo system, and FIG. 5 shows a state in which the modulation signal is recorded while being divided into segment units according to the recording area discrimination signal. FIG. 6 is a timing diagram and FIG. 6 is a diagram showing frequency characteristics of a recording signal when recording is performed based on a conventional recording method and recording apparatus. Here, the sample servo system is a system that performs tracking based on recording information that is distributed in advance on a recording medium. When recording, a signal can be recorded in a place other than the area of the recording information that is distributed. To control.
[0005]
In FIG. 4, 8 is an input terminal for a recording area discrimination signal, 9 is an input terminal for a digitized modulated signal, 10 is a modulation means for modulating the input signal, and 11 is a modulation signal output from the modulation means 10. Low-frequency component suppression means 12 for suppressing the low-frequency component of the recording signal, 12 is an output terminal of the recording signal.
[0006]
A modulated signal having 38 kbytes as a recording unit and the recording unit as one sector is input to the input terminal 8, and modulated by the modulating means 10 to output a modulated signal. For example, the NRZI plus system is used as the modulation means. In the NRZI plus system, an input modulated signal is divided into units having a predetermined data length, for example, 182 words as one line, and an initial value T (T = 0, 1, 2,..., 15) is used. Performs word-wise convolution. As a result, 16 types of modulation signals corresponding to the initial value T are obtained for one line input.
[0007]
The low-frequency component suppression unit 11 receives 16 types of modulation signals output from the modulation unit 10 in units of one line. Low-frequency component suppression can be realized by averaging the ratios of “0” and “1” in the recording signal. That is, the CDS calculation is performed for each of the 16 modulation signals that are convolutionally calculated using the initial value T. The CDS operation is an operation for obtaining a cumulative sum in one line by adding -1 when the bit data is "0" and adding +1 when the bit data is "1". By performing the CDS calculation, it is possible to know the ratio of the recording signals “0” and “1” in one line. Therefore, the modulation signal that obtains the minimum CDS calculation result is selected and output from the 16 modulation signals. To do.
[0008]
FIG. 6 is a graph showing the frequency characteristics of all segments output from the low-frequency component suppression unit 11. According to the graph of FIG. 6, it can be seen that attenuation starts at 20 kHz, decreases to about −10 dB at 0 kHz, and the low frequency component is suppressed (DC-free characteristics).
[0009]
Further, when a recording signal is output from the low frequency component suppression means 11 with a group of data consisting of N bits (N is a positive integer) as a segment, as shown in FIG. Divide into segments and output. That is, one segment is formed and output during a period indicating one effective recording area of the recording area determination signal. Also, segment division is always performed from the beginning of the sector. When recording / reproducing is performed on the optical disk using the sample servo system, the recording signal is recorded in the effective recording area using the recording area determination signal as described above.
[0010]
In this way, 38 kbytes as one sector is modulated in units of sectors, and low-frequency components are suppressed and recorded while being divided into segments, thereby improving the signal detection accuracy during reproduction.
[0011]
[Problems to be solved by the invention]
The above-described conventional configuration has the following problems.
[0012]
When recording a signal modulated in units of sectors and suppressing low frequency components while being divided in units of segments, the data length N constituting the segment depends on the arrangement interval of the recording information distributed on the recording medium. Therefore, as shown in FIG. 5, the data length of one sector and the data length of one segment do not become an integer ratio. Since segment division is always performed from the beginning of the sector, if the data output of the sector is completed in the middle of the segment, an indefinite signal is output and recorded until the segment ends (recording signal). The overall DC free characteristic cannot be compensated. That is, the detection accuracy of the reproduction signal is lowered.
[0013]
For these reasons, when recording a sector-by-sector modulated signal while segmenting it, it is desirable to record a signal in which the low frequency component is suppressed even in the idle period.
[0014]
Therefore, an object of the present invention is to provide a recording method and a recording apparatus that can output and record a signal in which a low frequency component is suppressed even in an empty period.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, a recording method according to the present invention receives a digital signal as input, modulates the digital signal in units of sectors, with a unit of data length of M bytes (M is a positive integer) as a sector, The low frequency component of the modulation signal is suppressed, and a group of data lengths of N bits (N is a positive integer, M × 8 bits> N bits) is used as a segment, and a low frequency component suppression signal is generated based on the recording region discrimination signal. In addition to outputting in segment units, during the period from the end of output of the low-frequency component suppression signal of a sector in an arbitrary segment to the end of the arbitrary segment, a data pattern is generated and output. Features.
[0016]
In the recording method according to the present invention, a period from the end of the low-frequency component suppression signal output in units of sectors to the start of the next sector is an empty period, and an empty period of the K + 1 (K is a positive integer) sector Preferably, the first fixed signal at is output based on the state of the last fixed signal in the empty period of the Kth sector.
[0017]
In order to achieve the above object, a recording apparatus according to the present invention uses a digital signal as an input, and modulates the digital signal in units of sectors, where a unit of data length of M bytes (M is a positive integer) is a sector. And a low frequency component of the modulation signal output from the modulation means, and a segment of a data length of N bits (N is a positive integer, M × 8 bits> N bits) is input Low-frequency component suppression means for outputting a low-frequency component suppression signal for each segment based on the recording region discrimination signal, and a period from the end of the output of the low-frequency component suppression signal of the sector within the arbitrary segment to the end of the arbitrary segment A signal generation means for generating a signal having a fixed data pattern based on at least control information indicating the control signal, and the low-frequency component suppression signal based on the control information Select the serial fixed signal, characterized in that a selection means for outputting.
[0018]
In the recording apparatus according to the present invention, a period from the end of a signal output in units of sectors to the start of the next sector is defined as an empty period, and the control information includes an empty space of the K + 1 (K is a positive integer) sector. In order to output the first fixed signal in the period, information indicating the state of the last fixed signal in the empty period of the Kth sector is preferably included.
[0019]
In the recording method and recording apparatus according to the present invention, it is preferable that the fixed signal is a signal in which a low frequency component is suppressed in advance.
[0020]
According to the above method and configuration, even if the data output of the sector is completed in the middle of the segment, the data pattern in which the low frequency component is suppressed in advance outputs and records a fixed signal, thereby improving the detection accuracy of the reproduction signal. Can be improved,
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1, 2, and 3.
[0022]
FIG. 1 is a block diagram showing the configuration of a recording apparatus according to an embodiment of the present invention, FIG. 2 is a timing diagram showing how recording is performed while dividing a modulation signal into segment units according to a recording area discrimination signal, and FIG. FIG. 5 is a diagram showing frequency characteristics of a recording signal when recording is performed based on the present embodiment.
[0023]
In FIG. 1, 1 is an input terminal for a recording area discrimination signal, 2 is an input terminal for a digitized modulated signal, 3 is a modulation means for modulating the input signal, and 4 is a modulation signal output from the modulation means 3. Low-frequency component suppression means for suppressing the low-frequency component of the signal, 5 is a signal generation means for generating a fixed signal, 6 is a low-frequency component suppression signal output from the low-frequency component suppression means 4, and the signal generation means 5 Selection means 7 for selecting and outputting the fixed signal to be output, and 7 is an output terminal for the selection signal.
[0024]
A modulated signal having 38 kbytes as a recording unit and the recording unit as one sector is input to the input terminal 1, and modulated by the modulation means 3 to output a modulated signal. For the modulation means 3, for example, an NRZI plus method is used in which 182 words are taken as one line and a convolution operation is performed in units of one line.
[0025]
The low-frequency component suppressing unit 4 receives 16 modulation signals output from the modulating unit 3 in units of one line. Low-frequency component suppression can be realized by averaging the ratios of “0” and “1” of the recording signal. That is, using the initial value T (T = 0, 1, 2,..., 15), the CDS calculation is performed for each of the 16 modulation signals subjected to the convolution calculation, and the minimum CDS calculation among the 16 modulation signals is performed. The modulation signal obtained as a result is selected and output.
[0026]
When a low-frequency component suppression signal, which is a recording signal, is output from the low-frequency component suppression means 4, a group of data consisting of N bits (N is a positive integer) is used as a segment, as shown in FIG. The recording signal is divided into a plurality of segments and output. That is, one segment is formed and output during a period indicating one effective recording area of the recording area determination signal. Also, segment division is always performed from the beginning of the sector. When recording / reproducing is performed on the optical disk using the sample servo system, the recording signal is recorded in the effective recording area using the recording area determination signal as described above. Further, in the period from the end of the sector data output in the middle of the segment to the end of the segment (empty period), a fixed signal with a low-frequency component previously suppressed from the signal generating means 5 is output. A selection means 6 selects and outputs. For example, in the idle period, a fixed signal such as “0011” is repeatedly output. Since the ratio of “0” and “1” has already been averaged for “0011”, the low frequency component is suppressed even if it is repeatedly output.
[0027]
The selection means 6 is controlled by control information (CI) output by the low-frequency component suppression means 4 recognizing the empty period. Since the data length of the sector, which is a recording unit, is fixed, when the segment is divided from the head of the sector, it is possible to know where in the segment the data output of the sector ends from the data length of the sector. Therefore, when the end position of the sector is detected, the selection unit 6 is controlled to select the output from the signal generation unit 5 based on the control information.
[0028]
Further, when the signal generating means 5 outputs a fixed signal in the empty period, the signal generating means 5 uses the control information indicating the start / end time of the empty period and the data length input from the low frequency component suppressing means 4 to the signal generating means 5. , When outputting from the start of the empty period following the output of the low frequency component suppression signal of the K + 1th sector (K is a positive integer), the last output of the empty period following the output of the low frequency component suppression signal of the Kth sector Control is made to start output based on the state. For example, when the fixed signal output from the signal generating means 5 is “0011” and the empty period following the low-frequency component suppression signal output of the Kth and (K + 1) th sectors can be output in 14 bits, the empty period of the Kth sector Is output with a fixed signal of “001100110011100” and outputs a fixed signal of “11001100110011” during the empty period following the output of the low-frequency component suppression signal of the (K + 1) th sector.
[0029]
FIG. 3 is a graph showing the frequency characteristics of the recording signal output from the selection means 7. According to the graph of FIG. 3, it can be seen that attenuation starts at 20 kHz, decreases to −20 dB at 0 kHz, and the low-frequency component is sufficiently suppressed (the DC-free characteristic is compensated).
[0030]
As described above, according to the present embodiment, it is possible to perform recording in which the low frequency component of the entire recording signal is sufficiently suppressed.
[0031]
【The invention's effect】
As described above, according to the present invention, the data pattern in which the low frequency component is suppressed in advance is fixed during the period from the end of the sector data output in the middle of the segment to the end of the segment. By selecting and outputting the signal, it is possible to compensate for the DC-free characteristic of the entire recording signal, and to further improve the detection accuracy of the reproduction signal.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a recording apparatus according to an embodiment of the present invention. FIG. 2 is a timing diagram of a recording signal according to an embodiment of the present invention. FIG. 4 is a block diagram showing a configuration of a conventional recording apparatus. FIG. 5 is a timing chart of a recording signal by a conventional recording apparatus. FIG. 6 is a graph showing a frequency characteristic of a recording signal by a conventional recording apparatus. Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Recording area discrimination | determination signal input terminal 2 Digital signal input terminal 3 Modulation means 4 Low frequency component suppression means 5 Signal generation means 6 Selection means 7 Recording signal output terminal

Claims (6)

A digital signal is input, and a unit of a data length of M bytes (M is a positive integer) is used as a sector to modulate the digital signal in units of sectors.
The low frequency component of the modulation signal is suppressed, and a group of data lengths of N bits (N is a positive integer, M × 8 bits> N bits) is used as a segment, and a low frequency component suppression signal is generated based on the recording region discrimination signal. Output in segment units,
A recording method comprising: generating and outputting a signal having a fixed data pattern during a period from the end of outputting the low-frequency component suppression signal of a sector in an arbitrary segment to the end of the arbitrary segment. The period from the end of the low-frequency component suppression signal output in units of sectors to the start of the next sector is an empty period, and the first fixed signal in the empty period of the K + 1 (K is a positive integer) sector is represented by K 2. The recording method according to claim 1, wherein the recording is performed based on a state of the last fixed signal in an empty period of a th sector. The recording method according to claim 1, wherein the fixed signal is a signal in which a low frequency component is previously suppressed. Modulation means for receiving a digital signal and modulating the digital signal in units of sectors, with a unit of data length of M bytes (M is a positive integer) as a sector;
The low frequency component of the modulation signal output from the modulation means is suppressed, and a group of data lengths of N bits (N is a positive integer, M × 8 bits> N bits) is segmented to determine the recording area to be input Based on the signal, outputs a low-frequency component suppression signal for each segment, and outputs control information indicating at least a period from the end of the output of the low-frequency component suppression signal of the sector to the end of the arbitrary segment within an arbitrary segment Low-frequency component suppression means to
Signal generating means for generating a signal with a fixed data pattern based on the control information;
A recording apparatus comprising: selection means for selecting and outputting the low-frequency component suppression signal and the fixed signal based on the control information. The period from the end of the signal output in units of sectors to the start of the next sector is an empty period, and the first fixed signal in the empty period of the K + 1 (K is a positive integer) sector is output as the control information. The recording apparatus according to claim 4, further comprising information indicating a state of the last fixed signal in an empty period of the Kth sector. The recording apparatus according to claim 4, wherein the fixed signal is a signal in which a low frequency component is previously suppressed.

Images