JPH0636283B2 - Optical recording / reproducing apparatus and method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus for recording / reproducing information on / from an optical recording disk having a sector-structured recording area divided into a plurality of areas.

Configuration of Conventional Example and Problems Thereof As an optical information recording / reproducing apparatus, for example, an optical recording disk coated or vapor-deposited with a photosensitive material is rotated, and a light beam from a laser light source has a diameter of 1 μm on the disk surface.
By irradiating a minute spot light focused to m or less and modulating the light output intensity with a recording signal, a phase change due to unevenness on the optical recording disk or an optical change such as reflectance or transmittance is recorded in real time. There is a device capable of recording information such as signals and digital signals and reproducing the recorded information by detecting the change in the optical characteristics.

In such an apparatus, a guide track that can be optically detected is concentrically formed on the surface of an optical recording disk for reasons such as high density recording information, discrete partial writing, and erasing.
Or it is a device that is provided in a spiral shape in advance, performs tracking control so that a minute spot light by a laser follows a guide track, records information on a predetermined track, and reproduces information from the track. Is.

When recording digital information with variable data length, some tracks are divided into a plurality of areas (hereinafter referred to as sectors) in order to efficiently use the recording area. An example of a conventional sector recording format is shown in FIG. Each sector has a sector address for identifying the sector 1, a sync signal for urging synchronization of the self-clock recovery circuit 2, a data head identification signal 3 (hereinafter referred to as a data mark) for identifying the head of data, and modulation. It is composed of encoded data 4. The data mark is composed of, for example, a special bit that does not appear in the data. When reproducing an optical recording disc having such a recording format, a data mark is detected from a binarized reproduction signal by a method such as bit pattern matching detection, and subsequent data is detected based on the detection timing. It is taken into a demodulation circuit to obtain reproduced data.

On the other hand, a GCR (Group Coded) for converting m-bit data into an n-bit modulation code for high density recording.
When using the recording) code modulation, for example, the 4/5, 2/3 modulation method, etc., at the time of demodulation, the data taken in after detecting the data mark is divided into N bits and demodulated into M bits. If the word synchronization for every N bits is deviated due to the influence of dropout existing on the optical recording disk, all the demodulated data thereafter may have an error.

As a method of preventing a demodulation error due to such a word synchronization shift, there is a method of configuring the sector recording format with a plurality of information recording units (hereinafter referred to as a frame configuration). FIG. 2 shows an example of the sector recording format when the sector has a frame structure. One frame is composed of the data mark 33 and the encoded data 4, and one frame is composed of a plurality of frames and the synchronization signal 2.

When reproducing a sector composed of a plurality of frames, a set of data demodulated for each frame is used as sector reproduction data with reference to the detection timing of the data mark of each frame.

In the case of using the bit pattern matching detection, for example, the data mark of each frame is often undetectable because a bit error occurs due to dropout of the optical recording disk, and in this case, all the data of the frame is in error. As a means for compensating for the non-detection of the data mark, there is a method of obtaining a pseudo data mark by counting the self-reproducing clock with the first detected data mark as a reference.

However, this method cannot compensate for the non-detection of the first data mark, and the detection rate of the first frame becomes lower than the detection rate of the second and subsequent frames, resulting in an uneven reproduction data error.

Further, the detection of the data mark of the first frame may be the reference of the reproduction sequence of the sector, and if the first frame cannot be detected, there is a possibility that error propagation will occur in the subsequent reproduction.

It is an object of the present invention to provide an optical recording / reproducing apparatus for increasing the detection rate of the first frame of a sector in the recording / reproducing of a sector having a frame structure.

According to the present invention, the data mark of the head frame of each sector is composed of a plurality of sets of different bit strings, and at the time of reproduction, it is considered that the head frame is identified when at least one of the bit strings of the plurality of sets is detected. It was done.

Description of Embodiments Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is an example of the sector recording format in the present invention. One sector is composed of n frames, and three different data marks DM1, D are provided in the first frame.
M2 and DM3 are added immediately before the data, and only the data mark DM4 is added immediately before the data after the second frame. Further, a sync signal 2 for promoting synchronization pull-in of the self-clock reproducing circuit is added to the head of the n frames to form a recording format of 1 sector.

The data actually recorded on the optical recording disk is modulated in accordance with a certain conversion algorithm for the purpose of extracting a clock pulse for self-clock reproduction and making the signal form suitable for the recording medium. It is encoded data.

When attempting to reproduce the data in this sector, in order to extract only the data portion from the reproduction signal and demodulate it, the data mark is detected and data demodulation is started at that timing.

FIG. 4 shows a block diagram of data reproduction. Photo detector 5
The reproduced signal 6 extracted by the signal passes through the amplifier 7, the waveform equalizer 8 and the binarized comparator 9, and the binarized reproduced signal 10
Becomes The binarized reproduction signal 10 is a clock reproduction circuit 11
In accordance with the clock pulse 12 extracted by, the shift register 13 sequentially shifts and serial-parallel conversion is performed. The pattern 14 after parallel conversion is input to the data mark detection circuit 15, and if the same bit pattern as the data mark is detected in the binarized reproduction signal, the data mark detection signal 16 is output. At this timing, demodulation of the binarized reproduction signal 10 input to the demodulation circuit 17 is started, and demodulation data 18 is output.

The details of the data mark detection circuit 15 in FIG.
Shown in the figure.

Playback signal 14 converted in parallel by the shift register 13
Is input to each of the beat pattern matching circuits 19 to 22 for DM1 to DM4, and when they match, the respective detection signals 23 to 26 are output.

When reproducing the signal recorded in the format as shown in FIG. 3, DM1, DM2, DM in the case of the first frame
Since the timings of the pattern matching detection signals 23, 24, and 25 of 3 are different from each other, the clock pulse 12 is counted, and the DM1 delay circuit 27 in the case of DM1 and the DM3 pattern matching detection signal 25 in the DM2 delay circuit 28 of DM2. Make the output timing the same. This 3
By inputting one coincidence detection signal to the 3-input OR gate 29, the data mark detection signal 30 of the first frame is obtained. Further, the data mark DM4 after the second frame is D
A DM4 detection signal 26 is output by the M4 detection circuit 22. The DM4 detection signal 26 and the data mark detection signal 30 of the first frame are input to the 2-input OR gate 31,
The data mark detection signal 16 is obtained. In this way, the first frame can be detected if any of the patterns DM1, DM2, DM3 can be detected, and the detection probability is three times higher than that of each of the second and subsequent frames.

In FIG. 3, DM1 to DM3 need to have different patterns, but it is clear from the description of FIG. 5 that DM3 and DM4 may have the same pattern.

As described above, in sector recording / reproducing having a frame structure, if the data mark of the first frame is composed of a plurality of different sets of patterns and at least one of the patterns is detected, By making it possible to detect a frame, the detection rate of the first frame is increased, and the detection rate is made equal to or higher than that of the second and subsequent frames in which the data mark can be compensated. There is an effect that the frame can be detected more reliably.

[Brief description of drawings]

FIG. 1 is a diagram showing a conventional sector recording format, and FIG.
FIG. 4 is a diagram showing a sector recording format in the case of a frame structure, FIG. 3 is a diagram showing a recording format in the present invention, FIG. 4 is a block diagram of data reproduction, and FIG. 5 is a data mark detection circuit. Is. DM1, DM2, DM3 ... Data mark, 15 ... Data mark detection circuit.

Claims (6)

[Claims] 1. A guide track which is optically detectable,
An optical recording / reproducing apparatus for recording / reproducing information on / from an optical recording disk in which the guide track is divided into a plurality of sectors, wherein a synchronization signal for detecting a clock at the time of reproduction and a data head identification signal are provided in the sector. Data recording means for recording data in a plurality of frames including a data section for recording data, data head identification signal means for detecting a data head identification signal from each frame of a sector during reproduction, and data head identification signal detection When the data head identification signal of the second and subsequent frames of the sector cannot be detected by the means, the data head identification signal complementing means for complementing the data head identification signal of the first frame of the sector to the data head identification signal portion of the subsequent frame And a data reproducing means for taking in the subsequent data portion as reproduced data by detecting the data head identification signal. For example, the optical recording and reproducing apparatus characterized by configured by a bit pattern of the first plurality of sets comprising different data head identification signal frame of the sector, it is recorded and reproduced. 2. The data head identification signal means determines that the first frame has been detected by detecting at least one pattern among a plurality of patterns of the first data head identification signal. 2. An optical recording / reproducing apparatus according to item 1. 3. A guide track which is optically detectable,
An optical recording / reproducing method for recording / reproducing information on an optical recording disk in which the guide track is divided into a plurality of sectors, wherein a synchronization signal for detecting a clock during reproduction, a data head identification signal and data are recorded. An optical recording / reproducing method, characterized in that, when data is recorded in a plurality of frames including a data section, the data head identification signal of the first frame of the sector is recorded and reproduced by a plurality of different bit patterns. 4. A guide track which is optically detectable,
An optical recording / reproducing method for recording / reproducing information on an optical recording disk in which the guide track is divided into a plurality of sectors, wherein a synchronization signal for detecting a clock during reproduction, a data head identification signal and data are recorded. When the data start identification signal is detected from the first frame of the sector in which data is recorded in a plurality of frames including the data section and the data start identification signals of the second and subsequent frames of the sector cannot be detected, the first An optical recording / reproducing method characterized in that a data head identification signal of a frame is complemented by a data head identification signal portion of a subsequent frame, and the subsequent data portion is taken in as reproduction data when the data head identification signal is detected. 5. The method according to claim 4, wherein it is determined that the first frame has been detected by detecting at least one pattern among a plurality of patterns of the first data head identification signal. Optical recording / reproducing method. 6. A third pattern according to claim 3, wherein one pattern among the plurality of patterns of the first data head identification signal is the same pattern as the data head identification signal of the second and subsequent frames. 6. The optical recording / reproducing method according to any one of items 5.