JPH0697539B2 - Optical information recording / reproducing device - 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 disc having an optically detectable guide track, and the guide track being divided into a plurality of sectors. It relates to the device.

2. Description of the Related Art Optical recording discs are provided with optically detectable guide tracks such as guide grooves in a concentric or spiral shape for reasons such as high density recording tracks, discrete partial writing, and erasing. The recording layer formed on the guide track is irradiated with a laser beam having a diameter of 1 μm or less, and recording is performed by making holes or changing reflectance and transmittance.

When recording digital information with variable data length, it is common to divide the track into a plurality of sectors and record / reproduce information in sector units in order to efficiently use the recording area. . An example of the sector structure is shown in FIG. Each sector is composed of an address portion 1 indicating a track number and a sector number, and a sector head identification mark 2 (hereinafter referred to as a sector mark) added before the address portion 1 for identifying the head of the sector. A field and a data field for recording and reproducing data.

The data recorded in the data field is usually PLL (Phase
(Looked Loop) sync pull-in signal portion for pull-in, data head identification mark (hereinafter referred to as data mark) added before recording data to identify the head of data, and data portion In this case, the data synchronization is detected by detecting the data mark.

On the other hand, when various defects, dust, scratches, etc. are present on the base material, recording film, protective layer, etc. of the optical recording disc, dropout is generated in the reproduction signal, but the recording pit and track pitch of the optical recording disc are Since it is as small as about 1 μm, the raw error rate is 10 ⁻⁴ to 10 ⁻⁵ , which is much worse than that of the magnetic media, and there are many long burst-like dropouts. This burst-like dropout often affects the operation of the PLL, and word synchronization may be lost during data demodulation, and all subsequent sector data may be in error.

In order to solve such a problem, the inventors
-58157 specification proposes a frame structure in which a sector is composed of a plurality of information recording units (hereinafter referred to as a frame). The format will be described with reference to FIG. The sector data is composed of m frames from F ₁ to Fm with the data mark 3 and the data 4 divided into m frames as one unit, and a sync pull-in signal 5 for PLL lock pull-in is added at the beginning. is doing. With this configuration,
As described above, even if the word synchronization of demodulation is deviated due to a long dropout or the like, the error is suppressed in frame units, and normal demodulation can be executed from the next frame.

FIG. 7 shows a data flow in the optical information recording / reproducing apparatus. When recording data, the user data sent from the host 6 is stored in the temporary data buffer memory 7, the error correction code is added by the error detection and correction circuit 8, and the data for one sector is stored in the sector buffer memory 9. . The modulation circuit 10 modulates and formats this data, and the optical disk drive 11 records sector-formatted data. For playback, optical disk drive
The reproduction signal from 11 is demodulated by the demodulation circuit 12 and the demodulated data is stored in the sector buffer 9. After the error detection and correction circuit 8 performs error processing, the data buffer memory 7
To send data to the host via.

Problems to be Solved by the Invention However, in a sector format having a frame structure, when a data mark cannot be detected due to dropout or the like when demodulating data, the data of the frame is not stored in the sector buffer memory,
The demodulated data on and after the next frame is stored in the address portions that are sequentially displaced, resulting in incorrect data. 8th
The situation will be described with reference to the figure. First, as shown in FIG. 8A, the recording data is stored in the sector buffer memory 9 after the data corresponding to the frames F ₁ , F ₂ , ... It is assumed that the modulation data is recorded on the optical disc by the modulation circuit 10 in the figure. After that, if the data mark of the frame 3 is not detected during the data demodulation, the demodulated data of F ₃ is not stored in the sector buffer memory 9 as the reproduced data as shown in FIG. 8 (b). Also, the F ₄ data is originally
The data of F ₃ is stored at the address that should be stored. Similarly, the F ₅ data is stored at the address where the F ₄ data should originally be stored. In the same manner, the data storage address is shifted by one frame, so
All data after F ₃ is incorrect.

In view of such a point, the present invention accurately detects, at the time of data demodulation of a sector format having a frame configuration, the frame data stored in the sector buffer memory, and the data mark cannot be detected. An object of the present invention is to provide an optical information recording / reproducing apparatus in which subsequent frame data is stored at a correct address even if frame data is lost.

MEANS FOR SOLVING THE PROBLEM The present invention stores means for generating one pulse for each frame demodulation in demodulating sector format data having a frame structure, and stores data for each frame based on a result of counting the pulses. The optical information recording / reproducing apparatus is provided with a means for designating the start address of the sector buffer memory at the time of writing.

With the above-described configuration, the present invention can store the subsequent frame data at the correct position in the sector buffer memory even if the data mark in the data cannot be detected and the frame data is lost.

Practical example In the present invention, when demodulating sector data, one per frame
One pulse (hereinafter referred to as a frame pulse) is generated, the pulse is counted, and the frame number to be demodulated next is detected.

As a method of generating one frame pulse in one frame, a method of detecting the data mark of each frame and counting the data mark itself or the pulse generated from the data mark is conceivable. When the data mark cannot be detected, the pulse cannot be generated. In this case, if it is an intermediate frame, it is possible to generate a pulse on the basis of the detection of the previous frame, but it cannot be compensated when the leading frame of the sector is missing.

Therefore, in the present invention, during sector demodulation, a frame pulse is generated using the sector mark of the sector identification field until the first data mark is detected, and once the data mark is detected, a frame pulse is generated using the data mark as a reference. Take a means to generate a pulse.

The present invention will be described with reference to FIG. 1. When demodulating the sector data shown in (a), the data marks of F ₁ and F ₃ cannot be detected due to dropout or the like, and _three of F ₂ , F ₄ , and F ₅ are detected. It is assumed that only the frame can be demodulated. At this time, as shown in (e), the sector buffer memory stores the demodulated data in the correct position without storing the demodulated data of other frames in the storage units of F ₁ and F _{3 that} cannot be detected. For this positioning, as shown in (d), one frame pulse generated for each frame is used. Then, as a method of generating this frame pulse, until the data mark in the data is detected, the sector mark of (c) is used as a reference,
After the data mark is once detected, the data mark of (b) is used as a reference.

Here, 1 for each frame based only on the sector mark
A method of generating two pulses is also conceivable. In this case 1
For the clock of the counter that generates frame pulses at frame intervals, use an accurate clock such as a crystal oscillator instead of the PLL clock that is easily affected by gaps or burst-like dropouts, but the sector length is long and the number of frames is large. In some cases, the sector length may change with time due to eccentricity, vibration, etc. of the disk, and the pulse position may deviate from the frame at the rear of the sector, and correct addressing may not be possible. Further, the positional accuracy of the substitute mark when the sector mark is not detected, and the accuracy of the counter that is a timer also pose problems.

FIG. 2 shows a block diagram of an embodiment of the present invention, FIG. 3 shows an operation timing diagram in a normal demodulation sequence, and FIG. 4 shows an operation timing diagram in a data mark non-detection sequence. The details of the present invention will be described.

In the optical disk drive 11, the reproduction signal 16 read out from the optical disk 13 by the photodetector 14 and amplified by the preamplifier 15 is waveform-shaped by the waveform equalization circuit 17 and is comparator 18
Is binarized to be a binarized reproduction signal 19.

On the other hand, the sector mark has a band of the sector mark pulse train different from that of the data part and the address part in order to prevent erroneous detection in the data part and the address part.
The sector mark pulse train is extracted through the band pass filter 20, and the sector mark 22 is detected by the sector mark detection circuit 21. The address reproduction circuit 23 reads the address signal 24 included in the binarized reproduction signal 19 at the detection timing of the sector mark 22.

When demodulating the data of a certain sector, the CPU 25 that controls the control confirms the sector mark 22 and the address signal 24 and outputs the demodulation command signal 26 to the demodulation circuit 12.

In the demodulation circuit 12, the PLL circuit 27 self-generates a reproduction clock 28 for the binarized reproduction signal 19 and sends the binarized reproduction signal 19 to the shift register 29 according to the reproduction clock 28.
The data mark detection circuit 30 matches the data mark pattern at the beginning of each frame and outputs the data mark detection signal 31. The demodulation clock generation circuit 32 generates a demodulation clock 33 for word synchronization from the reproduction clock 28 and the data mark detection signal 31. In the demodulation timing gate generation circuit 34, the enable signal 36 of the counter 35 that counts the demodulation clock is enabled, the counter output 37 is decoded by the decoder 38, and the demodulation circuit 40 demodulates the RAM 39 of the sector buffer memory. A sector buffer enable signal 41 for transferring the data 40 in frame units is output.

In this way, the playback data is demodulated for each frame,
When the demodulation ends for a predetermined number of frames, the demodulation end signal 42 is output when the demodulation ends.
And the demodulation counter enable signal 36 is closed. The CPU 25 recognizes the end of demodulation from the demodulation counter enable signal 36 and releases the demodulation command signal 26.

In generating the frame pulse, basically, the frame pulse A is generated as the decode output 43 of the decoder 38 at the middle of the frame in which the data mark is detected, and the OR gate 44, the demodulation command signal 26 for outputting the frame pulse only at the time of demodulation. of
It outputs to the RAM control circuit 46 of the sector buffer memory 9 through the AND gate 45. And the frame pulse of the frame where the data mark could not be detected is
The crystal clock 48 is counted by 47, and the decoded output 50 by the decoder 49 is output as a frame pulse B instead. This counter 47 has sector mark 22, frame pulse
It is cleared by the output of the OR gate 52 of 3 signals of the count disable signal 51 which becomes "H" from B and the detection of the data mark to the output of the frame pulse A at the frame intermediate point, as shown in FIG. The decoder 49 substitutes the frame pulse B when the time t ₁ from the sector mark to the middle of the first frame and the time t ₂ corresponding to each frame length are counted. For t ₁ and t ₂ , the switching signal 55 is output from the t ₁ and t ₂ switching circuit 54 when the first frame pulse 53 is output, and the position of the decode output is changed. In this way, until the first data mark is detected, the sector mark is used as a reference for frame pulse generation, and once the data mark is detected, the detected data mark is used as a reference for frame pulse generation.
A frame pulse can be accurately generated in each frame.

The RAM control circuit 46 of the sector buffer metallurgy 9 is internally provided with a frame pulse counter (not shown), which is cleared by the sector mark 22 and receives the frame pulse 56 as a clock input. A frame data storage start address signal 58 for each frame is set by this counter output 57. When storing frame data in RAM39, data write signal 5 from RAM control circuit 46
The output 61 of the RAM address counter 60, which receives the demodulation clock 33 in 9 and word units as clock input,
Store 0 in RAM.

If the frame data storage start address signal 58 is loaded into the RAM address counter 60 in the "L" section of the sector buffer enable signal 41, for example, as shown in FIG. Alternatively, even if the sector buffer enable signal is not output on the way, the frame data is stored at the correct address from the next frame.

By outputting the frame pulse near the center of each frame, eccentricity, vibration, and
It is possible to absorb a temporal change in the sector length due to a shock or the like.

As described above, according to the present invention, in the sector format data demodulation having a frame structure, the start address is specified when storing the data of each frame in the sector buffer memory in order to identify the start of the sector. This is done by a frame pulse generated for each frame from the sector mark and the data mark for identifying the beginning of the frame in the data. Even if the data mark cannot be detected, the data after the missing frame is stored in the correct position in the sector buffer memory. can do.

Further, since the frame pulse is generated with the sector mark as a reference until the first data mark is detected and the frame pulse is generated with the detected data mark as a reference after the data mark is detected, the sector length is long and the frame Even if the number is large, the frame pulse can be accurately generated at the center of each frame, and its practical effect is great.

[Brief description of drawings]

1 is an explanatory diagram of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, FIG. 3 is an operation timing diagram in a normal demodulation sequence, and FIG. 4 is a diagram when a data mark is not detected. 5 is an operation timing diagram, FIG. 5 is a conventional sector configuration diagram, FIG. 6 is a frame format sector format diagram, FIG. 7 is a data flow diagram in an optical information recording / reproducing apparatus, and FIG. 8 is a sector when a data mark is not detected. It is a state diagram showing that data storage in the buffer memory is deviated. 1 ... Address part, 2 ... Sector start identification mark, 3 ...
... data mark, 4 ... data, 8 ... error correction detection circuit, 9 ... sector buffer memory, 11 ... optical disk drive, 12 ... demodulation circuit, 25 ... CPU.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Norihisa Fukushima 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor, Yuji Takagi, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 56) References JP 59-185035 (JP, A)

Claims (2)

[Claims] 1. A guide track which can be optically measured,
A device for recording / reproducing on / from an optical recording disk, wherein the guide track is divided into a plurality of sectors, each sector comprising a sector identification field consisting of a sector head identification mark and a sector address, and a data field for recording / reproducing data. Recording means for connecting a plurality of information recording units composed of a data head identification mark for identifying the head of data and data to record in the data field of each sector, and reproducing by identifying the sector head identification mark from a reproduction signal. A means for identifying the target sector, a means for detecting the data head identification mark from the reproduction signal and storing the data in the buffer memory for each information recording unit, and one pulse for each information recording unit Until the data start identification mark is identified, the sector start identification mark is generated as a reference, and the data start identification is once identified. And a means for specifying the head address of the buffer memory at the time of storing data of each information recording unit from the result of counting the pulses after identifying the data An optical information recording / reproducing apparatus comprising: 2. The optical information recording / reproducing apparatus according to claim 1, wherein the pulse for each information recording unit is generated at the center of each information recording unit.