JP2705728B2 - Optical recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention uses a light beam such as a laser beam to write information on an optical disk recording medium such as a write-once type or a rewritable recording medium such as a magneto-optical recording. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording / reproducing apparatus for recording and reproducing, and more particularly, to an optical recording / reproducing apparatus suitable for using a pit-edge method advantageous for high-density recording.

[Prior Art] In general, in a recording / reproducing apparatus using an optical disk recording medium, there is a pit edge recording method as a recording method for performing high-density recording. In this method, the signal waveform is inverted only when the information changes from “0” to “1” or “1” to “0”, and the signal waveform is recorded with information at the rising and falling edges. The playback method is described in, for example,
No. 53722 describes a problem when a pit edge recording method is applied to a write-once optical disc and a solution to the problem.

Conventionally, the pit edge recording method has been applied to a read-only optical disk device such as a DAD (Digital Audio Disk).

In the pit edge method, the polarity of the last end of the data block becomes pit or non-pit depending on the number of "1" in one data block (sector). DAD
In this method, the polarity of the leading synchronization signal of the next data block is switched according to the polarity of the last end of the data block.

[Problems to be Solved by the Invention] When the pit edge method adopted for a read-only optical disk such as a DAD is performed on a write-only optical disk such as a write-once optical disk as in the above-described conventional technology, the following problems occur. A point occurs.

In a write-once optical disk or the like, data is recorded and reproduced by dividing the data into sector units (for example, 1024 bytes).

For this reason, the optical disk has portions (pre-format portion and ID portion) recorded in advance on the disk to indicate the start of a sector.

At the time of recording, data writing must be started with reference to the preformat portion, and the writing must be completed before the preformat portion of the next sector. Disks have rotational jitter, eccentricity, and variations in the writing speed of each disk device. To prevent overwriting (overwriting), the format has a margin area (for example, 20 bytes) at the end of data for each sector. Is prepared.

By the way, when the pit edge method is used, as described in the related art, the polarity of the final end of the data may be pit or non-pit depending on the data. If it ends with a pit, the irradiation state of the semiconductor laser will continue in the margin area up to the preformat of the next sector, and a long and wide hole will be opened. (If the irradiation state continues, the pit becomes gradually thicker. It becomes a wide pit.
Also, if similar pits are formed on adjacent tracks, the boundaries will be broken and solid holes will be formed. In this state, interference between tracks due to the wide hole occurs, and a state in which reflected light cannot be obtained occurs.
Tracking servo cannot be performed. Further, if the recording data is destroyed due to overwriting or the like in the preformat portion of the next sector, a problem may occur at any time.
No. 2 does not take this into account.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and to prevent long-time continuous irradiation of a light beam such as a semiconductor laser at the final end of each data block (data of each sector) during recording. It is another object of the present invention to provide an optical recording / reproducing apparatus that prevents recorded data from being destroyed and servo from being lost.

[Means for Solving the Problems] In order to achieve the above object, the optical recording / reproducing apparatus of the present invention is configured as in the following (1) to (5).

(1) Discontinuous information (data blocks for each sector)
Is converted into an NRZI signal (pit edge signal), and when this is recorded with a light beam such as a laser, a signal whose polarity is always on the non-pit side is added to the NRZI signal at each end of the discontinuous information. Recording means for performing recording.

(2) Specifically, the recording means stores the discontinuous information in an NR
The NRZI encoder includes an NRZI encoder that converts the information into a ZI signal and an end detection unit that detects an end of the discontinuous information. When the end detecting means detects the end (of each data block), the NRZI encoder outputs a signal of the non-pit side polarity, whereby the irradiation of the light beam is stopped. Alternatively, based on the detection of the termination, the light beam driving means (located after the NRZI encoder) is controlled to stop the light beam irradiation.

(3) It is also possible to convert discontinuous information into a run length limited code and further convert this into a corresponding NRZI signal and record it. In this case, the run length of the run length limited code is detected in order to detect the end. , NRZI code pulse width or light beam irradiation time is measured, and when the length exceeds a predetermined value, termination detection is performed.

(4) The polarity of the recording signal (NRZI signal) is not immediately changed to the non-pit side when the termination is detected, but is set to the same polarity as the polarity up to the predetermined period (2 bit period in the 2-7 format run length limiting code). In addition, the polarity can be set to the non-pit side, so that the code rule of the run length limited code is satisfied so that information can be demodulated without error at the time of reproduction, and a signal having the polarity set to the non-pit side is added. can do.

(5) To adjust the polarity of the NRZI signal to be recorded in the end area of the discontinuous information, a format that has been previously formatted is used.
Kind of polarity adjustment signal (00100000000000 as A pattern
00, 000000000000) are provided as 00 and B patterns. When the NRZI signal ends at the pit polarity at the end, one polarity adjustment signal (A pattern) is selected, and when the NRZI signal ends at the non-pit polarity, the other polarity signal is selected. By selecting (B pattern), a signal having a non-pitched polarity is added even when the signal ends in any polarity.

[Operation] According to the configuration of the above (1), when the last end of the discontinuous information ends on the pit side, the polarity is inverted and a signal of the non-pit side polarity is added, and the last end of the discontinuous information is on the non-pit side. At the end, a signal of the same polarity is added, and in any case, the polarity of the light beam (semiconductor laser) at the final end is in a non-irradiation state. As a result, data in the next sector is not destroyed, and a wide hole is not opened, so that the servo is not started.

According to the above (2), by adding an end detection signal (reset signal) at the end of discontinuous information to the NRZI encoder that performs NRZI encoding, a light beam (semiconductor laser) is obtained.
Can always be in the non-irradiation state.

Since the pulse width at the time of recording is limited by the above (3), a pulse width longer than the limit does not exist in a normal data area. Therefore, a pulse width longer than the limit is
It only occurs at the end of the data. By detecting a pulse width longer than this limit and forcibly setting the non-pit side, the polarity of the light beam at the final end can always be set to the non-irradiation state.

According to the above (4), the code format of the run length limited code can be satisfied, and the run length limited code can be decoded into the original discontinuous information without error during reproduction.

According to the above (5), if the polarity at the end of the data area is a pit, a polarity adjustment signal of one (for example, pattern A) is adopted, and if the polarity at the end of the data area is non-pit, the other (for example, A). B), the polarity adjustment signal is adopted.
The polarity of the signal added thereafter can be on the non-pit side (non-irradiation side).

[Embodiment] Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows a data encoding circuit in a write-once optical disc apparatus for performing pit edge recording.
FIG. 2 shows an example of the operation timing of the circuit of FIG.

In FIG. 1, reference numeral 1 denotes data before encoding to be recorded;
Is an encoder that encodes data 1 into a data sequence suitable for recording, 3 is an encoded code of encoder 2, 4 is a code 3
Is an NRZI encoder for encoding NRZI, and 5 is an NRZI encoded NRZI code. Reference numeral 7 denotes a start signal indicating that transfer of data 1 is started, 8 denotes a count signal for counting the number of data 1 inputs, 6 denotes a start signal 7 and a count signal 8, and the number of data 1 from the start of data. Is counted, and the end of data is recognized when a predetermined number of inputs are counted, and an end detection signal of 9 is output.

Since the end detection signal 9 serves as a reset signal for the NRZI encoder (reset means to return to the initial state and to be on the non-pit signal side), the NRZI code 5 is used.
Is forcibly reset to the non-pit side. Here, the non-pit side refers to a signal level in a state where irradiation of the semiconductor laser is not performed and a pit cannot be made on the recording surface of the optical disk. The pit side refers to a signal level at which the semiconductor laser is irradiated and a pit is formed on the recording surface of the optical disk.

Next, the operation of FIG. 1 will be described with reference to FIG. FIG. 2 shows the end of the discontinuous data 1. Reference numeral 10 denotes a data end indicating the end of data 1. In the figure,
When the data 1 is input as (... 010011) and terminated, the encoder 2 generates an encoded pattern of the code 3. The rules for converting data 1 to code 3 are, for example, as follows.

000 → 000100,10 → 0100,010 → 100100,0010 → 00100100,
11 → 1000,011 → 001000,0011 → 000010000. Here, as an example, a 2-7 code (a run length limited code in which the number (run length) of continuous “0” between “1” and the next “1” (run length) is at least 2 and at most 7) is used. I have. Next, the coding pattern of the code 3 is input to the NRZI encoder 4, and the coding pattern of the NRZI code 5 is generated. In this case, the polarity of the NRZI code 5 at the data end 10 is on the pit side. Therefore, the NRZI code 5 keeps the state of "1" until the next sector as it is, resulting in a long bit. In order to avoid this state, the NRZI encoder 4 is reset by the termination detection signal 9 and the NRZI code 5 is reset at 1T from the data termination 10. T is a pulse width of one bit of data 1 (two bits of data 5).

The reason for resetting at 1T from the end 10 is to satisfy the modulation / demodulation rule by the 2-7 code and reproduce data without error. When the 2-7 code is NRZI-coded, the pulse width becomes 1.5T to 4T. The 2-7 code has a variable length, and requires three or more dummy bits (for 1.5T) for final data determination in demodulation. In the present embodiment, by resetting at 1T, the dummy bit is set to three bits (001) or (000), and the irradiation-side pulse width at the data end portion becomes 1.5T to 4T. this is,
This is because the irradiation-side pulse width that can be taken at the data end 10 is 0.5T to 3T, and is 1.5T to 4T even if dummy bits are included. If the reset position is delayed from 1T, a pulse width of 4T or more is recorded. In this case, inter-track interference becomes a problem.

As described above, according to the present embodiment, the semiconductor laser after data termination can be set in the non-irradiation state regardless of the recording data in the pit edge recording. Even when the 2-7 code is used, normal recording and reproduction can be performed.

As an embodiment of the encoder 2 shown in FIG. 1, for example, a 2-7 code modulator disclosed in Japanese Patent Publication No. 55-26494 may be used. In addition, as an embodiment of the NRZI encoder 4 in the figure, a D-FF (D flip-flop) 60 with a reset input as shown in FIG. As is well known, this circuit outputs an NRZI code 5 every time a pulse is input to the code 3 input.
Are inverted.

FIG. 4 shows an embodiment of the data end detector 6 in FIG. In the figure, reference numeral 62 denotes Q ₁ and Q _{2 according} to the count signal.
...... Q counter output 61 of _n is one, a counter for increasing the counter output 61 is initialized by a start signal 7. Reference numeral 63 denotes a decoder which monitors the counter output 61, determines the end of data 10 after counting a predetermined number, and outputs the end detection signal 9 after 1.5T.

Next, a second embodiment of the present invention will be described with reference to FIG.

In the figure, 71, 72, 73, 74, 75 are the same as the components 1, 2, 3, 4, 5 of the same name in FIG. 76 measures the pulse width of the pit side signal of NRZI code 75 with clock 77,
When a pulse longer than a predetermined length is measured, a long bit signal detection signal 79 is output. The long bit signal detection signal 79 is NRZI
The NRZI code 74 acts as a reset signal for the encoder 74.
To the non-pit side signal.

When an RLL code (run length limiting code) such as a 2-7 code is used as the encoder 72, the pulse width of the NRZI code 75 is limited to a certain range. 1.5T-4T for 2-7 code
(T is equal to T in FIG. 2), and no pulse width of 4.5 T or more is generated. Therefore, if the longest pulse of all the recorded NRZI codes 75 including the synchronization signal and the like is 4T, 4.5T or more may be detected as a long bit.

In the above-described embodiment, when the NRZI code 75 ends on the pit side at the end of data, the pit side state continues and is detected by the long pit signal detector 76 as a long pit signal. Accordingly, the NRZI code 75 becomes a non-pit signal by the long bit signal detection signal 79, and the NRZI code 75 after data termination can always be made a non-pit signal.

Further, according to the present embodiment, even if a pit-side pulse width exceeding the limit occurs due to a circuit abnormality or the like during recording of the data area, the pulse width is limited by the long pit signal detector 76. This has the effect of preventing inter-track interference due to recording.

FIG. 5 One embodiment of the long pit signal detector 76 is shown in FIG. In the figure, reference numeral 77 denotes a clock having a fixed period as a reference, reference numeral 80 denotes an edge detector for detecting the rising and falling edges of the NRZI code 75 in synchronization with the clock 77, and reference numeral 84 denotes a rising edge detection which is an output of the edge detector 80. A signal 85 is a falling edge detection signal which is an output of the edge detector 80, 81 is a rising edge edge detection signal 84 as a start signal, starts counting the number of clocks of the clock 77, and stops the falling edge edge detection signal 85. A counter for stopping the count as a signal, 82 is an output of the counter 81, and 83 is a decoder for outputting a long bit signal detection signal 79 when the counter output 82 exceeds a predetermined value.

The counter 81 counts the number of clocks 77 from the rising edge to the falling edge of the NRZI code 75,
The pulse width on the “1” side can be measured. The result of the pulse width measurement is checked by the decoder 83, whereby a long bit signal detection signal 79 can be obtained.

In this embodiment, since the "1" side of the NRZI code 75 is the bit signal side, the start signal of the counter 81 is a rising edge detection signal 84, and the stop signal is a falling edge detection signal.
85. Therefore, when the bit "0" of the NRZI code 75 is a pit signal, the NRZI code 75 input to the edge detector 80 is used.
Or the start signal of the counter 81 and the stop signal are exchanged.

The same effect can be obtained by using the long bit signal detection signal 79 in FIG. 5 as the gate signal of the gate 90 as shown in FIG. In this case, the NRZI code 75 is gated by the long bit signal detection signal 79 until the NRZI code 75 becomes a non-pit signal after the detection of the long bit signal of the NRZI code 75, and the gate output 91 is set to the non-pit side. Keep it.

In addition, by supplying the long bit signal detection signal 79 to the drive circuit of the semiconductor laser for writing (later stage than the NRZI encoder 74, not shown), the semiconductor laser is not irradiated so that the semiconductor laser is not irradiated. May act.

Also, instead of the NRZI code 75, a monitor signal of the output of the semiconductor laser for writing may be used as an input for pulse width detection of the long bit signal detection signal 76 in FIGS.

A third embodiment of the present invention will be described with reference to FIGS.

In FIG. 8, 101, 102, 103, 104, 105, 106, 107, 10
8,109 are components 1,2,3,4,5,6,7,8,9 of the same name in Fig. 1.
Is equivalent to 110 is an AND gate, 111 is an OR gate, 112 is
The output of the OR gate 111, 114 is a latch circuit for delaying the NRZI code 105, and 113 is the NR which has delayed the NRZI code 105.
This is the ZI latch output.

 The operation will be described with reference to FIG.

The data 101 in FIG. 2A is encoded by an encoder 102,
This is the signal indicated by the code 103 in FIG. here,
As in FIG. 2, encoding into 2-7 codes is performed.

The code 112 in FIG. 3C is equivalent to the signal in FIG.
This is the output through the R gate 111.
Code 103. The signal in FIG. 3C is converted into an NRZI code 105 in FIG. Since the polarity of the signal shown in FIG. 3D at the data terminal 120 is "1" (here, the pit signal side), the data terminal 120
Thereafter, "1" is maintained. The termination detection signal 109 in FIG.
Becomes "1", the output of the AND gate 110 becomes "1", the NRZI latch output 113 of FIG. Becomes “1”.
As a result, the NRZI code 105 in FIG. 4D is inverted to the non-pit side.

The same effect as in the first embodiment can be obtained in the above manner.

Next, a fourth embodiment of the present invention will be described with reference to FIG. 10, FIG. 11, and FIG.

In the present embodiment, as shown in FIG. 11, a data area 140,
A postamble 141, which is a region for adjusting the polarity of a semiconductor laser, is formed between the buffer regions 142, and an example of an optical recording / reproducing apparatus for recording / reproducing based on this format is shown.

FIG. 10 shows the configuration of the modulation section of the present embodiment. 121, 122, 123, 124, 125, 126, 127, 128 are the same as the components 1, 2, 3, 4, 5, 6, 7, 8 of FIG.

133 is a postamble pattern generator for generating a pattern of the postamble 141, 130 is a postamble signal output from the postamble pattern generator 133, 129 is a postamble signal 130 from the code 123.
Code / postamble selection signal for selecting
1 is an end detection timing signal for touching the polarity of the NRZI code 125 at the data end, and 134 is a code /
A selector 132 selects and outputs one of the code 123 and the postamble signal 130 according to the postamble selection signal, and 132 is an output selected by the selector 134.

 Next, the operation will be described.

As the postamble 141 in FIG. 11, the pattern of the table shown in FIG. 12 is used. This is the encoder 122
Assuming a 2-7 modulation / demodulation method. In FIG. 12, the data is represented in a data format before NRZI encoding.

When the end of data is detected by the data end detector 126 in FIG. 10, the end detection timing 131 is input to the postamble pattern generator 133 to latch the NRZI code 125 input signal.

At this time, depending on the polarity of the latched NRZI code 125, the first
One of the patterns in Figure 2 is selected. For example, if the polarity at the end of the data area is pit, the pattern A is selected. Also, if the terminal polarity is non-pit,
The B pattern is selected. The selected pattern is output as a postamble signal 130. At the same time, selector 1
The code / postamble selection signal 129 is input to 34 so that the postamble signal 130 is selected. Accordingly, as the code 132, a postamble signal 130 based on the postamble 141 is output next to the code 123 in the data area 140. When pattern A is selected, the polarity of the output of the NRZI encoder is inverted at the third bit "1". When pattern B is selected, no polarity reversal of the NRZI encoder output occurs. In this way, code 123
9, the polarity of the NRZI code 125 at the end of data becomes "1" at 1T from the end of data only when the data is on the pit side, and the polarity of the NRZI code 125 is set to the non-pit side, as in the case of the code 112 in FIG. .

Even in the above manner, the same effects as those of the first and third embodiments can be obtained.

In the above embodiment, the case where a non-pit polarity signal is added to the last end of the data block of each sector has been described. A similar non-pit polarity signal is added to the preamble portion (ID portion) of each sector and the data block. Can be added to the buffer area between the two.

Further, the above embodiment is a case where the present invention is applied to a write-once type optical disk, but can also be applied to a magneto-optical disk. In this case, the polarity of the signal to be added to the terminal (the polarity corresponding to the above-mentioned non-pit side) may always be set to the direction in which the magneto-optical disk is erased. In the present invention, such "erasing direction" is also called "optical pit side".

[Effects of the Invention] As described above in detail, according to the optical recording / reproducing apparatus of the present invention, when recording discontinuous information (data block for each sector or the like) as an NRZI signal, the data of the discontinuous information is recorded. The polarity of the recording signal can always be set to the non-pit side at the terminal end, so that the recording light beam is not irradiated from the terminal end later. As a result, excellent effects such as prevention of destruction of the preformat portion due to a long pitch and a wide pitch, prevention of interference between tracks, and avoiding a servo failure can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a first embodiment of the present invention.
FIG. 2 is a timing chart for explaining the operation of FIG. 1,
FIG. 3 is a circuit diagram showing one embodiment of the NRZI encoder in FIG. 1, FIG. 4 is a block diagram showing one embodiment of the data end detector of FIG. 1, and FIG. 5 is a second embodiment of the present invention. FIG. 6 is a block diagram showing an embodiment of the long bit signal detector in FIG. 5, FIG. 6 is a block diagram showing an application example of the second embodiment, and FIG. Is the third of the present invention.
FIG. 9 is a block diagram showing the configuration of the embodiment, FIG. 9 is a timing chart for explaining the operation of FIG. 8, and FIG. 10 is a fourth embodiment of the present invention.
FIG. 11 is a block diagram showing the configuration of the embodiment, FIG. 11 is a diagram showing a part of the recording format of the fourth embodiment, and FIG. 12 is a diagram showing an example of the postamble pattern in FIG. 2,72,102 …… RLL encoder, 4,74,104 …… NRZI encoder, 6,1
06: Data end detector, 60: D flip-flop,
62 ... Counter, 63 ... Decoder, 76 ... Long bit signal detector, 79 ... Long bit signal detection signal, 80 ... Edge detector, 81 ... Counter, 83 ... Decoder, 9,109 ... Terminal detection signal.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takehiko Sekine 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Within Hitachi Video Engineering Co., Ltd. (72) Inventor Naomi Yoshida 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi Video Engineering (56) References JP-A-1-300429 (JP, A)

Claims (5)

(57) [Claims] 1. An optical recording / reproducing apparatus for recording discontinuous information on an optical recording medium as an NRZI signal using a light beam, wherein the NRZI signal always has a non-polarity at each end of the discontinuous information. An optical recording / reproducing apparatus comprising recording means for adding and recording a pit side signal. 2. The recording means according to claim 1, wherein said recording means stores said discontinuous information in an NRZI
An NRZI encoder for converting the signal into a signal, and end detection means for detecting the end of the discontinuous information, and upon detection of the end, the NRZI encoder outputs a signal having a non-pit side polarity; or 2. An optical recording / reproducing apparatus according to claim 1, wherein said light beam driving means is controlled to forcibly stop irradiation of said light beam. 3. The recording means includes an RLL encoder for applying the discontinuous information to the NRZI encoder as a run length limited code, the NRZI encoder corresponding to a run length of the run length limited code. A pulse width NRZI signal is generated, and the termination detection means terminates when any of the run length of the run length limiting code, the pulse width of the NRZI signal, or the irradiation time of the light beam exceeds a predetermined value. 3. The optical recording and reproducing apparatus according to claim 2, wherein the optical recording and reproducing apparatus is configured to generate a detection output. 4. When the end detecting means detects the end,
3. The apparatus according to claim 2, wherein the polarity of the NRZI signal to be recorded for a predetermined period is not changed, and thereafter, a signal whose polarity is always on the non-pit side is added, or irradiation of the light beam is stopped. 3. The optical recording / reproducing apparatus according to 3. 5. A preformatted two kinds of polarity adjustment signal for adjusting the polarity of the NRZI signal to be recorded is provided in an end area of the discontinuous information, and the NRZI signal is provided at the end. When the NRZI signal ends at the pit side, the polarity of the NRZI signal is inverted by selecting one polarity adjustment signal. When the NRZI signal ends at the non-pit side polarity, the other polarity adjustment signal is selected. The optical recording / reproducing apparatus according to any one of claims 1 to 4, wherein recording is performed while maintaining the polarity of the signal.