JPH06150563A - Device for detecting sector mark of optical disk - Google Patents

Abstract

PURPOSE:To simply detect a sector mark at high definition with a low frequency in a device for detecting the sector mark recorded on an optical disk. CONSTITUTION:A gate signal is generated in a gate signal generation circuit 23. from a timing signal generated from a pulse signal read from the optical disk in a ring counter 22. The widths of the gate signals are counted by counter circuits 25 respectively at a prescribed frequency, and matching with match data to be set by being properly revised by a match data generation circuit 27 is performed by a pattern matching circuit 26. The sector mark with a bit rate different from the matching value and mark length data generated by a mark length generation circuit 24 is eliminated and the relevant sector mark is discriminated and detected by a discrimination circuit 28.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sector mark detecting device for an optical disc for detecting sector marks recorded on the optical disc.

[0002]

2. Description of the Related Art Conventionally, in a recording medium such as a recordable and reproducible optical disk, address information indicating an address on a track is recorded on an area formed on the track at a predetermined interval at a predetermined interval. . Then, a sector mark is added to the head of this sector, and a desired sector is started by detecting the sector mark.

Therefore, FIG. 5 shows a diagram for explaining a conventional sector mark detection circuit.

In FIG. 5A, a predetermined number of signals of each pattern in the input signal (IN) are the pattern detector 1.
1, 12 are respectively detected, and the respective detection signals are input to the delay circuits 13, 14. Delay circuit 13, 1
In 4, the delay signal is output to the threshold circuit 15 after the set time. The threshold circuit 15 is the delay circuit 1
When the number of coincidences between the delay signals from the signals 3 and 14 and the signal from the pattern detector 11 exceeds a threshold value, a signal indicating that a sector mark has been detected is output.

The sector mark detection circuit shown in FIG. 5B is a simplified version of the delay circuit shown in FIG. 5A. The input signal (IN) is once input to the shift register 16 to obtain sufficient resolution. Is sampled with the clock CLK to obtain the output signal a and the output signal a is output in parallel to the matching circuit 17.
The matching circuit 17 performs matching with each sampling value and a preset pattern, and outputs the resulting signals b _{1 to} b ₅ to the threshold circuit 18. And
The threshold circuit 18, in which a majority of the matched signals of the signal b ₁ ~b ₅ is at a higher threshold, and outputs a signal indicative of the detected sector mark.

[0006]

However, the MCAV (Modified Constant) in which the reference clock for recording and reproduction differs depending on each zone on the optical disk and the frequency increases toward the outer periphery.
When the sector mark of the sector recorded by the Angular Velocity method is detected by the sector mark detection circuit shown in FIGS. 5A and 5B, the sector mark of the unknown zone of unknown data rate is sampled at the same frequency. 5A, it is necessary to provide the matching pattern of the number of zones and the delay amount of each delay circuit in FIG.
In (B), it is necessary to provide the matching value corresponding to each sector mark in the number of zones.

Therefore, there is a problem that the circuit becomes complicated and that the sampling frequency must be made very high in order to determine which zone the zone is in by the matching value.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a sector mark detecting apparatus for an optical disc, which is simple and performs high-resolution sector mark detection at a low frequency.

[0009]

An object of the present invention is to provide an optical disc which detects a sector mark attached to a predetermined sector when seeking to a predetermined sector in an optical disc in which a predetermined number of sectors are arranged by a predetermined recording format. In the sector mark detection device, sequentially generate timing signals between pulse signals read from the optical disc,
A gate signal generation unit for generating a predetermined number of gate signals at predetermined intervals from the timing signal, a mark length generation unit for generating mark length data of the sector mark from the timing signal, and a width of each gate signal at a predetermined frequency. And a matching unit that matches the count value with matching data that is appropriately changed and set, and determines the sector mark from the matching result and the mark length data of the sector mark. This is solved by being configured with a determination unit.

[0010]

As described above, a match signal is generated by further generating a gate signal from the timing signal generated from the pulse signal read from the optical disk, counting the width of this gate signal at each predetermined frequency, and appropriately changing the setting. Match with the data. The sector mark having a bit rate different from the matching value and the mark length data of the sector mark is excluded, and the sector mark is discriminated and detected.

Accordingly, even if the optical disc is a recording format of the MCAV system, the match data may be set by appropriately changing it by a simple pattern of the count value in the width of the gate signal, and the sampling frequency of the optical disc. A clock frequency twice the bit rate is sufficient.

That is, the sector mark can be easily detected with high frequency and high resolution.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a block diagram of an embodiment of the present invention.
In FIG. 1, in the sector mark detecting device 21, the target recording medium is an MCAV type optical disc, and the plurality of zones are recorded with different numbers of sectors.

The sector mark detecting device 21 of FIG. 1 includes a ring counter 22 and a gate signal generating circuit 23 which form a gate signal generating unit, a mark length generating circuit 24 which is a mark length generating unit, and a counter circuit which is a counting unit. 25, a pattern matching circuit 26 and a match data generation circuit 27 that form a matching unit, and a determination circuit 28 that is a determination unit.
Composed of and.

Here, the mark length generating circuit 24 outputs the input signal IN and the output from the ring counter 22 as a clock C.
The mark length data of the entire length of the sector mark is generated by sampling with LK and is output to the determination circuit 28. The counter circuit 25 samples the output signal from the gate signal generation circuit 23 according to the clock CLK. Also,
The match data generation circuit 27 generates the match data of the count pattern corresponding to the sector mark for each zone and outputs it to the pattern matching circuit 26.

Therefore, FIG. 2 shows an operation time chart of FIG. First, an input signal (pulse signal) IN read from an optical disk sequentially generates a timing signal between pulse signals in hexadecimal by a ring counter 22, and a gate signal generating circuit 23 outputs a predetermined number including gate signals a and b. Is generated.

The gate signal is a signal in the entire mark length, which is a feature of the sector mark signal, or in a section close to it, and is generated between the rising edges of the input signal IN. For example,
The gate signal a is a signal (75 channel bits) between six (hexadecimal) pulses, and the gate signal b is generated as a signal between three pulses.

On the other hand, the mark length generation circuit 24 detects the mark length of the input signal IN and the hexadecimal timing signal, and outputs the mark length data c to the determination circuit 28 as mark length data c. The mark length data c is data for eliminating sector marks having different bit data in the determination circuit 28.

Further, the gate signals a and b are supplied to the counter circuit 2
5, the open interval is counted by the clock CLK having a constant frequency (necessary and sufficient clock frequency), and the count value is matched by the pattern matching circuit 26 in the match data of the count pattern set by the match data generation circuit 27. Is matched by and. Then, the matching values d and e are output to the determination circuit 28.

The determination circuit 28 outputs the sector mark detection signal f when the data of the matching values d and e is the sector mark data and the bit rates of the mark length data c match.

As a result, a sector mark can be detected with a resolution of 2% or less in a zone having a double bit rate with a clock frequency at least twice as high as that of an optical disc in the MCAV system.

Next, FIG. 3 shows a circuit diagram of an application example of the present invention. In the sector mark detection circuit 21 of FIG. 3, the hexadecimal ring counter 22 generates timing signals T _{1 to} T ₆ based on the input signal IN (in the hexadecimal, IN _{1 to} IN ₆ are repeated), and the timing signals T _{1 to} T ₆ are generated. Signals T _{1 to} T
₆ is a gate signal generation circuit 23 and a mark length generation circuit 24
Output to. Here, the timing signals T ₁ , T ₃ , T
₆ is input to the gate circuit 23 ₁ of the gate signal generation circuit 23, and the timing signals T ₂ , T ₄ , T ₁ are sequentially supplied to the gate circuit 23 ₂ , and the timing signals T ₃ , T ₅ , T ₂ are sequentially supplied to the gate circuit 23 _3. The timing signals T ₄ , T ₆ and T ₃ are supplied to the gate circuit 23 ₄ , and the timing signals T ₅ , T ₁ and T ₄ are supplied to the gate circuit 23 _4.
To the gate circuit 23 ₅ , timing signals T ₆ , T ₂ , T
₅ is input to the gate circuit 23 ₆ . The number of gates and the gate positions may be any as long as they are characteristic locations where the sector marks can be discriminated.

Gate circuit 23₁Gate signal output from
Issue G₁, G₂Is the counter 25 of the counter circuit 25₁Enter
Gate circuit 23₂~ 23₆Gate from
Issue G ₃~ G₁₂Is the counter 25₂~ 25₆2 each
Numbers are entered one by one. Also, the counter 25₁~ 25₆In
Clock (clock frequency twice the minimum bit rate)
CLK is input.

The signals of the count values output from the counters 25 _{1 to} 25 ₆ are respectively the pattern matching circuit 2
6 comparators 26 _{1 to} 26 ₆ are input. In addition, the match data signals (corresponding to the count value signals) appropriately changed by the match data generation circuit 27 are supplied to the matching units 26 _{1 to} 26 _6.
Is entered. This match data generation circuit 27
The matching data is freely changed for an AV type optical disc or the like.

The matching value signals M _{1 to} M ₁₂ output from the matching devices 26 _{1 to} 26 ₆ are input to AND gate circuits 28 _{1 to} 28 ₆ of the determination circuit 28, respectively.
Further, at the input ends of the AND gate circuits 28 _{1 to} 28 ₆ , the mark length generating circuit 24 samples the input signal IN and the timing signals T _{1 to} T ₆ with the clock CLK and generates the mark length data signals E ₁ to. E ₆ is input respectively.

The outputs from the AND gate circuits 28 _{1 to} 28 ₆ are input to the OR gate circuit 28 ₈ in the determination circuit 28, and the sector mark detection signal f is output from the OR gate circuit 28 ₈ .

Therefore, FIG. 4 shows an operation time chart of FIG. In FIG. 4, it is assumed that the AND gate circuit 28 ₃ of the determination circuit 28 detects the sector mark.

In FIG. 4, first, the input from the optical disk is performed.
The hexadecimal ring counter 22 using the force signal IN as a clock
Input to the
Timing signal T at the timing₁~ T₆Is output.
This timing signal T₁~ T ₆Gate signal generation circuit 2
Gate signal G at 3₁~ G₁₂Generate.

Here, the gate circuit 23 ₃ generates the gate signals G ₅ and G ₆ by using the timing signals T ₃ , T ₅ and T ₂ . The gate signal G ₅ rises at the rising edge of the timing signal T ₃ and falls at the next rising edge of the timing signal T ₂ . Further, the gate signal G ₆ is rising at a rising timing signal T _3, down standing in the rise of the timing signal T _5.

The count value obtained by counting the gate open section of these gate signals T _{1 to} T _{6 with} the clock CLK in the counter circuit 25 matches the value of the match data generated in the match data generating circuit 27 in the pattern matching circuit 26. If so, matching output is performed as the matching signals M _{1 to} M ₁₂ . If the matching is performed by the matching device 26 ₃ , the matching signals M ₅ and M ₆ become high at the next stage of the timing signal T ₂ .

On the other hand, in the mark length generation circuit 24, the input signal is
No. IN (IN₁~) Is the input signal IN ₁Based on the pulse width T of
In the case of quasi, 2 high-level pulse signals of 3T or more
At the timing detected above, the mark length data E₁~ E₆To
Output. This threshold is based on the MCAV data
It is set freely according to the dynamic range of the card.
In this case, the input signal IN_FourMark length data E₃Stands
Up, next stage input signal IN₂Fall on the trail of.

Therefore, in the decision circuit 28, the sector mark detection signal D ₁ is output from the OR gate circuit 28 ₈ when the matching signals M _{1 to} M ₁₂ and the mark length data E _{1 to} E ₆ are both in the high state. In this case, the output of only the AND gate circuit 28 ₃ is in the high state, and the outputs of the other AND gate circuits are in the low state. That is, if all the conditions of the matching signals M _{1 to} M ₁₂ and the mark length data E _{1 to} E ₆ are aligned, the detection output is performed at any phase of the input signal.

Thus, for example, when the present invention is applied to an MCAV type optical disc in which the number of sectors per track is 25 to 48, the data rate of 25 sectors / track is 14.
5MHz / 3000rpm double clock 29MHz
It becomes possible to detect sector marks in all zones and discriminate zones by matching data. That is, a zone having a double bit rate can be detected with a resolution of 2% or less at a clock frequency twice the minimum bit rate of the MCAV type optical disc.

In the above embodiment, the MCAV type optical disk has been described.
It can also be applied to optical disks such as the stant linear velocity method.

[0035]

As described above, according to the present invention, the width of the gate signal generated from the input signal from the optical disk is counted at a predetermined frequency, and the count value and the match data are matched to determine the sector mark. By performing the above, it is possible to perform the high-resolution sector mark detection simply and at low frequency.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is an operation time chart of FIG.

FIG. 3 is a circuit diagram of an application example of the present invention.

FIG. 4 is an operation time chart of FIG.

FIG. 5 is a diagram for explaining a conventional sector mark detection circuit.

[Explanation of symbols]

 21 Sector Mark Detection Device 22 Ring Counter 23 Gate Signal Generation Circuit 24 Mark Length Generation Circuit 25 Counter Circuit 26 Pattern Matching Circuit 27 Match Data Generation Circuit 28 Judgment Circuit

Claims (1)

[Claims] 1. A sector mark detecting device for an optical disc, which detects a sector mark attached to a predetermined sector in an optical disc having a predetermined number of sectors arranged in a predetermined recording format, wherein And a gate signal generator for sequentially generating timing signals between the pulse signals read from the pulse signals and generating a predetermined number of gate signals at predetermined intervals from the timing signals, and mark length data of the sector mark from the timing signals. A mark length generation unit, a counting unit that counts the width of each of the gate signals at a predetermined frequency, a matching unit that matches the count value with match data that is appropriately changed and set, the matching result and the A determination unit that determines the sector mark from the mark length data of the sector mark; A sector mark detecting device for an optical disc having the above.