JP2591411B2 - Optical disk sector mark detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

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

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

In FIG. 5A, a predetermined number of signals of each pattern in an input signal (IN) are applied to a pattern detector 1.
1 and 12 respectively, and respective detection signals are input to delay circuits 13 and 14. Delay circuit 13, 1
In 4, the delay signal is output to the threshold circuit 15 after a set time. The threshold circuit 15 is a delay circuit 1
When the number of coincidences between the delay signals from the patterns 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 and the like. Is sampled with the clock CLK obtained, and the output signal a is output to the matching circuit 17 in parallel.
The matching circuit 17 matches each sampling value with a preset pattern and outputs the resulting signals b _{1 to} b ₅ to the threshold circuit 18. And
The threshold circuit 18 outputs a signal indicating that a sector mark has been detected when the majority of the signals that match the signals b _{1 to} b ₅ is equal to or greater than the threshold.

[0006]

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

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide an optical disk sector mark detecting apparatus that can easily detect a high-resolution sector mark at a low frequency.

[0009]

An object of the present invention is to seek for a predetermined sector on an optical disk on which a predetermined number of sectors are arranged according to a predetermined recording format, and to detect a sector mark attached to the sector. In the sector mark detection device, sequentially generates a timing signal between pulse signals read from the optical disk,
A gate signal generation unit that generates a predetermined number of gate signals at predetermined intervals from the timing signal; a mark length generation unit that generates mark length data of the sector mark from the timing signal; And a matching unit that matches the count value with match data that is appropriately changed and set, and determines the sector mark based on the result of the matching and the mark length data of the sector mark. And a determination unit.

[0010]

As described above, a gate signal is further generated from the timing signal generated from the pulse signal read from the optical disk, and the width of the gate signal is counted at a predetermined frequency, and a match is set by appropriately changing the width. Perform matching with data. A 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 determined and detected.

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

That is, it is possible to easily detect a high-resolution sector mark at a low frequency.

[0013]

FIG. 1 is a block diagram showing an embodiment of the present invention.
In FIG. 1, in the sector mark detection device 21, the target recording medium is an MCAV optical disk, which is recorded with different numbers of sectors having sector marks in a plurality of zones.

1 includes a ring counter 22 and a gate signal generation circuit 23 constituting a gate signal generation section, a mark length generation circuit 24 as a mark length generation section, and a counter circuit as a counting section. 25, a pattern matching circuit 26 and a match data generation circuit 27 that constitute a matching unit, and a determination circuit 28 that is a determination unit
It is composed of

Here, the mark length generation circuit 24 outputs the input signal IN and the output from the ring counter 22 to a clock C.
The data is sampled by the LK to generate mark length data of the entire length of the sector mark and output to the determination circuit. 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 match data of a count pattern corresponding to a sector mark for each zone, and outputs it to the pattern matching circuit 26.

FIG. 2 shows an operation time chart of FIG. First, the input signal (pulse signal) IN read from the optical disk is sequentially generated, for example, in hexadecimal, by a ring counter 22 in timing signals between pulse signals. Is generated.

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

On the other hand, the mark length of the input signal IN and the hexadecimal timing signal are detected by the mark length generation circuit 24 using the clock CLK, and are output to the determination circuit 28 as mark length data c. The mark length data c is data for eliminating a sector mark having different bit data in the determination circuit 28.

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

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

This makes it possible to detect a sector mark in a zone having a double bit rate with a resolution of 2% or less at least twice the clock frequency of the optical disc in the MCAV system.

Next, FIG. 3 shows a circuit diagram of one application example of the present invention. In the sector mark detection circuit 21 shown in FIG. 3, a hexadecimal ring counter 22 generates timing signals T _{1 to} T ₆ based on an input signal IN (in hexadecimal, IN _{1 to} IN ₆ are repeated). Signals T _{1 to} T
₆ to the gate signal generation circuit 23 and the 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 generating circuit 23, the following sequence timing signals T _2, T _4, T ₁ is the gate circuit 23 _2, the timing signal T _3, T _5, T ₂ gate circuit 23 ₃ to, the timing signal T _4, T _6, T ₃ is a gate circuit 23 _4, the timing signal T _5, T _1, T ₄
In but the gate circuit 23 _5, a timing signal T _6, T _2, T
₅ are input to the gate circuit 23 _6. Note that the number of gates and the gate positions may be any as long as they are characteristic places where sector marks can be discriminated.

Gate circuit 23₁Gate signal output from
No.G₁, G_TwoIs the counter 25 of the counter circuit 25₁Enter
The gate circuit 23_Two~ 23₆Gate letter from
No.G _Three~ G₁₂Is counter 25_Two~ 25₆Two letters each
Are entered one by one. Also, the counter 25₁~ 25₆To
Clock (clock frequency twice the minimum bit rate)
CLK is input.

The signal of the count value output from the counter 25 _to 253 _6, respectively, the pattern matching circuit 2
6 comparators 26 _{1 to} 26 ₆ . Further, appropriately modified match data signals in the match data generating circuit 27 to the matching device 26 ₁ to 26 ₆ (corresponding to the count value signal)
Is entered. This match data generation circuit 27
The matching data is freely changed for an AV type optical disk or the like.

The signals M ₁ ~M ₁₂ matching values outputted from the matcher 26 _{1-26 6} are input to the AND gate circuits 28 ₁ to 28 ₆ of the decision circuit 28.
Further, the AND gate circuit 28 ₁ to 28 ₆ the input signal IN and the timing signal T ₁ through T ₆ the signals E ₁ ~ mark length data generated by sampling the clock CLK to the input terminal in the mark length generating circuit 24 of E ₆ are respectively input.

The output from the AND gate circuit 28 ₁ to 28 ₆ is input to the OR gate circuit 28 ₈ in the judging circuit 28, the sector mark detection signal f from the gate circuit 28 ₈ is output.

FIG. 4 shows an operation time chart of FIG. In Figure 4, the sector mark at the AND gate circuit 28 ₃ of the decision circuit 28 is described as being detected.

In FIG. 4, first, input from an optical disc is performed.
Hexadecimal ring counter 22 using force signal IN as a clock
When the clock is input to
Timing signal T₁~ T₆Is output.
This timing signal T₁~ T ₆To the gate signal generation circuit 2
3 for gate signal G₁~ G₁₂Generate.

[0029] Here, the gate circuit 23 _3, the timing signal T _3, T _5, with T ₂ generates the gate signals G _5, G _6. Gate signal G ₅ is rising at a rising timing signal T _3, down falling at the next rising 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 section of the gate signals T _{1 to} T _{6 in which} the gates are open by the clock CLK in the counter circuit 25 matches the value of the match data generated by the match data generation circuit 27 by the pattern matching circuit 26. if, matching output as the matching signal M ₁ ~M _12. If matching in the matching unit 26 _3, matching signal M _5, M ₆ is at the high state at the next stage of the timing signal T _2.

On the other hand, in the mark length generation circuit 24, the input signal
No. IN (IN₁~) Is the input signal IN ₁Based on the pulse width T of
In case of standard, two high-level pulse signals of 3T or more
At the timing detected above, the mark length data E₁~ E₆To
Output. Note that this threshold is the data
It can be set freely according to the dynamic range of the port.
In this case, the input signal IN_FourAnd mark length data E_ThreeStanding
Up, next stage input signal IN_TwoFall at the fall.

[0032] Therefore, the decision circuit 28, the sector mark detection signal D ₁ is outputted from the matching signal M ₁ ~M ₁₂ and the mark length data E ₁ to E ₆ and the OR gate circuit 28 ₈ at the high state together. In this case, the output of only the AND gate circuit 28 ₃ is at a high state, the output of the other AND gate is low. 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 made at any phase of the input signal.

Thus, for example, when the present invention is applied to an MCAV optical disk having 25 to 48 sectors per track, a data rate of 25 sectors / track is used.
5MHz / 3000rpm double clock 29MHz
, It becomes possible to detect sector marks of 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 optical disk.

In the above embodiment, the optical disk of the MCAV system has been described.
The present invention can be applied to an optical disk of a stant linear velocity (Stant Linear Velocity) method or the like.

[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 counted value is matched with the match data to determine the sector mark. , Simple and high-resolution sector mark detection at a low frequency can be performed.

[Brief description of the 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 one application example of the present invention.

FIG. 4 is an operation time chart of FIG. 3;

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

[Explanation of symbols]

 Reference Signs List 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)

(57) [Claims] 1. An apparatus for detecting a sector mark attached to a predetermined sector on an optical disk on which a predetermined number of sectors are arranged according to a predetermined recording format, wherein the sector mark is detected. A gate signal generator for sequentially generating a timing signal between pulse signals read from the memory, and generating a predetermined number of gate signals at predetermined intervals from the timing signal; and generating mark length data of the sector mark from the timing signal. 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, and a result of the matching and the matching A determination unit for determining the sector mark from the data of the mark length of the sector mark; An optical disk sector mark detection device, comprising: