JPH10326426A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk device that can demodulate information from a wobble signal even in arbitrary multiple speed reduction using a decoder, in which the circuit constant is decided in accordance with a prescribed linear velocity, in reproduction of an optical disk. SOLUTION: After a wobble detecting signal reproduced with (m) times speed is made a wobble signal by a matrix circuit 11 and made a binarized wobble signal (WHL) being FM-modulated by a comparator 12, the signal is converted into digital data being parallel in a serial/parallel converter 13 with a clock CK corresponding to (m) times speed, and written in a memory 14. At the time of reading out, data is read out from the memory 14 with a clock of CK/m clock, that is, corresponding to unmultiplied speed, WHL being serial and having a speed of I/m is made by a parallel/serial converter 15, various signals are obtained by an ATIP generator 19, ATIP information and ADIP information are demodulated by a decoder 20 thereon. The clock CK, CK/m are automatically generated by a variable frequency oscillator 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical disk device, and more particularly, to an optical disk device suitable for high-speed reproduction of an optical disk.

[0002]

2. Description of the Related Art An optical disc apparatus for recording and reproducing data on and from an optical disc records data on a track formed on the optical disc while performing tracking control for following the track formed on the optical disc by a laser from an optical pickup, or performs recording on the track. Is performed to reproduce the data recorded in the.

In order to perform this tracking control well, there is a system in which a track groove called a groove formed in an annular or spiral shape is provided along the circumference of an optical disk.

FIG. 7 is a diagram for explaining a track groove and a wobble signal included in the track groove of such an optical disk. FIG. 7A shows the track groove and tracking control. b) shows an example of the shape of the track groove.

As shown in FIG. 7A, track grooves 7 are provided on the optical disc 1 at a predetermined track pitch Tp, and land portions 8 (or groove portions) are formed between adjacent track grooves 7. The recording of data on the optical disc 1 is performed at the position of the land 8 (or groove). The tracking control at this time is performed, for example, by irradiating the laser beam 4 to the meandering track groove 7 via the objective lens 3 and causing the return light to enter the photodetector 5 so that the photodetector 5 is divided into two. The comparator 6 detects a tracking error signal based on the outputs of the light receiving units 5a and 5b, and inputs the tracking error signal to a tracking servo circuit (not shown).

As shown in FIG. 1B, the track groove 7 is meandering at a predetermined period, and information such as an address is recorded by slightly changing the meandering period. From this information, the position of the track being recorded or reproduced can be recognized. The signal embedded in the track groove 7 is referred to as a wobble signal, and the track groove is FM-modulated to perform ATIP (Absolute Tim).
e In Pregroove) and ADIP (Addre
ss In Pregroove) is written in advance. The meandering reproduction frequency is called a wobble frequency.

[0007] In order to increase the recording capacity of an optical disc, information is often recorded in a rotating system called CLV (Constant Linear Velocity) in which the linear velocity is constant. By controlling the rotation speed to an accurate value corresponding to the position, a specified linear velocity, that is, a specified frequency change can be obtained.

Recently, for example, with an increase in the speed of personal computers and the like and an increase in the capacity of processing information, high-speed access to optical disks has been demanded. When the original rotation speed is expressed as 1 × speed, it is increasingly used at a higher linear velocity such as 2 × speed rotating at 2 ×, or 4 × speed rotating at 4 ×. When the above-mentioned wobble signal is represented by 1 × speed reproduction of a disc, information is recorded by modulating a carrier wave of 22.05 kHz with a slight frequency change of ± 0.5 kHz, so that the wobble frequency at 2 × speed is 44. 1 ± 1 kHz, wobble frequency at 4 × speed is 8
8.2 ± 2 kHz.

FIG. 8 shows a reproduced waveform of a wobble signal, and FIG. 8A shows a waveform when the wobble signal is reproduced at a linear velocity v which is 1 time. The frequency F of the wobble signal is obtained by modulating ± f to the fundamental frequency F ₀ , and the above-described ATIP information and ADIP information are recorded. FIG. 3B shows a waveform when the reproduction is performed at m times speed, the rotation is controlled so that the linear velocity becomes m × v, the wobble frequency becomes m × F, and the modulation of m × (± f). The frequency is obtained.

[0010] The wobble signal obtained as described above is restored in information by a demodulator (hereinafter, referred to as "decoder"). However, normally, when the wobble information is demodulated by the decoder, it is possible to demodulate the frequency fluctuation of about 20% of the wobble frequency corresponding to the circuit constant set in the decoder, but it is difficult to exceed the frequency fluctuation. Therefore, for the 2 × speed, 4 × speed, and the like, the circuit constants must be set in a stepwise manner corresponding to each of them, and it is not possible to correspond steplessly.

[0011]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a decoder for which a circuit constant is determined corresponding to a predetermined linear velocity, that is, a predetermined wobble frequency, without changing the circuit constant. The present invention also provides an optical disk device that enables accurate demodulation of information from a wobble signal recorded in a track groove at a high speed, and is suitable for high-speed reproduction.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and according to the first aspect, detects a signal in a track groove having a meandering pattern formed on an optical disk by modulation of a meandering frequency. In an optical disc apparatus for controlling the position of an optical pickup, the detected signal is
Binarizing means for digitizing, a first clock generating means for generating a clock for digitally encoding the binarized signal, and a first clock generating means for converting the digitally encoded binary signal to the first signal Storage means for storing the clock based on the clock generated by the clock generation means, and a second means for generating a clock for reading out the binary signal stored in the storage means
And a decoder that operates in accordance with the clock frequency generated by the second clock generating means, and demodulates a signal read from the storage means by the second clock by the decoder. An optical disk device to be configured.

According to the second aspect of the present invention, the linear velocity of the optical disk at the time of high-speed reproduction is set to v ₁ , and the first clock frequency at this time is set to CK ₁ , while the linear velocity at which the decoder can operate is set to v ₂ , where CK ₂ is the second clock frequency at this time, v ₁ / v ₂ = CK ₁ / CK ₂ = m
The above problem is solved by configuring an optical disk device having a relationship of (positive number).

According to the structure of the present invention, even if the decoder can cope only with a predetermined speed of the optical disk, the reproduction is performed at a higher speed without changing the circuit constant. Information can be accurately read from the recorded wobble signal.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described with reference to FIGS. FIG. 1 is a block diagram of a wobble signal processing circuit according to the present invention, and FIG. 2 is a diagram for describing processing of a wobble signal reproduced at a predetermined speed. FIG. 3 is a diagram showing address information of a wobble signal. FIG. 4 is a block diagram of a circuit for writing a wobble signal reproduced at a predetermined speed to a memory, and FIG. 5 is a block diagram of a circuit for reading a wobble signal from the memory at a speed of 1 / (predetermined speed). FIG. 6 is a block diagram of a circuit for extracting information from the read wobble signal.

FIG. 1 shows the configuration of a wobble signal processing circuit according to the present invention. The blocks surrounded by broken lines in FIG. 1 relate to the configuration of the present invention. According to the present invention, even when an optical disk is reproduced at m-times speed, for example, a decoder having circuit constants set for 1-times speed uses ATIP information or ADI information.
The purpose is to obtain P information. Note that m is a positive number including a decimal point, and the following description is not limited to an integer multiple speed.

The block configuration includes a matrix circuit 11 for creating a wobble signal, a comparator 12 for converting the created wobble signal into a rectangular signal, and a serial / parallel converter for converting a rectangular signal into a parallel digital signal. , A memory 14 for recording the signal, a parallel / serial converter 15 for converting a signal read from the memory 14 into a serial digital signal, a CPU 16 for controlling the entire apparatus, and a VFO for generating a clock.
(Variable Frequency Oscillator) 17, an address counter 18 for forming signals for controlling the serial / parallel converter 13, the memory 14, and the parallel / serial converter 15, and an ATIP generator 19 for receiving data from the parallel / serial converter 15. And a decoder 20 for demodulating information from a signal generated by the ATIP generator 19.

Next, the operation of each circuit block will be described. First, information from the meandering track groove 7 is detected by the optical pickup 2 from the optical disc 1 rotating at a linear velocity v of m times speed, and input to the matrix circuit 11.
The matrix circuit 11 calculates the signal from the optical pickup 2 to reduce the meandering component of the track groove 7 as shown in FIG.
It is extracted as a wobble signal shown in FIG. As shown in FIG. 3, the wobble signal includes A, such as minutes, seconds, and frames.
TIP information and address information of ADIP information such as an address and a sector are included and recorded at a period T (for example, if information repetition is 75 Hz, T = 1/7)
5 sec). Therefore, in reading, the period T
The reading operation needs to be performed for a longer time.

Next, this wobble signal is input to a comparator 12, compared with a predetermined voltage, for example, 0 V, and subjected to an FM-modulated binary wobble signal (hereinafter simply referred to as "WHL") shown in FIG. ) Is formed. This WHL is converted into, for example, 8-bit parallel data shown in FIG. 2D by the serial / parallel converter 13 using the clock CK shown in FIG. The clock CK is the CPU 16
The clock frequency is generated by the VFO 17 based on the above control, and the clock frequency matches the reproduction speed at that time. The clock used at this time needs to include a frequency change of m × (± f) Hz, and the sampling frequency is higher than m × F × (F / 2f) Hz.

As shown in FIG. 4, a clock CK is input to the address counter 18 and the serial / parallel converter 13 for converting the WHL into parallel data and writing to the memory 14.
And the latch signal generated by the address counter 18 are input. The memory 14 has an address counter 18
And write control signal (WR) generated by
WHL converted into parallel data is input from the serial / parallel converter 13 to the memory 14.
Is written to.

Next, as shown in FIG. 5, reading of the WHL converted into parallel data from the memory 14 uses a clock generated by the VFO 17 under the control of the CPU 16 which matches the operation speed of the decoder 20. For example, if the operation speed of the decoder 20 is set to 1 × speed, the frequency of the generated clock is CK / m since the data writing speed was m × speed.

The clock CK / m is the address counter 18
Is input to the parallel / serial converter 15, and the latch signal generated by the address counter 18 is further input to the parallel / serial converter 15. The address signal generated by the address counter 18 and the read control signal (RD) are input to the memory 14, the WHL converted into parallel data is read from the memory 14, and the parallel / serial converter 15 converts the WHL into serial WHL. It is converted and output at a speed of 1 / m at the time of writing.

As shown in FIGS. 5 and 6, WHL demodulation is performed on WH output from the parallel / serial converter 15.
L is input to the ATIP generator 19 and FMDT
(ATIP or ADIP data input), FMCK
(ATIP or ADIP read clock),
ATFG (ATIP or ADIP carrier signal)
Are extracted and input to the decoder 20. Decoder 2
At 0, FMDT and FMC match the set linear velocity.
Since K and ATFG are input, they can be demodulated. Therefore, the demodulated signal is input to the CPU 16 so that ATIP information and ADIP information can be read.

Therefore, the wobble signal recorded in the track groove is set at a predetermined speed even when the optical disk is reproduced at an arbitrary double speed, or even when the linear speed is set steplessly. Demodulated by a decoder having the obtained circuit constants, ATIP information such as minutes, seconds, frames, addresses,
ADIP information on sectors and the like can be obtained.

[0025]

As is apparent from the above description, even in a decoder in which a circuit constant is set corresponding to a predetermined speed, a faster angular velocity constant rotation (without changing the circuit constant) of the optical disk can be achieved. CAV: Constant Angular Vel
ocity) or faster linear speed constant rotation (CLV: Consta
The information can be read out from the wobble signal recorded in the track groove by the reproduction of the nt linear velocity (velocity), and the position control of the optical pickup can be performed quickly and accurately.

[Brief description of the drawings]

FIG. 1 is a block diagram of a wobble signal processing circuit according to the present invention.

FIG. 2 is a diagram for explaining processing of a wobble signal reproduced at a predetermined speed.

FIG. 3 is a diagram showing address information of a wobble signal.

FIG. 4 is a block diagram of a circuit that writes a wobble signal reproduced at a predetermined speed to a memory;

FIG. 5: 1 / (predetermined double speed) of a wobble signal from a memory
FIG. 3 is a block diagram of a circuit that reads data at a speed of 3.

FIG. 6 is a block diagram of a circuit for extracting information from a read wobble signal.

FIG. 7 is a diagram for explaining a track groove of an optical disc and a wobble signal included therein.

FIG. 8 is a diagram for explaining a wobble signal when an optical disc is reproduced at a predetermined speed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical disk, 2 ... Optical pickup, 3 ... Objective lens, 4 ... Laser light, 5 ... Photodetector, 6 ... Comparator, 7 ... Track groove, 8 ... Land part, 11 ... Matrix circuit, 12
... Comparator, 13 ... Serial / parallel converter, 1
4 ... memory, 15 ... parallel / serial converter, 16 ...
CPU, 17 ... VFO, 18 ... Address counter, 19
... ATIP generator, 20 ... Decoder

Claims (2)

[Claims] 1. An optical disc apparatus for controlling a position of an optical pickup by detecting a signal of a meandering frequency in a track groove having a meandering track formed on an optical disc, wherein the detected signal is binarized. Means, a first clock generating means for generating a clock for digitally encoding the binarized signal, and a digitally encoded binary signal generated by the first clock generating means. Storage means for storing the clock based on the read clock, second clock generation means for generating a clock for reading out the binary signal stored in the storage means, and the second clock generation means.
An optical disk device, comprising: a decoder that operates in accordance with a clock frequency generated by the clock generation means, and demodulates a signal read from the storage means by the second clock by the decoder. 2. The linear velocity of the optical disk during high-speed reproduction is represented by v ₁ , and the first clock frequency at this time is represented by CK ₁ ,
On the other hand, assuming that the linear velocity at which the decoder can operate is v ₂ and the second clock frequency at this time is CK ₂ , v ₁ / v ₂ = CK ₁ / CK ₂ = m m: a positive number 2. The optical disk device according to claim 1, wherein: