JPH04177669A - Optical information recorder/reproducer - Google Patents

Abstract

PURPOSE:To always rapidly seek a target track in an MCAV system by measuring a time per one sector at a reaching position of a pickup when address information cannot be demodulated, and corresponding the frequency of a reference clock and frequency characteristic of waveform equalizing means to the zone of the reaching position. CONSTITUTION:The output of a waveform equalizing circuit 32 is demodulated based on a reference clock from a reference clock frequency varying circuit 43, and supplied to a CPU 24. The circuit 43 outputs a reference clock of a frequency corresponding to a zone in response to the zone designation signal of the CPU 24. On the other hand, clocks from a frequency dividing circuit 55 is counted by a counter 56 from the output of an envelope detection circuit 33 through a level decision circuit 58, and a time per one sector is measured. When address information cannot be demodulated by a demodulation circuit 42, a zone is sensed based on the time per one sector, and a delay amount of the equalizer 32 and the frequency dividing ratio of the circuit 43 are reset to values corresponding to the zone. Thus, seeking can be always rapidly conducted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an optical information recording/reproducing apparatus for recording and reproducing information on a disk-shaped recording medium such as a magneto-optical disk or an optical disk.

[Prior Art] As an optical information recording/reproducing apparatus using a conventional disk-shaped recording medium, a so-called CAV uses a disk 1 as shown in FIG.
(Constant Angular Velocity
y) method. In this type of CAV type optical information recording and reproducing device, when moving the pickup to the target track for recording and reproducing, the difference between the track number currently being tracked by the pickup and the target track number to which the pickup is to be moved is calculated. Based on this difference, the pickup is moved to the target track while monitoring the number of tracks crossed by the recording/reproducing laser beam while the pickup is moving, that is, a tracking error signal.

However, as shown in FIG. 8A, the disc 1 has a preformat section 2 and a data section (group section) 3, and the spot 4 of the laser beam for recording and reproduction indicates the preformat section 2 with an arrow. The tracking error signal when crossing the group part 3 as shown in FIG.
The amplitude decreases compared to , and the S/N ratio of the signal decreases.

Therefore, when seeking the pickup to the target track by monitoring the trunking error signal and counting the number of tracks crossed by the laser beam as described above,
In order to reduce counting errors due to a drop in signal level or disturbance noise, etc., a predetermined interpolation is performed, and the track number is read at the track reached, and if it is incorrect, the error track number is calculated and the target is picked up again. The vehicle is controlled to move to the track of

[Problem to be solved by the invention]

As mentioned above, in the so-called CAV method, in which recording and reproduction are performed by keeping the rotational speed of the disk constant at all times, the clock frequency, which is the reference signal processing standard for recording and reproducing information, is constant, so when the pickup reaches the current Even if the track being tracked is different from the target track, there is no problem in reading out the track number or sector number.

However, this method improves on the shortcoming of CAV 2 in that the storage capacity per disk is small, and the number of sectors per track is gradually increased from the inner circumference to the outer circumference while keeping the rotation speed of the disk constant. MCAV (Modified
When using a disc 11 using the CAV system, it is necessary to switch the clock frequency, which is the standard for signal processing for recording and reproducing information, for each zone. When moving from position 13 to target track 15 of zone 14, if the seek is mistakenly entered into zone 16 or 17 which is different from the target track 15, the target track 15
With the predetermined clock frequency in the zone 14, the RF multiplied signal cannot be accurately demodulated, and the track number and sector number cannot be read.

Therefore, in this type of MCAV method, if the track number or sector number cannot be read due to a wrong seek, the pickup is performed at a mechanical origin (home position) where the correlation between the number of sectors and the reference clock frequency is known. After moving once, the number of tracks to be moved from home position 5 to target track 15 is calculated and seek is performed again. Therefore, there is a problem that seeking takes time.

The present invention was made in view of these conventional problems, and an object of the present invention is to provide an optical information recording/reproducing apparatus suitably configured so as to always be able to rapidly seek a target track in the MCAV system. do.

[Means and effects for solving the problem] In order to achieve the above object, the present invention rotates a disk-shaped recording medium whose number of sectors gradually increases in the radial direction from the inner circumference to the outer circumference at a constant rotation speed. In an optical information recording/reproducing apparatus, the optical information recording/reproducing apparatus records or reproduces information via a pickup movable in the radial direction while the disk-shaped recording medium is moving.
a reference clock generating means for generating reference clocks of different frequencies for recording or reproducing information; and a reference clock generating means for generating reference clocks of different frequencies for recording or reproducing information; a waveform equalizing means for equalizing the waveform of the RF multiplied signal by changing the frequency characteristics; and a waveform equalizing means for equalizing the waveform of the RF multiplied signal by changing frequency characteristics; and measuring time per sector based on the RF multiplied signal of the preformat section in which address information of the disk-shaped recording medium is recorded. and the frequency characteristics of the reference clock generated by the reference clock generation means and the waveform equalization means based on the measurement time per sector measured by the measurement means, and the frequency characteristics of the reference clock generated by the reference clock generation means and the frequency characteristics of the waveform equalization means, based on the measurement time per sector measured by the measurement means. and a control means for selectively controlling the pickup so that the address information of the preformat part becomes the respective value corresponding to the value, and when the address information of the preformat section cannot be demodulated at the arrival position of the pickup when moving the pickup to the target track, Based on the measurement time per sector at the reached position measured by the measuring means, the frequency of the reference clock generated by the reference clock generation means and the frequency characteristics of the waveform equalization means are matched to the zone of the reached position. The configuration is configured to control the value to be the same.

〔Example〕

FIG. 1 is a block diagram showing one embodiment of the present invention.

A magneto-optical disk 21 of the MCAV system is rotated by a spindle motor 22, and information is recorded and reproduced on the magneto-optical disk 21 by a pickup 23 having an optical system such as an objective lens. pickup 23
is a voice coil motor (VCM) via a voice coil motor (VCM) driver 25 under the control of a control device (CPU) 24.
The focus and tracking actuators in the pickup 23 are configured to be movable in the radial direction of the magneto-optical disk 21 by the actuator driver 2.
7 so that the light beam projected onto the magneto-optical disk 21 always follows the track in a focused state.

The RF multiplied signal from the pickup 23 is supplied to a preformat data signal detection circuit 28 that detects the phase information of the preformat section, and a magneto-optical data signal detection circuit 29 that detects the magneto-optical signal of the group section, and their output is sent to the CPU 24. The signal is selected by a switch 30 under the control of , and is supplied to a waveform equalization circuit 32 and an envelope detection circuit 33 via an auto gain controller (AGC) 31 .

The waveform equalization circuit 32 includes an AGC 31 as shown in FIG.
an analog multiplexer 35 that switches the output signal from the CPU 24 in response to a zone designation signal from the CPU 24; and a delay circuit 3 that receives the output of the analog multiplexer 35.
6, an analog multiplexer 37 that switches the output signal of the delay circuit 36 in response to the zone designation signal from the CPU 24, an inverter 38 that inverts the output signal of the AGC 31, and an attenuator that attenuates the output of the inverter 38. 39 and an adder 40 that adds the output of the attenuator 39 and the output of the delay circuit 36, thereby changing the frequency characteristics in the radial direction of the magneto-optical disk 21, that is, depending on the zone. To change the way in which high-frequency components of the RF multiplied signal are emphasized. That is, the frequency characteristic H(ω) of the waveform equalization circuit 32 is H((El) = (1k cosωTd) e−J″
``'' (where Td is the delay time and k is the gain constant of the attenuator 37). By controlling the delay amount of 36, the frequency characteristics are made suitable for the zone.

In FIG. 1, the output of the waveform equalization circuit 32 is binarized by a binarization circuit 41 and supplied to a demodulation circuit 42, where it is demodulated based on the reference clock from a reference clock frequency variable circuit 43 and sent to the CPU 24. supply

As shown in FIG. 3, the reference clock frequency variable circuit 43 includes a crystal oscillator 46 connected to a crystal 45, a frequency divider 47 that divides the output of the crystal oscillator 46, and an output of the reference clock frequency variable circuit 43. Programmable counter 48 that divides the frequency by 1
and the output of this programmable counter 48 and the frequency divider 4
A phase comparator 49 that compares the phase with the output of the LPF 50, an LPF 50 that extracts the low frequency component of the output, and a voltage controlled oscillator that controls the oscillation frequency based on the output of the LPF 50
VCO) 51 and a ROM 52 that stores the frequency division ratio in the programmable counter 48 corresponding to the zone designation signal from the CPU 24. By controlling the frequency division ratio, a reference clock having a frequency corresponding to the zone is output.

The output of this reference clock frequency variable circuit 43 is also supplied to a frequency dividing circuit 55 as shown in FIG.

On the other hand, the output of the envelope detection circuit 33 is supplied to the counter 56 via a level determination circuit 58.
, the clocks from the frequency dividing circuit 55 are counted based on the output of the level determination circuit 58, and the counted value is sent to the CPU 2.
4, so that the CPU 24 measures the time per sector.

The operation of this embodiment will be explained below.

First, in order to move the pickup 23 to the target track, the CPU 24 connects the switch 30 to the preformat data signal detection circuit 28 side, and
The delay amount of the delay circuit 36 in the waveform equalization circuit 32 and the frequency division ratio of the programmable counter 48 in the reference clock frequency variable circuit 43 are respectively set to values corresponding to the zone of the target track, and the pickup 23 is currently tracking. Based on the difference between the current track number and the target track number, the pickup 23 is moved to the target track while monitoring the number of tracks crossed by the light beam, that is, the tracking error signal.

Thereafter, at the position reached by the pickup 23, the RF multiplied signal obtained from the preformat data signal detection circuit 28 is processed by the waveform equalization circuit 32 and the binarization circuit 4 as shown in FIG. to demodulate. At the same time, the RF multiplied signal envelope detection circuit 33 shown in FIG. 4A performs detection to obtain an envelope detection circuit shown in FIG.
As shown in Figure 4, it is binarized and supplied to the counter 56, which counts the clock shown in Figure 4 from the frequency divider circuit 55 in synchronization with the rise of the output of the level judgment circuit 58, and calculates the counted value. The CPU 24 then measures the time per I sector based on the count from the counter 56.

The above-mentioned time measurement per sector is performed for a predetermined number of sectors in order to prevent erroneous judgment due to the influence of disturbance noise, etc. During this time, the demodulation circuit 42 measures the time per sector as shown in FIG. The binary signal is synchronized with the reference clock set corresponding to the zone of the target track from the reference clock frequency variable circuit 43, and as a result, the track number, sector number, etc. recorded in the preformat section are synchronized. When the address information is demodulated and supplied to the CPU 24, it is determined that the pickup 23 is correctly located in the zone of the target track, and at that point time measurement per sector is stopped.

Thereafter, based on the demodulated address information, the CPU 24
When the track on which the pickup 23 is located is the target track, the switch 30 is switched to the magneto-optical data signal detection circuit 29 side to record or erase user data on the target track. Play user data! In addition, if the truck where the pickup 23 is located is not the target track even if it matches the zone of the target truck, the difference from the target truck is determined, and predetermined instructions are given to the VCM driver 25 and the actuator driver 27 accordingly. Then, the pickup 23 is moved to the target track.

On the other hand, as shown in FIG. 6, the binarized signal from the binarization circuit 41 and the reference clock set corresponding to the target track zone from the reference clock frequency variable circuit 43 cannot be synchronized. Therefore, even if the time measurement per sector for a predetermined plurality of sectors is completed, if the address information such as the track number and sector number recorded in the preformat part is not demodulated in the demodulation circuit 42 during that time, It is determined that the pickup 23 is not located at the corner of the target track, and the pickup 23 is moved based on the time of one sector measured by the CPU 24.
detects the zone in which it is currently located, and picks up the delay amount of the delay circuit 36 in the waveform equalization circuit 32 and the frequency division ratio of the programmable counter 48 in the reference clock frequency variable circuit 43 according to the detected zone. 23 is reset to a value corresponding to the zone of the track being tracked. As a result, the frequency characteristics of the waveform equalization circuit 32 and the reference clock from the reference clock frequency variable circuit 43 are changed to those corresponding to the zone of the track currently being tracked by the pickup 23, and the track information of that track is read. .

Thereafter, in the same manner as above, the delay amount of the delay circuit 36 in the waveform equalization circuit 32 and the frequency division ratio of the programmable counter 48 in the reference clock frequency variable circuit 43 are respectively set to values corresponding to the zone of the target track. Then, based on the difference between the trunk number currently tracked by the pickup 23 and the target track number to which the pickup 23 is to be moved, move the pink-up 23 while monitoring the number of tracks crossed by the light beam, that is, the tracking error signal. The above operation is repeated, thereby moving the pickup 23 to the target trunk.

As described above, according to this embodiment, even if the pickup 23 is moved to a track in a zone different from the target track by mistake, the pickup 23 will not be returned to the home position (one sector at that position). The frequency characteristic of the waveform equalization circuit 32 and the frequency of the reference clock from the reference clock frequency variable circuit 43 are changed to those corresponding to the zone of the trunk currently being tracked by the pickup 23 by measuring the time of the hit. So you can read the track information of the current track,
Therefore, the pickup 23 can be moved to the target track in an average seek time that is almost the same as when using a CAV type disk.

Note that the present invention is not limited to the above-mentioned MCAV type magneto-optical disk, but can also be effectively applied to a case where an MCAV type optical disk is used.

〔Effect of the invention〕

As described above, according to the present invention, the simple structure of adding means for measuring the time per sector based on the RF signal of the preformat part in which address information of the disk-shaped recording medium is recorded, When moving the pickup to the target track, when the address information in the pre-format section cannot be demodulated at the arrival position of the pickup, recording or reproduction is generated from the reference clock generation means based on the measurement time per sector measured by the measurement means. The frequency of the reference clock for carrying out the process and the frequency characteristics of the waveform equalization means for equalizing the waveform of the RF signal when binarizing the RF signal are controlled so as to have a value corresponding to the zone of the arrival position. Therefore, the target track can always be quickly sought in the MCAV method as in the CAV method.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of an example of the waveform equalization circuit shown in FIG. 1, and FIG. 3 is a block diagram showing an example of the reference clock frequency variable circuit. FIGS. 4A-D are block diagrams showing the configuration; FIGS. 5 and 6 are signal waveform diagrams for explaining the operation of the embodiment shown in FIG. 1; FIGS. 7A and B.
, FIGS. 8A and 8B, and FIG. 9 are diagrams for explaining the conventional technology. 21... magneto-optical disk 22... spindle motor 23... pickup 24... CPU 25... VCM driver 26... VCM 27... actuator driver 28... pre-format data signal detection circuit 29・
・・Magneto-optical data signal detection circuit 30 ・・Switch 31 ・・AGC 32 ・・Waveform equalization circuit 33 ・・Enherobe detection circuit 35 ・・Analog multiplexer 36 ・・Delay circuit 37 ・・Analog Multiplexer 38... Inversion circuit 39... Attenuator 40... Adder 41... Binarization circuit 42... Demodulation circuit 43... Reference clock frequency variable circuit 45... Crystal 46...・Crystal oscillator 47...Frequency divider 48...Programmable counter 49...Phase comparator 50...LPF 51...vCo 52...ROM 55...Frequency divider 56...Counter 58... Level determination circuit patent applicant Olympus Optical Industry Co., Ltd. Representative Patent Attorney Akatsuki Sugimura Examiner Patent Attorney Sugi
Written by Oki Mura Patent attorney Sato
An, Deok-dong, Patent Attorney, Tomi 1) Hierarchy, Patent Attorney, Masa Umemoto, Patent Attorney, Takashi Ninpei, Figure 1, Figure 2, Figure 3, Figure 4, Dm Yeongsan-Yeoshan 1''- Figure 5, Figure 6, Figure 7. Figure 8 Figure 9 Proceedings Amendment Written January 10, 1991 Mr. Satoshi Uematsu, Commissioner of the Japan Patent Office 1, Indication of the Case Patent Application No. 303974 of 1990 2, Name of the Invention Optical Information Recording and Reproducing Device 3; Relationship with the case of the person making the amendment Patent applicant (037) Olympus Optical Industry Co., Ltd. 4, Agent (corrected diagram) Figure 1

Claims (1)

[Claims] 1. A disk-shaped recording medium whose number of sectors is gradually increased in the radial direction from the inner circumference to the outer circumference is rotated at a constant rotation speed, and a pickup that is movable in the radial direction is used. In an optical information recording/reproducing device for recording or reproducing information, corresponding to a zone in the radial direction of the disk-shaped recording medium,
a reference clock generating means for generating reference clocks of different frequencies for recording or reproducing information; and a reference clock generating means for generating reference clocks of different frequencies for recording or reproducing information; a waveform equalizing means for equalizing the waveform of the RF signal by changing the frequency characteristics thereof, and measuring the time per sector based on the RF signal of the preformat section in which address information of the disk-shaped recording medium is recorded. and a measuring means for measuring the frequency of the reference clock generated by the reference clock generating means and the frequency characteristics of the waveform equalizing means based on the measurement time per sector measured by the measuring means, in the zone of the measured track. and a control means for selectively controlling the pickup so that the address information of the preformat part becomes the respective value corresponding to the value, and when the address information of the preformat section cannot be demodulated at the arrival position of the pickup when moving the pickup to the target track, Based on the measurement time per sector at the reached position measured by the measuring means, the frequency of the reference clock generated by the reference clock generation means and the frequency characteristics of the waveform equalization means are matched to the zone of the reached position. 1. An optical information recording/reproducing device characterized in that the optical information recording/reproducing device is configured to perform control so that the value becomes the same.