JPH0485765A - Correction system for detection timing of sector mark - Google Patents

Abstract

PURPOSE:To secure the margin of the sector mark read timing by correcting the sector gate signal transmission timing in response to the variance of the revolving speed of a spindle motor. CONSTITUTION:A counter 18 is reset by an index signal transmitted fro each revolution of an optical disk driven by a spindle motor and counted up with each input of a reference clock. An operational amplifier 19 calculates the variance value of the index signal based on the count value of the counter 18 and the index signal and sends this calculated variance value to a byte conversion circuit 20. The circuit 20 converts the variance value of the index signal into a byte number to send this number to a correction value conversion circuit 21. The circuit 21 sends the correction value of the transmission timing of a sector gate signal to a sector gate signal transmission circuit 22 based on the variance value of the revolving speed of the optical disk shown by the byte number. Therefore the circuit 22 corrects a prescribed time set previously based on the correction value of the transmission timing at transmission of the sector gate signal. Thus it is possible to always detect a sector mark in the timing having the margin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] This invention relates to a sector mark detection timing correction method that corrects the sending timing of a sector gate signal sent to detect a sector of an optical disk in response to rotational fluctuations of a spindle motor. In order to correct the signal sending timing and provide a margin for the sector mark reading timing, the track formed on the optical disk is divided into multiple sectors, and the sector mark is recorded in the leading area of the sector. , an optical disk device that detects subsequent sector marks by a sector gate signal that is sent every time a predetermined time elapses after positioning a light beam on the track, based on the timing at which the sector mark is first detected. wherein means is provided for detecting fluctuations in the rotational speed of the optical disc based on a reference clock and an index signal that is sent once per rotation of the optical disc, and correcting the sending timing of the sector gate signal; The sector gate signal is transmitted at a timing in which the predetermined time is corrected in response to variations in the rotational speed of the optical disk every rotation.

[Industrial application field]

The present invention relates to an optical disk 152, and more particularly to a sector mark detection timing correction method for correcting the sending timing of a sector gate signal sent to detect a sector of an optical disk in response to rotational fluctuations of a spindle motor.

Generally, optical discs form tracks in a spiral shape.
This track is divided into a plurality of sectors, and the optical disc device records/reproduces data in each sector.

Each sector is provided with an area where a sector mark is recorded, an ID area where index information for indexing this sector is recorded, and a data area where data is recorded.

The optical disc device then selects a target sector to record/reproduce data. When selecting this sector, the gate is opened in response to a sector gate signal and the sector mark is read.

By the way, after the head is positioned on the target track, these sector gate signals are sent out sequentially after a certain period of time has elapsed based on the detection timing of the first detected sector mark. It is necessary that the sector mark reading margin not be insufficient due to rotational fluctuations.

[Conventional technology]

FIG. 3 is a block diagram illustrating an example of the prior art.

The 7'o setter 14 operates by reading a program stored in the ROM 13, and drives the spindle motor 3 to rotate the optical disc 1 at a predetermined rotational speed.

Further, the processor 14 controls the servo circuit 7 based on the address sent by the host device via the interface circuit 15, and moves the optical head 2 to the vicinity of a designated track on the optical disc 1.

Then, the tracking servo positions the light beam to follow the target track, and the focus servo focuses the light beam on the l-rack.

The electrical signal obtained from the reflected light of the light beam projected onto the optical disk l is sent from the optical head 2 to the AGC circuit (automatic gain adjustment circuit) 5, and after being amplified to a certain level by the AGC circuit 5, The signal is sent to the gate timing control circuit 10 via the FO circuit (voltage controlled oscillation circuit) 8.

In addition, the iD soli circuit 11 is provided with a VFO circuit 8.
The data is sent out together with a clock synchronized with the read data, and the gate timing control circuit 10 outputs the data to rD.
When the read gate signal is applied and the sector information in the data is extracted, it is sent to the processor 14.

Further, data amplified to a certain level by the AGC circuit 5 is sent to the pulse generator 9, and a sector mark in the pulsed data is extracted by a search sector circuit 12 using a sector gate signal to be described later. and is sent to the pro sensor 14.

Once the processor 14 has positioned the light beam on the designated track as described above, it repeatedly sends a sector gate signal to the search sector circuit 12 to detect a sector mark.

When the search sector circuit 12 detects a sector mark, it notifies the gate timing control circuit 10 and the processor 14. Therefore, the processor 14 stops sending the sector gate signal to the search sector circuit 12, and the gate timing control circuit 1o controls the rotation speed of the spindle motor 3 every time a predetermined period of time elapses from the rotational speed of the spindle motor 3, with the sector mark detection timing as a reference. , a sector gate signal is sent to the search sector circuit 12 to sequentially read the sector mark of the next sector.

When the search sector circuit 12 reads the sector mark, the processor 14 checks the sector information read by the ID read gate signal as described above by the ID read circuit 11, and instructs the gate timing control circuit 10 to LEm the designated sector. Then, the data read from the corresponding sector is sent to the host device via the interface circuit 15.

In the case of data writing, the data input to the gate timing control circuit 10 via the interface circuit 15 is
A modulated light beam is sent to the optical head 2 by the write circuit 6 and projected onto the optical disk 1 .

At this time, a magnetic field is applied to the optical disk 1 from the bias circuit 4 controlled by the gate timing control circuit 10, and a focus with a different magnetization direction is formed in a predetermined sector of the optical disk 1, and data is recorded.

[Problem to be solved by the invention]

FIG. 4 is a diagram illustrating the relationship between sector gate signals and sector marks.

In each sector, as shown in FIG. 4, an ID, which is sector index information, is recorded following a sector mark, and then data is recorded. Finally, a CRC for error detection and correction is recorded.

All of these sectors have the same length.

Therefore, when a sector mark is detected, if there is no variation in the rotational speed of the spindle motor 3, the time until the sector mark of the next sector is detected is determined. Therefore, as described above, after the optical head 2 is positioned on the designated track, a predetermined period of time has elapsed based on the timing at which the sector mark was first detected.
As shown in FIG. 4, a sector gate signal is sent out from the gate timing control circuit 10, and the sector gate signal opens the gate of the search sector circuit 12 to read the sector mark.

However, the rotational speed of the spindle motor 3 is not constant (
Since conventional circuits do not take this variation into consideration, there is a problem in that there may be insufficient margin in the read timing of the sector gate signal.

In view of these problems, the present invention provides a spindle motor 3.
The purpose of this invention is to correct the sector gate signal sending timing in accordance with fluctuations in the rotational speed of the controller, and to provide a margin for the sector mark reading timing.

[Means to solve the problem]

FIG. 1 is a block diagram illustrating the invention in detail.

A track formed on the optical disc 1 is divided into a plurality of sectors, and a sector mark is recorded in the leading area of each sector. When the optical beam emitted from the optical head 2 is positioned on this trunk, an electrical signal is input from the optical head 2 to the search sector circuit 12 via the AGC circuit 5 and the pulse generator circuit 9, as explained in FIG.

As explained in FIG. 4, the correction means 17 of the gate timing control circuit 16 of the optical disk device uses the timing at which the first sector mark is detected from this electric signal as a reference clock, and the correction means 17 outputs the signal from the reference clock and the spindle motor 3. Based on the index signal sent out once for each revolution of the optical disc 1, fluctuations in the rotational speed of the optical disc 1 are detected, and a predetermined period of time is determined in response to the fluctuation in the rotational speed for each revolution of the optical disc 1. Correct. That is, after correcting the sending timing of the sector gate signal, it is sent to the search sector circuit 12.

The search sector circuit 12 opens the gate based on the corrected sector gate signal and detects a sector mark.

[Effect]

With the above configuration, the sector gate signal sent by the correction means 17 is corrected for rotational fluctuations of the optical disk l, so that a margin can be provided for the reading timing when detecting sector marks.

〔Example〕

FIG. 2 is a block diagram of a circuit showing one embodiment of the present invention.

As explained in FIG. 1, the counter 18 is reset by an index signal sent from the spindle motor once per revolution of the optical disk, and counts up each time a reference clock is input.

The operational amplifier 19 calculates the amount of variation in the index signal from the count value of the counter 18 and the index signal, and sends it to the byte conversion circuit 20.

The byte conversion circuit 20 converts the amount of variation in the index signal into the number of bytes, and sends it to the correction amount conversion circuit 21.

The correction amount conversion circuit 21 sends a correction amount for the sending timing of the sector gate signal to the sector gate signal sending circuit 22, depending on the amount of variation in the rotational speed of the optical disk indicated by the Hyde number.

Therefore, the sector gate signal sending circuit 22 corrects a predetermined time period using this correction amount when sending out the sector gate signal.

[Effects of the Invention] As explained above, the present invention corrects the sending timing of the sector gate signal that opens the game 1 for extracting sector marks in response to fluctuations in the rotational speed of the optical disc, so that the timing always has a margin. Sector marks can be detected using .

[Brief explanation of the drawing]

FIG. 1 is a block diagram explaining the present invention in detail, FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention, FIG. 3 is a block diagram explaining an example of the prior art, and FIG. 4 is a block diagram showing a sector. FIG. 3 is a diagram illustrating the relationship between gate signals and sector marks. In the figure, 1 is an optical disk, 2 is an optical head, 3 is a spindle motor, 4 is a bias circuit, 5 is an A, GC circuit, 6 is a write circuit, 7 is a servo circuit, 8
is a VFO circuit, 9 is a pulse generation circuit, 10.16 is a gate timing control circuit, 11 is an ID
IJ-do circuit, 12 is search sector circuit, 13 is R
OM, 14 is a processor, 15 is an interface circuit, 17 is a correction means, 18 is a counter, 19 is an operational amplifier, 20 is a byte conversion circuit, 21 is a correction amount conversion circuit, and 22 is a sector gate signal sending circuit.

Claims (1)

[Claims] A track formed on an optical disc (1) is divided into a plurality of sectors, a sector mark is recorded in the leading area of the sector, and after positioning a light beam on the track, first Based on the timing when the sector mark is detected,
In an optical disc device that detects subsequent sector marks using a sector gate signal sent every time a predetermined time elapses, the optical disc device detects a sector mark after a sector gate signal is sent out every time a predetermined time elapses.
means (17) for correcting the sending timing of the sector gate signal by detecting a variation in the rotational speed of the optical disk (1) based on the index signal sent twice, the optical disk (1) making one revolution; A sector mark detection timing correction method, characterized in that the sector gate signal is transmitted at a timing in which the predetermined time is corrected in response to rotational speed fluctuations.