JP2000048378A - Access method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a trace position from being deviated out of a non-recorded area even though the trace position by an optical head after seek operation is fluctuated unstably by areas where a tracing is conducted. SOLUTION: A prescribed area in the front side from a last address including the last address of the data recorded in a non-close session is set as a boundary area. If a target address is located within the boundary area, the address being this side of a prescribed amount from the target address, is set as the seek target, which is retrieved by a seek operation and the seek target is conducted by the access in which an already recorded address is referred. If a seek target is retrieved, it is switched to a trace condition and the target address is retrieved by the trace condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of accessing an unclosed session of a disc recorded by a recordable disc recording apparatus.

[0002]

2. Description of the Related Art There is known an optical disk recording apparatus which performs recording by changing the reflectance of a recording layer of an optical disk by irradiating a light beam from an optical head. So-called write-once (writ) that cannot physically erase erased data
e-once) CD (Compac
CD-R (Recordable) drives of the (t Disc) family are well known.

[0003] As is well known, a CD-R blank disc has a pre-groove (Pre-groov) as a signal track.
e) is formed and the pregroove has 22.05
ATIP (Absolute Time I) for kHz wobble
n-pre-groove) is recorded by FM modulation.

[0004] The CD-R drive can perform an access to search for a trace position by the optical head with reference to the ATIP.

[0005]

By the way, in a CD-R drive, it may be necessary to access the vicinity of the end of an unclosed session, which is a session not closed by lead-in and lead-out, in the process of recording a disc. is there.

In such a case, if an access is made with reference to the address (sub-code Q channel data) added to the recorded data, the objective lens of the optical head becomes unstable immediately after a seek operation involving a track jump. As a result, there is a fear that the trace position by the optical head enters an unrecorded area where no data is recorded, tracking cannot be performed, and a runaway state occurs.

Further, when accessing by referring to the ATIP, it is necessary to switch the signal reading to the recording data in order to synchronize with the recording data in order to read the recorded data. If the operation is performed in a state in which the position is not stable, there is a fear that a runaway state may occur due to entering into an unrecorded area.

Therefore, when accessing with reference to the ATIP, it is possible to prevent a runaway state by waiting for switching of signal reading to recording data until the objective lens of the optical head becomes stable. However, if such an access is adopted not in the vicinity of the end of the unclosed session but in a place where there is no possibility of a runaway state, there is a problem that an excessively long access time is required due to synchronization switching or the like.

[0009]

According to the present invention, a predetermined area on the near side from the last address including the last address of data recorded in an unclosed session is set as a boundary area. When the target address is within the boundary area, an address that is a predetermined amount before the target address is set as a seek target to be searched by a seek operation, and the seek target is performed by an access that refers to a recorded address. When the seek target is searched, the state is switched to the trace state, and the target address is searched according to the trace state.

[0010]

1 is a flowchart showing an example of an access method according to the present invention, and FIG. 2 is a circuit block diagram showing a CD-R drive employing the access method shown in FIG.

In FIG. 2, reference numeral 1 denotes an optical head which emits a laser beam for tracing the disk, and writes and reads data on and from the disk. Reference numeral 2 denotes a disk formed by recording data by the optical head 1. A head amplifier that amplifies an RF signal (high-frequency signal) obtained by reading the read pit, binarizes the RF signal and outputs it as digital data, and 3 feeds back the output of the optical head 1 via the head amplifier 2. And
A head servo circuit that performs focusing control for focusing the laser beam on the signal surface of the disk and tracking control for causing the laser beam to follow the signal track of the disk, and also performs thread feed control for sending the optical head 1 itself in the radial direction of the disk. is there.

Reference numeral 4 denotes a decoder for performing signal processing for demodulating digital data output from the head amplifier 2, and reference numeral 5 denotes a subcode demodulation circuit for demodulating the separated subcode.

Reference numeral 6 denotes an encoder for adding the address data generated by the address generation circuit 7 to the input data, and modulating the input data to which the address data has been added into data to be recorded on the disk. This is a laser drive circuit that drives a laser light source that emits a laser beam from the optical head 1 based on data.

An ATIP demodulation circuit 9 extracts a wobble component from a pre-groove signal of the disc obtained through the head amplifier 2, generates a component necessary for controlling the rotation of the disc, and demodulates the ATIP from the wobble component.
Is a wobble decoder including:

Reference numeral 11 denotes a system control circuit for performing system control relating to recording and reproduction of a disk. The system control circuit 11 includes a subcode address of absolute time information in the Q channel data (sub Q data) of the subcode demodulated by the subcode demodulation circuit 5, and an ATIP
An access control means 12 for selectively referring to the ATIP address of the absolute time information in the ATIP demodulated by the demodulation circuit 10 to control access is provided.

In the thus constructed CD-R drive, disc reproduction is requested, and access is executed by the access control means 12 in accordance with the requested data address.

If a disc to be reproduced is mounted before access is performed, there is an unclosed session that has not been closed by lead-in and lead-out depending on whether there is TOC data in the last session of the disc in advance. Is determined.

In the case of a disc having an unclosed session, the access control means 12 executes an access mode according to the program shown in the flowchart of FIG.

In the case of a disc having an unclosed session, the address of the requested data is set as a target address to be searched by the access control means 12, and the target address is the last address of the last data block recorded in the unclosed session. It is compared with the address (step a).

If the target address is larger than the last address, the pre-groove wobble is read, and the access control means 12 is set to control to refer to the ATIP demodulated by the ATIP demodulation circuit 10, and the AT is controlled.
The target address is accessed with reference to the IP (step b).

On the other hand, if the target address is equal to or less than the final address, it is determined whether the target address is within a preset boundary area (step c).

As shown in FIG. 3, the boundary area B is set to a predetermined range on the near side from the last address EA including the last address EA, and the predetermined range is set when the optical head 1 is moved at high speed by access. The predetermined range is set in advance in consideration of the distance at which the objective lens fluctuates. Since the distance over which the objective lens fluctuates after the access differs depending on the acceleration for accelerating and decelerating the optical head 1 by the access, the boundary area B has a range set according to the acceleration and deceleration of the optical head 1 used for the access.
For example, it is set to 300 frames.

If it is determined in step c that the target address TA is outside the boundary area B, the pits formed on the disk are traced and the RF signal is read, and the access control means 12 performs subcode demodulation. The control is set to refer to the sub-Q data demodulated by the circuit 5, and the target address TA is accessed with reference to the sub-Q data (step d).

When it is determined that the target address TA is within the boundary area B, the address of the seek target ST searched by a seek operation involving a track jump in the access is set to an address that is a predetermined amount before the target address TA. (Step e).

The address serving as the seek target ST is set in consideration of the time until the objective lens is stabilized when the optical head 1 is moved at a high speed by access.

If the drive speed of the disk is different, even if the time required for the objective lens to stabilize is the same, there is a difference in the distance traced within that time.
The difference between the address of T and the target address TA is set according to the difference in the traced distance. For example, if the frame is set to m frames per rated speed of the disk and the drive speed of the disk is n times the rated speed, m × n frames are set.

Specifically, the address of the seek target ST is m
= 50 frames, and if the drive speed of the disk is 8 times the rated speed, 400
Set to the address before the frame.

When the address of the seek target ST is set, the access control means 12 is set to control to refer to the ATIP demodulated by the ATIP demodulation circuit 10, and the AT is controlled.
A search for the seek target ST is performed by a seek operation with reference to the IP (step f).

When it is detected that the search for the seek target ST has been completed (step g), the access control means 12 switches the access to a trace state without a track jump (step h). Demodulates the wobble by ATI
Synchronization detection by ATIP demodulated by the P demodulation circuit 10 is performed (step i).

When the state is switched to the trace state, the current address PA demodulated by the trace is compared with the target address TA, and the current address PA is shifted by a first predetermined frame (for example, 20 frames) before the target address TA. When it is determined that the disk has reached the area E1 (step j), the state is switched to a state of tracing pits formed on the disk, and synchronization detection is performed by sub-Q data demodulated by the sub-code demodulation circuit 5 (step j). Step k).

Further, the tracing proceeds in a state where the synchronization is detected by the sub-Q data, and the second address before the second predetermined frame (for example, 10 frames) in which the current address PA is smaller than the target address TA by the first predetermined frame. Area E
2 (step 1), all the demodulation processing by the decoder 4 is performed by the synchronization with the sub-Q data, and the demodulation processing of the header which is the address of the CD-ROM data starts. (Step m).

When it is detected that the sub-Q data demodulated by the sub-code demodulation circuit 5 is the target address TA (step n), reading of the data demodulated by the decoder 4 is started from that point. (Step o).

In this way, the access to the vicinity of the end of the unclosed session is performed, the seek operation is performed up to a predetermined amount before the target address, and thereafter, the access is switched to the access in the trace state. The trace position by the optical head immediately after the operation is prevented from entering the unrecorded area.

The search for the seek target is performed by accessing with reference to the ATIP. The trace after the search for the seek target is first synchronized with the ATIP so that the trace is promptly shifted to the trace after the seek operation.
By switching to a state of synchronizing with the sub-Q data added to the data recorded on the disk after performing the trace synchronized with P, the data recorded on the disk can be read immediately when the target address is reached. Be started.

[0035]

As described above, according to the present invention, when there is a target address to be searched for by access within a boundary area set in a predetermined range on the near side from the last address including the last address of an unclosed session, An address that is a predetermined amount before the target address is set as a seek target to be searched by a seek operation. When the seek target is searched, the state is switched to the trace state, and the target address is searched according to the trace state. Even if the trace position of the optical head fluctuates and becomes unstable after the seek operation due to the region to be moved, the trace position can be prevented from falling out of the unrecorded region, and the runaway state can be prevented.

In this case, the search for the seek target is performed by accessing with reference to the recorded address, and the trace after the search for the seek target is initially synchronized with the wobble. After tracing to synchronize with the wobble, the state is switched to the state of synchronizing with the data recorded on the disk, so that the data is immediately recorded on the disk when the target address is reached. You can start reading the data.

Since the difference between the target address and the target address is set according to the drive speed of the disk, the trace time in the period from the seek target search to the detection of the target address is changed to the drive speed of the disk. When the drive speed of the disk is slow, the trace time is too long, so that the access to the target address is slow, and when the drive speed of the disk is fast, the trace time is too short, so that the target address can be set. It is possible to prevent the synchronization detection with the data for starting the data reading from being missed before the data is reached.

Further, when the target address is an area on the front side of the boundary area, the target address is accessed by referring to an address added to data, and the target address is located behind the last address. In the case of the area on the side, the target address is set by access referring to the recorded address, so that the access speed of the area other than the boundary area is not sacrificed.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an example of an access method according to the present invention.

FIG. 2 is a circuit block diagram showing a CD-R drive employing the access method shown in FIG.

FIG. 3 is an explanatory diagram for explaining an access method according to the present invention by using a signal track which is linearly formed into a graphic in the order of addresses.

[Description of Signs] 1 Optical head 4 Decoder 5 Subcode demodulation circuit 6 Encoder 9 Wobble decoder 10 ATIP demodulation circuit 11 System control circuit 12 Access control means

Claims (4)

[Claims] An access for referring to a recorded address added to a signal track recorded in advance on a blank disk and an access for referring to an address added to data to be recorded on the disk are used, and lead-in and read-out are performed. An access method in an unclosed session that is a session that has not been closed by the lead-out, and including a last address of data recorded in the unclosed session, setting a predetermined range on the near side from the last address as a boundary area, If the target address which is the address of the data requested to be read is within the boundary area, an address that is a predetermined amount before the target address is set as a seek target to be searched by a seek operation, and the seek target is referred to a recorded address. Access, and An access method characterized by switching to a trace state after a network target is searched, and searching for a target address according to the trace state. 2. When the target address is an area on the front side of the boundary area, the target address is accessed by referring to an address to be added to data, and the target address is higher than the last address. 2. The access method according to claim 1, wherein when the area is on the rear side, the target address is accessed by referring to a recorded address. 3. After switching to the trace state, when an address that is a second predetermined amount before the target address is detected, data recorded on the disk from a state in which the signal track is synchronized with a wobble that has been added in advance to the signal track. 2. The method according to claim 1, further comprising:
The access method described. 4. The access method according to claim 1, wherein a difference between the seek target address and the target address is set in accordance with a drive speed of a disk.