Disk reproducing device, a disk reproducing method, a disk...

Details Disk reproducing device, a disk reproducing method, a disk... Disk reproducing device, a disk reproducing method, a disk...

2002-02-07

2003-03-04

Hindi, Nabil (Department: 2653)

Dynamic information storage or retrieval

Control of storage or retrieval operation by a control...

Mechanism control by the control signal

C369S047360

Reexamination Certificate

active

06529456

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a reproducing device and reproducing method for a disk such as a CD-ROM in which coded data are recorded, and particularly to a device and method of reproducing an optical disk in which data are recorded in the constant linear velocity system.
Recently, as an example of a device for reproducing data recorded on an optical disk, there are a compact disk player (hereinafter, referred to as CD player), a CD-ROM drive device in which a compact disk (hereinafter, referred to as CD) is used a read-only memory, etc. As a CD-ROM drive device becomes popular, the request for providing a CD-ROM drive device with a reproducing function which enables fast access while attaining low-power consumption is growing.
Recording systems for a disk include the constant linear velocity system (hereinafter, referred to as CLV system) which is characterized in high-density recording, and the constant angular velocity system (hereinafter, referred to as CAV system) which is characterized in high-speed search. For example, Japanese Patent Unexamined Publication (Tokkai) No. Hei6-36289 discloses a method in which a disk wherein recording was performed by the CLV system is reproduced under CAV-rotation. Japanese Patent Unexamined Publication (Tokkai) No. Sho62-88170 discloses a method in which a disk wherein recording was performed by the CLV system is reproduced at a linear velocity higher than a specified linear velocity. In the former method, influences of the rotation settlement of a spindle servo can be eliminated, and the pickup-moving time is substantially equal to the access time. The latter is a system in which reproduction can be started even in a period when the CLV rotation settlement has not yet reached the final linear velocity. As the rotation number of a spindle motor is increased to a double speed or a quadruple speed, the effects of these systems are further recognized. For example, results of a technical study on the variable linear velocity reproduction system are reported in NIKKEI ELECTRONICS No. 628 (Feb. 13, 1995), pp. 111 to 119. In the report of NIKKEI ELECTRONICS, the term of variable velocity reproduction is used. In the following description, however, reproduction under the state where the linear velocity has not yet reached the final target is called the variable linear velocity reproduction system.
In a usual CD player or a CD-ROM device, the read clock signal is fixed, and the rotation of a disk is synchronized in phase with the read clock signal. Such a player or device is configured so that data which were once stored in a memory or the like by using the write clock signal synchronized with the regenerative clock signal are read out in synchronization with the read clock signal, thereby absorbing the time fluctuation.
By contrast, in a CD-ROM drive device, it is not particularly necessary to read out data by using a fixed clock signal. Therefore, such a device may be configured so as to read out data in accordance with rotation of a disk. The above-mentioned variable linear velocity reproduction system is a reproduction system which was developed in view of the above.
Hereinafter, a conventional CD-ROM drive device using the CLV system, and the variable linear velocity reproduction system exemplified by Japanese Patent Unexamined Publication (Tokkai) No. Hei3-36289 will be described.
FIG. 57
is a block diagram showing the configuration of a conventional CD-ROM drive device using the CLV system. The device comprises: a CD-ROM disk (hereinafter, referred to as CD)
1
wherein recording was performed by the CLV system; an optical pickup
5
; a binarizing circuit
8
which converts a reproduced signal into a digital signal; an EFM (Eight to Fourteen Modulation code) demodulation circuit
10
; a serial-parallel converting circuit
30
; a write clock signal generating circuit
31
; a PLL (Phase Locked Loop) circuit
9
which extracts a clock signal from a binary signal; a synchronization detecting circuit
11
which extracts a synchronizing signal recorded in each frame; a buffer RAM
13
which is used as a temporary memory for storing EFM—demodulated data and executing absorption of rotation jitter and error correction based on a CIRC (Cross Interleave Reed-Solomon Code); a parallel-serial converting circuit
32
; a read clock signal generating circuit
33
; a RAM write address generating circuit
34
which generates a write address for the buffer RAM
13
; a RAM read address generating circuit
35
which generates a read address for the buffer RAM
13
; a crystal oscillation circuit
36
; a frequency divider
37
; a CD-ROM decoder
22
which performs a CD-ROM decoding process; a CIRC decoder
21
which executes error correction based on a CIRC; a frequency comparison circuit
38
which compares the output of the PLL circuit
9
with that of the crystal oscillation circuit
36
and obtains a frequency difference; a phase comparison circuit
39
which compares the output of the REM write address generating circuit
34
with that of the BAM read address generating circuit and obtains a phase difference; a spindle control circuit
3
which controls a spindle motor by using results of the frequency comparison and the phase comparison; the spindle motor
2
; and a traverse motor
7
which moves the optical pickup
5
in a radial direction.
Hereinafter, the operation of the device shown in
FIG. 57
will be described.
The optical pickup
5
performs focus and tracking—processes on pit strings on the CD
1
, and outputs a reproduced analog signal. The output is converted into a digital signal by way of the binarizing circuit
8
. The digital signal is demodulated by the EFM demodulation circuit
10
. Then, the clock signal is extracted by the PLL circuit
9
, and the synchronizing signal recorded in each frame is detected by the synchronization detecting circuit
11
. An address for the buffer RAM
13
is generated by using the synchronizing signal extracted by the synchronization detecting circuit
11
. On the other hand, in a signal processing side, the output of the crystal oscillation circuit
36
is used as the reference clock signal. The read address is generated from the reference clock signal. The signal processing side is a portion (including the CIRC decoder
21
) which executes the data processing subsequent to the buffer RAM
13
. The buffer RAM
13
is used as a buffer for absorption of rotation jitter and error correction. In a compact disk player which is used for the purpose of audio, generally, such a buffer for absorbing rotation jitter is disposed in order to prevent rotation fluctuation due to rotation of a motor from being transmitted to a reproduced audio signal. The phase comparator
39
compares the phase difference between the clock signal written into the buffer RAM
13
and that read out therefrom, and the phase difference is used in the control of the spindle motor
2
, thereby enabling the difference between the write and read addresses generated by rotation fluctuation to be canceled in a rotation control side.
FIG. 58
illustrates the memory management of the buffer RAM
13
of
FIG. 57
, in the form of a ring. The buffer RAM
13
is divided into an error correction region and a rotation jitter absorption region, and performs address generation and a ring buffer operation. Reproduced data are written into a clockwise direction. Similarly, the operation of reading out reproduced data is performed in a clockwise direction. Reproduced data are stored in a region extending from point C to point A in a clockwise direction. Therefore, the region extending from point A to point C is a spare space region. The spindle motor
2
is controlled so that the write address is settled down to point C where is the middle point of the rotation jitter absorption region. When the rotation jitter is operated in a direction along which the data transfer rate is increased, point C approaches point A in a counterclockwise direction. When the rotation jitter is operated in a direction along which the data transfer

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