JP2002367168A - Disk discriminating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problems that even a recording disk fails to be detected of wobbles and is erroneously discriminated to be a reproduction-only disk and the reliability of disk discrimination is poor when the disk discrimination is performed by detecting the wobbles. SOLUTION: In discriminating the disk, the wobbles are detected by setting a tracing position by an optical head at the prescribed position in the diametral direction of the disk and driving the disk by changing the number of revolutions around the prescribed number of revolutions corresponding to this prescribed position. As a result, even if there is a factor that the number of revolutions of the disk deviates from the intrinsic number of revolutions, a period when the disk is rotated at the intrinsic number of revolutions is disposed and the wobbles are detected in this period, by which the accuracy of discriminating the recording disk and the reproduction-only disk is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc discriminating apparatus for discriminating between a recording disc and a read-only disc which are compatible with a constant linear velocity system. The present invention relates to a disc discriminating apparatus for discriminating between a recording disc and a read-only disc based on whether or not a wobble exists in a dedicated disc.

[0002]

2. Description of the Related Art As an optical disk on which signals are optically read using an optical head, a compact disk (CD) is used.
sc) The CD format conforming to the format has become widespread,
As a disk recording / reproducing device of this CD family, C
DR (Recordable) device and CD-RW (ReWritable)
Devices are known.

In these disc recording / reproducing apparatuses, it is necessary to switch the intensity of the light beam used during recording and during reproduction, and to switch the signal processing system to be used. It is necessary to switch the light beam intensity and the signal gain in accordance with the difference in optical characteristics such as the reflectance between the dedicated disk and the recording disk.

[0004] Therefore, a disk recording / reproducing apparatus is provided with a disk discriminating apparatus for discriminating between a read-only disc and a recording disc.

[0005] Such a disk discriminating apparatus focuses on the fact that a wobble exists in a recording disk and a wobble does not exist in a read-only disk. There is known a device for determining whether or not the above is true.

[0006]

Since the rotation speed of a disk of a constant linear velocity system changes in accordance with the position in the radial direction, a disk discriminating apparatus corresponding to a disk of a constant linear velocity system has a disk discrimination method. At times, the trace position by the optical head is set at a predetermined position in the radial direction of the disk, and the disk is rotated at a predetermined rotation speed corresponding to the predetermined position to detect a wobble.

However, depending on the disk (1.2 to 1.4 m / sec for a CD), the linear velocity has a width, and even at a predetermined position in the radial direction of the disk, the rotational speed has a width. In addition, a switch is mounted on the innermost circumference of the disk to set the predetermined position. However, it is difficult to set the switch to a fixed position due to the mounting position accuracy of the switch and variations in mechanical load. The wobble decoder is provided with an oscillation circuit for extracting a wobble synchronization signal. However, since this oscillation circuit has a remarkable temperature dependency, there is a problem that the wobble demodulation range changes due to a temperature change.

Therefore, the disc position is determined by setting the trace position of the optical head at a predetermined position in the radial direction of the disk, rotating the disk at a predetermined rotation speed corresponding to the predetermined position, and detecting the wobble. In this case, even if the recording disk is used, the wobble is not detected and the disk may be erroneously determined as a read-only disk, and there is a problem that the reliability of the disk determination is poor.

[0009]

According to the present invention, when a disc is discriminated, a trace position by an optical head is set to a predetermined position in a radial direction of the disc, and the rotation speed is changed around a predetermined rotation speed corresponding to the predetermined position. Drive to detect wobble. As a result, even if there is a factor in which the rotational speed of the disk deviates from the original rotational speed, a period occurs in which the disk is rotated at the original rotational speed. During this period, wobble detection can be performed, and the recording disk and the read-only disk And the accuracy of discrimination is improved.

[0010]

FIG. 1 is a block diagram of a disk discriminating apparatus according to the present invention.
FIG. 3 is a circuit block diagram illustrating an example used for a DR drive.

In FIG. 1, reference numeral 1 denotes an optical head which emits a laser beam for tracing a signal track of a disk D, and writes and reads recording data on the disk D.

2 amplifies an RF signal (radio frequency signal) of a received light output obtained by the optical head 1, and amplifies the RF signal.
An RF amplifier 3 for binarizing the signal, the feedback of various light-receiving outputs obtained by the optical head 1, the focusing control for focusing the laser beam emitted from the optical head 1 on the signal surface of the disk D, and the control of the laser beam This is a head servo circuit that performs tracking control for following the signal track of the disk D and also performs thread feed control for sending the optical head 1 itself in the radial direction of the disk D.

Reference numeral 4 denotes a data processing circuit for performing a demodulation process on the binary data of the RF signal output from the RF amplifier 2 in accordance with the signal format of the disk D.

Reference numeral 5 denotes a demodulator for demodulating a 22.05 kHz wobble included in a pre-groove of the disc D from a push-pull signal generated by the RF amplifier 2 by a push-pull method. ATIP (Absolute Time In Pre-groov)
e) An ATIP demodulation circuit 6 for demodulating an address and its A
The wobble decoder includes a CRC check circuit 7 for detecting an error based on a CRC (Cyclic Redundancy Code) of the TIP address.

Reference numeral 8 denotes a spindle motor for driving the disk D to rotate, and 9 a motor servo circuit for controlling the drive of the spindle motor 8. The motor servo circuit 9 is capable of controlling the rotation in a constant linear velocity system when reproducing the disk D on which the signal is recorded at a constant linear velocity, and generating a pulse signal corresponding to the rotation of the spindle motor 8. The rotation can be controlled in a constant angular velocity manner by the rotation speed set by the rotation speed setting means 11 using a pulse signal from the device (FG) 10. Here, the rotation speed setting means 11 sets the rotation speed in accordance with numerical data set in a register (not shown). To change.

The motor servo circuit 9 has a disk D
During recording, the rotation of the disk D is controlled using the wobble signal demodulated by the wobble decoder 5.

Reference numeral 12 denotes a switch detection circuit for detecting a switching state of a switch 13 which is closed when the optical head 1 is displaced to the innermost position of the disk D. Reference numeral 14 controls the execution of disk discrimination and the wobble decoder 5 CR
The recording disk (CD-CD) is determined by the presence or absence of a CRCOK signal indicating that error detection by the C check circuit 7 is normal.
The disc discriminating circuit discriminates whether the disc is an R or CD-RW disc or a read-only disc (CD-DA or CD-ROM disc).

Next, a description will be given of the operation of executing the disc discrimination in the disc discriminating apparatus thus configured.

When the optical head 1 is displaced to the innermost position of the disk D in the initial state in which the disk D is mounted, the switch detection circuit 12 detects that the switch 13 has been closed, and the disk determination circuit 14 The control for executing the discrimination of the loaded disc D is performed, and the disc discrimination operation is started.

When the disc discriminating operation is started, the motor servo 9 is in a state of controlling the rotation by the constant angular velocity method, and drives the disc D to rotate at the initially set rotational speed.

Here, when the trace position of the optical head 1 is the innermost peripheral position of the disk, the predetermined rotational speed corresponding to the innermost peripheral position of the disk is approximately 500 rotations / minute (rpm) at the rated speed. Therefore, in this embodiment, the rated speed is 2
Explaining the double speed, the predetermined rotation speed is approximately 1000
rpm.

When the disc discriminating operation is started, the disc D
Is set to 1100 rpm, which is + 10% of the predetermined rotation speed of 1000 rpm, and the register of the rotation speed setting means 11 is set to rotate the disk D at this initial rotation speed. Is set to numerical data corresponding to 1100 rpm.

The register of the rotation speed setting means 11 includes:
Numerical data for decreasing the rotation speed of the disk D by 10 rpm at regular intervals, for example, every 0.1 second, is sequentially set,
If the disc discrimination circuit 14 does not end the disc discrimination, as shown in FIG.
Is performed until 900 rpm of -10% is set.

The disk discriminating circuit 14 generates a CRCOK signal indicating that the error detection by the CRC check circuit 7 of the wobble decoder 5 is normal for a predetermined period before changing the rotational speed of the disk D from 1100 rpm to 900 rpm. If it is confirmed that the wobble exists, the disc is determined as a recording disc.
If it is not confirmed that the RCOK signal is generated continuously for a predetermined period, it is determined that there is no wobble and the disc is determined to be a read-only disc.

In this manner, when the disc D is loaded, the disc is discriminated between the recording disc and the read-only disc. In this case, the linear velocity width of the disc, the mounting accuracy of the switch 13 and the optical head (1) Even if there is a factor that the rotation speed of the disk D deviates from the original rotation speed due to a variation in load of the feed mechanism and a change in circuit characteristics due to a temperature change, the period during which the disk is rotated at the original rotation speed. Occurs, and wobble detection can be reliably performed during this period.

[0026]

As described above, according to the present invention, a period in which the disk is rotated at the original rotational speed occurs even if there is a factor that the rotational speed of the disk deviates from the original rotational speed. Thus, the wobble detection can be performed reliably, so that the discrimination accuracy between the recording disk and the read-only disk can be improved.

At the time of disc discrimination, 1
Since the rotation speed of the disk is changed by changing the angular speed step by step, the rotation speed can be changed smoothly by reducing the gain of the motor servo, which is also advantageous in terms of disk determination accuracy.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing an example used for a CD-R drive of a disk discriminating apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing a change in a disk rotation speed at the time of disk determination.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical head 5 Wobble decoder 6 ATIP demodulation circuit 7 CRC check circuit 8 Spindle motor 9 Motor servo circuit 11 Rotation speed setting means 12 Switch detection circuit 14 Disk discrimination circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5D066 HA01 5D090 AA01 BB02 BB04 CC18 DD03 DD05 GG03 HH03 JJ11 5D109 KA02

Claims (2)

[Claims] 1. A disc having a wobble and a read-only disc having no wobble are discriminated as a recording disc or a read-only disc according to the presence or absence of a wobble, and a disc corresponding to a constant linear velocity method. A disc discriminating device for discriminating between a recording disc and a read-only disc, wherein at the disc discriminating time, a trace position by an optical head is set to a predetermined position in a radial direction of the disc, and a predetermined rotational speed corresponding to the predetermined position is set at a center. The disc discrimination is performed such that the disc is driven by changing the rotation speed to detect the wobble, the disc for recording is discriminated when the wobble is detected, and the read-only disc is discriminated when the wobble is not detected. apparatus. 2. The disk rotation control according to claim 1, wherein the disk rotation control at the time of discrimination is performed at a constant angular velocity, and the angular velocity is changed by one step at regular time intervals to change the rotation number of the disk. Disk discriminator.