JPH10302380A - Disk discriminating method and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To finely discriminate a kind of a disk even when a feature of an external shape is in common. SOLUTION: A motor 5 for moving a thread by a thread control circuit 17 and a driving circuit 21, an optical pickup 2 is moved in the direction of a radius of an optical disk 1, and information is read out. A read-out signal is binarized by a slicer 7 and supplied to inversion interval detecting circuits 9, 11. The maximum and the minimum inversion intervals detected by these circuits are compared with the reference length by an inversion interval length comparing circuit 12. And the rotation of a spindle motor 4 is controlled by a spindle control circuit 14 and a driving circuit 18 in accordance with the comparison result. The rotation current of the spindle motor 4 is detected by a motor rotation current detecting circuit 23, and the number of rotations is measured by a motor rotation numbers measuring circuit 24. These detected result are supplied to a disk discriminating circuit 22, when rotation is faster, it is discriminated as a normal density disk such as a CD, and when rotation is slower, it is discriminated as a high density disk such as a DVD.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc discriminating method and apparatus, and more particularly to an improvement in disc discriminating technology suitable for discriminating between a CD and a DVD.

[0002]

2. Description of the Related Art Various types of disk media, such as CDs and LDs, are known. It is convenient and convenient if one device can record and reproduce data on and from such various disk media in common. In this case, in order for a single device to handle various types of disk media, it is necessary to determine which standard the disk is compliant with. Conventionally, since the appearance of a disk is different, the disk is identified by providing a sensor for identifying the shape.

[0003] Recently, large-capacity DVDs with high recording density have been provided. The DVD standard disk has a configuration in which two disks having the same radius and a half thickness of the CD are bonded together as compared with the CD standard disk. For this reason, the external characteristics of the disc are almost common between the CD and the DVD. Therefore, it is difficult to discriminate these disks only by external factors.
It is necessary to discriminate the disc by using a difference other than the disc outer shape.

The present invention focuses on the above points,
It is an object of the present invention to provide a disc discriminating method and a disc discriminating method capable of discriminating the type well even when the external features are common.

[0005]

In order to achieve the above object, the present invention detects an inversion interval of data read from a disc to be discriminated and compares it with a preset inversion interval reference value. The disk is discriminated by detecting the rotation state of the motor when the rotation of the disk drive motor is controlled according to the comparison result.

According to the main mode, either the rotation current of the motor or the rotation speed of the motor is detected as the rotation state. Data reading is performed on the innermost peripheral side of the disk. The above and other objects, features, and advantages of the present invention will be apparent from the following detailed description and the accompanying drawings.

[0007]

Embodiments of the present invention will be described below in detail. FIG. 1 shows a main configuration of an optical disc reproducing apparatus provided with a disc discriminating apparatus according to one embodiment. In the figure, an optical disc 1 is, for example, a DV.
This is a disc to be discriminated as a disk having a high recording density such as D or a disk having a normal recording density such as a CD. The optical pickup 2 irradiates the optical disc 1 with laser light and detects reflected light, thereby outputting a readout signal of information recorded on the optical disc 1, a focus error signal of the laser light, and a tracking error signal. Has functions.

Of these, the information read signal is RF
The signals are supplied to a maximum inversion interval detection circuit 9 and a minimum inversion interval detection circuit 11 via an amplifier 6, a slicer 7, and a changeover switch 8, respectively. These inversion interval detection circuits 9,
The clocks generated by the clock generation circuit 10 are supplied to the clocks 11 respectively. This clock is set to a frequency sufficiently higher than the binary data input to the inversion interval detection circuits 9 and 11. Inversion interval detection circuit 9,
The detection result of 11 is compared with the reference inversion interval length by the inversion interval length comparison circuit 12.

The focus error signal is supplied to a focus control circuit 16, which drives an actuator (not shown) of the optical pickup 2 by a focus drive circuit 20 provided on the output side thereof to focus the output beam. Control is performed. The tracking error signal is output from the tracking control circuit 15 and the thread control circuit 1.
7. And the tracking control circuit 1
5 drives the actuator of the optical pickup 2 to perform tracking control of the output beam. The sled drive circuit 21 provided on the output side of the sled control circuit 17 drives the sled motor 5 to control the movement of the optical pickup 2 in the disk radial direction. The position in the radial direction is detected by the radial position detection sensor 3.

The optical disc 1 is rotationally driven by a spindle motor 4, and its rotation is controlled by a spindle control circuit 14 and a spindle drive circuit 18 based on the comparison result of the inversion interval length comparison circuit 12. The rotation current value of the spindle motor 4 is detected by a motor rotation current detection circuit 23, and the rotation speed is measured by a motor rotation speed measurement circuit 24. The disc discrimination circuit 22 discriminates the optical disc 1 based on these outputs. The determination result is supplied to the controller 13.

The controller 13 has an operation control function for disc discrimination and a control function for controlling the operation of each part according to the discrimination result. The changeover switch 8, spindle control circuit 14, tracking control circuit 15, focus control Control signals are supplied to the circuit 16 and the thread control circuit 17.

FIG. 2 shows an example of the motor rotation current detection circuit 23. In the figure, a drive current is supplied to the coils 4U, 4V, 4W of the spindle motor 4 by a spindle drive circuit 18. This current is
It flows from power supply V to GND. The motor rotation current detection circuit 23 is configured to connect a resistor R to GND and detect a rotation current flowing through the motor coils 4U, 4V, 4W as a voltage value. The output side of the motor rotation current detection circuit 23 is connected to the comparator 22A of the disk discrimination circuit 22. A reference voltage corresponding to a reference current is supplied from the reference voltage generation circuit 22B to the comparator 22A for comparison. Comparator 22A
Is connected to a discrimination unit 22C, and the discrimination unit 22C discriminates the optical disc 1.

FIG. 3 shows an example of the motor speed measuring circuit 24. In the figure, Hall elements 24U,
24V and 24W are provided in the spindle motor 4 corresponding to the coils 4U, 4V and 4W, and a necessary bias is applied by a Hall bias circuit 24A.
Among these, the output side of the Hall element 24W is connected to the operational amplifier 24B, so that a pulse having a frequency proportional to the rotation speed of the spindle motor 4 is output. The output side of the operational amplifier 24B is
It is connected to the counter 24C. A clock generation circuit 24D is connected to the counter 24C, and the number of pulses supplied from the operational amplifier 24B is counted based on the clock generated by the clock generation circuit 24D. This number of pulses corresponds to the number of rotations of the spindle motor 4.

When comparing FIG. 2 and FIG. 3, when the spindle motor 4 has a Hall element, either method of detecting the motor rotation current or detecting the motor rotation speed may be used. However, when the spindle motor 4 is relatively inexpensive such as not having a Hall element, disc discrimination is performed by a method of detecting a motor rotation current.

The output side of the counter 24C is connected to a count value comparison circuit 22D of the disk discrimination circuit 22. The count value comparison circuit 22D includes a reference value generation circuit 2
A reference value of the count is supplied for comparison from 2E.
The output side of the count value comparison circuit 22D is connected to a discrimination unit 22F, and the discrimination unit 22F discriminates the optical disc 1.

Next, the operation of the apparatus configured as described above will be described. First, in brief, the minimum pit 3T corresponding to the minimum inversion interval of the CD is 0.87 μm.
On the other hand, the minimum pit 3T of the DVD is 0.40 μm.
It is assumed that the rotation speed or rotation speed (corresponding to current) of the disk is controlled so that pits having different lengths are detected with the same time length (the same pulse width). Then C
The D pit is longer than the DVD, so the CD is
It will rotate faster than VD. By utilizing such a relationship, it is possible to determine the disk from the number of rotations or the rotation current of the disk.

After the optical disc 1 is set, the spindle motor 4 is driven by the spindle control circuit 14 and the spindle drive circuit 18 based on an instruction from the controller 13, and the optical disc 1 is driven to rotate. The controller 13 performs an operation for determining the optical disc 1 in the following procedure.

(1) Movement of Optical Pickup 2 and Focus / Tracking Control First, based on an instruction from the controller 13, the sled control circuit 17 and the sled driving circuit 21 drive the sled moving motor 5. Thereby, the optical pickup 2 moves in the radial direction of the optical disc 1. The position of the optical pickup 2 is detected by the radial position detection sensor 3. As a result, the optical pickup 2 moves to an appropriate radius position. On the other hand, in the optical pickup 2,
A focus error signal and a tracking error signal are generated and output. Then, based on the focus error signal, the focus control circuit 16 and the focus drive circuit 20
Performs focus control. Further, the tracking control is performed by the tracking control circuit 15 and the tracking drive circuit 19 based on the tracking error signal.

(2) Reading of Information When the radial position detection sensor 3 detects that the optical pickup 2 has reached a predetermined position, information is read from the optical disk 1 and an information read signal is output. The information read signal is amplified by the RF amplifier 6 and then shaped into binary data by the slicer 7. The binarized data is sequentially supplied to the inversion interval detection circuits 9 and 11 under the control of the changeover switch 8 by the controller 13.

(3) Detection and Comparison of Inversion Interval When the changeover switch 8 is switched to the maximum inversion interval detection circuit 9, the maximum inversion interval detection circuit 9 uses the clock supplied from the clock generation circuit 10. The maximum inversion interval length is measured from the input binary data. The detected maximum inversion interval is supplied to an inversion interval length comparison circuit 12, where it is compared with a reference maximum inversion interval length. When the changeover switch 8 is switched to the minimum inversion interval detection circuit 11, the minimum inversion interval detection circuit 11 uses the clock supplied from the clock generation circuit 10 to determine the minimum inversion interval length from the input binary data. Measured. The detected minimum inversion interval is supplied to an inversion interval length comparison circuit 12, where it is compared with a reference minimum inversion interval length.

(4) Rotation control of the spindle motor 4 corresponding to the reversal interval length As a result of comparing the reference maximum reversal interval length and the detected maximum reversal interval length, if there is a difference between them, the difference is used to perform spindle control. The rotation of the spindle motor 4 is controlled by the circuit 14 and the spindle drive circuit 18. Similarly, as a result of comparing the reference minimum inversion interval length and the detected minimum inversion interval length, if there is a difference between them, the spindle control circuit 14 and the spindle drive circuit 18 control the rotation of the spindle motor 4 using the difference. You.

For example, in a CD, the maximum inversion interval is 11T and the minimum inversion interval is 3T with respect to the data bit interval T. On the other hand, in the case of DVD, the maximum inversion interval is 14
T, the minimum inversion interval is 3T. Assuming that a high-density disc such as a DVD and a normal-density disc such as a CD are rotated at the same reference maximum inversion interval length or reference minimum inversion interval length, the rotation of the spindle motor 4 becomes
The normal density disk rotates faster than the high density disk by the lower information recording density.

(5) Detection of the rotating current of the spindle motor 4 The rotating current of the spindle motor 4 whose drive is controlled as described above is detected by the motor rotating current detecting circuit 23.
The detection result is supplied to the disc determination circuit 22. That is, the motor coils 4U and 4U are controlled by the resistance R shown in FIG.
The rotating current flowing through V, 4W is detected as a voltage. The detected voltage is compared with the reference voltage by the comparator 22A, and the comparison result is input to the determination unit 22C.

(6) Detection of the number of revolutions of the spindle motor 4 On the other hand, the number of revolutions of the spindle motor 4 is measured by a motor revolution number measuring circuit 24, and the detection result is
2 is supplied. That is, the Hall element 2 shown in FIG.
The 4 W, operational amplifier 24B detects a pulse having a frequency proportional to the motor speed. The detection pulse is counted by the counter 24C and supplied to the count value comparison circuit 22D of the disk discrimination circuit 22. In the count value comparison circuit 22D, the input value is compared with the reference value supplied from the reference value generation circuit 22E, and the comparison result is input to the determination unit 22F.

(7) Disc Discrimination A discrimination unit 22 on the motor rotation current side of the disc discrimination circuit 22
In C, when the detected value of the motor rotation current is larger than the reference value, it is determined that the rotation speed of the spindle motor 4 is “fast”,
On the other hand, if it is small, it is determined that it is “slow”. In addition, the determination unit 22F on the motor rotation speed side determines that the rotation speed of the spindle motor 4 is “fast” when the motor rotation speed is greater than the reference value, and determines that the rotation speed is “slow” when the motor rotation speed is low. When it is determined to be "fast", the optical disc 1 is determined to be a normal density disc such as a CD, and when it is determined to be "slow", the optical disc 1 is determined to be a high density disc such as a DVD. I do. The result of the determination is
3 is supplied. In the controller 13, the spindle control circuit 14, the tracking control circuit 15, the focus control circuit 16, the thread control circuit 1,
An instruction is issued to perform a reproduction control operation corresponding to the disk corresponding to 7.

Next, a specific example for discriminating between a CD and a DVD will be described. (1) CD In the case of a CD, the source information such as images, sound, and data is 0.
The pits are converted into nine types of irregularities called pits of 87 μm to 3.18 μm and recorded on the disk. The pit row is formed in a spiral shape from the inner circumference to the outer circumference of the disk.
The minimum pit (0.87 μm) is generally called “3T”, which corresponds to the minimum inversion interval. The maximum pit (3.18 μm) is called “11T”, which corresponds to the maximum inversion interval. The 3T pit indicates that three bits of only the logical value "0" or only the logical value "1" are arranged. The 11T pit indicates that only “0” or only “1” is arranged for 11 bits. Such pit string information is read from the optical disc 1 by the optical pickup 2.

As an information read signal of the optical pickup 2, in the case of a CD, if reading is performed at a clock timing of a frequency of 4.3218 MHz per bit, the light beam of the optical pickup 2 passes through the pit row at a speed corresponding thereto. The spindle motor 4 must be rotated.
This speed is 0.87 μm / (1 / (4.3218 MHz / 3)) = 1.25 m / sec in the case of a “3T” pit (1). This speed is generally called "linear speed". The spindle motor 2 is controlled so that this linear velocity is constant at the inner and outer circumferences.
, And the information of the CD is read from the innermost circumference to the outermost circumference.

Here, assuming that the position of a radius 25 mm of the optical disk 1 is the innermost circumference, the rotation speed of the spindle motor 2 at that position is ((1.25 m / sec) / (25 mm × 2 × 3.14)) × 60 = 477.7 rpm (2) Assuming that a position with a radius of 58 mm is the outermost periphery, the rotation speed of the spindle motor 2 at that position is ((1.25 m / sec) / (58 mm × 2 × 3.14)) × 60 = 205.9 rpm. (3)

(2) DVD On the other hand, in the case of a DVD which is a high density disc, 0.40 μm
There are twelve types of pits ranging from 3T to 14T of ~ 1.87 µm. In a DVD, information is recorded on a disk having the same external shape as a CD with pits smaller than the CD, so that the recording efficiency is increased and the density is increased. In this case, the read frequency per bit is 26.16 MHz, and when the linear velocity is 3T pit, 0.40 μm / (1 / (26.16 MHz / 3)) = 3.49 m / sec (4) Becomes

As in the case of the above-mentioned CD, assuming that the position of the radius 25 mm of the optical disk 1 is the innermost circumference, the rotation speed of the spindle motor 2 at that position is ((3.49 m / sec) / (25 mm × 2 x 3.14)) x 60 = 1333.8 rpm ... (5) Further, assuming that a position with a radius of 58 mm is the outermost circumference, the rotation speed of the spindle motor 2 at that position is ((3.49 m / sec) / (58 mm × 2 × 3.14)) × 60 = 574.9 rpm. (6)

(3) Linear velocity and rotational speed at the time of disc discrimination Here, consider the case where discs are discriminated from the motor rotational speed using the minimum inversion interval in a state where a CD is set. This optical disc is read from the DVD at the read frequency.
Using 26.16MHz, the minimum inversion interval 3T is 26.16 / 3M
When the spindle motor 4 is controlled to be in Hz, the disk linear velocity is expressed by the following equation (7). 0.87μm / (1 / (26.16MHz / 3)) = 7.59m / sec ……………… (7)

Assuming that information is read at a position of a radius of 25 mm, which is the innermost circumference, the rotation speed of ((7.59 m / sec) / (25 mm × 2 × 3.14)) × 60 = 2900.6 rpm (8) As a result, the spindle motor 4 rotates. These values correspond to the spindle motor 4
(4) and (5) are the speed and rotation speed when controlling
Each value is twice or more as compared with the formula. For this reason,
By detecting the disk rotation speed, it is possible to determine whether the disk is a CD disk or a DVD disk.

The case where the disc is determined from the motor rotation speed using the maximum inversion interval is as follows. Similarly, using the DVD read frequency of 26.16 MHz, the maximum inversion interval of 11T for CD and 14T for DVD is 26.16 /
It is assumed that the spindle motor 4 is controlled to be 14 MHz. The linear velocity in the case of CD is 3.18 μm / (1 / (26.16 MHz / 14)) = 5.94 m / sec (9), and the rotational speed at the innermost peripheral position is ((5.94 m / sec) / (25mm x 2 x 3.14)) x 60 = 2270.1 rpm ... (10)

On the other hand, the linear velocity in the case of DVD is 1.87 μm / (1 / (26.16 MHz / 14)) = 3.49 m / sec (11), and the rotational speed at the innermost peripheral position Is ((3.49m / sec) / (25mm × 2 × 3.14)) × 60 = 1333.8rpm (12)

As is apparent from comparison of these, DV
In the case of CD, the number of rotations of the spindle motor 4 becomes 1.7 times that of D. By detecting such a difference in the number of rotations, it is possible to determine whether the disc is a CD disc or a DVD disc.

The present invention has many embodiments,
Various modifications can be made based on the above disclosure. For example, the following is also included. (1) If the disc discriminating operation is performed at the innermost peripheral position of the optical disc 1, the amount of movement of the optical pickup 2 required for performing reproduction is smaller than that at the outermost peripheral position, and the disc discriminating is completed. The subsequent reproduction operation can be performed in a short time afterward. (2) It is optional to use either the maximum inversion interval or the minimum inversion interval of the read data. It is also optional whether to use the rotation current or the number of rotations of the spindle motor. (3) In the above embodiment, the case of a CD and a DVD has been mainly described. However, as long as digital data modulated by a run-length limited code is recorded, the same applies to other types of discs. Applicable.

[0037]

As described above, according to the present invention,
The following effects are obtained. (1) The disc is discriminated from the rotation state when the motor is controlled to rotate by referring to the inversion interval of the read data. Therefore, even when the external features are common, a simple configuration can be used for the disc. The type can be determined. (2) The determination can be performed in a shorter time than in the case where the determination is made using the output of digital signal processing such as channel decoding.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a motor rotation current detection circuit of FIG. 1;

FIG. 3 is a block diagram showing a motor speed measurement circuit of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical disk 2 ... Optical pick-up 3 ... Arbitrary radius position detection sensor 4 ... Spindle motor 4U, 4V, 4W ... Motor coil 5 ... Thread moving motor 6 ... Information readout signal amplifier 7 ... Waveform shaping slicer 8 ... Changeover switch 9 ... Maximum inversion interval detection circuit 10 ... Clock generation circuit 11 ... Minimum inversion interval detection circuit 12 ... Inversion interval length comparison circuit 13 ... Controller 14 ... Spindle control circuit 15 ... Tracking control circuit 16 ... Focus control circuit 17 ... Thread control circuit 18 ... Spindle Drive circuit 19: Tracking drive circuit 20: Focus drive circuit 21: Thread drive circuit 22: Disk discrimination circuit 22A ... Comparator 22B ... Reference voltage generation circuit 22C ... Discrimination unit 22D ... Count value comparison circuit 22E ... Reference value generation circuit 22F ... Discrimination Part 2 ... current detection circuit 24 ... motor speed measuring circuit 24A ... Hall bias circuit 24B ... op 24C ... counter 24D ... the clock generation circuit 24U, 24V, 24W ... Hall element

Claims (6)

[Claims] A step of detecting an inversion interval of data read from a disc to be determined; a step of comparing a preset inversion interval reference value with the detected inversion interval; A disc discriminating method comprising: controlling a rotation of a drive motor; detecting a rotation state of a disc drive motor whose rotation is controlled by the drive motor; and discriminating a disc based on a result of the detection. 2. The rotating state of the disk drive motor is as follows.
2. The disk discriminating method according to claim 1, wherein the discrimination information is one of a rotation current of the motor and a rotation speed of the motor. 3. The disk discriminating method according to claim 1, wherein reading of data from the disk is performed on an innermost peripheral side of the disk. Reading means for reading data from a disc to be discriminated; inversion interval detection means for detecting an inversion interval from the data read by the reading means; a preset inversion interval reference value and the inversion interval Reversal interval comparison means for comparing the reversal intervals detected by the detection means; rotation control means for controlling rotation of the disk drive motor based on the comparison result by the reversal interval comparison means;
A rotation state detection unit configured to detect a rotation state of the motor whose rotation is controlled by the rotation control unit; and a determination unit configured to determine a disk based on the rotation state of the motor detected by the rotation state detection unit. Discrimination device. 5. The disk discriminating apparatus according to claim 4, wherein said rotation state detecting means detects one of a rotation current of the motor and a rotation speed of the motor. 6. The data reading device according to claim 1, wherein said reading means reads data at an innermost peripheral side of the disk.
Disc discrimination method described.