KR100219585B1 - Spindle speed control method and device for optical disc - Google Patents

Abstract

Disclosed are an optical disc, a rotation speed control method of an optical disc for controlling the rotation speed thereof, and an apparatus thereof. An optical disc has groove information corresponding to a high frequency, dense modulated signal. In order to extract a signal for controlling the spindle motor for driving the optical disk from the groove information, the groove signal detection unit 30 for detecting a modulated signal according to the groove portion information in the optical pickup, and modulation from the modulated signal. And a demodulator 33 for demodulating a carrier used at the time, and a comparator 34 for comparing the carrier with a reference signal. It is possible to control the rotation speed of the optical disc by forming a groove by a high frequency modulated signal having no influence on recording or reproducing signals or disturbances, and extracting a signal resistant to noise through modulation and demodulation therefrom.

Description

Optical disc and its rotation speed control method and device

1 is a plan view of an optical disc.

2 (a) and 2 (b) are cross-sectional views each showing a tracking groove shape of a conventional optical disk.

3 (a) and 3 (b) are cross-sectional views each showing the shape of a tracking groove of an optical disc according to the present invention.

(A) and (b) are side views of each laser cutting device forming the tracking groove shown in FIG. 3 (a) and (b).

5 is a circuit diagram of a modulator for modulating a modulated signal for controlling a laser diode or an objective lens driving element shown in FIG. 4 (a) (b).

6 is a signal waveform input to each terminal of the modulator shown in FIG. 5, in which (a) and (b) are dense first and second modulated waves. (c) shows a carrier wave, and (d) shows a modulated signal.

7 is a circuit diagram showing a rotation speed control apparatus for an optical disk according to the present invention.

8 is a waveform diagram of a signal appearing in each part of the rotational speed control apparatus of the optical disk according to the present invention, (a) is a tracking signal according to the tracking groove of the optical disk, (b) is a demodulation signal demodulating the tracking signal, And (d) indicates a reference signal.

* Explanation of symbols for main parts of the drawings

1,1 ': optical disc 7,7': groove

9a, 9b: Dense first and second waveform portions 16,16 ': Modulated signal

22: carrier 22 ': track following signal

23: spindle motor 24: optical pickup

30: groove signal detector 31: band pass filter

32: demodulation part 33: comparison unit

34: reference signal generator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc for use in an optical disc player for optically recording and reproducing information, and to a method and apparatus for controlling the rotation speed of an optical disc for controlling the rotational speed thereof. A rotation speed control method for an optical disk and a device for controlling a motor for driving the optical disk so that the optical disk maintains a constant linear velocity from tracking information.

In an optical disc player, an optical disc rotates by a spindle motor. When the number of turns of the spindle motor is made constant, the optical disk increases linear speed from the inner circumference to the outer circumference. Therefore, in order to improve the recording density of the optical disc, it is necessary to change the rotational speed of the spindle motor in accordance with the recording and reproducing position of the optical disc so as to maintain a constant linear velocity in both the inner and outer circumferences.

Referring to FIG. 1, the optical disc 1 is a donut type having a center hole 2, and has a lead-in area 5 and a lead-out area at portions adjacent to the innermost circumference 3 and the outermost circumference 4, respectively. Has (6). A continuous spiral groove 7 and a land 8 are formed between the lead in region 5 and the lead out region 6. Tracking information is recorded in the lelouve 7 and data information is recorded in the land 8. That is, while reproducing the information recorded on the land 8 by the optical pickup (not shown), the current rotational speed of the optical disc 1 is detected from the tracking information in the groove 7, and the detected By controlling the spindle motor that rotates the optical disc based on the signal, the portion can be rotated at a constant linear speed.

In recording the above-mentioned tracking information, conventionally, the wobble of the side surface 8a or the bottom surface 8b of the groove 8 is fixed at regular intervals as shown in (a) or (b) of FIG. The spindle motor was formed by forming a mold, taking the frequency directly from the wobble type of the groove 8 from the optical pickup. However, in this conventional technique, since the wobble frequency taken directly from the lelouve 8 is taken, errors due to interference of adjacent signals (for example, recording or reproducing signals) frequency, influence of disturbance, noise, etc. frequently occur. There was a problem.

Accordingly, an object of the present invention is to provide an optical disc having improved tracking information modulated to a predetermined high frequency and capable of controlling the rotational speed of the optical disc to solve the root cause of this problem. It is done.

It is another object of the present invention to provide a method and apparatus for controlling the rotation speed of an optical disk for controlling the optical disk having the improved tracking information as described above at a constant linear speed.

The present invention to achieve the first object,

In an optical disk having a groove formed in a spiral,

There is provided an optical disc in which the optical information according to a modulated signal modulated to have predetermined dense first and second frequencies repeating to each other continuously is provided in the groove.

Optical disk rotation speed control method of the present invention to achieve the second object,

Optical disks having spirally grooved grooves and optical information corresponding to modulated signals modulated to have predetermined dense first and second frequencies that are repeated successively with each other are stored in the grooves and are rotated by a spindle motor. In the rotational speed control method of an optical disc for controlling the rotational speed of,

A detection step of detecting the modulated signal from the optical information recorded in the groove at an arbitrary position of the rotating optical disk;

A demodulation step of demodulating a track following signal having a second frequency corresponding to a period changed from the detected modulated signal to respective regions of its first and second frequencies;

And comparing the demodulated track following signal with a predetermined reference signal and outputting a driving voltage, wherein the spindle motor is driven with the output driving voltage.

And, the optical disk rotation speed control apparatus of the present invention to achieve the second object,

Optical disks having spirally grooved grooves and optical information corresponding to modulated signals modulated to have predetermined dense first and second frequencies that are repeated successively with each other are stored in the grooves and are rotated by a spindle motor. In the rotational speed control apparatus of an optical disk for controlling the rotational speed of

Detecting means for detecting the modulated signal from the optical information contained in the groove at an arbitrary position of the rotating optical disk;

Demodulation means for demodulating a track following signal having a third frequency corresponding to a period varying from the detected modulated signal to its respective first and second frequencies;

And a comparison means for comparing the demodulated track tracking signal with a predetermined reference signal and outputting a driving voltage, wherein the spindle motor is driven with the output driving voltage.

As described above, according to the present invention, the frequency corresponding to the reference synchronization signal that can control the spindle motor for driving the optical disk at a constant speed is modulated in high frequency and recorded in the groove of the optical disk, The rotational speed of the spindle motor can be smoothly increased by demodulating the reference synchronization signal from the high frequency signal of the woofer and comparing the demodulated signal with the original reference synchronization signal. Since the phase difference between the demodulated signal and the original reference synchronizing signal will be gradually increased or decreased depending on the radial position of the optical disc while the spindle motor is rotating at a constant speed, the optical disc has a rotation speed depending on its recording or playback position. It is automatically adjusted to maintain a constant linear velocity at any position. In the present invention, since the signal initially detected from the optical disk is a high frequency, it is hardly affected by other adjacent signals, for example, recording and playback signals, disturbance noise, and the like. Therefore, almost no error occurs in maintaining a constant linear velocity of the optical disk.

When described in detail with reference to the accompanying drawings a preferred embodiment of the present invention as follows.

(A) and (b) of FIG. 3 show the form of optical information formed in the helical groove 7 'of the optical disk according to the present invention. The optical information consists of a first waveform portion 9a and a second waveform portion 9b formed on the side or bottom of the groove 7. The first waveform portion 9a and the second waveform portion 9b are successively repeated and have two dense frequency components corresponding to each waveform.

Fig. 4A is a laser cutting device for manufacturing the master 10 of the optical disk, and the groove 7 'having the first waveform portion 9a and the second waveform portion 9b is shown. Seems to form. Here, the master 10 is controlled to maintain a constant linear velocity by the motor 11. The optical system 12 includes a laser diode 13, a reflector 14, and a focusing lens 15, and is moved in the radial direction of the rotating master 10. In order to form the groove 7 'in which the first waveform portion 9a and the second waveform portion 9b are formed, the laser is formed as shown in (a) according to the predetermined modulated signal 16. The diode 13 may be switched or the actuator 15a for driving the focusing lens 15 in the vertical direction as shown in (b) may be operated. As the actuator 15a, a voice coil and a liquid crystal element are used.

5 is a diagram for explaining the principle of the simple modulator 17 for modulating the modulated signal 16 described above. The modulator 17 has two input terminals 18a and 18b and an output terminal 19 and a control terminal 20. The first modulated signal 21a of FIG. 6A is input to one input terminal 18a, and the second modulated signal 21b of FIG. 6B is input to the other input terminal 21b. . The two input terminals 18a and 18b are switched to alternately switch according to the carrier wave 22 of FIG. 6 (C) input to the control terminal 20. Accordingly, the modulated signal 16 modulated so that the first and second modulated signals 21a and 21b described above are dense first and second frequencies is continuously obtained from the output terminal 19. . The first waveform portion 9a corresponds to the frequency of the first modulated signal 21a, and the second waveform portion 9b corresponds to the frequency of the second modulated signal 21b. The carrier wave 22 corresponds to, for example, a reference synchronization signal of a predetermined frequency used to control a spindle motor for driving the optical disc in an optical disc player as described later.

The optical disc according to the present invention having the groove 7 'formed in this way can be rotated at a constant linear speed by using a signal extracted from the groove 7' during subsequent recording or reproduction.

7 is a circuit diagram showing an apparatus for controlling the rotational speed of an optical disk according to the present invention, wherein 1 'is an optical disk having the groove 7' described above, 23 is a spindle motor for driving the optical disk 1 ', and 24 is Optical pickup for recording and playback. The optical pickup 24 includes a laser diode 25 for emitting a laser beam, a half mirror 26 for partially passing and partially reflecting the laser beam, and an objective lens 27 for focusing the laser beam on the optical disc 1 '. And a photodetector 28 which receives a reflected beam from the optical disk 1 'and detects an electrical signal, which is mounted on a carriage 29 conveyed by a transfer motor (not shown). Horizontally transported in the radial direction. In addition to the data information recorded on the optical disc 1 ', the reflection beam of the optical disc 1' also contains the information by the groove 7 '.

The present invention provides a groove having a dense first and second waveform portions 9a and 9b described above from the photodetector 28 in the groove signal detection section 30 for controlling the spindle motor 23. A groove signal corresponding to 7 '), i.e., a dense modulated signal 16' as shown in FIG. The modulated signal 16 'is amplified by the amplifier 32 after passing through the band pass filter 31 through which the above-described carrier wave can pass, and by the demodulator 33 as shown in FIG. The track following signal 22 'is demodulated. The track following signal 22 'is input to one terminal of the comparator 34. The other terminal of the comparison unit 34 receives the reference signal as shown in FIG. 8 (C) provided from the reference signal generator 35, that is, the carrier 22 described above. The comparator 34 is, for example, a phase detector, and outputs a driving voltage which varies in accordance with the phase difference between the demodulated track following signal 22 'and the carrier 22. The driving voltage is applied to the spindle motor 23 via another power amplifier 36.

In FIG. 7, if the recording or reproducing position of the optical disc 1 'on which the laser beam is focused from the optical pickup 24 is rotating at a speed faster than the reference linear velocity, the track following signal 22' detected and demodulated is The phase becomes faster than the reference signal, that is, the phase of the carrier 22. In this case, the comparator 34 outputs a reduced voltage, thereby lowering the speed of the spindle motor 23. On the contrary, the speed of the optical disc 1 'is slower than the reference linear speed, and the phase of the track following signal 22' is delayed than the carrier wave 22, and the increased voltage is output from the comparator 34 and the spindle thereof. The speed 23 of the motor becomes faster. On the other hand, if the track tracking signal 22 'and the carrier wave 22 are in phase, the speed of the spindle motor 23 does not change.

As described above, the present invention records predetermined optical information in the groove of the optical disk through high frequency modulation using the controllable frequency of the spindle motor driving the optical disk as a carrier wave, and records and reproduces the data information on the optical disk. The invention is to control the rotation of the spindle motor by using the signal extracted from the groove, and the groove is applied directly to the groove since the groove is performed at a frequency that does not affect the frequency of the recording or reproducing signal or other frequencies. It is an extremely effective invention that can control the rotation speed of optical disk with high precision, which is much more resistant to noise and particularly accurate signal extraction through modulation and demodulation.

Claims (9)

In an optical disk having a groove formed in a spiral, And groove information corresponding to a modulated signal modulated to have predetermined dense first and second frequencies that are successively repeated to each other in the groove. 2. The optical disc of claim 1, wherein the groove information comprises dense first and second waveform portions corresponding to the dense first and second frequencies, respectively, on a side surface or a bottom surface of the groove. . Groove information is provided in the groove having a helically formed groove and modulated to have predetermined dense first and second frequencies that are continuously repeated with each other. The groove is rotated by a spindle motor. In the rotational speed control method of an optical disk for controlling the rotational speed of an optical disk, A detecting step of detecting the modulated signal from groove information recorded in the groove at an arbitrary position of the rotating optical disc; A demodulation step of demodulating a track following signal having a third frequency corresponding to a period changed from the detected modulated signal to respective regions of its first and second frequencies; And a comparison step of outputting a driving voltage by comparing the demodulated track tracking signal with a predetermined reference signal, wherein the spindle motor is driven with the output driving voltage. 4. The method of claim 3, further comprising a filtering step of filtering the modulated signal detected by the detecting step with a band pass filter having a predetermined frequency pass band. 4. The method of claim 3, wherein the comparing step is compared with a phase detector for outputting a voltage which varies according to a phase difference between the track tracking signal and a reference signal. 4. The method of claim 3, wherein the reference signal is a carrier wave used to modulate the modulated signal. Groove information is provided in the groove having a helically formed groove and modulated to have predetermined dense first and second frequencies that are continuously repeated with each other. The groove is rotated by a spindle motor. In the rotation speed control apparatus of an optical disk for controlling the rotation speed of the optical disk, Detection means for detecting the modulated signal from groove information recorded in the groove at an arbitrary position of the rotating optical disk; Demodulation means for demodulating a track following signal having a third frequency corresponding to a period varying from the detected modulated signal to its respective first and second frequencies; And comparison means for outputting a driving voltage by comparing the demodulated track following signal with a predetermined reference signal, wherein the spindle motor is configured to drive the spindle motor with the output driving voltage. 8. An apparatus according to claim 7, further comprising a band pass filter having a predetermined frequency pass band for filtering the dense modulated signal between the detection means and the demodulation means. 8. The rotational speed control apparatus according to claim 7, wherein the comparing means comprises a phase detector for outputting a voltage which is varied in accordance with the phase difference between the tracking signal and the reference signal.