KR980011125A - How to determine the disc recording density of an optical disc player - Google Patents

Abstract

The present invention relates to a technology for discriminating the recording density of an optical disk such as a CD or a DVD, , It performs a unique function of controlling the driving of the optical pickup device and the disk motor through the servo system to maintain an accurate reproducing condition state, but it is a high density disk such as a low density disk such as a CD or a DVD The setting condition can not be set automatically so that it is suitable for the type of the disc, and there is a defect that the optimum reproducing condition can not be ensured.

Therefore, in order to solve the problem, the present invention detects a point at which the difference between the sub-beam detection signals is maximum using a three-beam method, compares the detected difference signal with a reference signal, It is determined whether the disc is a high-density disc or a low-density disc, a corresponding determination signal is output, and a reproducing condition according to the disc density is automatically set based on the disc type determining signal.

Description

How to determine the disc recording density of an optical disc player

FIG. 1 is a block diagram of a tracking servo control block of a general optical disc player; FIG.

FIG. 2 is a layout view of the optical detector of the optical pickup device in FIG.

FIG. 3 is a detailed circuit diagram of the signal processing section in FIG. 1; FIG.

FIG. 4 is a block diagram of a servo control system of an optical disc player to which the disc recording density determination method of the present invention is applied.

5 (A) - (C) are explanatory diagrams of signals detected by the 3-beam method. (D) is a waveform diagram of a tracking error signal.

(A) and (b) of FIG. 6 show a track pitch configuration of a CD and a DVD.

FIG. 7 is an illustration of sub-beam signal detection according to the present invention; FIG.

FIG. 8 is a signal flow diagram of a method for determining a disc recording density of an optical disc player according to the present invention; FIG.

DESCRIPTION OF THE REFERENCE NUMERALS

11: Disk 12: Optical pickup device

13: Signal processing section 14: Information signal processing section

15: Microcomputer 16: Focus servo control unit

17: tracking servo control unit 18: spindle motor driving unit

19: Disk drive

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for discriminating the recording density of an optical disk such as a CD (Compact Disc) or a DVD (Digital Video Disc) An optical disc player which is suitable for discriminating whether a disc mounted on a current tray is a disc having a high recording density such as a DVD or a disc having a low recording density such as a CD, To a disk recording density discrimination method.

FIG. 1 is a servo-system control block diagram of a general optical disc player. As shown in FIG. 1, the disc 1 is designed to project light onto the disc 1 in order to reproduce an information signal recorded on the disc 1, An optical pickup unit 2 for converting an optical signal into an optical signal; A signal processing unit 3 for processing the signal converted into an electrical signal by the optical pickup unit 2 to generate an information signal RF, a focus error signal e _f and a tracking error signal e ₃ ; An information signal processing unit 4 for processing the information signal RF to output a reproduction signal and generating a spindle motor control signal e _d ; A focus servo control unit 5 for controlling the optical pick-up device 2 according to a focus error signal e _f outputted to the signal processing unit 3 to perform focus servo; A tracking servo controller 6 for controlling the optical pickup device 2 according to the tracking error signal e ₃ to perform a tracking servo; A spindle motor driving unit 7 for outputting a spindle motor driving signal in accordance with the spindle motor control signal e _d outputted from the information signal processing unit 4; And a disk drive unit 8 that rotates the disk 1 according to a spindle motor drive signal outputted from the spindle motor drive unit 7. The operation of the disk drive unit 8 will be described with reference to FIGS. 2 and 3 .

First, in order to reproduce data recorded on the disk 1, the spindle motor driving unit 7 is driven with the initial driving value, and the disk driving unit 8 rotates the disk 1 to correspond to the initial driving value do.

At the same time, the focus servo control unit 5 and the tracking servo control unit 6 also drive the optical pickup device 2 as initial values.

Accordingly, the optical pickup device 2 projects light to a designated position of the disc 1 using a light emitting diode, receives light reflected from the disc 1 by a light receiving diode and converts it into an electrical signal And supplies the signal thus converted to the signal processing unit 3.

That is, the light receiving diode in the optical pickup device 2 receives the light reflected by the first to sixth light receiving diodes AF as shown in FIG. 2, converts the light into an electric signal af, 3).

The signal processing unit 3 performs selective differential amplification of the input electrical signal af with the first to third differential amplifiers 3a to 3c as shown in FIG. The signal e _f and the tracking error signal e ₃ (? T). And then inputs it to the track key servo control unit 6.

In addition, the second differential amplifier 3b receives the Maybe beam among the electrical signals, adds the ad signal converted into the electrical signal (a + b + c + d), amplifies the resultant value, (RF), and inputs it to the information signal processing section 4. [

Further, among the electric signals inputted to the third differential amplifier 3c, the main beam is received and the ad signal converted into the electric signal is added (a - b + c - d) An error signal e _f is obtained and is input to the focus servo control section 5. [

Therefore, the focus servo control unit 5 controls the optical pickup device 2 according to the input focus error signal e _f to perform the focus servo, and the tracking servo control unit 6 also outputs the tracking error signal e ₃ (? t)), the tracking error is compensated by controlling the optical pick-up device 2.

On the other hand, the information signal processing section 4 reproduces and outputs the inputted reproduction information signal RF, and on the other hand, the spindle motor control signal e _d is calculated and input to the spindle motor driving section 7.

The spindle motor driving unit 7 outputs a spindle motor driving signal according to an input spindle motor control signal e _{d and} inputs the spindle motor driving signal to the disk driving unit 8. The disk driving unit 8 drives the spindle motor 8, The disk 1 is rotated at a speed corresponding to the signal.

However, in the conventional optical disc player including such a servo control system, a signal converted from an optical signal into an electrical signal is regenerated and output, and the driving of the optical pickup device and the disc motor is controlled through the servo system, It is not necessary to provide a means for detecting whether the currently loaded disc is a low-density disc such as a CD or a high-density disc such as a DVD, so that the setting condition is automatically set to be suitable for the disc type And therefore, there is a defect that the optimum reproduction state can not be guaranteed.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method and apparatus for detecting the size of a signal at a point where a difference of a beep detection signal is maximum using a three-beam method, comparing the detected signal size with a reference value, The present invention provides a disc recording density discrimination method for discriminating whether a disc has a high recording density such as a DVD or a disc having a low recording density such as a CD.

According to an aspect of the present invention, there is provided a method for determining a disc recording density of an optical disc player, the method comprising: a first step of detecting a point at which a difference between two sub-beam detection signals is maximum using a three-beam method; Comparing a magnitude of the detected difference signal with a reference signal, determining whether the loaded disc is a high-density disc or a low-density disc according to a result of the comparison, and outputting a corresponding determination signal; And a third step of setting a reproduction condition according to the density of the disc based on the disc type determination signal.

FIG. 4 is a block diagram of a servo control system of an optical disc player to which the disc recording density discrimination method of the optical disc player according to the present invention is applied. As shown in FIG. 4, in order to reproduce information signals recorded on the disc 11, An optical pickup unit 12 for projecting light and converting the reflected light into an electrical signal; The optical pickup unit 12 processes the signal converted into an electrical signal to generate an information signal RF, a focus error signal e _f and a tracking error signal e ₃ , A signal processing unit 13 for detecting a point at which the difference between the sub-beam detection signals is maximum, comparing the detected point with a reference signal, and outputting a disc type determination signal DEC corresponding thereto; An information signal processing unit 14 for processing an information signal RF supplied from the signal processing unit 13 to output a reproduction signal and generating a spindle motor control signal e _d ; A microcomputer 15 for collectively controlling the system and setting a reproduction condition according to the disc density based on the disc type determination signal DEC; A focus servo control unit (16) for controlling the optical pickup device (12) according to a focus error signal (e _f ) output from the signal processing unit (13) to perform focus servo; A tracking servo controller 17 for controlling the optical pickup 12 according to the tracking error signal e ₃ to perform a tracking servo; A spindle motor driving unit 18 for outputting a spindle motor driving signal according to the spindle motor control signal e _d outputted from the information signal processing unit 14; And a disk drive 19 for rotating the disk 11 according to a spindle motor driving signal outputted from the spindle motor driving unit 18. The operation and effect of the present invention will be described in detail as follows.

First, the principle of the 3-beam method applied to the present invention will be briefly described with reference to FIG. 5.

The sub beam for tracking detection is disposed on both sides of the main beam for reading the signal, so that the signal detection and the tracking detection are performed independently. The three beams are arranged such that the line connecting the center has an offset angle The upper side of the sub beam S 1 is brighter than the lower side S 2 as shown in FIG. 5 (B) in the case where the beam is deflected to the right side, , The phase of S 2 becomes brighter than the phase of S 1 as shown in (C) of FIG. 5. However, when the track is correctly matched, both sides are uniformly bright as shown in Fig. 5 (a). For reference, the flat portion of the photodiode PD is bright and the shadow portion of the pit is dark do.

Therefore, when the reflected light quantity of the sub beam is relatively compared with S 1, S 2 and the automatic amplifier (AMP), when the beam is deflected to the right side, the positive voltage (+ The negative voltage (-V) is output as shown in FIG. 5 (C) when the beam is deflected to the left. When the track is correctly matched, a negative voltage (-V) FIG. 5 (d) is a graphical representation of the tracking error signal thus output.

Typically, the track pitch of a high density disc such as a DVD is 1.6 占 퐉 as in FIG. 6 (A), and is 0.7 占 퐉 as in FIG. 6 (B), which is a low density disc such as a CD.

Since the track pitches of the DVD and the CD are different from each other as described above, the photodiodes E and F for auxiliary beam detection for tracking are fixed for a specific disc (CD or DVD), that is, Since the photodiode E and the photodiode F are arranged at a distance of Tp / 4 with respect to the main beam, the magnitude of the signal detected from the CD differs from the magnitude of the signal detected from the DVD.

When the photodiode E and the photodiode F are arranged at a distance of Tp / 4 relative to the main beam and the disk 11 is a CD as described above, the photodiode E and the photodiode F are scanned The phase difference of the sub beam becomes 180 DEG, and the difference ef of the detection signal becomes maximum at this time.

However, when the disk 11 is a DVD, as shown in the above description, the track pitch is 0.74 mu m, which is 1/2 times smaller than 1.6 mu m of the CD. Therefore, since the phase difference between the sub-beams scanned by the photodiode E and the photodiode F is 90 degrees, the difference e-f of the detection signal becomes small.

If the difference (ef) _CD and a DVD of the detection signal when the CD is expressed as follows if the difference (ef) of the detection signal to the _DVD type.

Hereinafter, a disc recording density discrimination method according to the present invention will be described with reference to FIG.

When the disc 11 is loaded, the signal processor 13 performs a focus search using a 3-beam method and outputs a signal e, (f) is scanned. When the difference ef is maximum, the maximum value of the difference ef is compared with a preset reference value. If the difference ef is greater than the reference value, the currently loaded disc 11 is copied to the CD And outputs the disc type determination signal DEC as " high ". When the disc type determination signal DEC is smaller than the reference value, the disc type determination signal DEC is output as " low "

Accordingly, the microcomputer 15, which controls the whole system, checks whether the currently mounted disk 11 is a CD or a DVD based on the disk type determination signal DEC, that is, whether the disk 11 is a low density disk or a high density disk And then sets a reproduction condition (e.g., coefficient) suitable for reproduction processing of the disk.

As described in detail above, according to the present invention, the size of a signal is detected at a point where the difference between the sub-beam detection signals is maximum using the 3-beam method, and the size of the detected signal is compared with a reference value. It is possible to provide convenience to the user by determining whether the loaded disc is a disc having a high recording density such as a DVD or a disc having a low recording density such as a CD and setting a reproducing condition automatically, So that the setting time can be shortened.

Claims (1)

A first step of detecting a point at which a difference between the sub-beam detection signals is maximum using a 3-beam method; and a step of comparing a magnitude of the detected difference signal with a reference signal, A second step of determining whether the disc is a disc and outputting a corresponding determination signal, and a third step of setting a reproduction condition according to the disc density based on the disc type determination signal. Method for determining recording density. ※ Note: It is disclosed by the contents of the first application.