KR0176925B1 - Recording density discrimination device of optical disk - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for discriminating an optical disc such as a CD or a DVD. In a conventional optical disc reproducing system, a means for detecting whether a disc currently mounted is a CD or a multi-layer DVD is provided. Since it is not possible to automatically set the setting conditions to suit the type of disk, this not only provides inconvenience to the user, but also takes a long time to set.

Accordingly, to solve this problem, the present invention provides a display apparatus comprising: focus error signal detecting means for detecting a point of time when the focus error signal is output at a predetermined level or more during initial driving; Recording density judging means for judging whether the disc currently being reproduced is a high density disc or a low density disc by comparing the detection time with a preset reference time; On the basis of the determination result, an optical disc reproducing system is configured by including control means for setting a reproducing condition suitable for reproducing the corresponding disc.

Description

Recording density discrimination apparatus of optical disc

1 is a focus servo block diagram of a general disc playback system.

(A) of FIG. 2 is a waveform diagram of the focus driving signal in FIG.

(b) is a waveform diagram of a focus error signal.

3 is an exemplary block diagram of an apparatus for determining a recording density of an optical disk according to the present invention.

(A) of FIG. 4 is a longitudinal cross-sectional view of a DVD.

(b) is a longitudinal cross-sectional view of the CD.

5A is a waveform diagram of driving voltage of an objective lens actuator.

(b) is a waveform diagram of a focus error signal.

(c) and (d) are zero crossing detection waveform diagrams of the focus error signal.

6 is an operation signal flowchart of the recording density discriminating apparatus of the present invention.

* Explanation of symbols for main parts of the drawings

31: disc 32: optical pickup device

33: focus error signal generator 34: rising edge detector

35: comparator 36: microcomputer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for discriminating an optical disc such as a CD (Compact Disc) or a DVD (Digital Video Disc). Particularly, the present invention is based on a time when a level of a focus error signal is above a certain value. The present invention relates to an optical disc recording density discriminating apparatus which is adapted to be recognized as a CD when the mounted disk is found to be a single layer disk and to be discriminated as a CD when it is determined as a multilayer disk.

In general, in the optical disc reproducing system, in order to accurately read the signal recorded on the disc, the focal point of the objective lens must be exactly matched (condensed) to the recording pit of the disc. It is the focus servo device of the optical disc player.

FIG. 1 is a focus servo block diagram of a general optical disc reproducing system, as shown in FIG. 1, driven according to a drive signal supplied from the outside to scan a laser at a designated position of the disc 1, and electrically reflect the reflected optical signal. An optical pickup device 2 for reading data by converting the signal into a signal; A focus error signal generator (3) for detecting a focus error signal from an output signal of the optical pickup device (2); It consists of a focus drive signal output unit 5 for supplying a drive signal to the optical pickup device 2 in accordance with the focus error signal supplied through the switch 4, the operation thereof will be described with reference to FIG. Same as

When the disk 1 is mounted on the tray, the switch 4 is opened to keep the distance between the surface of the disk 1 and the objective lens mounted on the optical pickup device 2, that is, to apply the focus servo. In the state where the focus servo loop is blocked, the focus driving signal as shown in (a) of FIG. 2 is output from the focus driving signal output unit 5, whereby the focus lens is temporarily lowered and then gradually raised.

At this time, the focus error signal generating unit 3 outputs a focus error signal as shown in FIG. 2 (b), and the focus error signal is zero-crossed at the time when the focus driving signal rises to a predetermined level. It can be seen that this position corresponds to the position where the focus of the objective lens is correctly focused on the recording string of the disk, and in this position, the focus servo is applied by shorting (on) the switch 4 so that a constant focal length is always maintained. It becomes possible.

However, in the conventional optical disc reproducing system, there is no means for detecting whether the disc currently mounted is a CD or a multi-layer DVD. Therefore, the setting conditions cannot be automatically set to be suitable for the disc type. There was a defect that could not guarantee an optimal regeneration state. Recently, a technique for discriminating CDs and DVDs has been proposed. However, since CDs and DVDs are discriminated on the basis of disc information recorded on a predetermined area of the disk, there is a defect that requires a large amount of time.

Accordingly, an object of the present invention is to mount the current tray on the basis of the time when the level of the focus error signal output from the optical pickup device at the initial driving time exceeds a predetermined value without reproducing the disc information recorded in a predetermined area of the disc. Disclosed is an apparatus for determining whether a used disk is a low density disk such as a CD or a high density disk such as a DVD.

According to an aspect of the present invention, there is provided an apparatus for determining a recording density of an optical disc, comprising: focus error signal detecting means for detecting a point of time when the focus error signal is output at a predetermined level or more at the initial stage of driving; Recording density judging means for judging whether the disc currently being reproduced is a high density disc or a low density disc by comparing the detection time with a preset reference time; And control means for setting the playback condition to be suitable for the playback process of the disc on the basis of the determination result.

3 is a block diagram showing an embodiment of the optical density recording apparatus for an optical disc of the present invention for achieving the above object. As shown therein, an optical signal is scanned from a laser beam at a designated position of the disc 31 and reflected therefrom. An optical pickup device 32 for converting the signal into an electrical signal and outputting the converted signal; A focus error signal generator (33) for generating a focus error signal (FE) from an output signal of the optical pickup device (32); A rising edge detector (34) for detecting a zero crossing of the focus error signal (FE) to generate a square wave, and detecting a rising edge of the square wave; A comparator 35 for comparing the rising edge detection time output from the rising edge detection unit 34 with a reference time and determining whether the disc currently mounted is a DVD or CD based on the comparison result; On the basis of the determination signal of the comparator 35, the microcomputer 36 checks whether the disc currently loaded is a DVD or a CD having a low recording density, and sets the playback conditions so as to be suitable for the playback process. If described in detail with reference to Figures 4 to 6 attached to the operation and effects of the present invention configured as described above are as follows.

In the initial driving state, the optical pickup device 32 scans the laser at the designated position of the disk 31 and converts the optical signal reflected therefrom into an electrical signal and outputs the electrical signal.

At this time, the focus error signal generation unit 33 generates a focus error signal FE as shown in FIG. 5B from the high frequency signal RF converted into an electrical signal by the optical pickup device 32 and outputs an output signal. The rising edge detector 34 detects the zero crossing of the focus error signal FE and generates a square wave as shown in (c) of FIG. 5 or a square wave as shown in (d).

Here, the reason why square waves having different periods as shown in (c) and (d) of FIG. 5 will be described.

Discs with high recording density, such as DVDs, have a thickness of 0.6 mm, and discs with low recording density, such as CDs, have a thickness of 1.2 mm. Therefore, when the objective lens mounted on the optical pickup device 32 is moved in the vertical direction and based on the driving voltage DV of the actuator for adjusting the depth of focus, the driving level of the DVD as shown in FIG. It is lower than the driving level of the CD, and accordingly, different focus error signals FE are output as shown in FIG. 5 (b). When the zero crossing is detected, the rising edge time as shown in FIG. While the square wave having the t1 is detected, the square wave having the rising edge time t2 is detected in the case of the CD as shown in (d) of FIG.

In addition, the comparator 35 compares the rising edge detection time output from the rising edge detector 34 with a preset reference time t1 t _ref t2 and is smaller than the reference time t _ref . A predetermined signal (eg, high) is output to indicate that the disk is a DVD, and a signal (eg, low) indicating a CD is output when the disk is larger than the reference time t.

Accordingly, when the high signal is output from the comparator 35, the microcomputer 36 determines that the disc currently being reproduced is a disc having a high recording density, such as a DVD, sets the reproducing condition to be suitable for the reproducing process, and sets the low signal. Is outputted, the disc currently being reproduced is judged to be a DVD having a low recording density, such as a CD, and the reproduction conditions are set to be suitable for the reproduction processing.

As described in detail above, the present invention does not reproduce the disc information recorded in the predetermined area of the disc, and the current tray is based on the time when the level of the focus error signal output from the optical pickup apparatus at the initial driving time exceeds a predetermined value. It is possible to shorten the setting time and provide convenience to the user by determining whether the disc installed in the disc is a low density disc such as a CD or a high density disc such as a DVD and automatically setting the playback conditions suitable for the playback process. It works.

Claims (2)

A system for reproducing or recording an optical disc, comprising: focus error signal detecting means for detecting a point of time when the focus error signal is output at a predetermined level or more at the initial stage of driving; Recording density judging means for judging whether the disc currently being reproduced is a high density disc or a low density disc by comparing the detection time with a preset reference time; And control means for setting a reproduction condition so as to be suitable for the reproduction processing of the disc on the basis of the determination result. 2. The apparatus of claim 1, wherein the focus error signal detecting means comprises a zero crossing detecting device for detecting zero crossing of the focus error signal.