KR20060025661A - Method and apparatus of identifying disc types - Google Patents

Abstract

The present invention relates to a method and apparatus for determining the type of an optical recording medium, the frequency of the wobble signal according to the recording track shape of the mounted optical recording medium and the rotational speed of the optical recording medium which is a variable value affecting the frequency, The current track position is detected, and the type of the optical recording medium is determined as DVD + RW or DVD-RW based on the detected frequency and the variable value.

Disc, type, tracking error signal, wobble frequency, DVD +/- RW

Description

Method and apparatus for determining type of optical record carrier {Method and apparatus of identifying disc types}             

1 shows a configuration of an apparatus for recording / reproducing an optical recording medium in which a method for determining the type of optical recording medium according to the present invention is implemented.

2A to 2C are diagrams showing experimental measurements of tracking error signals detected by the DPD method for each disc type.

3 is a graph showing a relationship between the level of the tracking error signal of the DPP method and the depth difference between the land / groove or the pit of the disc;

4A to 4C are diagrams showing experimental measurements of the tracking error signal detected by the DPP method for each disc type.

5 is a table roughly dividing the levels of the DPD and DPP error signals that appear for each disc type of the optical record carrier according to the present invention.

6 is a flowchart of an embodiment of a method of determining the type of optical record carrier according to the present invention;

7A and 7B are views schematically showing reference values for determining a disc type stored in a memory and a magnitude of each reference value in comparison with a level of a tracking error signal according to the present invention.

FIG. 8 is a view showing roughly the magnitudes of reference values used according to another embodiment of the present invention compared with the level of the tracking error signal.

<Description of the symbols for the main parts of the drawings>

10: optical record carrier 12: optical pickup

14: RF unit 15: light drive unit

16a: reproduction digital signal processing (DSP) unit 16b: recording DSP unit

18: DPD error detector 20: DPP error detector

22: wobble frequency detection unit 24: servo control unit

26: micom 28: spindle motor

30: rotation speed detection unit 32: memory

The present invention relates to a method and apparatus for determining the type of optical record carrier.

As is well known, an optical recording medium capable of recording or reading information on a recording medium by an optical scanning method is widely used according to the necessity of semi-permanently recording and accumulating image and audio information. According to its function and use, it is classified into ROM type developed for read-only, write once type, and rewritable type that can record repetitive information.

Here, the ROM type optical recording medium is represented by a digital versatile disc read only memory (DVD-ROM), and a DVD-R type is representative of a write once type, and a DVD-R is a rewritable optical recording medium. RW, DVD-RAM, DVD + RW, etc.

Digital multi-function discs (DVD) can secure storage capacity of about 2.6 GByte to 4.7 Gbytes when only one side of the disc is used as the recording layer. Dual-layer DVDs have been developed and commercialized in which a dual recording layer is provided on the device so that different information can be recorded on each recording layer at different wavelengths of optical power.

Therefore, in order for the optical recording medium reproducing apparatus to play or record such various types of DVDs, it is necessary to accurately determine the type of the loaded disc. This is because the intensity of the reflected beam and the characteristics of the signal for servo control are different for each type, so it is necessary to set the correct servo characteristics for the type of the mounted disk.

Accordingly, the present invention has been made in view of the above circumstances, and an object thereof is to provide a method and apparatus for determining the type of an optical recording medium capable of accurately determining various types of optical recording media.

In order to achieve the above object, the type discrimination of the optical recording medium according to the present invention is performed for each of the first tracking error signal and the second tracking error signal generated by different methods from the reflected light to the mounted optical record medium. Compared with the set reference value and the type of the optical recording medium according to the comparison result.

In addition, the type determination of the optical recording medium according to the present invention detects the frequency of the wobble signal and the variable value affecting the frequency according to the recording track shape of the mounted optical recording medium, and based on the detected frequency and the variable value. And determining the type of the optical recording medium.

In one embodiment according to the present invention, a DVD-based optical recording medium is discriminated.

In addition, in one embodiment according to the present invention, a tracking error signal based on a DPD method is used as the first tracking error signal, and a tracking error signal based on a DPP method is used as the second tracking error signal.

Hereinafter, a preferred embodiment of the method and apparatus for determining the type of optical recording medium according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram showing the configuration of an apparatus for recording / reproducing an optical recording medium to which a method for determining the type of the optical recording medium according to the present invention is applied.

The optical recording medium recording / reproducing apparatus of FIG. 1 includes an optical pickup 12 for reading out or recording a signal of the optical recording medium 10, a reproduced signal binarized from the read signal, and a focusing error (FE) signal. And an RF unit 14 for outputting an electrical signal for tracking error TE, a reproduction DSP unit 16a for restoring the binarized reproduction signal to digital data, the focusing error signal, and a DPD error detection unit 18; The servo control unit 20 and the spindle motor driving the spindle motor 28 for controlling the optical pickup 12 and rotating the optical recording medium 10 according to the tracking error signal output from the DPP error detection unit 20. A rotation speed detector 30 for detecting the rotational speed of 28, the DPD error detector 18 for detecting a DPD tracking error signal from the electrical signal, and the DPP error detector for detecting a DPP tracking error signal from the electrical signal 20, A frequency detector 22 for detecting the frequency of the wobble signal according to the shape of the recording track from the signal detected by the optical pickup 12, and a recording DSP unit for configuring external input data in an ECC format and then modulating it into a signal for recording ( 16b) an optical driver 15 for applying a recording beam driving current to the optical pickup 12 according to an input signal, a memory 32 in which data is stored, and a microcomputer 26 for controlling recording / reproducing operations as a whole. It is composed.

The DPD error detection unit 18 generates a diagonal cross signal from the electrical signals a, b, c, d generated from the four divided main photodetecting elements A, B, C, and D in the RF unit 14. The tracking error signal is detected due to the phase difference between the sum signals a + c and b + d. By the way, the DVD-RAM has a pre-pit row on the formed header intermittently in the recording track, and the DVD-ROM has a pre-pit row recorded along the recording track, and the pre-pit has its boundary. Is clear compared to the mark in which the medium is changed in the DVD +/- RW, the tracking error signal due to the phase difference between the DVD-RAM and the DVD-ROM is relatively larger than that in the DVD +/- RW. 2a to 2c are measurement results showing this. FIG. 2A is a waveform diagram obtained by the same unit of measurement. In the case of the DVD-ROM of FIG. 2A, the signal has a large amplitude along the entire recording track. In the case of the DVD-RAM of FIG. (S-marked part), and in the case of DVD +/- RW in Fig. 2C, shows that a low amplitude DPD error signal is output. If no mark is formed on the track of the DVD +/- RW, i.e., if there is no recorded EFM signal, the DPD tracking error signal is much weaker.

The DPP error detection unit 20 further includes left and right difference signals MPPe = (a + d) − (b +) obtained from the four divided main photodetecting elements A, B, C, and D in the RF unit 14. In c), an error signal obtained by properly amplifying and subtracting the left and right difference signals SPPe = (e + f)-(g + h) obtained from the auxiliary photodetecting elements E | F and G | H respectively divided into two, that is, MPPe-k * SPPe is detected.

However, in the case of the DPP tracking error signal, the size of the signal is divided according to the type of the disk by the influence of the diffraction interference of the incident beam and the reflected beam due to the depth difference of the land / groove of the disk or the depth of the pit. do. FIG. 3 is a graph showing the level of the DPP error signal with the RF modulator against the depth difference of the pit or the land / groove.

In DVD-ROM, the depth of the pit is? / 4, the depth difference of the land / groove is? / 6 in the DVD-RAM, and the depth difference is? / 16 in the DVD +/- RW. Therefore, in view of the graph characteristics of the DPP error signal in Fig. 3, the DPP error signal is detected the largest in the DVD-RAM, the intermediate information is detected in the DVD +/- RW, and weakly detected in the DVD-ROM. 4A to 4C show the detection characteristics of the DPP error signals in the order of DVD-RAM, DVD +/- RW, and DVD-ROM, respectively. = 0.5 V).

Accordingly, when the magnitudes of the tracking error signals obtained by the DPD error detector 18 and the DPP error detector 20 are divided roughly, the result shown in FIG. 5 is obtained. In the embodiment of the present invention, the result of FIG. To determine the type of disc loaded.

In the following, a preferred embodiment of the present invention for determining the type of disc is described. 6 is a flowchart for determining the type of disc according to the embodiment.

The microcomputer 26 is, for performing the method of Figure 6, the reference value for discriminating between the reference value REF _{DPD_HIGH} and "Great" hereinafter to distinguish between "large" and "Great" of the DPD error signal REF _{DPD_LOW,} and DPP error The reference values REF _{DPP_HIGH} and REF _{DPP_LOW} are stored in the memory 32 as shown in FIG. 7A. As shown in FIG. 7B, the reference values are determined to be the most appropriate values based on the change width of the measured value of each error signal obtained in the experiment.

When the disk 10 is inserted and mounted, the microcomputer 26 controls the servo controller 20 to focus the incident beam of the optical pickup 12 and rotates the spindle motor 28 at a predetermined initial speed. After the loaded disc 10 is rotated, the disc type determination routine of Fig. 6 is executed.

According to the disc discrimination routine, the microcomputer 26 first measures the magnitude of the signal input from the DPD error detector 18 and the DPP error detector 20 (S10), and calculates the DPD error signal from the measured values. The value is first compared with the reference value REF _{DPD_HIGH} (S11). If the DPD error signal is larger than the reference value REF _{DPD_HIGH} , the DPP error signal is compared with the reference value REF _{DPP_HIGH} (S12). If the DPP error signal is larger than the reference value REF _{DPP_HIGH} , the microcomputer 26 determines the loaded disk 10 as a DVD-RAM (S13) and checks its capacity.

The capacity check is determined based on the frequency of the wobble signal detected by the wobble frequency detector 22, the rotation speed detected by the rotation speed detector 30, and the position (radius) of the optical pickup 12. . That is, if the frequency of the wobble signal according to the detected rotation speed at the current position (radius) is higher than the 'RAM capacity reference value' determined at the corresponding position and the corresponding speed (S14), it is lower than 4.7 Gbytes (S15). If not, it is determined as 2.6 Gbytes (S16) and the disk discrimination routine ends.

Since the detected wobble frequency varies depending on the radius of the optical pickup and the rotation speed of the disk (the wobble frequency is proportional to the product of the radius and the rotation speed), the microcomputer 26 calculates a formula for the 'ram capacity reference value'. The one closest to the condition is selected either directly or by various reference values stored in the memory 32 as a table according to position and rotation speed. The position (radius) of the optical pickup 12 is determined by tracking the distance traveled through the kick from the initial position of the innermost circumference. In general, since the disc discrimination is made in the innermost circumference, the radius of the initial position, which is the innermost circumference, becomes the current position without tracking the moving distance.

If the DPP error signal is less than the reference value REF _{DPP_HIGH} in the S12 comparison step, the value is compared with the reference value REF _{DPP_LOW} again (S20). As a result of the comparison, if the DPP error signal is smaller than the reference value REF _{DPP_LOW} , the microcomputer 26 determines that the loaded disc 10 is a DVD-ROM (S21). Otherwise, the microcomputer 26 determines that it is a disc determination error (S30).

Further, in the S11 comparison step, if the value of the DPD error signal is smaller than the reference value REF _{DPD_HIGH} , the microcomputer 26 compares the value of the DPP error signal, which is another tracking error signal, with REF _{DPP_LOW} (S24). If greater than REF _{DPP_LOW} , the loaded disc is judged to be DVD +/- RW (S25), and then the rotation speed and wobble frequency of the current disc are read to discriminate between DVD + RW and DVD-RW. Then, the wobble frequency is compared with one 'RW judgment reference value' determined from the current position and rotational speed (S26). If the wobble frequency currently measured is high, it is determined as DVD + RW (S27), otherwise DVD- It determines with RW (S28). Similarly to the RAM capacity reference value, the 'RW determination reference value' may be obtained through a directly programmed formula or by selecting one closest to a condition from various reference values stored in the memory 32.

If the value of the DPP error signal is less than REF _{DPP_LOW} in the S24 comparison step, the microcomputer 26 determines that the disc discrimination error is performed (S30). If it is determined that the disk determination error, the microcomputer 26 repeats the above-described determination routine of FIG. 6 or determines a disk error to notify the external host.

In the above-described embodiment, when determined to be DVD +/- RW, the microcomputer 26 may further determine whether the disk is blank or blank in which data has already been recorded. As described above, since DVD +/- RW with data recorded has a larger DPD tracking error signal than DVD +/- RW with no data recorded, blank DVD +/- RW using a separate DPD reference value distinguishing this value. It is possible to determine whether the recognition data is recorded DVD +/- RW.

In addition, when data is recorded, a mark is generated along the track, so that the reflectance of the beam is slightly lowered, so that a change in the level of the DPP error signal occurs. That is, when data is recorded, the level of the DPP error signal is lower than that of the blank. Therefore, a separate DPP reference value for distinguishing this level change is used to determine whether the blank DVD +/- RW or the DVD +/- RW data is recorded. It may be.

If it is determined to be a blank disk, the microcomputer 26 immediately reports the status of the disk to the external host.

In the above-described embodiment, the disc type is determined by setting a plurality of reference values for the DPD error signal and the DPP error signal, respectively, but the disc type may be determined by setting a single reference value for each error signal.

An example of setting a single reference value is shown in FIG. 8. If the reference value is one set, respectively, as shown in FIG. 8, the microcomputer 26 is the DPD error signal is greater than REF _DPD, DPP error signal is greater than REF _DPP, a DVD-RAM, the DPD error signal is greater than REF _DPD, If the DPP error signal is smaller than the REF _DPP , it is determined as a DVD-ROM, and if the DPD error signal is smaller than the REF _DPD and the DPP error signal is larger than the REF _DPP , the DVD +/- RW is determined. In other cases, the disk type determination error is handled, the determination of the capacity of the DVD-RAM and the further division of the DVD + RW and the DVD-RW are performed in the same manner as in the above-described embodiment.

On the other hand, the present invention is not limited to the above-described typical preferred embodiments, but can be carried out in various ways without departing from the gist of the present invention, various modifications, alterations, substitutions or additions are common in the art Those who have knowledge will easily understand. If the implementation by such improvement, change, replacement or addition falls within the scope of the appended claims, the technical idea should also be regarded as belonging to the present invention.

According to the present invention described in detail above, the type of the mounted DVD recording medium can be accurately determined through a plurality of signals, so that the servo control characteristic can be set according to the mounted recording medium. Through accurate setting of the servo control characteristics, it is possible to prevent playback or recording errors due to servo errors during playback or recording.

Claims (10)

Detecting a frequency of the wobble signal according to the recording track shape of the mounted optical recording medium and a variable value affecting the frequency; And determining the type of the optical recording medium based on the detected frequency and the variable value. The method of claim 1, And the variable value is a radius of a track in which the rotational speed of the optical record medium and the frequency of the wobble signal are detected. The method of claim 1, The determining of the second step is to determine one of two types of recordable optical record carrier. The method of claim 3, wherein The two types are DVD + RW and DVD-RW. The method of claim 4, wherein In the step 2, if the detected frequency is higher than a predetermined reference value under the same condition, the optical disc is determined as DVD + RW, and if it is low, DVD-RW is determined. . An apparatus for recording or reproducing data on an optical recording medium, Reading means for irradiating a beam to a track of the optical record carrier and converting the reflected light into an electrical signal; Detecting means for detecting a frequency of a wobble signal according to the shape of a recording track and a variable value affecting the frequency from the electrical signal; A servo unit for performing servo control on the reading means; And And a controller for determining the type of the optical record carrier based on the detected frequency and the variable value. The method of claim 6, And the variable value is a radius of the track at which the rotational speed of the optical record carrier and the frequency of the wobble signal are detected. The method of claim 6, And the determining operation of the controller is to determine one of two types of recordable optical record carrier. The method of claim 8, The two types are DVD + RW and DVD-RW. The method of claim 9, And the controller determines that the optical recording medium is DVD + RW if the detected frequency is higher than a predetermined reference value under the same condition as the variable value, and DVD-RW if it is low.

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