KR100767169B1 - Method for erasing recorded data on optical disc - Google Patents

Abstract

A method of erasing data of an optical disk is provided to erase data of the optical disk reliably and to prevent the danger of hacking the data stream by overwriting the null data on a data area of the optical disk. A large sized beam spot is formed over a plurality of tracks of an optical disk and the laser power value is increased when a data erasing mode of the optical disk is set. The null data is overwritten randomly on a data area of the optical disk by using the large sized beam spot while the tracking servo is off.

Description

How to delete data on an optical disc {Method for erasing recorded data on optical disc}

1 shows a configuration of a general optical disc recorder.

2 to 4 illustrate an embodiment of a data erasing method of a general optical disc.

5 illustrates an embodiment in which a delete button according to the present invention is additionally installed in an optical disc drive.

6 illustrates an embodiment of a de-focus state in an optical disc data erasing mode according to the present invention;

7 illustrates an embodiment of a tracking servo off state in an optical disc data erase mode according to the present invention;

8 is a flowchart illustrating an operation of deleting a data of an optical disc according to the present invention;

9 shows an embodiment in which data of an optical disc is deleted according to the present invention.

※ Explanation of code for main part of drawing

10: optical disc 11: optical pickup

12: spindle motor 13: sled motor

14: motor drive 15: optical drive

16: encoder 17: recording digital signal processing unit

18: RF signal processing unit 19: reproduction digital signal processing unit

20: servo controller 21: microcomputer

22: memory

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data erasing method of an optical disc, and more particularly, to a data erasing method of an optical disc for more efficiently deleting data recorded on a write once media (WORM).

FIG. 1 shows a configuration of a general optical disc recorder. For example, an optical disc recorder such as a DVD-Reorder or the like may include an optical disc 10, an optical pickup 11, a spindle motor 12, and a sled. Motor 13, motor drive 14, optical drive 15, encoder 16, recording digital signal processing unit 17, RF signal processing unit 18, reproduction digital signal processing unit 19, servo controller 20 , A microcomputer 21, a memory 22, and the like.

On the other hand, in the microcomputer 21, when the optical disc 10 is inserted and seated in the device, for example, when the writeable optical disc WORM is inserted and seated in the device, a lead-in area of the optical disc is provided. Navigation information and the like recorded in a specific area, such as the same, are read out and stored in the memory 22.

In addition, when the navigation information stored in the memory 22 is searched and referred to, a data recording operation or a reproduction operation requested by the user is performed. When data is recorded in the data area of the writeable optical disc WORM In the microcomputer 21, the data writing operation is no longer performed.

On the other hand, in recent years, a data deletion method has been proposed to make it impossible to reproduce data recorded on the once-writable optical disc WORM. For example, as shown in FIG. The navigation information recorded in the lead-in area (LIA) of the optical disc that can be written once, and the file system information recorded in the file system information area (FMIA), can be set to any null ( Null) Overwrites data.

As a result, navigation information and file system information necessary for reproduction control of the data stream recorded in the data area of the write once optical disc can no longer be used. Therefore, the data stream recorded in the data area of the optical disc can no longer be used. Indirectly deleted.

Further, as a second embodiment, as shown in Fig. 3, when an encrypted data stream is recorded in a data area of a writeable optical disc, the encrypted data stream is decrypted into the original data stream. Only the encryption key necessary for overwriting is overwritten with any null data and deleted, resulting in indirectly deleting the data stream recorded in the data area of the optical disc.

As another embodiment, as shown in Fig. 4, by using the apparatus, the user deliberately damages the optical disk by using a user to form a scratch or the like on the optical disk, or by using a heater or a compressor. In other words, a method of forcibly damaging an optical disc has been proposed.

However, when only the navigation information, the file system information, and the encryption key information are deleted as described above, since the data stream recorded in the data area exists as it is, the data stream may be exposed by hacking or the like. In the case of using the apparatus water, the heater, and the compressor as described above, there is a problem in that inconvenience in use and expensive equipment are required separately.

Therefore, the present invention was created in order to solve the above problems, and for example, when the delete button is installed in the optical disc drive (ODD), the data erasing mode of the writeable optical disc is set as well. To form a large beam spot over a plurality of tracks of the optical disc, and to superimpose unnecessary data on the data area of the optical disc, so that the data erasing operation of the optical disc can be performed more reliably and efficiently. To provide a, that is the purpose.

According to an aspect of the present invention, there is provided a data erasing method of an optical disc, comprising: forming a beam spot of a large size covering a plurality of tracks of the optical disc when a data deletion mode of the optical disc is set; And using the large size beam spot, superimposing and recording unnecessary data in a data area of the optical disc.

In the first step, at the time of inputting a delete button installed in the optical disc drive, a data erasing mode of an optical disc that can be recorded once is set, and the focus lens of the optical pickup is adjusted to a preset defocus state, thereby providing a plurality of at least two or more plurality. In addition to forming a large beam spot over the track, the laser power value is increased,

In the second step, in the state where the tracking servo is turned off, by using the large size beam spot, random data is randomly transmitted to the data area of the optical disc while shifting the focus lens of the optical pickup from the inner circumference to the outer circumferential direction. When recording is superimposed and the focus lens of the optical pickup is no longer shifted, the sled motor is rotated to move the optical pickup, and then the focus lens is shifted from the inner circumference to the circumferential direction.

The method may further include the step of counting the number of revolutions of the sled motor, predicting whether the end address of the last recorded data is exceeded, and ending the data erasing operation, wherein the end address is recorded on the optical disc. Searched by the navigation information, and whether or not the end address is exceeded, characterized in that it is predicted based on a value multiplied by the number of revolutions of the counted sled motor and the address moved during one revolution of the sled motor.

Hereinafter, a preferred embodiment of a data erasing method of an optical disc according to the present invention will be described in detail with reference to the accompanying drawings.

First, the data erasing method of the optical disc according to the present invention is applied to an optical disc recorder such as a DVD-Recorder configured as described above with reference to FIG. 1 or a host such as a personal computer (PC). It can be applied to the optical disc drive (ODD) used.

Meanwhile, as illustrated in FIG. 5, an erase button may be additionally installed in the optical disk drive, separately from an eject button. For example, the delete button may be input. In this case, the microcomputer 21 described above with reference to FIG. 1 sets the operation mode of the optical disc drive to the data erasing mode.

In addition, in the microcomputer 21, the servo controller 20 is operated to control the focus lens Lens included in the optical pickup 11, as shown in FIG. 6, in a defocus state. By forming a large beam spot (Large Beam Spot) over a plurality of tracks, for example at least two tracks of the optical disk.

In addition, the power value of the laser diode LD included in the optical pickup 11 is increased so that the power value of the laser beam does not decrease even when the size of the beam spot is increased. As shown in FIG. 7, while the tracking servo operation is turned off, the focus lens is shifted from the inner direction to the outer direction by a predetermined amount.

On the other hand, the microcomputer 21 superimposes and records unnecessary data in the data area of the optical disc using a large beam spot formed over a plurality of tracks as described above, so that the data deletion operation can be performed more efficiently. This will be described in detail as follows.

FIG. 8 is a flowchart illustrating a method of deleting data of an optical disk according to the present invention. For example, in the microcomputer 21, as described above with reference to FIG. 5, an additional disk is installed in an optical disk drive (ODD). When an erase button is input, even if an optical disc WORM capable of recording once is inserted into the apparatus, the data erase mode of the optical disc is set (S10).

Then, the navigation information, etc. recorded on the optical disc is searched and checked, and an end address at which data is finally recorded in the data area of the optical disc is checked (S11).

In addition, as described above with reference to FIG. 6, the microcomputer 21 operates and controls the servo controller 20 so that the focus lens of the optical pickup is in a de-focus state. After the power value of the laser diode LD is increased, unnecessary data is randomly or sequentially overwritten in the data area by using the large beam spot (S12). ).

On the other hand, in the microcomputer 21, as described above with reference to FIG. 7, the servo controller 20 is operated to turn off the tracking servo operation, and the inner portion of the focus lens is fixed by a predetermined amount. Direction is shifted to the outer direction (Shift) (S13).

For example, assuming that the movable range capable of shifting only the focus lens in the horizontal direction at the position where the optical pickup 11 is fixed is 10 tracks, the servo controller sequentially shifts the focus lens by 2 tracks. It is shifted five times.

When the focus lens is no longer shifted by the five shift operations (S14), the servo controller 20 controls the sled motor to move the entire optical pickup from the inner circumference to the circumferential direction. (S15) For example, assuming that 10 tracks are jumped by one step rotation of the sled motor, the servo control 20 determines the focus lens position immediately after the one step rotation of the sled motor. It shifts in the innermost direction within the movable range, and then gradually shifts by two tracks in the outer circumferential direction.

On the other hand, in the microcomputer 21, the number of revolutions of the spindle motor rotated as described above is counted (S16), so that the recording position at which the beam spot is formed is approximately estimated. For example, the sled motor has one step. In the case of rotation, in the data area of the optical disc, the address to which the optical pickup is moved becomes a fixed predetermined value, so that the number of rotations of the counted spindle motor is multiplied by the fixed predetermined value, and the current The recording position can be estimated roughly.

In addition, when the address predicted through the above process reaches or exceeds the end address (End_Address) searched and confirmed by the navigation information of the optical disc (S17), the data deletion operation is terminated. As shown in Fig. 9, as shown in Fig. 9, the data erasing operation is not unnecessarily performed for the portion of the data area of the optical disc in which data is not actually recorded.

For reference, any predetermined value at which the optical pickup is moved when the sled motor is rotated by one step is previously stored in the memory as an experimental result value in advance, or before the data erasing operation, in the process of performing a data recording operation. Detection can be stored.

Or more, preferred embodiments of the present invention described above, for the purpose of illustration, those skilled in the art, within the technical spirit and the technical scope of the present invention disclosed in the appended claims below, to further improve various other embodiments Changes, substitutions or additions will be possible.

The data erasing method of the optical disc according to the present invention made as described above sets a data erasing mode of an optical disc that can be written once, for example, upon input of a delete button installed in the optical disc drive (ODD), By forming a large-sized beam spot and superimposing unnecessary data on the data area of the optical disc, data erasing operation of the optical disc can be performed more reliably and efficiently, thereby preventing the data stream from being exposed by hacking or the like. In addition, it is a very useful invention that does not need to use separate apparatus water, a heater, and a compressor.

Claims (8)

A step (1) of forming a beam spot of a large size covering a plurality of tracks of the optical disc in setting a data erasing mode of the optical disc; And And using the large sized beam spot, superimposing and recording unnecessary data in the data area of the optical disc. The method of claim 1, In the first step, the data erasing method of the optical disc, which can be written once, is set when the delete button installed in the optical disc drive is input. The method of claim 1, In the first step, when the data erasing mode of the optical disc is set, an optical disc is formed in which a beam spot having a large size covering at least two or more tracks is formed by adjusting a focus lens of the optical pickup to a predetermined defocus state. How to delete data from The method of claim 1, In the first step, when the data erasing mode of the optical disc is set, a large sized beam spot is formed on a plurality of tracks of the optical disc, and the laser power value is increased. The method of claim 1, In the second step, the superimposition of random data is superimposed on the data area of the optical disc by using the large beam spot while shifting the focus lens of the optical pickup from the inner circumference to the outer circumference with the tracking servo off. The data erasing method of an optical disc, characterized in that. The method of claim 5, In the second step, when the focus lens of the optical pickup is no longer shifted, the sled motor is rotated to move the optical pickup, and then the focus lens is shifted from the inner circumference to the outer circumferential direction. Way. The method of claim 6, And counting the number of revolutions of the sled motor, predicting whether or not the end address at which the data was last recorded has been exceeded, and then terminating the data deletion operation. The method of claim 7, wherein The end address is retrieved by the navigation information recorded on the optical disc, and whether the end address is exceeded is based on a value multiplied by the number of revolutions of the counted sled motor and the address moved during one revolution of the sled motor. Data erasing method of an optical disc, characterized in that predicted by.

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