JPS61145763A - Optical disk device - Google Patents

Abstract

PURPOSE:To inhibit the reading or deleted data by recording a prescribed deletion pattern to a data area when a sector is deleted. CONSTITUTION:When information on a certain sector is deleted, a main controller 1 selects a deletion pattern generating circuit through a switch circuit 4 and at the same time reads a pre-format area like a writing mode. Then the controller 1 outputs the deletion flag-on data to a flag read/write circuit 9 after a desired sector is detected. At the same time, the deletion pattern outputted from the circuit is recorded on a data area following the pre-format area. Then a deletion pattern is recorded on the original record data in the data area of a deletion sector. At the same time, the deletion flag of a flag F of the pre-format area is turned on. In such a way, the data superposed with a deletion pattern is recorded on the data area of the deletion sector. Thus it is impossible to read out the original record data.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an optical disc device, and more particularly, to an optical disc device that can reliably prevent information in deleted sectors from being read.

[Prior Art] In recent years, there has been a proposal to use an optical disk device that uses an optical disk made of a photoreactive recording material formed into a five-disc shape as a storage medium as an auxiliary storage device of a computer system.

This optical disc has one spiral recording track formed on its surface at a track pitch of approximately 1.5 μm.
In accordance with the information to be stored, pits with a diameter of about 0.5 μm are directly written on this track by a laser spot narrowed to a minute diameter of about 1 μm. Also.

For example, an optical disk with a diameter of about 30c++ can store data of about 1011 to 1012 bits per disk.

In this way, optical disk devices have a large storage capacity,
Furthermore, since data is written directly onto the optical disk, it is advantageous in terms of storage of stored data compared to storage devices using magnetic storage media.

Furthermore, storage data is divided into fixed-length sectors and recorded on recording tracks. Each sector has a sector synchronization signal SS at the beginning of the sector for detecting the beginning of the sector.
, a preformat area is arranged in which a plurality of consecutive sector addresses SA for identifying a sector and a plurality of flags F for indicating the state of recorded data in the sector are formed (see FIG. 3).

This flag F includes a delete flag for determining whether the data recorded in that sector has been deleted, a write flag for determining whether data is recorded in that sector, and a write flag for determining whether data is recorded in that sector. It consists of a defect flag and the like for determining whether a defective sector has a large number of defects or not.

Traditionally, deleting data written to a sector is
This was done by turning on the delete flag of flag F.

When data is read, the state of the delete flag of flag F is determined in each sector, and if the delete flag is turned on, the data recorded in that sector is not read.

However, in reality, data remains in the data area of the deleted sector, and therefore, if the above-mentioned data read prohibition processing using flag F is removed, there is a risk that the data may be read by a malicious user. be. especially.

If the recorded data is highly confidential information, this will cause a huge inconvenience.

[Objective] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical disc device that can reliably make deleted data unreadable.

[Configuration] The present invention takes advantage of the fact that optical discs cannot be rewritten, and when a sector is deleted, a predetermined delete pattern is recorded in the data area to make the deleted data unreadable.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an apparatus according to one embodiment of the present invention.

In the figure, 1 is the main controller that controls the entire device and exchanges data with an external device (host machine). Recorded data added from the external device is
After being applied to the modulation circuit 3 from the main controller 1 via the data transfer circuit 2 and modulated, the data is sent to the main controller 1 via the switching circuit 4 which selects the modulation circuit 3 and the read/write control circuit 5. The data is transferred to the optical disc driver 6, and thereby recorded on the optical disc.

Further, data read from the optical disk by the read/write control circuit 5 is converted into a digital signal by the demodulation circuit 7, outputted to the main controller 1 via the data transfer circuit 2, and further transferred to an external device. .

At the same time, the data read from the optical disc is
A sector address SA is detected in synchronization with the detection timing of a sector synchronization signal SS added to the sector detection circuit 8 and stored in its preformat area, and the result is output to the main controller 1.

The data read from the optical disk is also applied to the flag read/write circuit 9, and the flag F in the preformat area is determined and output to the main controller 1.
It also has a function of recording flag data added from the main controller 1 onto an optical disk.

The delete pattern generation circuit 1o generates a delete pattern to be recorded in the data area of a sector when data recorded in the sector is deleted. This delete pattern consists of a button that can be reliably tracked by a tracking mechanism that positions an optical pickup, which records data on the optical disc and reads data from the optical disc, on the recording track.

That is, as shown in FIG.
If the length on the track of the portion where data is recorded on 1 is a, and the data recording interval is b, then what is the level of the tracking error signal that the tracking mechanism refers to for controlling the tracking of the optical pickup? is also (b/(a+b)) times as large as that of the unrecorded portion.

Therefore, if a becomes large, there is a possibility that the tracking control of the tracking mechanism will be impaired. Furthermore, since the delete pattern is continuously recorded in the data area of one sector, a pattern that can prevent such a situation when the pattern is repeated is set as the delete pattern.

When recording data, the main controller 1 receives the sector address SA of the target sector transferred from the external device.
At the same time, the read/write control circuit 5 is activated to enter the preformat area reading state. At this time, the sector detection circuit 8 is enabled, the sector address SA is detected from the data in the preformat area of the optical disk, and the main controller 1 compares it with the target sector address SA, and the flag read/write circuit 9 The contents of flag F are output to main controller 1.

When the main controller 1 detects the target sector address SA, the main controller 1 causes the switching circuit 4 to select the modulation circuit 3 when the preformat area is completed, and sets the read/write control circuit 5 to the write state, and transfers data from the external device. The recorded data is output to the modulation circuit 3 via the data transfer circuit 2.

As a result, the recording data is recorded in the target sector of the optical disc.

At the same time, the main controller 1 outputs write flag on data to the flag read/write circuit 9 to turn on the write flag of the flag F in the preformat area of the target sector. Therefore, from now on, by determining the on/off state of the write flag of flag F, it is possible to determine whether or not the sector is writable.

In addition, when the main controller 1 reads the preformat area and detects the target sector in the same way as when writing, the main controller 1 sends the data in the data area that continues to the preformat area to the demodulation circuit 1.
The digital data is converted into digital data, received via the data transfer circuit 2, and transferred to an external device.

Now, when deleting information in a certain sector, the main controller 1 causes the switching circuit 4 to select the delete pattern generation circuit 10, and enters the preformat area reading state in the same way as when writing.

When the target sector is detected, delete flag-on data is output to the flag read/write circuit 9, and
The delete pattern output from the delete pattern generation circuit 10 is recorded in a data area that is continuous with the preformat area.

As a result, the delete pattern is recorded in the data area of that delete sector over the originally recorded data,
At the same time, the delete flag of flag F in the preformat area is turned on.

In this way, data in which the delete pattern is superimposed on the recorded data is recorded in the data area of the delete sector, so it is no longer possible to read out the original recorded data.

Note that the delete pattern is not limited to one type, and may be a combination of multiple types. However, it is necessary that the result satisfies the above-mentioned delete pattern conditions.

[Effects] As explained above, according to the present invention, when a sector is deleted, a predetermined delete pattern is recorded in the data area, so the deleted data changes and the original data cannot be reliably read. Therefore, there is an advantage that a highly secure optical disk device can be realized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an apparatus according to an embodiment of the present invention, FIG. 2 is a partial perspective view illustrating the state of data recording on an optical disk, and FIG. 3 is a signal arrangement diagram illustrating the recording format of the optical disk. It is. DESCRIPTION OF SYMBOLS 1... Main controller, 2... Data transfer circuit, 3... Modulation circuit, 4... Switching circuit, 5... Read/write control circuit, 6... Optical disc driver, 7
... Demodulation circuit, 8... Sector detection circuit, 9... Flag read/write circuit, 10... Delete pattern generation circuit. -/' Figure 1

Claims (1)

[Claims] a sector synchronization signal for detecting the beginning of a sector;
Data is stored in a recording format in which a preformatted area in which a sector address for identifying a sector and a plurality of consecutive delete flags indicating whether or not the sector has been deleted is set before a fixed-length data area. An optical disc device for recording includes a delete pattern generating means for generating a predetermined delete pattern, and a switching means for switching the output of the delete pattern generating means and recording data and outputting the same to the optical disc driving means, and when deleting a sector, the above-mentioned method is used. An optical disc device characterized in that a switching means selects the output of the delete pattern generating means and records a delete pattern in a data area of the sector.