JPS6325831A - How to delete data on a write-once optical disk - Google Patents

Abstract

PURPOSE:To read data on a DRAW (Direct Read After Write) type optical disc to protect data by projecting the laser light for deletion to an used area of the optical disc. CONSTITUTION:When an Ar laser 1 emits the laser light, the light is divided into the recording laser light, the deleting laser light, and the reproducing laser light by beam splitters 2, 14 and 5. The deleting laser light has a power weaker than that of the recording laser light and stronger than that of the reproducing laser light not to cause the servo error of focusing/tracking. When data on an optical disc 10 is deleted, the beam which passes the deleting beam splitter 14 is projected to a data part to be deleted on the optical disc 10 to change the reflectivity in this part, and data read from this part is impossible.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for erasing an optical disc by irradiating the used portion of a write-once optical disc with a laser to make it impossible to read data.

BACKGROUND ART FIG. 2 shows the configuration of a conventional optical disc device. In FIG. 2, 1 is an Ar laser, 2 is a recording beam splitter, 3 is a multi-channel modulator, 4 is a beam combiner, 5 is a reproduction beam splitter, 6 is a polarization beam splitter, 7 is a recorded detection circuit, 8 is a light detection array, 9
is a beam expander, and 10 is an optical disk.

Next, the operation of the above conventional example will be explained. In Figure 2, A
The beam from the r laser 1 is transmitted through a semi-transparent reflecting mirror 10a,
llb, and a part of it is bent by the recording beam slitter 2.
The rest of the signal is modulated by the input signal at the multi-channel modulator 3 via the reproducing beam splitter 5 and the polarizing beam splitter 6 at the beam combiner 4 together with the output of the multi-channel modulator 3. It is synthesized, passes through the reflecting mirror 11c and the beam expander 9, is bent again by the reflecting mirror lie, and is directed to the objective lens 12.
The light is focused and irradiated onto the optical disc 10. optical disc 1
At 0, writing is performed by irradiation, and at the time of reading, the reflected light is taken out from the polarizing beam splitter 6 through a reverse route, condensed by the lens 13, and an output for reproduction is obtained from the photodetector array 8. Furthermore, when deleting data on a write-once optical disc, information indicating that the management information of the data to be deleted is to be deleted is recorded in another area of the optical disc, thereby making the data unreadable.

Problems to be Solved by the Invention However, in the above-mentioned conventional optical disc device, a recorded completion detection circuit 7 is installed because writing data twice may cause a focus/tracking servo error. Therefore, the data on the optical disc 10 cannot be destroyed by double writing, and the data can be read by taking a dump of the optical disc 10, posing a problem in terms of data protection.

The present invention solves these conventional problems,
An object of the present invention is to provide a method for deleting an optical disc that makes it impossible to read data from a write-once optical disc.

Means for Solving the Problems In order to achieve the above object, the present invention provides an optical disc device with a deletion beam splitter, and writes data twice on a write-once optical disc using a laser beam weaker than the recording laser beam. It is designed to be deleted.

Therefore, according to the present invention, by irradiating a used area of an optical disk with a laser beam for erasing, it is possible to make reading of data impossible.

Embodiment FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, 14 is a beam slitter for deletion, ie is a translucent reflecting mirror, and other symbols similar to those in FIG. 2 represent the same names. When the Ar laser 1 emits a laser beam, a beam splitter divides the laser beam into recording, erasing, and reproducing laser beams.

Here, the power of the laser beam for deletion is weaker than that of the laser beam for recording, but stronger than the power of the laser beam for reproduction, and is set to a level that does not cause focus/tracking servo errors.

Next, the above embodiment will be explained. In the above embodiment, when data is deleted from the optical disc 10, when the beam that has passed through the deletion beam splitter 14 is irradiated onto the data portion of the optical disc 10 as soon as the data is deleted, the reflectance of that portion changes, making it impossible to read the data. Become.

Effects of the Invention As is clear from the above embodiments, the present invention has the following effects.

(1) Since a beam splitter for deletion is provided,
By irradiating the optical disc with a laser beam for deletion,
To make data reading impossible without focus/tracking servo error.

(2) By separating the laser beams for recording and erasing,
It is possible to use a recorded detection circuit when recording data to prevent double writing except when deleting data.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an optical disc device according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional optical disc device. 1...Ar laser, 2...recording beam splitter,
3...Multi-channel modulator, 4...Beam combiner, 5...Beam splitter for reproduction, 6...Polarization beam splitter, 7...Recorded detection circuit, 2...Photodetector array , 9...beam expander, 10...
...Optical disk, 14...Beam splitter for deletion. Name of agent: Patent attorney Satoshi Nakao and one other person Figure 1 Figure 2

Claims (1)

[Claims] An optical disk device is provided with a beam splitter for erasure, and a laser beam passing through the beam splitter is irradiated onto the used portion of the write-once optical disk to change the reflectance, thereby making it impossible to read data. How to delete data from optical discs.