JPH10162371A - Treatment of phase transition type optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it impossible to write a correct data and to prevent the data from forging by irradiating an area on the phase transition type optical disk with laser light from a high output semiconductor laser and generating the initialization defective state in this area. SOLUTION: The area A of the phase transition type optical disk D is irradiated with the laser light from the high output semiconductor laser L having a degree of flatness <=60% of its near-field pattern. When initialization is satisfactorily performed with light intensity of a crest part of the near-field pattern, initialization is defective in a trough part, so that a good initialization part and a defective initialization part take place in the irradiated area to make the initialization ununiform. Consequently, the correct data cannot be written in the area A from now on, and hence the data showing A cannot be written anymore on this optical disk D.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing a phase change optical disk used for recording data.

[0002]

2. Description of the Related Art At present, prepaid cards such as telephone cards are widely used. Also, recently, prepaid cards have been used for pachinko ball lending and the like. For recording data on such a prepaid card or the like, a magnetic method is often used.

On the other hand, recently, as a data recording medium, a phase change optical disk of a type in which a phase change is caused by irradiation with a low-power semiconductor laser and data is read based on a difference in reflectance due to the phase change has been attracting attention. The use of this phase change optical disk for prepaid cards and the like is also being considered.

[0004]

By the way, in the case of magnetic data recording, it is easy to initialize and write data. Therefore, in a prepaid card or the like employing such a magnetic recording method, data is altered.・ Counterfeiting is becoming a major problem.

[0005] The present invention has been made in view of such circumstances, and when initializing unnecessary data, it is necessary to prevent the subsequent writing of accurate data in that area, It is an object of the present invention to provide a method for processing a phase change optical disc which can prevent alteration and forgery of the optical disc.

[0006]

In order to achieve the above object, a processing method according to the present invention comprises irradiating a certain area of a phase change optical disk with laser light from a high-power semiconductor laser.
It is characterized by generating a state of initialization failure in that area.

Here, the high-power semiconductor laser used in the present invention means that the flatness of the near-field image pattern (the ratio of the light intensity between peaks and valleys [V / P]; see FIG. 2) is 60% or less. Broad-strip laser.

Next, the operation of the present invention will be described. First, for initialization of this type of phase change optical disk, the output is, for example, 50
A high-power semiconductor laser with a near-field image pattern of about 0% to 1500 mW and a flatness of a near-field image pattern of about 80% or more (see FIG. 3) is used, and the entire irradiation area is favorably initialized by the irradiation of the laser light. be able to.

On the other hand, when the phase change optical disk is initialized using a high-power semiconductor laser having a poor near-field image pattern flatness as described above, the peak portion of the near-field image pattern shown in FIG. Even if the initialization is performed satisfactorily with the light intensity of the above, the initialization becomes poor at the light intensity of the valley portion, and conversely, the initialization is satisfactorily performed with the light intensity of the valley portion of the near-field image pattern. Even if it is performed, the light intensity in the mountain portion results in poor initialization.

When a high-power semiconductor laser with a poor near-field image pattern is irradiated with a laser beam onto a phase-change optical disk, an initialization failure portion always occurs in the irradiated area. This initialization failure portion cannot write data with a low-power semiconductor laser that is usually used for writing data, and therefore, when processing by such laser light irradiation is performed, the processing area is In this case, accurate data cannot be written.

[0011]

FIG. 1 is an explanatory diagram of an embodiment of the present invention. In this embodiment, the phase-change optical disc D
As a high-power semiconductor laser L for initializing, the laser light output is about 500 mW to 1500 mW, the output wavelength of the laser light is around 800 nm, and the emission spot width is 50 μm to
A broad stripe laser having a flatness [P / V] of about 300 μm and a near-field image pattern shown in FIG. 2 of 60% or less is used.

The laser light from the high-power semiconductor laser L is condensed by the optical system C, and is applied to the area A of the phase change type optical disc D where data initialization is desired. In addition,
The phase change optical disk D is rotated at a high speed by a driver (not shown). The high-power semiconductor laser L is provided with a scanning mechanism (not shown), and the irradiation position of the laser light on the disk D can be moved in the diameter direction of the disk.

Then, the flatness of the near-field image pattern [P /
V] is 60% or less, when the laser light from the high-power semiconductor laser L is applied to the region A of the phase-change optical disc D, as described above, the light intensity at the peak of the near-field image pattern is increased as described above. If the initialization is performed well, an initialization failure occurs at the valley portion, and a good initialization portion and a defective portion are formed in the irradiation region, and the initialization becomes non-uniform. This allows
Thereafter, accurate data cannot be written to the area A, and data representing A cannot be written to the disk D.

Next, an embodiment in which the present invention is applied to a prepaid card will be described below with reference to FIG.
The phase change optical disk D1 used in this example includes a,
In each area of b, c, ..., n, 10,000 yen,
Data representing 9000 yen, 8000 yen,..., 1000 yen is recorded in advance. In addition, a low-power semiconductor laser for reading data and a high-power semiconductor laser having a flatness of the above-mentioned near-field image pattern of 60% or less are built in the fee payment machine using the phase-change optical disk D1. Have been. The reading of the phase change type optical disk in the fee payment machine is performed in the following manner: a region → b region → c region →
... → n regions are performed in this order.

When the phase change type optical disk D1 is loaded into a fee payment machine to pay a fee, the area a of the phase change type optical disk D1 is read and the disk D1 is read.
Is unused, first, the fee payment machine recognizes that the balance is 10,000 yen.

Now, the actual amount spent is, for example, 100
If the price is 0 yen, the difference is 9000 yen. In this case, data in the area a of the disk D1 becomes unnecessary, and the area a is irradiated with laser light from a high-power semiconductor laser. As a result of this processing, the initialization of the area a becomes non-uniform, and thereafter, writing of data to the area a and reading of data of the area a become impossible. At this point, data representing the remaining balance of 10,000 yen can be read from the disk D1. become unable. Further, it becomes impossible to write data representing the remaining balance of 10,000 yen.

Next, when the phase change type optical disk D1 with the balance of 9000 yen is loaded into the fee payment machine, the data in the area a cannot be read as described above. It is recognized that it is a circle. If the actual payment amount at this time is 2,000 yen, the regions b and c are irradiated with laser light from a high-power semiconductor laser to make initialization of these two regions non-uniform. By this processing, the balance of 9000 yen and 80
It becomes impossible to read data representing 00 yen and write the data to the disk D1.

Each time a fee is paid, the same processing as described above is performed. When the balance of the phase change type optical disc D1 becomes zero, all the areas a, b, and .., n cannot be accurately written, and it is difficult for the used phase-change type optical disc D1 to falsify or forge data.

In the above embodiment, the disk D
Although the output of the high-power semiconductor laser used in the process (1) is fixed, the laser light output may be changed appropriately during one rotation of the phase change optical disc D. In this case, the near-field shown in FIG. In the image pattern, for example, the light intensity at the peak is reduced to the level of the light intensity at the valley, and conversely, the light intensity at the peak is increased to the light intensity level at the valley. The intensity level fluctuates with the valley,
As a result, a good initializing portion and a bad initializing portion are formed on the same circumference of the disk D. As a result, it is more certain that accurate data cannot be written.

[0020]

As described above, according to the present invention,
When the data written on the phase-change optical disk is no longer needed, the area where the data is written is irradiated with laser light from a high-power semiconductor laser having a poor near-field image pattern flatness. By generating a state, it becomes impossible to write accurate data thereafter in that area, so that it is difficult for the phase-change type optical disc which has been subjected to this processing to falsify or forge data.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

FIG. 2 is a diagram showing a near-field image pattern (flatness of 60% or less) of a high-power semiconductor laser.

FIG. 3 is a diagram showing a near-field image pattern (flatness: 80%).

FIG. 4 is an explanatory view of an embodiment of the present invention.

[Explanation of symbols]

 D Phase change optical disk L High power semiconductor laser C Optical system

Claims (1)

[Claims] 1. A method for processing a phase-change optical disc, wherein a phase change is generated by irradiation with a low-power semiconductor laser, and data is read based on a difference in reflectance due to the phase change. Irradiating a laser beam from a high-power semiconductor laser to a certain area to generate a state of initialization failure in the area, thereby processing a phase-change optical disc.