JPS61168148A - Optical information storage medium - Google Patents

Abstract

PURPOSE:To record erasable information and unerasable information by providing the 1st recording area where information can be erased with converged light and the 2nd recording area where information can not be erased. CONSTITUTION:An information storage medium 1 is divided into its information storage area 2 and the 2nd recording area 4 where information can be erased with the converged light. Information to be recorded in an erasable state, e.g. general data are stored in the 1st recording area 3 and information to be recorded permanently and never erased, e.g. indexes of recording information, the manufacture number of the information storage medium are recorded in the 2nd recording area 4. Consequently, two kinds of information, i.e. erasable and unerasable pieces of information are recorded on one information storage medium 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an optical information storage medium capable of at least recording and reproducing information using focused light.

[Technical background of the invention and its problems]

Currently, information storage media of the above type are being developed that can not only record and reproduce information on a recording film using focused laser light, but also erase information once recorded. .

By the way, from the user's perspective, the information recorded on such an information storage medium can be expressed as ``temporarily leave it as data, delete it when it is no longer needed, and put in new data'' or ``approximately. Temporarily record the contents and partially change the data contents as necessary.

What you want to record in an erasable state, such as ``Serial number and date of manufacture of the information storage medium,'' ``Index of recorded data,'' and ``Major categories of content to be recorded,'' etc. However, there are two types of things that should not be erased.

However, there are two types of conventional information storage media: those that have only a recording area where information can be erased, and those that have only a recording area that cannot erase information. There is no one that has both. Therefore, there is a problem in that two types of information storage media are required to record information that is desired to be recorded in an erasable state and information that is to be recorded permanently and must not be erased.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and its purpose is to provide an optical system capable of recording information that is desired to be recorded in an erasable state and information that is to be recorded permanently and must not be erased. The objective is to provide a digital information storage medium.

[Summary of the invention]

In order to achieve the above object, the present invention provides an information storage medium capable of at least recording and reproducing information using focused light. This is characterized by comprising a second recording area in which information cannot be erased.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a disc-shaped information storage medium 1, and FIG. 2 shows a card-shaped information storage medium 1. Each of these information storage media 1.1 has an information storage area 2 of A first recording area 3 where information can be erased by focused light, and a second recording area 3 where information cannot be erased by focused light.
It is divided into a recording area 4 and a recording area 4. Information that should be recorded in an erasable state, such as general data, is recorded in the first recording area 3, and information that must be permanently recorded and not erased, such as an index of recorded information, is recorded in the second recording area 4. The serial number of the information storage medium and the serial number of the information storage medium are recorded. Note that 5 is the center hole of the disk-shaped information storage medium 1.

According to such a configuration, information that is desired to be recorded in an erasable state and information that must be recorded permanently and must not be erased can be recorded on one information storage medium 1.
Only one type of information storage medium is required.

Next, the principle for arbitrarily setting a portion of the information storage area 2 to the first recording area 3 or the second recording area 4 will be explained.

Figure 3 shows the relationship between laser power and laser pulse width when recording on a recording film that uses the transition between crystallization and amorphization, using the recording state as a parameter. By changing the laser power or laser pulse width, the recording state (
membrane condition) can be changed. Therefore, as shown in FIG. 4, in the information storage medium 1 in which the recording film 7 is provided on the substrate 6, the amount of exposure by the laser beam is increased to prevent film deformation (local destruction of the film) such as holes. By causing this to occur, a non-erasable recording state section 9 can be created, and the second recording area 4 is thereby set. Further, the erasable recorded state portion 10 can be created by changing the exposure amount of laser light to a certain appropriate value and making it amorphous.
As a result, the first recording area 3 is set.

Similarly, as shown in FIG. 5, in the case of the recording film 11 using a perpendicular magnetization film, the amount of exposure to the laser beam is increased to cause film deformation (local destruction of the film) such as holes. By doing so, it is possible to create an unerasable recorded state part 9,
As a result, the second recording area 4 is set. Further, by setting the exposure amount of laser light to a certain appropriate value and reversing the magnetization direction, an erasable recorded state portion 10 can be created, and thereby the first recording area 3 is set.

Note that the erasable recorded state portion can be created not only by local destruction of the recording film 7 but also by a local change in the shape of the recording film 7.

For example, as shown in FIG. 3, a transparent base layer 11 is provided between the substrate 6 and the recording film 7, and this base layer 11 is locally exploded or expanded to produce protrusions. It is also possible to create a recorded state section 9 that cannot be erased.

Next, as shown in Fig. 7, the exposure level (laser power) is divided into three levels, starting from the lowest: exposure level 12 for information reading, exposure level 13 for erasable recording, and exposure level 13 for non-erasable recording. By using the exposure amount 14 properly, the recording film 7
An optical head for recording, reproducing, and erasing information will be described below.

FIG. 8 shows an optical head applied to an information storage medium 1 that performs recording using crystal phase change. In this figure, reference numeral 15 denotes a semiconductor laser for recording and reproducing, and a diverging noser beam for recording and reproducing is generated from this semiconductor laser 15. In this case, when writing information to the recording film 7 of the information storage medium 1, a laser beam beam whose light intensity is modulated according to the information to be written is generated, and when reading information from the recording film 7, a laser beam flux is generated that is constant. A laser beam is generated with a light intensity of . The diverging laser beam generated from the semiconductor laser 15 is
It is converted into a parallel light beam by the collimator lens 16,
It is guided to a polarizing beam splitter 17. The laser beam guided to the beam splitter 17 in this polarized manner is reflected by the polarizing beam splitter 17, and is then reflected by the 1/4 wavelength plate 18.
The light passes through and enters the objective lens 19, and is focused by the objective lens 19 toward the recording film 7 of the information storage medium 1. Here, the objective lens 19 is supported movably in the front axis direction and in the direction (radial direction) perpendicular to the optical axis, and when the objective lens 19 is positioned at a predetermined position, the objective lens 19 The beam waist of the focused laser beam emitted from is projected onto the surface of the recording film 7,
A minimum beam spot is formed on the surface of the recording film 7.

In this state, the objective lens 19 is maintained in a focused state and a focused track state, and information can be written and read. When writing information, bits are formed on the tracking guide on the storage film 7 by a laser beam whose light intensity is modulated, and when reading information, a laser beam having a constant light intensity is used for tracking. The light intensity is modulated and reflected by the bits formed on the guide.

The diverging laser beam reflected from the recording film 7 of the information storage medium 1 is converted into a parallel beam by the objective lens 19 at the time of focusing, passes through the quarter-wave plate 18 again, and is returned to the docking beam splitter 17. It will be done. By reciprocating through the 1/4 wavelength plate 18, this laser beam has a plane of polarization of 9 compared to when it is reflected by the polarized beam splitter 17.
Since it is rotated by 0 degrees, it passes through the polarizing beam splitter 17 without being reflected by the polarizing beam splitter 17. The laser beam that has passed through the polarizing beam splitter 17 is irradiated onto a photodetector 24 through a quarter-wave plate 20, a dichroic mirror 21, a spherical lens 22, and a cylindrical lens 23 in this order. As a result, information signal detection 1, track deviation detection, and defocus detection are performed.

-〇- On the other hand, 25 is a semiconductor laser for erasing, and a diverging laser beam is generated from this semiconductor laser 25. In this case, a laser beam beam having a constant light intensity and a frequency different from the frequency of the recording/reproducing laser beam beam 1- is generated. Then, the diverging laser beam L' generated from the semiconductor laser 25 is converted by collimator lenses 26, 27, and 28 into a parallel beam having a diameter smaller than the size of the recording/reproducing laser beam, and is sent to the docking beam splitter 17. be guided.

After the laser beam guided to this polarizing beam splitter 17 is reflected by this polarizing beam splitter 17,
Passing through the 1/4 wavelength plate 20, the dichroic mirror 21
guided by. This erasing laser beam L' has a frequency different from that of the recording/reproducing laser beam, and is reflected by this dichroic mirror 21 and is again reflected by the 1/4 wavelength plate 2.
0 and is returned to the stopped beam splitter 17. By reciprocating through the quarter-wave plate 20, the plane of polarization of this laser beam is rotated by 90 degrees compared to when it is reflected by the polarized beam splitter 17, so it is not reflected by the AT beam splitter 17. Then, it passes through this polarized beam splitter 17. The laser beam L' that has passed through the deflection beam splitter 17 is incident on the objective lens 19 via the quarter-wave plate 18, and is focused by the objective lens 19 toward the recording film 7 of the information storage medium 1. In this case, the spot diameter of the laser beam beam for erasing on the recording film 7 is larger than the spot diameter of the laser beam beam for recording and reproduction on the recording film 7, so that information can be erased. It has become.

Next, the driver circuit of the recording/reproducing semiconductor laser 15 will be described. Reference numeral 29 is a series circuit in which a 30° resistor FET 31 and a resistor 32 are sequentially connected. II (not shown), and the other end is grounded via a recording/reproducing semiconductor laser 15. A series circuit 36 consisting of a resistor 34 and an NPN transistor 35, and an NPN transistor 37 are connected in parallel to the series circuit 29. Then, the above-mentioned FE switch 31 is turned on by supplying the control signal C to the gate, and thereby,
An information reading exposure amount 13 is defined. Further, the transistor 37 is turned on by supplying the a signal to its base, thereby defining the exposure amount 13 for erasable recording. moreover,
The transistor 37 is turned on by supplying the b signal to its base, and thereby the exposure amount 1 for non-erasable recording is generated.
4 is now specified.

FIG. 9 shows an optical head applied to an information storage medium 1 that performs recording using a perpendicularly magnetized film. In this figure, 38 is a semiconductor laser, and this semiconductor laser 38
A diverging laser beam is generated. The diverging laser beam generated from the semiconductor laser 38 is converted into a parallel beam by the collimator lens 39, and then sequentially passes through the first and second half prisms 40, 41 and enters the objective lens 42. The light is focused toward the recording film 7 of the information storage medium 1 by the objective lens 42 . Here, when the objective lens 42 is positioned at a predetermined position, the beam waist of the focused laser beam emitted from the objective lens 42 is projected onto the surface of the recording film 7, and the minimum beam spot is set on the recording film 7. formed on the surface. Note that an electromagnet 43 is arranged on the opposite side of the information storage medium 1 onto which the laser beam is projected.

The diverging laser beam reflected from the recording film 7 of the information storage medium 1 is converted into a parallel beam by the objective lens 42 when it is in focus, returned to the second half prism 41, and divided into two directions.

The laser beam reflected by the second half prism 41 is guided to the polarized beam splitter 45 via the 1/2 wavelength plate 44, and the laser beam reflected by the mooring beam splitter 45 is detected by the first optical detector. The laser beams that have passed through the polarized beam splitter 45 are projected onto a second photodetector 47, respectively. Then, information detection is performed based on the detection results of these first and second photodetectors 46.4.7. On the other hand, the laser beam that has passed through the second half prism 41 is returned to the first half prism 40 and divided into two directions. The laser beam reflected by this first half prism 40 is reflected by a spherical lens 48.
and is projected onto a third photodetector 50 via a cylindrical lens 49.

Based on the detection results of the third photodetector 50, track deviation detection and defocus detection are performed. Note that the driver circuit for the semiconductor laser 38 has the same configuration as the driver circuit shown in FIG. 8 described above.

Next, as shown in Figure 10, the exposure level (laser power) is divided into two levels, and the lower one is the exposure amount for information reading.
2, and furthermore, the higher exposure time is divided into two types, and the shorter one is used as the erasable recording exposure amount 13 and the longer one is used as the non-erasable recording exposure amount 14, thereby increasing the exposure time for the recording film 7. An optical head for recording, reproducing, and erasing information will be described.

Fig. 11 shows an optical head applied to an information storage medium 1 that performs recording using crystal phase change, and Fig. 12 shows an optical head applied to an information storage medium 1 that performs recording using a perpendicular magnetization film. This figure shows the optical head that is used. These optical heads have a different configuration from the optical heads shown in FIGS. 8 and 9 described above only in the driver circuit, so the same components are given the same reference numerals and the explanation will be omitted, and only the driver circuit will be explained.

In the figure, 51 is a series circuit in which a resistor 52, a FET 53, and a resistor 54 are connected in sequence.
One end is connected to a DC power source (not shown) via a resistor 55, and the other end is grounded via a semiconductor laser 38. The series circuit 51 includes an NPN transistor 56.
are connected in parallel. The FET 53 is turned on by supplying the control signal d to its gate, thereby defining the exposure amount 12 for reading information. Further, the transistor 56 is turned on by supplying the e signal to its base, and depending on the pulse interval of the e signal, the exposure amount for erasable recording 13 and the exposure amount for non-erasable recording [Effects of the Invention] As described above, according to the present invention, an information storage medium capable of at least recording and reproducing information using focused light includes a first recording area where information can be erased using focused light; Since the information storage medium is equipped with a second recording area that cannot be erased, it is possible to record information that is to be recorded in an erasable state and information that must be recorded permanently and must not be erased. It has excellent effects such as only one type is required.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing one embodiment of the present invention, FIG. 2 is a plan view showing another embodiment of the present invention, and FIG. 3 is a record recorded using the transition between crystallization and amorphism. FIG. 4 is a diagram showing the relationship between laser power and laser pulse width during recording on a film using the recording state as a parameter; FIG. 4 is a sectional view showing the recording state of an information storage medium that performs recording using crystal phase change Figure 5 is a cross-sectional view showing the recording state of an information storage medium that performs recording using a perpendicular magnetization film, and Figure 6 is a cross-sectional view showing the recording state of another information storage medium that performs recording using crystal phase change. Figure 7 is a diagram showing the relationship between the exposure level and the exposure position on the information storage medium when the exposure level is changed depending on the recording state, and Figure 8 is a diagram showing the relationship between the exposure level and the exposure position on the information storage medium when the exposure level is changed depending on the recording state. A configuration diagram showing an optical head applied to a storage medium that changes the exposure level depending on the recording state. Figure 9 is an optical head applied to an information storage medium that performs recording using a perpendicular magnetization film. A configuration diagram showing a head in which the exposure level is changed according to the recording condition. FIG. 10 shows the relationship between the exposure level and the exposure position on the information storage medium when the exposure time is changed according to the recording condition. FIG. 11 is a configuration diagram showing an optical head applied to an information storage medium that performs recording using crystal phase change, in which the exposure time is changed depending on the recording state,
FIG. 12 is a configuration diagram showing an optical head applied to an information storage medium that performs recording using a perpendicularly magnetized film, in which the exposure time is changed depending on the recording state. 1... Information storage medium, 3... First recording area, 4.
...Second recording area. Applicant's Representative Patent Attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 0.1 1 10 The and the Pass Communication (1S) Figure 7 Rehorai Seishanrei. 282726L. l-isL. L. ．． 22 ゝ、・ 123

Claims (5)

[Claims] (1) In an information storage medium capable of at least recording and reproducing information using focused light, there is a first recording area where information can be erased using focused light, and a first recording area where information cannot be erased using focused light. 1. An optical information storage medium comprising: 2 recording areas. (2) The optical information storage medium according to claim 1, characterized in that the first recording area and the second recording area are provided on the same recording surface. (3) The optical information storage medium according to claim 1, wherein the first recording area and the second recording area are made of a recording film made of the same material. (4) The optical information storage medium according to claim 1, wherein the second recording area is in a recorded state by locally destroying the recording film. (5) The optical information storage medium according to claim 1, wherein the second recording area has a recording state in which the shape of the recording film is locally changed.