JPS61188749A - Information recording and reproducing device - Google Patents

Abstract

PURPOSE:To perform exposure for erasable and inerasable records on an information recording medium at the same time by controlling an exposure of the information recording medium in >=3 levels. CONSTITUTION:The information recording medium 2 is exposed to a record reproducing semiconductor laser 1 at three levels, an information reading expo sure level 17, an exposure level for erasable record 18 and an exposure level for inerasable records 19. An FET23 is turned on by a control signal a input to a gate to give the exposure level 17 for reading information. A transistor 27 is turned on by a control signal input to the base b to give the exposure level 18 for erasable records. Furthermore, a transistor 29 is turned on by a control signal input to the base c to give the exposure level 19 for inerasable records.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an information recording and reproducing apparatus that can record, reproduce, and erase information on an information storage medium using focused light.

[Technical background of the invention and its problems]

Currently, information storage media and information storage/reproduction devices are being developed that can not only record and reproduce information on a recording film using a focused laser beam, but also erase information once recorded. Currently, the most promising recording methods are ``recording using local reversal of the magnetization direction of a perpendicularly magnetized film and reading using the Kerr effect,'' and ``a method that uses local reversal of the magnetization direction of a perpendicularly magnetized film,'' and A method that utilizes structural changes, that is, transitions between crystallization and amorphism.”
“There is.

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 manufacturing date 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. Furthermore, there are cases where it is necessary to use and record both of the above two types of information in the same information storage medium.

However, in the past, recording of erasable information and recording of non-erasable information can be performed simultaneously on the same information storage medium, depending on the information that needs to be erased or the information that must not be erased. There is no.

[Purpose of the invention]

The present invention was made based on the above circumstances, and its purpose is to record erasable information on the same information storage medium depending on the information that needs to be erased and the information that should not be erased. It is an object of the present invention to provide an information recording/reproducing device which can perform recording of non-erasable information and recording of non-erasable information at the same time and which can be switched very easily.

[Fake invention]

In order to achieve the above object, the present invention provides an information recording and reproducing apparatus capable of recording, reproducing, and erasing information on an information storage medium using focused light. A light condensing means for condensing light onto the information storage medium, a light detection means for detecting light emitted from the information storage medium, and a control means for controlling the exposure level of the information storage medium by the light source to at least three levels or more. It is characterized by having the following.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 7.

FIG. 1 shows an optical head as an information recording/reproducing device that performs recording using crystal phase change. In this figure, reference numeral 1 denotes a recording/reproducing semiconductor laser, and this semiconductor laser 1 generates a diverging recording/reproducing laser beam. In this case, the information is transferred to the recording film 3 of the information storage medium 2.
When writing, a laser beam whose light intensity is modulated according to the information to be written is generated, and when reading information from the recording 113, a laser beam having a constant light intensity is generated. The diverging laser beam generated from the semiconductor laser 1 is converted into a parallel beam by the collimator lens 4 and guided to the polarizing beam splitter 5.

After being reflected by this polarizing beam splitter 5, the laser beam guided to this polarizing beam splitter 5 becomes 1/4
The light passes through the wavelength plate 6 and enters the objective lens 7, and is focused by the objective lens 7 toward the recording film 3 of the information storage medium 2. Here, the objective lens 7 is supported movably in the direction of its optical axis and in the direction (radial direction) perpendicular to the optical axis, and when the objective lens 7 is positioned at a predetermined position, the objective lens 7 The beam waist of the focused laser beam emitted from the recording film 3 is projected onto the surface of the recording film 3, and a minimum beam spot is formed on the surface of the recording film 3. In this state, the objective lens 7 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 3 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 m3 of the information storage medium 2 is converted into a parallel beam by the objective lens 7 at the time of focusing, passes through the quarter-wave plate 6 again, and is returned to the polarizing beam splitter 5. . This laser beam is
By reciprocating through the quarter-wave plate 6, the plane of polarization is rotated by 90 degrees compared to when it is reflected by the polarizing beam splitter 5, so it is not reflected by the polarizing beam splitter 5.
It passes through this polarizing beam splitter 5. The laser beam that has passed through the polarizing beam splitter 5 is passed through a quarter-wave plate 8, a dichroic mirror 9, a spherical lens 10. The light is then irradiated onto the photodetector 12 via the cylindrical lens 11. As a result, information signal detection, track deviation detection, and defocus detection are performed.

On the other hand, 13 is a semiconductor laser for erasing, and this semiconductor laser 13 generates a diverging laser beam. 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 is generated. The diverging laser beam L' generated from the semiconductor laser 13 is converted into a parallel beam having a diameter smaller than the size of the recording/reproducing laser beam by the collimator lenses 14, 15, 16, and the polarizing beam splitter 5 guided by.

Laser beam L guided to this polarizing beam splitter 5
' is 1/ after being reflected by this polarizing beam splitter 5.
The light passes through a four-wavelength plate 8 and is guided to a dichroic mirror 9. The mouth erasing laser beam L' has a frequency different from that of the recording/reproducing laser beam, and is reflected by this dichroic mirror 9, passes through the quarter-wave plate 8 again, and is returned to the polarizing beam splitter 5. By reciprocating through the 1/4 wavelength plate 8, this laser beam bundle has a polarization plane of 90° compared to when it is reflected by the polarizing beam splitter 5.
Since the beam is rotated by a degree, it passes through the polarizing beam splitter 5 without being reflected by the polarizing beam splitter 5. The laser beam that has passed through the polarizing beam splitter 5 is 1
The light enters the objective lens 7 via the /4 wavelength plate 6, and is focused by the objective lens 7 toward the recording film 3 of the information storage medium 2. In this case, the spot diameter of the erasing laser beam L' on the record 113 is larger than the spot diameter of the recording/reproducing laser beam on the recording film 3, so that information is erased. ing.

In particular, the exposure level (laser power) for the information storage medium 2 by the semiconductor laser 1 for recording and reproduction is divided into three levels as shown in FIG. The exposure level 18 is for possible recording and the exposure level 19 is for non-erasable recording. This allows information to be recorded, reproduced, and erased on the recording film 3.

That is, to explain the driver circuit 20 of the semiconductor laser 1 for recording and reproducing (see FIG. 1), 21 is a series circuit in which a resistor 22, a FET 23, and a resistor 24 are connected in sequence, and one end of this series circuit 21 is resistance 25
The other end is connected to a DC power source (not shown) via a recording/reproducing semiconductor laser 1, and the other end is grounded via a recording/reproducing semiconductor laser 1. A series circuit 28 consisting of a resistor 26 and an NPN transistor 27, and an NPN transistor 29 are connected in parallel to the series circuit 21. And the above FE
T23 is turned on by supplying the burial signal a to its gate, thereby defining the exposure level 17 for reading information. In addition, the transistor 27
The transistor 29 is turned on by supplying the b signal to its base, thereby defining the exposure level 18 for erasable recording.
is turned on by supplying the C signal to the base, thereby defining an exposure level 19 for non-erasable recording.

Further, as described above, the information storage medium 2 performs recording using crystal phase change.

Here, FIG. 3 shows the relationship between the laser power and the laser pulse width during recording on the recording film 3 using the transition between crystallization and non-crystallization, using the recording state as a parameter. As can be seen from this figure, the recording state (film state) can be changed by changing the laser power or laser pulse width. Therefore, as shown in FIG. 4, if the recording film 3 of the information storage medium 2 is exposed to a large amount of laser light to cause film deformation (local destruction of the film) such as holes, it becomes impossible to erase the data. It is possible to create a recording state section 30 .

In addition, the recorded state portion 31 is erasable by changing the amount of exposure to laser light to a certain appropriate value to make it amorphous.
・Can be made.

By switching the exposure level of the recording/reproducing semiconductor laser 1, as shown in FIG. A first recording area 33 consisting of a recorded state area 31 from which information can be erased is a second recording area 33 consisting of a recorded state area 30 from which information cannot be erased by the focused light at the recording exposure level 19 which cannot be erased. Recording area 34
are set respectively, and the exposure level 17 for reading the information is set.
The information in the first and second recording areas 33 and 34 is read by the focused light. Note that information that should be recorded in an erasable state, such as general data, is recorded in the first recording area 33, and information that must be permanently recorded and not erased, such as an index of recorded information, is recorded in the second recording area 34. and the serial number of the information storage medium are recorded.

According to the above configuration, by simply switching the exposure level of the recording/reproducing semiconductor laser 1, erasable information can be stored on the same information storage medium 2 according to the information that needs to be erased or the information that must not be erased. In addition to being able to use recording and recording non-erasable information at the same time,
This information can be read. Moreover, not only can switching be made very easily, but only a slight circuit change is required in a conventional optical head.

Further, since information that is desired to be recorded in an erasable state and information that must be permanently recorded and must not be erased can be recorded on one information storage medium 2, only one type of information storage medium is required.

Note that the erasable recorded state portion 31 can be created not only by local destruction of the recording film 3 but also by locally changing the shape of the recording film 3. For example, as shown in FIG. 6, a transparent underlayer 36 is provided between the substrate 35 and the recording film 3, and this underlayer 36 is locally exploded or expanded to produce protrusions that cannot be erased. It is also possible to create a recording state section 31.

Further, although the information storage medium 2 is disk-shaped in the above embodiment, it may be card-shaped as shown in FIG.

Next, another embodiment of the present invention will be described with reference to FIGS. 8 and 9.

FIG. 8 shows an optical head as an information recording/reproducing device applied to an information storage medium 2 that performs recording using a perpendicular magnetization film. In this figure, 41 is a semiconductor laser, and a diverging laser beam is generated from this semiconductor laser 41. The diverging laser beam generated from this semiconductor laser 41 is transmitted through a collimator lens 42.
After being converted into a parallel light beam by
The light is incident on the recording film 3 of the information storage medium 2 by the objective lens 45 .

Here, when the objective lens 45 is positioned at a predetermined position, the beam waist of the focused laser beam emitted from the objective lens 45 is projected onto the surface of the recording film 3, and the minimum beam spot is set on the recording film 3. formed on the surface. Note that an NIa stone 46 is placed on the opposite side of the information storage medium 2 onto which this laser beam is projected.

The diverging laser beam reflected from the recording film 3 of the information storage medium 2 is converted into a parallel beam by the objective lens 45 when it is in focus, returned to the second half prism 44, and split into two directions.

The laser beam reflected by this second half prism 44 is guided to a polarizing beam splitter 48 via a 1/2 wavelength plate 47, and the laser beam reflected by this polarizing beam splitter 48 is sent to a first photodetector. 49, the laser beams that have passed through the polarizing beam splitter 48 are projected onto second photodetectors 50, respectively. Then, information detection is performed based on the detection results of these first and second photodetectors 49,50. On the other hand, the second half prism 4
The laser beam that has passed through 4 is transferred to the first half prism 4.
3 and divided into two directions. The laser beam reflected by this first half prism 43 is projected onto a third photodetector 53 via a spherical lens 51 and a cylindrical lens 52.

Then, based on the detection results of the third photodetector 53, track deviation detection and defocus detection are performed. Note that the driver circuit 2 of the semiconductor laser 41
0 has the same configuration as the driver circuit 20 shown in FIG. 1 described above.

Further, as described above, the information storage medium 2 performs recording using a perpendicular magnetization film. As shown in FIG. 9, in the case of the recording film 3 using a perpendicular magnetization film, the above-mentioned crystal also undergoes film deformation such as holes by increasing the amount of exposure by laser light (localized in II) It is possible to create a recorded state section 30 that cannot be erased by causing permanent damage (destruction). Furthermore, erasable recorded state portions 31 can be created by changing the exposure amount of laser light to a certain appropriate value and reversing the magnetization direction.

Therefore, even in such a configuration, the same effects as in the above embodiment can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, an information storage/reproduction device capable of recording, reproducing, and erasing information on an information storage medium using focused light includes a light source and a light emitted from the light source. a light collecting means for condensing light onto an information storage medium; a light detection means for detecting light emitted from the information storage medium; and a control means for controlling an exposure level of the information storage medium by the light source to at least three levels or more. With this feature, it is possible to simultaneously record erasable information and non-erasable information on the same information storage medium, depending on the information that needs to be erased or the information that must not be erased. , it has excellent effects such as being able to be switched very easily.

[Brief explanation of drawings]

Figures 1 to 7 show one embodiment of the present invention.
The figure shows the configuration of an optical head applied to an information storage medium that performs recording using crystal phase change. Figure 2 shows the exposure level and information storage medium when changing the exposure level depending on the recording state. Figure 3 shows the relationship between laser power and laser pulse width when recording on a recording film that utilizes the transition between crystallization and amorphization, using the recording state as a parameter. 4 is a sectional view showing the recording state of an information storage medium that performs recording using crystal phase change, and FIG. 5 is a plan view showing the information storage medium.
FIG. 6 is a sectional view showing the recording form of another information storage medium that performs recording using crystal phase change, FIG. 7 is a plan view showing another embodiment of the information storage medium, and FIGS. Fig. 9 shows another example of the Mizumoto force, Fig. 8 is a configuration diagram showing an optical head applied to an information storage medium that performs recording using a perpendicular magnetization film, and Fig. 9 shows a perpendicular magnetic head. FIG. 2 is a cross-sectional view showing a recording state of an information storage medium that performs recording using a magnetized film. 1... Light source (semiconductor laser for recording and reproduction), 2...
Information storage medium, 7... Objective lens, 12... Photodetector, 17... Exposure level for reproducing information, 18... Exposure level for recording erasable information, 19... Non-erasable information. Exposure level for recording possible information, 20... Driver circuit, 41... Light source (semiconductor laser), 45... Objective lens, 49.50.53... Photodetector. Exposure value of the first picture information book, Torabee Taikyu! Fig. 3 0.1 1 10 Rev. 7 & (JJS) Fig. 4 Fig. 5 @ Fig. 8 Fig. 9

Claims (3)

[Claims] (1) A device capable of recording, reproducing, and erasing information on an information storage medium using focused light, including a light source and a condensing means for condensing the light emitted from the light source onto the information storage medium. An information recording and reproducing apparatus comprising: a light detection means for detecting light emitted from the information storage medium; and a control means for controlling the exposure level of the information storage medium by the light source to at least three levels. Device. (2) Among at least three or more exposure levels, at least one is an exposure level for reproducing information, at least one other is an exposure level for recording erasable information, and at least one of the remaining is an exposure level for recording erasable information. 2. The information recording and reproducing apparatus according to claim 1, characterized in that the exposure level for recording information is set to a level that is possible for recording information. (3) Information according to claim 1, characterized in that at least one exposure level for recording non-erasable information is higher than at least one exposure level for recording erasable information. Recording and playback device.