JPS61188750A - 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 carrying out an exposure in >=2 steps of exposure time for the information recording medium. CONSTITUTION:Exposure time at the information recording exposure level 18 is divided into the short exposure time 18a for erasable records 18a and long exposure time for inerasable records 18b either of which is selected depending on the purpose. An FET22 is turned on by a control signal a input to a gate to give an information reading exposure level 17. A transistor 25 is turned on by a control signal b input to the base to give the exposure level for records 18. Further, the exposure time for erasable records 18a or that for inerasable records 18b is selected depending on the pulse interval of signal b.

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 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.'' ``methods that utilize structural changes, that is, transitions between crystallization and amorphism.''

By the way, from the user's point of view, the information recorded on such information storage media is "temporarily left as data, and when it is no longer needed, it is deleted and new data is inserted." 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.

[Summary of the 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 collecting means for condensing light onto the information storage medium; a light detection means for detecting light emitted from the information storage medium; and an exposure time for recording on the information storage medium by the light source in at least two stages. The present invention is characterized by comprising a control means for controlling.

[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 recorded on the information storage medium 2.
3, a laser beam beam whose light intensity is modulated according to the information to be written is generated, and when information is read from the recording film 3, a laser beam 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 is 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 memory [13] using a laser beam whose intensity is modulated, and when reading information, a laser beam with a constant optical intensity is used to track The light intensity is modulated and reflected by the bits formed on the guide.

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 7 when it is focused, passes through the quarter-wave plate 6 again, and is returned to the polarizing beam splitter 5. It will be done. 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 irradiated onto a photodetector 12 via a quarter-wave plate 8, a dichroic mirror 9, a spherical lens 10, and a cylindrical lens 11 in this order. 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 L' having a constant light intensity and a frequency different from the frequency of the recording/reproducing laser beam is generated. The diverging laser beam L' generated from the semiconductor laser 13 is converted into a parallel beam having a smaller diameter than the recording/reproducing laser beam by the collimator lenses 14, 15, and 16, and is sent to the polarizing beam splitter 5. be guided.

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. This 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.
Because of the degree of rotation, the light 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 recording film 3 is larger than the spot diameter of the recording/reproducing laser beam on the recording film 3, so that information can be erased. It has become.

Next, as shown in FIG. 2, the exposure level (laser power) for the information storage medium 2 by the semiconductor laser 1 for recording and reproduction is divided into two levels, the lower one is the exposure level 17 for information reading, and the higher one is the exposure level 17 for information storage. It can be used as the exposure level 18 for recording.

Furthermore, the exposure time at exposure level 18 for information recording is 2
It is divided into two types, the shorter one is erasable recording exposure time 18a, the longer one is non-erasable recording exposure time 18b
It can be used as a. This allows information to be recorded, reproduced, and erased on the recording film 3.

That is, to explain the driver circuit 19 of the semiconductor laser 1 for recording and reproducing (see FIG. 1), 20 is a series circuit in which a resistor 21, a FET 22, and a resistor 23 are connected in sequence, and one end of this series circuit 20 is resistance 24
The other end is connected to a DC power source (not shown) through the semiconductor laser 1, and the other end is grounded through the semiconductor laser 1. An NPN transistor 25 is connected in parallel to the series circuit 20. The FET 22 is turned on by supplying the control signal a to its gate, thereby defining the exposure level 17 for reading information. Further, the transistor 25 is turned on by supplying the b signal to its base, and thereby the recording exposure level 18
is now regulated. Furthermore, the pulse interval of the b signal defines an erasable recording exposure time 18a and a non-erasable recording exposure time 18b.

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 (exposure time). 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. A recording state section 26 can be created.

In addition, the recorded state portion 27, which can be erased by changing the exposure amount of laser light to a certain appropriate value and becoming amorphous,...
・Can be made.

By simply switching the exposure level and exposure time of the recording/reproducing semiconductor laser 1, the information storage f! of the information storage medium 2 is changed as shown in FIG. In the fourth area 28, a first recording area 29 consisting of a recording state part 27 in which information can be erased by focused light based on the exposure level 18 for information recording and erasable recording exposure time 18a is provided. A second recording area 30 consisting of a recorded state part 26 in which information cannot be erased is set by a focused light based on a recording exposure time 18b which is at a recording exposure level 18 and cannot be erased, and the second recording area 30 is set for reading the information. The information in the first and second recording areas 29 and 30 is read by the focused light at an exposure level of 17. Note that information that should be recorded in an erasable state, such as general data, is recorded in the first recording area 29, and information that must be permanently recorded and not erased, such as an index of recorded information, is recorded in the second recording area 30. and the serial number of the information storage medium are recorded.

According to the above configuration, by simply switching the exposure times 18a and 18b by the recording and reproducing semiconductor laser 1, it is possible to erase information on the same information storage medium 2 according to the information that needs to be erased and the information that should not be erased. It is possible to simultaneously record permanent information and record non-erasable information. Further, by switching to the information reading exposure level 17 which is lower than the information recording exposure level 18, 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 27 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, the substrate 31 and the recording 1f! It is also possible to create the non-erasable recorded state portion 26 by providing a transparent underlayer 32 between the recording medium 3 and the underlayer 32 and locally exploding or expanding the underlayer 32 to produce protrusions.

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
is incident on the information storage medium 2 by this objective lens 45! It is focused towards 113.

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 electromagnet 46 is arranged 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 [13] 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 divided 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 passing through 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 1 of the semiconductor laser 41
Reference numeral 9 has the same configuration as the driver circuit 19 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 (!l) by increasing the amount of exposure by laser light. By causing local destruction), an unerasable recorded state portion 26 can be created. Furthermore, erasable recorded state portions 27 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 recording/reproducing apparatus 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 condensing means for condensing light onto an information storage medium, a light detection means for detecting light emitted from the information storage medium, and an exposure time for recording on the information storage medium by the light source is controlled in at least two stages. Since the system is equipped with a control means for erasing information, it is possible to use the recording of erasable information and the recording of 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. They can be performed simultaneously and can be switched very easily, providing excellent effects.

[Brief explanation of the drawing]

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 exposure time when changing the exposure level and exposure time depending on the recording state. Figure 3 is a diagram showing the relationship between laser power and laser pulse width when recording on a recording film that utilizes the crystallization/amorphous transition, using the recording state as a parameter. Fig. 4 is a cross-sectional view showing the recording state of an information storage medium that performs recording using crystal phase change, Fig. 5 is a plan view showing the information storage medium, and Fig. 6 is a cross-sectional view showing the recording state of an 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. 8 and 9 show other embodiments of the present invention. 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 recording state of an information storage medium that performs recording using a perpendicular magnetization film. FIG. 1... Light source (semiconductor laser for recording and reproduction), 2...
Information storage medium, 7... Objective lens, 12... Photodetector, 17... Exposure level for information reproduction, 18... N-light level for information recording, 18a... Erasable information 18b... Exposure time for recording non-erasable information, 19... Driver circuit, 41... Light source (semiconductor laser), 45... Objective lens, 49°50.53 ...Photodetector. Applicant's agent Patent attorney Takehiko Suzue 1 Figure 9 Toki + Δ ζ ~

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. and a light detection means for detecting light emitted from the information storage medium, and a control means for controlling the exposure time for recording on the information storage medium by the light source in at least two stages. Information recording and reproducing device. (2) The control means controls the exposure level in at least two levels, at least one of which is an exposure level for information reproduction, and at least one other is an exposure level for information recording; The exposure time of the exposure level is controlled in at least two stages, and at least one of them is
2. The information recording and reproducing apparatus according to claim 1, wherein one of the exposure times is for recording erasable information, and at least one of the other exposure times is for recording non-erasable information. (3) The control means is configured to control the exposure time for recording non-erasable information to be longer than the exposure time for recording erasable information. The information recording and reproducing device described in Section 1.