JPS61206937A - Optical information processor - Google Patents

Abstract

PURPOSE:To rerecord information while erasing information by irradiating an information erasing condensed spot in advance of irradiation of an information recording spot. CONSTITUTION:An objective lens 14 is supported by a voice coil movably in the direction of the optical axis and the radial direction of this voice coil; and when the objective lens 14 is placed in a prescribed position, beam waists of converging laser lights L1 and L2 discharged from the objective lens 14 are projected onto the surface of an information recording medium 15. Thus, two condensed spots different in length, namely, a shorter (l1) information recording and reproducing condensed spot (information recording condensed spot) 17 and a longer (l2) information erasing condensed spot 18 are formed with the center interval (d) spaced on an information recording track 16 of an information recording medium 15 moving a prescribed speed V so that the former precedes the latter with respect to time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an optical information processing device that can at least record and erase information using focused light that moves relative to an information storage medium.

[Technical background of the invention and its problems]

By applying thermal energy using a laser beam, a reversible phase change between a crystalline phase and an amorphous phase is created locally in a semiconductor thin film, and the local change in light reflectance caused by this phase change is erased. The idea of using it as a possible optical recording film was an old one, created by S.

MetaNurot by R. Ovshinsky et al.
ca+Transactions vo12641
(1971).

Subsequently, optical discs having such erasable recording patterns were created, and many optical recording/reproducing devices using them were created. All of these prior art devices employ a method of changing the spot area of the laser beam irradiated onto the optical disk surface for recording/reproducing operations and erasing operations, and the following known examples are available.

Known example 1. A single laser light source is used to create a recording spot and an erasing spot of different sizes on the optical disk surface.

1-1 Utility Model 56-432 Utility Model 56-29785 Place a beam splitter in the optical path of the laser beam to separate it into a recording beam and an erasing beam, and create a recording spot and an erasing spot using two focusing optical systems. That's what I do.

Lenses placed in the optical path of the focusing optical system are mechanically switched to create recording spots and erasing spots of different sizes.

1-3 Japanese Patent Publication No. 59-27011 By switching the focus servo, the position of the condensing lens is mechanically moved back and forth to change the size of the spot.

1-4 Japanese Patent Publication No. 59-14814 A small reproducing spot and a long erasing spot are created, and means for selectively driving the reproducing spot and the erasing spot is provided so that an erasing operation can be performed after a predetermined time delay following the reproducing operation.

11m Japanese Patent Publication No. 59-20168 In addition to the laser for recording and reproducing, there is also a separate laser for erasing spot, which has multiple optical fibers lined up in a row along the bonding surface of the semiconductor laser, and erases at the tip of this optical fiber. I'm trying to create a spot. That is, two condensing optical systems are used, one for recording and reproduction and one for erasing.

All "Aim" L31 JP-A-53-148244 The size of the spot is not particularly limited and recorded.

Three types of lasers with different wavelengths and powers are used for each erasing and reproducing operation.

However, in these conventional devices, when re-recording information, first, only the erasing focused spot irradiation means is operated to erase the previously recorded information, and then the erased area is used for recording. Information is recorded by operating only the focused spot irradiation means. Therefore, there is a problem that it is not possible to speed up the re-recording of information.

Note that the above-mentioned conventional device has a large number of parts and the adjustment of the optical system is complicated, so there are also problems in that the reliability and productivity are low and the device is expensive.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and its purpose is to provide optical information that can be re-recorded while erasing information, thereby speeding up the re-recording of information. The purpose of this invention is to provide a processing device.

[Summary of the invention]

In order to achieve the above object, the present invention provides an optical information processing device capable of at least recording and erasing information using focused light that moves relative to an information storage medium, comprising:
A focused spot irradiating means is provided for irradiating at least an information recording focused spot and an information erasing focused spot onto the information recording track on the information storage medium, and the focused spot irradiating means includes an information erasing focused spot. The present invention is characterized in that it is configured to be able to irradiate a focused spot for information recording temporally in advance.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 shows an optical recording and reproducing device as an optical information processing device according to the present invention. In this figure, 1 indicates the width of the pn junction that emits light, that is, the width of the emitted light is narrow, about 5 μm. A recording/reproducing semiconductor laser (first semiconductor laser) 2 is an information erasing semiconductor laser (second semiconductor laser) having a wide emission width of about 15 μm. These semiconductor lasers 1, 2, and lens 3,
4. An imaging light source device 6 is constituted by a right-angle mirror 5 and the like. Thus, the semiconductor laser 1.2 generates a diverging information recording/reproducing laser beam L1 and an information erasing laser beam L2, respectively, and these laser beams Ll
, 12 are made into converging light beams by passing through lenses 3 and 4, respectively.

Next, these laser beams Lr and L2 are passed through a right angle mirror 5.
are guided to reflective surfaces 5a and 5b, reflected in the same direction, and imaged. As a result, two closely spaced imaging light sources 7 for recording and reproducing information and imaging light sources 8 for erasing information having different lengths are created.

The laser beams L1°L2 from the imaging light source 7.8 are guided to a lens 10 of the condensing optical system 9, and converted into a parallel beam by this lens 10. The laser beam L1. which is converted into this parallel light beam. L2 is guided to a polarizing beam splitter 12 via a mirror 11. After passing through the polarizing beam splitter 12, the light passes through a quarter-wave plate 13 and enters an objective lens 14, where it is focused toward an information storage medium 15 such as an optical disk. Here, the objective lens 14 is supported movably in the optical axis direction and radial direction by a voice coil (not shown), and when the objective lens 14 is positioned at a predetermined position, a focused beam emitted from the objective lens 14 is Sex laser light LL.

The beam waist of L2 is projected onto the surface of the information storage medium 15. As a result, as shown in FIG. 2, the information recording track 16 of the information storage medium 15 moving at a predetermined speed
On the top, there are two focusing spots of different lengths, namely a short (C1) information recording/reproduction focusing spot (information recording/reproducing focusing spot) 17 and a long (C2) information erasing spot. The condensing spots 18 are spaced apart from each other by a center distance d such that the latter temporally precedes the former.

Divergent laser light L reflected from the information storage medium 15
1. When the light L2 is in focus, it is converted into a parallel light beam by the objective lens 14, passes through the quarter-wave plate 13 again, and is returned to the polarizing beam splitter 12. Laser light L1. L
By reciprocating the 1/4 wavelength plate 13, the laser beam L1. L2 is polarized beam subli 4 ivy 12
The plane of polarization is rotated by 90 degrees compared to when it passes through the laser beam Ll, and the plane of polarization is rotated by this 90 degrees.

L2 is reflected by the polarizing beam splitter 12 without passing through it. Then, the laser beam L1. reflected by the polarizing beam splitter 12. L2
passes through a focusing lens 20 and a cylindrical lens 21 to form two separated images. Of these two images, the image created by the reflected light from the short information recording/reproducing condensed spot 18 is projected onto the 4-split photodetector 22 .

Note that the objective lens 14 is connected to the photodetector 2.
Two servo circuits (not shown) receiving signals from the servo circuits 2 perform the operations of focusing the converging spots 18 and 19 on the recording surface of the information storage medium 15 and tracking the desired information recording track 16. It has become.

Here, with such a configuration, semiconductor laser 1.
Even if the same total radiation output P (W) is used for 2, the ratio of the power density of the focused spot 18.19 can be expressed as length C1 and C
It is possible to have an inverse ratio relationship with 2. That is, if the power density of the focused spot 18 is pt (Wcm4), the power density of the focused spot 19 is p2 = pt <
1. s /Q2)(WCl2), and the focused spot 1
The power density can be lower than that of 8.

Therefore, when such a focused spot 18° 19 is irradiated onto the moving information recording track 16 of the information storage medium 15, a temperature history as shown in FIG. 3 is created at a certain point Q on the information recording track 16. can give. That is, first, the temperature of the point Q irradiated by the focused spot 19 rises to a temperature θC proportional to its power density, and the temperature becomes 22/
It remains at θC for the time v-tl, and when the focused spot 19 passes, the temperature returns to room temperature due to heat diffusion to the surroundings.

The power density p of the focused spot 19 is adjusted so that this θG becomes the crystallization temperature of the phase change recording film provided on the information storage medium 15.
2, the point Q through which the focused spot 19 passed
The recording film has a reflectance corresponding to the crystal phase. Then, after a time of d/v-t2, the point Q is 4
It is irradiated with a power density p1 that is high by a flight time of 1/V-t3. Since the relationship is l) 1 = 1) 2 (/12//lr), after the temperature of point Q rises to a temperature θa higher than θC which is proportional to pl, when the focused spot 18 passes, heat is transferred to the surrounding area. The recording film at point Q is rapidly cooled at a cooling rate proportional to the temperature increased by diffusion, and the recording film at point Q transitions to an amorphous phase and changes to the reflectance of that phase. Therefore, if we define and use the information storage medium 15 so that recording occurs when the recording film becomes an amorphous phase, any point Q that gave the temperature history in FIG. Regardless of whether it is present or not, it first enters an erased state corresponding to a crystalline phase due to the focused spot 19, and then, when irradiated by the focused spot 18, becomes an amorphous phase and enters a recording state. Therefore, the information erasing semiconductor laser 2 that creates the information erasing focused spot 19 is operated continuously, and at the same time, the information recording/reproducing semiconductor laser 1 that creates the information recording/reproducing focused spot 18 is operated at a low power level used during reproduction. If the operation is pulse-modulated with the information to be recorded while being superimposed on the continuous operation, the information on the desired information recording track 16 of the information storage medium 15 can be recorded while being erased.

In addition, the information recorded as points with different reflectances in this way can be collected by stopping the operation of the information erasing semiconductor laser 2 that creates the information erasing focused spot 19, and forming the information recording/reproducing focused spot 18. The semiconductor laser 1 for recording and reproducing is set to a low power, that is, the focused spot 1 for recording and reproducing information.
When the information storage medium 15 is rotated with only continuous power operation such that the power density is less than 1/3 of the peak power density during recording, the difference in reflectance is recorded on the information recording track 16. The obtained information can be reproduced from the sum signal of the four-division photodetector 22.

According to experiments, the ratio 22/Ilx of the lengths of the information erasing focused spot 19 and the information recording/reproducing focused spot 18 is 3 or more, which is larger than the boiling point to melting point ratio for many phase change recording films. When doing so, stable erasing and recording operations were obtained. In addition, in the phase change recording film used in the erasable information storage medium 15, approximately 2 μs is sufficient for the time t2 required for the erased point Q to become completely stable after going through the temperature history of erasure and to be able to record again. there were. Therefore, in many optical recording/reproducing apparatuses in which the speed (2) of the information recording track 16 is up to 10 m/s, the information erasing focused spot 1 is
The distance d between 9 and the information recording/reproducing light spot 18 is 20μ.
It is enough to keep it at least the distance away from the door.

According to the above configuration, since the information erasing focused spot 19 can be irradiated temporally in advance of the information recording focused spot 18, information can be rerecorded while erasing it. Therefore, it is possible to speed up the re-recording of information.

In addition, semiconductor lasers 1.2 with different emission widths are used as light sources.
``The condensing optical system can be simplified.'' ``The condensing optical system 9, which requires complicated optical adjustment, can be combined into one.'' ``The optical system can be changed to switch between erasing and recording.'' Since no mechanical drive is required, switching between erasing and recording/reproduction can be made faster.'' ``Special optical components such as optical fiber bundles are not required.'' It is easy to manufacture and practical. It is possible to provide a device with a highly sensitive erasing function.

In the above embodiment, the information recording/reproducing light spot 1
8 and a focused spot 19 for information erasing, semiconductor lasers 1 and 1 in separate packages are used as light sources.
Although two imaging light sources 7 and 8 were created and used in close proximity to each other by an imaging light source device 6 having a built-in imaging light source device 2, the present invention is not limited to this, and for example, as shown in FIG. The information recording/reproducing semiconductor laser 1 and the information erasing semiconductor laser 2 having different widths may be housed in one package and placed at the position of the imaging light source 7.8 shown in FIG. 1.

Furthermore, the erasable information storage medium (recording medium) to be used is not limited to a rotating optical disk; for example, a beam scanning device in which two focused spots 18° 19 and an information recording track 16 move relative to each other. Even if the device uses a type or card type information storage medium, if the erasing and recording operations are the same, the i! Of course you can join @.

[Effects of the Invention] As explained above, according to the present invention, data can be transferred relative to an information storage medium. 71. An optical information processing device capable of recording and erasing at least information using focused light, the apparatus comprising at least an information recording focused spot and an information erasing focused spot on an information recording track on the information storage medium. The focused spot irradiating means is configured to be able to irradiate the information erasing focused spot temporally in advance of the information recording focused spot, so that the information can be erased. Can be re-recorded while
This brings about significant effects such as speeding up the re-recording of information.

[Brief explanation of the drawing]

Figures 1 to 3 show one embodiment of the present invention.
2 is a plan view showing a condensed spot on an information storage medium, FIG. 3 is an explanatory diagram of the operation, and FIG. 4 is a diagram showing another embodiment of the present invention. It is a schematic block diagram. DESCRIPTION OF SYMBOLS 1... First semiconductor laser (semiconductor laser for information recording/reproduction), 2... Second semiconductor laser (semiconductor laser for information erasing), 6... Imaging light source device, 9...
Focusing optical system, 15... Information storage medium, 16... Information recording track, 18... Focusing spot for information recording (focusing spot for information recording/reproduction), 19... Focusing light for information erasing. spot. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure F? IvI 44 Figure

Claims (7)

[Claims] (1) At least information can be recorded and erased using focused light that moves relative to the information storage medium, and at least an information recording focused spot and an information recording track on the information storage medium are formed. A condensed spot irradiation means for irradiating a condensed spot for information erasure is provided, and the condensed spot irradiation means is configured to be able to irradiate the condensed spot for information erasure temporally in advance of the condensed spot for information recording. An optical information processing device characterized by: (2) The information erasing focused spot has a lower power density and a longer length in the direction along the information recording track than the information recording focused spot. The optical information processing device described in Section 1. (3) The condensed spot irradiation means includes first and second semiconductor lasers that emit light with different widths, and forms at least a condensed spot for information recording with the first semiconductor laser that has a shorter emission width; 2. The optical information processing device according to claim 1, wherein the second semiconductor laser having a longer emission width forms a condensed spot for erasing information. (4) The optical information processing device according to claim 3, wherein the first and second semiconductor lasers are housed in one package. (5) The focused spot irradiation means irradiates the information erasing focused spot and the information recording focused spot onto the information recording track with a center-to-center spacing of 20 μm or more and a length ratio of 3 or more. An optical information processing device according to claim 1. (6) The focused spot irradiation means is configured to operate the first semiconductor laser continuously, modulate the second semiconductor laser with information to be recorded, and operate the second semiconductor laser simultaneously with the first semiconductor laser. An optical information processing device according to claim 3, characterized in that: (7) The focused spot irradiation means operates only the second semiconductor laser and continuously irradiates the information recording track with the power density of the focused spot being 1/3 or less of the peak power density during information recording. 4. The optical information processing device according to claim 3, wherein information can be reproduced by the following.