JPS5914814B2 - Kogaku Tekijiyouhouki Kakusaisei Souchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical information recording/reproducing device.

Attempts have been made to use disks as information recording media to record and reproduce information such as video signals and 10-tone audio signals in large volumes and at high density.

In such conventional information recording and reproducing devices, a spiral or concentric track is formed on the disk surface, and minute diffraction elements of several μm or less are imprinted 15 along the track. The reading ratio of information from the recording medium is performed by using a light beam such as a laser beam that can be efficiently converged and irradiating a beam spot onto a minute diffraction element formed along a track on the disk surface. That is, the 20 minute diffraction elements whose optical densities differ depending on the recorded signal change the intensity of reflected or transmitted light. The reflected or transmitted light thus changed is converted into an electrical signal by a photoelectric detector. To give a specific example, a concave portion called a pit, having a length of 1 to 425 μm, a width of 0.8 μm, and a depth of 0.16 μm, is formed on a disk made of vinyl chloride resin to form a recording medium. To read information, use He-Ne laser light at 1μ
The laser beam converges into a spot of about 30 m in diameter and irradiates it along a track on the disk surface rotating at 1,500 or 1,800 revolutions per minute, and detects the reflected light from the 30 pits. In another example, unlike the previous example, minute protrusions were formed as signal recording elements on a Mylar sheet with a thickness of several hundred Pm, and these were arranged along a spiral track as a recording medium. There are various other examples, but all 35 use high-energy laser beams to record information,
Recording media were created by irreversibly changing the shape of photoresist or metal thin films. f ■, q - Conventional information recording and reproducing devices using recording media created in this way only have recording and reproducing functions, so it is necessary to erase recorded information and record new information, that is, rewrite information. The drawback was that it was not possible.

On the other hand, research on amorphous semiconductors has become active in recent years, and it has been revealed that when this material absorbs light energy, its optical properties change, allowing it to function as an optical memory. For example, as chalcogenide glass-based materials, three-component systems such as Ge-As-Te and Si-As-Te, and those having a composition of As-S have been announced at academic conferences and in literature. In addition, as oxide-based ones, Ge-0, Te-0, Bi-0, In-0, Sb-O
It is believed that amorphous amorphous having a composition such as When such amorphous amorphous is deposited as a thin film of several hundred amperes on the surface of a disk, it is effective as a large capacity, high density optical information recording medium and is rewritable. In this respect, it has a great advantage over the previous example. That is, this material has an increased optical density due to absorption of light energy above the recording threshold energy. For example, when irradiating with a sufficiently focused laser beam,
The portion corresponding to the shape of the irradiated beam spot becomes black when heated above the phase transition point. To read a signal from this recorded state, a beam spot having an energy less than the recording threshold energy is irradiated along a track on the disk surface, and the reflected light modulated into the recorded signal or Transmitted light is obtained. On the other hand, this material returns to its initial state by rapid heating and slow cooling with respect to the recording state described above. That is, when light absorbs energy exceeding the erasing threshold energy, the recording surface becomes molten, and when slowly cooled, the optical density decreases. Therefore, when using a laser beam as the erasing beam, it is necessary to use the laser beam as a high-energy beam. When the temperature converges and cooling is performed by intermittent irradiation, the recorded state is erased and the initial state is restored. In this way, since amorphous material can be used as a rewritable recording medium, an optical information recording/reproducing device using amorphous material as a recording medium has been proposed. However, this optical recording/reproducing device has the disadvantage that it is not possible to erase only the desired part because it cannot erase while monitoring whether or not already recorded information is needed when rewriting. Ta. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optical information recording/reproducing apparatus that can erase a desired portion while monitoring recorded information.

FIG. 1 is a block diagram of an embodiment of an optical recording/reproducing apparatus of the present invention. In the figure, 1 is a laser light source, 2 and 3 are convex lenses, 4 is a rectangular slit that turns a circular light beam into a rectangle, 5 is a pulse signal generator, and 6 is a light modulator that uses an acousto-optic light modulation element and has a black diffraction effect. Accordingly, O-order or first-order diffracted light is used as modulated light. 7 is a rectangular slit, 8 is a concave lens, 9 is a semicylindrical focusing lens,
Reference numeral 10 denotes a case for storing the read head, which moves in the radial direction of the disk-shaped recording medium 11 (in the direction of the arrow in the figure) in accordance with the rotation of the disk-shaped recording medium 11.

Reference numeral 12 denotes a motor that drives the disk-shaped recording medium 11.

The disk-shaped recording medium 11 is constructed by depositing the aforementioned amorphous semiconductor thin film on a base sheet.
13 is a turntable made of a transparent material that holds the disk-shaped recording medium 11; 14 is a total reflection mirror that can be rotated by a minute angle at high speed; 15 is a half mirror; 16 is a half mirror smaller than the half mirror 15; 17 is a mirror with a focal length. A short semi-cylindrical focusing lens, 18 a voice coil for keeping the semi-cylindrical focusing lens 17 at a constant distance from the disk-shaped recording medium 11, 19a and 19b the reflected light reflected from the surface of the disk-shaped recording medium 11; 20 is a differential amplifier that outputs an output based on the difference between the photodetecting elements 19a and 19b;
Reference numeral 1 denotes a readout signal photodetection element, 22 a readout signal amplifier, 23a and 23b tracking control photodetection elements arranged in parallel to detect the amount of light transmitted through the recording medium 11, and 2
4 is a differential amplifier that outputs an output based on the difference between the photodetecting elements 23a and 23b.

The differential amplifier 20 does not output when the same amount of reflected light beams arrive at the photodetecting elements 19a and 19b, but outputs when there is a difference in the amount of reflected light beams arriving at the voice coil 18.
to drive. As a result, the semicylindrical focusing lens 17 moves up and down as shown. The focusing lens 17 is the photodetecting element 19
When it moves to a position where it irradiates the same amount of reflected light beams to a and 19b, the output of the differential amplifier 20 becomes O, so it stops at that position. In this case, the photodetecting elements 19a,
19b is configured so that when the recording medium 11 is located at the narrowest part of the irradiated light beam from the semicylindrical focusing lens 17, the same amount of reflected light beam arrives. In this way, so-called focus control is performed to keep the distance between the semicylindrical focusing lens 17 and the recording medium 11 constant. The differential amplifier 24 is the photodetector element 2
When the same amount of transmitted light reaches 3a and 23b, it is not output, but when there is a difference in the amount of transmitted light, it is output and the total reflection mirror 1
Rotate 4. In this case, the light spot of the irradiated light beam from the semicylindrical focusing lens 17 is focused on the recording medium 11.
When located at the center of a track (not shown), the same amount of transmitted light reaches the photodetecting elements 23a and 23b, and when the light detecting elements deviate from the center of the track, a difference occurs in the amount of transmitted light. When a difference occurs in the amount of transmitted light, the differential amplifier 24
The total reflection mirror 4 is rotated by the output from the mirror 4 so as to eliminate the difference in the amount of transmitted light. In this way, so-called tracking control is performed so that the light spot of the irradiated light beam is positioned at the center of the track of the recording medium 11. FIG. 2 is an enlarged perspective view of the optical head shown in FIG. 1.

In the figure, 25 is a track formed on the disk-shaped recording medium 11, 26 is a minute recording element in a recording state,
27 is a light spot of the read light beam, and 28 is a light spot of the erase light beam. The disk-shaped recording medium 11 then runs in the direction of the arrow shown. In operation, the recording of information is performed using the semicylindrical focusing lens 17 illustrated in FIG.
This can be achieved by using a convex lens instead, inputting the signal to be recorded into the pulse signal generator 5, and modulating the light beam with the optical modulator 6 using the signal.

To read information, the laser light source 1 irradiates the recording medium 11 with a readout light beam that is weak enough not to cause any change in the recording medium 11 . As a result, the optical path of the reflected light from the recording medium 11 is bent by the half mirror 16, and the light detecting element 2
1 and is amplified by an amplifier 22. The waveform of the read signal in this case is shown in FIG. 3A. Next, to erase information,
This can be done by inputting the erase signal shown in FIG. 3B to the pulse signal generator 5. Next, monitor erasure is performed by performing the above-mentioned information read operation. Then, only when the portion to be erased is scratched, an erase signal is inputted to the optical modulator 6 through the pulse signal generator 5, and the erase light beam L is irradiated onto the recording medium 11 to erase that portion. In this way, monitor erasure is performed. More specifically, during monitoring (reading), the light beam that has been shaped into a substantially rectangular shape by the rectangular slit 4 is further shaped into a rectangular shape by the optical modulator 6 as shown in FIG. 4, and the majority of the light beam is blocked. The remaining ablated portion becomes a readout light beam and irradiates the recording medium 11 to perform readout. That is, the optical modulator 6 is configured to further shape the substantially rectangular light beam from the long force type slit 4 into a rectangular shape and to block the majority of the light beam. Next, when you are monitoring and find a part to be erased, the optical modulator 6
Input the erase signal to. As a result, the optical modulator 6 is modulated and driven to irradiate the shielded portion of FIG. 4 with a diffracted light beam. That is, by irradiating the shielded portion with the diffracted light beam, the irradiation light beam that irradiates the recording medium 11 has a modulated region (erasing light beam) and a non-modulated region (reading light beam). The rectangular slit 7 in FIG. 1 blocks unnecessary light beams within the modulation area. The concave lens 8 further spreads the irradiated light beam and improves the degree of convergence at the semicylindrical focusing lens 17. In this case, the semicylindrical lens 9 is
The once diffused irradiation light beam is converted into a parallel beam again. The optical path of the irradiated light beam is changed by the total reflection mirror 14 and directed onto the recording medium 11 . As shown in FIG. 2, the non-modulated region of the irradiation light beam that has passed through the focus control half mirror 15 further passes through the half mirror 16, but the modulated region that is the erasing light beam does not pass through this. The non-modulated area, ie, the readout light beam, is focused by the semicylindrical lens 9, and a minute light spot 27 illuminates the recording element 26 of the recording medium 11. The reflected light beam is then guided by the half mirror 16 to the photodetector element 21 and amplified by the amplifier 22 to become a readout signal. The modulation area, ie, the erasing light beam, is formed by a semicircular focusing lens 17.
As a result, the light spot 28 of the aperture irradiates and erases the recording element 26 of the recording medium 11. In this case, the light spot 28 of the light beam of the modulation area, that is, the erasing light beam
is quite long in the running direction of track 25, so recording element 2
No unerased items from 6 occur. In this way, according to this embodiment, it is possible to erase a desired portion while monitoring.

Furthermore, since the light spot 28 of the erasing light beam is long in the running direction of the track 25, the recording element 2 of the adjacent track 25 is
A desired recording element can be completely erased without erasing 6. Furthermore, since one light beam from the laser light source 1 is divided and used for recording, reading, and erasing, the configuration is simplified, and focus control and tracking control for each of recording, reading, and erasing can be performed collectively. be able to. FIG. 5 is a block diagram of another embodiment of the present invention.

In the figure, 30 is a light source such as a laser that generates a light beam a. Reference numeral 31 denotes an optical modulator, and a recording signal or a signal for controlling the intensity of the light beam a during recording, reading, and erasing is input to terminal A.

Reference numeral 32 denotes a light beam a' distribution device that generates only a light beam a'' during recording and reading, and generates a monitoring light beam a'' and an erasing light beam b during monitor erasing.

33 is a projection lens; 34 is a reflecting mirror for changing the direction of the optical path and controlling tracking; 35 is a half mirror; 36 is an objective lens; 37 is an objective lens driving device; 38
39 is a differential amplifier, and its output drives an objective lens driving device 37.

Reference numeral 40 indicates an information track formed on the recording medium, and an arrow indicates the direction in which the track 40 travels.

Reference numeral 41 indicates a point at which the information track 40 is irradiated with the recording/reading beam.

42 is 2 for detecting the transmitted light image of the information track 40.
Optical detection element for tracking control consisting of two regions.

Reference numeral 43 denotes a differential amplifier, which rotates the reflecting mirror 34 when a track deviation occurs to correct the deviation.

A total reflection mirror 44 changes the direction of the erasing beam b generated by the distribution device 32 during monitor erasing.

45 is a projection lens for enlarging or reducing the incident erasing light beam b.

The light ahead is reflected by the tracking total reflection mirror 34 and projected onto the semicylindrical lens 46. The output light from the semicylindrical lens 46 forms an elongated tanzo-shaped beam spot in the vicinity of the focal point of the semicylindrical lens 47 in the same direction as the longitudinal direction of the track 40, as shown. This light is irradiated onto the information track 40 by a semicylindrical lens 47 as a substantially parallel beam. 48 indicates the beam spot at this time.

That is, a beam spot is created by emitting long light in the longitudinal direction of the track 40 using an eye slightly wider than the width of the track 40. As a result of this configuration, a desired portion can be erased while monitoring recorded information.

Note that the tracking control and focus control of the light beam a'2 are performed in the same manner as in the embodiment shown in FIG. Further, since the tracking control of the erasing light beam b is performed by also using the reflecting mirror 34 for tracking control of the light beam a'', as long as the tracking control of the light beam a'' is being performed, the tracking control of the erasing light beam b is performed. will also be carried out. Further, since the erasing light beam b irradiated onto the information track 40 can be substantially parallel light, there is no need to specially control the focus of the semicylindrical lenses 46 and 47 with respect to the recording medium. As described above, the optical information recording/reproducing apparatus of the present invention can erase a desired portion while monitoring recorded information.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is an enlarged perspective view of the main part thereof, FIG. 3 is a waveform diagram of the read signal and erase signal of FIG. 1, and FIG. 4 is a waveform diagram of the read signal and erase signal of FIG. FIG. 5, which is a sectional view of the irradiation light beam of the optical modulator, is a configuration diagram of another embodiment. 1... Laser light source, 4... Slit,
5... Pulse signal generator, 6... Optical modulator, 11... Recording medium, 13... Turntable, 14... Total reflection mirror, 15,
16...Fumira, 17...Kamaboko-shaped focusing lens, 25...Truck, 26
. . . Recording element, 27 . . . Light spot of reading light beam, 28 . . . Light spot of erasing light beam.

Claims (1)

[Claims] 1. A reading means for reading recorded information from the recording track by sequentially irradiating a light spot of a readout light beam onto a recording track consisting of recording elements in a rewritable recording medium recorded by irradiation with a light beam; and the readout light beam. A light spot of an erasing light beam having a rectangular or oval shape whose length in the longitudinal direction of the track is sufficiently longer than that of the light spot of the readout light beam is applied to the readout track itself. an erasing means for erasing information recorded on the recording element irradiated with the light spot by successively irradiating the read element with a delay of a predetermined time; and a driving means for selectively driving the erasing means. An optical information recording/reproducing device comprising: