JPS60197936A - Erasable optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To execute stably recording and reproduction by constituting a titled device so that the sum total of length in the track direction of recording and reproducing, and erasing optical spots formed on an optical recording medium and a distance between the optical spots becomes shorter than the length of a gap placed in the sector head part. CONSTITUTION:A recording and reproducing optical spot L and an erasing optical spot m are placed adjacently on a guide track 51 of an optical recording medium which can record and reproduce a signal reversibly by using a light source of a laser, etc., and an area scanned by the spot M is placed so as to be scanned continuously by the spot L. The sum total D of length in the track direction of the spots L, M and a distance between the spots L, M is set so as to be shorter than the length of a gap area GAP1 provided so as to be continued from an index area IDn. In this way, uniform temperature raising condition and cooling condition can be given to a data section T in a sector irrespective of a place, and recording and reproduction can be executed stably.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical recording/reproducing device. More specifically, the laser beam is 1 μm in diameter using a lens etc.
Erasable optical recording that can repeatedly record and reproduce signals by narrowing the light beam to a very small beam and irradiating it onto an optical recording medium to record and reproduce signals at high density, and erase the recorded signals by laser irradiation. The present invention relates to a playback device.

Conventional Structure and Problems Conventionally, as an example of an optical recording/reproducing apparatus, a method has been proposed in which a rotating optical recording disk is irradiated with a laser beam having the minute beam diameter. In this device, a signal is recorded by using the laser energy to record a predetermined signal on the optical recording disk at high density by modulating the intensity of the laser beam irradiated onto the optical recording disk with the signal to be recorded. Record. - To reproduce the signal, a laser beam of a certain intensity is irradiated to the signal recording area of the optical recording disk, and the recorded signal is reproduced by detecting the change in reflected light or transmitted light on the optical recording disk. do.

This optical recording and reproducing device has high recording density, low memory cost per bit, high-speed access, and stable recording and reproducing without contact between the optical head and optical recording disk. Therefore, it is attracting attention as a means of providing a new memory medium for the future information society.

As the above-mentioned optical recording/reproducing method, a write-once type and an erasing type have been proposed.The write-once type recording/reproducing method uses the thermal energy of the irradiated laser to locally damage the optical recording thin film. A method of recording and reproducing signals by evaporating it to form small holes, and a method of recording and reproducing signals by locally changing the optical density of the recording thin film using the thermal energy of irradiated light have been proposed. .

On the other hand, erasure-type optical recording and reproducing devices use magneto-optical recording materials that record and reproduce signals through the cooperation of the thermal effect of a laser and an external magnetic field. As a recording method for changing the optical density in the write-once recording, a method has been proposed in which the optical density is reversibly changed using only thermal energy such as a laser.

One way to obtain reversible concentration changes in the recording film is to transition between the amorphous and crystalline states of the recording film, or between one amorphous state and another stable amorphous state. There is a method that repeatedly utilizes transitions between crystal particles or changes in the size of crystal grains in an amorphous matrix.

OBJECTS OF THE INVENTION It is an object of the present invention to provide an optical recording/reproducing device that can record new signals while stably erasing previously recorded signals.

Structure of the Invention The present invention provides an optical recording and reproducing apparatus that reversibly changes the optical characteristics of a recording thin film by utilizing a thermal phenomenon caused by the laser source, etc. The spot and the second oval light spot for providing heating and slow cooling conditions are formed by the same aperture lens, and means is provided for arranging both the spots close to each other on the same guide track on the optical recording disk. , the second oval original spot is used as an erasing light, the first circular light spot is used at least for recording a signal, and the area scanned by the second light spot on the optical recording medium is , and subsequently scanned with the first original spot. In addition to arranging the second light spot, the first original spot diameter and the interval between the first and second original spots are set to This is an optical recording/reproducing device that is set so that the total length of the second original spot along the guide track is shortened, and is capable of writing while erasing stably.

DESCRIPTION OF EMBODIMENTS The present invention relates to an optical recording and reproducing device that utilizes the reversible density change of the optical recording thin film described above.Prior to explaining the present invention, the principle thereof will be briefly explained below. do.

For the sake of simplicity, the explanation will be based on the assumption that an optical density change is obtained using a transition between an amorphous state and a crystalline state.

FIG. 1 briefly shows a model of the transition between the amorphous state and the crystalline state.

Figure 1 shows the amorphous state of an optical recording thin film.

In an amorphous state, the recording thin film has a low light reflectance and a high light transmittance. Further, the crystalline state is indicated by q, and the recording thin film in the crystalline state has a large reflectance and a small transmittance.

With this recording thin film that can reversibly change its optical density, if the temperature of the recording thin film, which is in the amorphous state equation in Figure 1, is locally raised to near the melting point and then slowly cooled, it changes to the crystalline state (q
becomes. On the other hand, if the temperature of a recording thin film in a crystalline state is locally raised to 1 near the melting point and the area is rapidly cooled, it becomes an amorphous state^).

Figure 2 shows the heating and cooling conditions on the recording thin film.

One specific method for realizing the temperature raising and slow cooling conditions will be shown.

Fig. 2(a) shows a substantially circular micro spora formed by a laser or the like on a recording medium that moves relatively in the direction of the arrow.
shows. When the light intensity of this light spot L is increased for a short period of time to raise the temperature of a local part of the thin film, the temperature rise in this local area is quickly diffused into the recording thin film and the support member for the thin film, creating conditions for rapid heating and cooling.

On the other hand, as shown in FIG. 2(b), an elongated light spot M is formed on the recording medium in the direction in which the recording medium advances (arrow) using a laser or the like, and the intensity of the light spot M is adjusted continuously or intermittently. If the heating temperature is made stronger, the heated portion of the recording thin film will be cooled much more slowly than in the case (a), and a gradual heating and cooling condition can be obtained.

A minute circular beam is applied to the relatively advancing recording thin film,
By temporally modulating the intensity and irradiating it as a pulsed light, conditions for heating and rapidly cooling can be obtained.Also, the relatively advancing recording thin film is continuously or intermittently irradiated with an elongated original beam in the direction of its progress. By doing so, υ heating and slow cooling conditions can be obtained.

Next, specific embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 shows a radial cross-sectional view of an optical recording disk having optical guide tracks used in the present invention.

Here, as an example of an optical guide trunk, an example of a grooved optical recording disk having grooves over the entire signal recording area on the disk is shown. In the figure, the base material 50 is made of a transparent material,
A groove 51 having a width W, a depth d, and a rack pitch p is formed thereon in a spiral or concentric shape. A recording thin film 62 having a thickness t is formed thereon by vapor deposition or other methods, and a protective layer 63 is provided thereon. The groove 51 is designed to have a depth d9 and a width W so that it functions as an optically detectable guide track for the laser irradiation light 64.

This groove allows the irradiation light 54 to record or reproduce a signal along a specific groove.

FIG. 4 shows an embodiment of the present invention.

In the figure, reference numeral 101 indicates a semiconductor laser that generates light of wavelength λ1, and its output light beam is indicated by a side. Reference numeral 102 denotes a condensing lens which condenses the output light of the semiconductor laser having a magnification of 9 into a substantially parallel light beam.

Reference numeral 106 indicates an original beam combiner that transmits light of wavelength λ1 and reflects light of wavelength λ2, which will be described later. Reference numeral 106 indicates a beam splitter. Reference numeral 107 indicates a reflecting mirror. The original beam 2 of the semiconductor laser 101 passes through these optical elements and enters the aperture lens 108.
incident on . The aperture lens 108 focuses the incident light beam λ
Squeeze down and place a roughly circular shape on the guide track 51) L
make.

Reference numeral 109 denotes an actuator for driving the aperture lens 108, which drives the aperture lens in the optical axis direction in response to surface wobbling of the disk to perform known focus control. Furthermore, in order to carry out a known tracking control on the guide track which is inherently eccentric, the diaphragm lens 108 is driven in a direction perpendicular to the incident optical axis and the guide trunk.

In FIG. 4, 103 is a semiconductor laser that generates an original beam m of wavelength λ2, and 104 is a condenser lens. The light beam m is reflected by the beam combiner 105 and enters the diaphragm lens 108 through almost the same optical path as the original beam C. Original spot M whose direction coincides with the longitudinal direction of the groove 61
is formed.

FIG. 6 shows an enlarged view of the mutual relationship between the groove 61 and the two optical spora (L, M) having different wavelengths formed on the groove 61 as described above. The original spots L and M are arranged close to each other on the same guide groove and separated by a desired distance.

In FIG. 4, the source reflected by the optical recording disk is the aperture lens 108. Beam splitter 106 through mirror 107
The beam enters the filter plate 111 after being reflected by the beam splitter 106 . Here, a filter plate is shown that transmits only the light of wavelength λ1 and does not transmit the light of wavelength λ2. A single lens 112 converts the reflected light beam λ into apertured light. Reference numeral 113 indicates a reflecting mirror, which functions to block approximately half of the aperture source formed by the single lens 112, reflect it, and guide the source toward the photodetector 115. Reference numeral 114 indicates a two-split photodiode for detecting a focus error signal, which is placed at the focus point of the single lens 112, and the split element I! , 1, a conventionally known focus error signal is detected in response to the movement. Reference numeral 115 denotes a two-split photodiode for detecting a tracking error signal, and detects a conventionally known tracking error signal using reflected light λ2 from the mirror 113.

Further, a reproduced signal of the signal recorded in the groove 61 on the optical recording disk is obtained from the photodetector 114 or 116.

116 is a circuit that drives the laser 103 and controls the intensity of the oval shape M formed on the groove 51.

117 is a circuit that drives the laser 101 and controls the intensity of the approximately circular original spot L formed on the groove 61.

The amplifier 120 amplifies the difference signal between each element of the divided photodiode 116, and generates a tracking error signal at the terminal TR. The amplifier 121 is a circuit that amplifies the sum signal of the valley outputs of the divided photodiodes 116, and outputs a reproduced signal to the terminal PB. The amplifier 122 is a circuit that amplifies the difference signal between each element of the divided photodiode 114, and outputs a focus error signal to the terminal FD.

In the above configuration, two source spots are formed close to each other on the same guide track, one source spot is approximately circular, and the other source spot is oval along the guide track, and these lights are It contains a desired intensity or a desired signal and is irradiated onto the recording thin film of the optical recording disk while tracking a guide track on the optical recording disk.

FIG. 5 shows an enlarged example of two light spots L and M formed close to each other on the same guide track in the configuration shown in FIG. 4.

The light spot L is a substantially circular minute spot with a wavelength λ1, and is used for recording or recording/reproducing signals along the guide trunk 61, and is also used for detecting control signals such as focus control and tracking control. On the other hand, the optical spora) M, which has a long axis in the tangential direction of the guide track, has a wavelength λ2 different from that of the original spot L, and influences the recording or recording/reproduction of the signal by the original spot L, as well as focus control and tracking control. It acts as a light spot that erases the recorded signal.

In FIG. 6, reference numeral 61 indicates one guide track on the optical recording disk, and arrow A indicates the direction in which the recording medium moves relative to the two optical spoilers L and M. When a circular optical spora) L and an oval optical spot M are arranged in the traveling direction of the recording medium with respect to A as shown in FIG.
One point X on the top is first scanned by an oval optical spora) M, and then by a circular optical spora) L. This arrangement can be realized by making the angles of incidence of the light beams l and m incident on the aperture lens 108 of FIG. 4 different from each other.

a circular first light beam L and an oval second light beam M;
are arranged as shown in FIG. 5 with respect to the traveling direction A of the recording medium, and an oval light beam M is used for erasing the signal.
A circular light beam L is used for recording and reproducing signals. In this case, the signal recorded at point XK on the groove 61 is erased by the erasing light M
By being scanned with , heating and slow cooling conditions are applied and erased.

When point X subsequently comes under the recording/reproducing light, a new signal can be recorded by pulse-modulating the intensity of the light spot with the recording signal. In the manner described above, a novel optical recording and reproducing device can be obtained which is capable of recording a new signal almost simultaneously while erasing a previously recorded signal.

Specifically, an electrical means is used to input an erase command signal from the terminal Q in FIG. With this, a new signal can be recorded almost simultaneously while erasing a previously recorded signal.

FIG. 6 shows a specific example of recording and reproducing signals on an optical recording disk having the sector configuration described above.

FIG. 6 (→, (bl) shows the output signal when the circular light beam L shown in FIG. 6 scans one sector on the optical disk. IDn and ■Dn+1 are track addresses.

Gap 1 (QAPl) is placed at the beginning of the sector, indicating the index ID area containing the sector address signal, and no data is recorded between the two ID signals.

Gap 2 (GAP2) placed at the rear end of sector 〇.

And a DATA section T for recording and reproducing data is set. (a) schematically shows an output signal of a sector in which no data is recorded, and (b) schematically shows an example of an output signal when data (DATAn) is recorded in the sector.

Similar to FIG. 5, arrow A indicates the direction of movement of the recording medium.
indicates the length in the direction along the guide track 61 of the irradiated light consisting of the two optical spora) (L, M), including the interval between the two light spots.

For example, in FIG. 6(b), while erasing the pre-recorded data (DATAn) with optical spora) M,
When recording new data with the optical spora) L, it is necessary to read n with the optical spot L, recognize the content of the ID signal, and then raise the optical spora) M to the level required for erasing. This erasing light also needs to provide the temperature rising conditions necessary for erasing to the leading part PVc of the data section shown in FIG. ) must be larger than the length D of the two light spots in the direction along the guide track.This ensures uniform temperature conditions due to the irradiation light at any location in the data section shown in FIG. can be given, and stable recording and reproduction can be performed.In FIG.
The spatial length is determined by reading the IDn of the ID area with a circular first light spot and identifying the content.
This is determined by the timing of supplying the recording signal to the first source spot, the recording medium, and the relative speed of each party spot.

Furthermore, in FIG. 4, it has been explained that the erasing laser light source 103 produces the oblong light beam M in FIG. 5 on the optical recording disk. It is also possible to create a laser array with a light beam M (in this case, an optical spora) M can be formed as a collection of a plurality of laser spots. In addition, although the embodiments have been described with reference to optical recording disks, the present invention is not limited to optical recording disks and can be applied to other forms of optical recording media.

Effects of the Invention According to the present invention, the sum of the lengths of two light spots formed on the optical recording medium in the direction along the guide track (however, the gap length disposed at the head of the sector is (including the distance between the optical fibers), it is possible to provide uniform heating and cooling conditions to the data section within the sector regardless of the location, and stable recording and reproduction can be performed.

[Brief explanation of drawings]

Figure 1 is a diagram schematically showing the operating principle of an optical recording medium that exhibits reversible changes, and Figure 2 shows the conditions under which the recording thin film is heated and rapidly cooled.
FIG. 3 is a diagram illustrating a configuration example of an optical recording disk, FIG. 4 is a configuration diagram illustrating an embodiment of the present invention, and FIG. 5 is a diagram illustrating a method of providing temperature raising and slow cooling conditions. A diagram showing the arrangement of the light spots and the traveling direction of the optical recording medium. Fig. 6 shows the arrangement of the two light spots) L, when recording and reproducing the sector 1 signal.
It is a figure explaining the relationship between M and each section in a selfie. 101...Recording/reproducing laser, 1Q3/old...
Erasing laser, 61... Guide track on optical recording disk, L... Recording/reproducing light spot, M.
...Light spot for erasing. Name of agent: Patent attorney Toshi Nakao (1 person)
Figure (C) Figure 2 (a) (b) Figure 4

Claims (1)

[Claims] This is a device that reversibly records and reproduces signals using a light source such as a laser, and uses the same aperture lens to emit two or more laser beams. having means for arranging at least one first optical spot for recording and reproduction and a second original spot for erasing in close proximity on the same track on the optical recording medium;
The area on the optical recording medium scanned by the second optical spot for erasing is subsequently scanned by the first original spot for recording, and an index area on the optical recording medium is arranged. Subsequently, the lengths of the first original spot and the second optical spot in the track direction and the first . An erasable optical recording/reproducing device configured such that the sum of distances between second original spots is shortened.