JPH0660399A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve the information recording density by adding the offset corresponding to information to be recorded to a tracking control signal at the time of recording and performing the tracking operation without the offset at the time of information reproducing. CONSTITUTION:A recording control circuit 17 digitizes an analog signal to be recorded and sends it to a servo control system 28 as the track control offset. The servo control system 28 adds the track control offset from the circuit 17 to the track detection signal from an adder 27 and performs the tracking operation of an object lens 13 on a magneto-optical recording medium 16 in accordance with the signal resulting from this addition by actuator control. A laser driving circuit 12 drives a semiconductor laser 12 to record the signal on the medium 16 in accordance with the track control offset. The servo control system 28 controls actuators to perform the tracking operation without the offset by the tracking detection signal from the adder 27. Thus, information is multiplexed and recorded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing device such as an optical disk device.

[0002]

2. Description of the Related Art Conventionally, an optical information recording / reproducing apparatus such as an optical disc device irradiates an optical information recording medium such as an optical disc with a laser beam to change the length or interval of the mark in the rotating direction of the optical information recording medium. There is one that digitally records information by recording. In addition, JP-A-2-2814
No. 43 describes a non-magnetic field overwrite device for magneto-optical recording. This magnetic-field-free overwrite device for magneto-optical recording forms a reversed magnetic domain smaller than a light spot by irradiating a magneto-optical recording medium with laser light, and moves the position of this reversed magnetic domain within the area of the light spot. Is recorded in analog.

Further, as shown in FIG. 8, a semiconductor laser is driven by a pulse signal having a width corresponding to the magnitude of a data signal, and a laser beam from this semiconductor laser is irradiated onto the magneto-optical medium to mark the mark in an analog manner. There is a magneto-optical disk device for recording a mark, reading a mark from a magneto-optical medium with a laser beam having an effective diameter of the mark, and reproducing a pulse signal.

[0004]

In the above optical information recording / reproducing apparatus, the optical information recording medium is irradiated with laser light to record the marks at different lengths or intervals in the rotation direction of the optical information recording medium. Since information is recorded digitally, the upper limit of the information recording density is determined by the diameter of the light spot formed on the optical information recording medium by the irradiation of laser light.
Further, in the above-mentioned magneto-optical recording non-magnetic field overwrite device, a reversed magnetic domain smaller than the light spot is formed by irradiating the magneto-optical recording medium with laser light, and the position of this reversed magnetic domain is moved within the area of the light spot. Since the information is recorded in an analog manner, the magneto-optical recording medium is intended for a special magnetic domain formation, and cannot be applied to an optical information recording medium in which information cannot be rewritten. Further, the above-mentioned magneto-optical disk device is targeted at a magneto-optical medium, which is also a somewhat special recording medium.

The present invention solves the above-mentioned drawbacks, and multi-valued information can be recorded on a general optical information recording medium to dramatically improve the information recording density. The purpose is to provide a device.

[0006]

To achieve the above object, the invention according to claim 1 records an information by converging a light beam by an objective lens while performing a tracking operation with respect to an optical information recording medium. In an optical information recording / reproducing apparatus for reproducing information, an offset corresponding to information to be recorded is added to a tracking control signal at the time of information recording, and a tracking operation is performed by this tracking control signal, and a tracking operation is performed at the time of information reproduction without an offset. It is equipped with means.

According to a second aspect of the invention, information is recorded by performing a tracking operation on the optical information recording medium and condensing a light beam by an objective lens to deform the surface of the optical information recording medium. In an optical information recording / reproducing apparatus which obtains information from reflected light from the optical information recording medium by condensing a light beam by an objective lens while performing a tracking operation with respect to the optical information recording medium, a constant offset is applied during information recording. In addition to the tracking control signal, the tracking control signal modulates the intensity of the light beam to the optical information recording medium in accordance with the information to be recorded while performing the tracking operation, and the information on the optical information recording medium is reproduced at the time of reproducing the information. It is provided with a means for detecting a track and reading information from the fluctuation included in the track detection signal.

According to a third aspect of the present invention, there is provided an optical information recording / reproducing apparatus for recording / reproducing information by condensing a light beam by an objective lens while performing a tracking operation on an optical information recording medium. A recording medium having a coating layer having a different reflectance from that of the information track is formed between the information tracks, and when the information is recorded, an offset corresponding to the information to be recorded is added to the tracking control signal to perform the tracking control. A tracking control means for performing a tracking operation by a signal and performing a tracking operation without offset at the time of reproducing information is provided.

The invention according to claim 4 is the invention according to claim 1 or 2.
Alternatively, in the optical information recording / reproducing apparatus described in 3, the maximum frequency f of a movable band of the optical spot on the optical information recording medium in the tracking direction, the number of multi-valued information steps n, and the optical information on the optical information recording medium. The relationship between the diameter d of the spot and the linear velocity v of the information track at the time of recording information is such that v> = 2ndf.

According to a fifth aspect of the present invention, in the optical information recording / reproducing apparatus according to the fourth aspect, the linear velocity of the information track is higher during information reproduction than during information recording.

According to a sixth aspect of the present invention, in the optical information recording / reproducing apparatus according to the fifth aspect, the optical information recording medium is rotated at a linear velocity at which information can be reproduced while keeping the intensity of the light beam at the time of recording during reproduction. It is configured as follows.

[0012]

According to the first aspect of the invention, the tracking control means adds an offset corresponding to the information to be recorded at the time of information recording to the tracking control signal to perform the tracking operation, and at the time of reproducing the information, the tracking is performed without the offset. To work.

According to a second aspect of the present invention, the means adds a constant offset to the tracking control signal at the time of recording information, and the tracking control signal corresponds to the information to be recorded while performing the tracking operation to the optical information recording medium. The intensity of the light beam is modulated, the information track on the optical information recording medium is detected at the time of information reproduction, and the information is read from the fluctuation included in the track detection signal.

According to the third aspect of the present invention, as the optical information recording medium, one having a coating layer having a reflectance different from that of the information tracks is formed between the information tracks. Then, the tracking control means adds an offset corresponding to the information to be recorded to the tracking control signal at the time of recording the information and performs the tracking operation by the tracking control signal, and performs the tracking operation without the offset at the time of reproducing the information.

According to a fourth aspect of the present invention, in the optical information recording / reproducing apparatus according to the first, second or third aspect, the maximum frequency f of the band movable in the tracking direction of the optical spot on the optical information recording medium and the information The relation among the number of multi-valued steps n, the diameter d of the light spot on the optical information recording medium, and the linear velocity v of the information track at the time of information recording is v> = 2ndf.

According to the invention described in claim 5, in the optical information recording / reproducing apparatus according to claim 4, the linear velocity of the information track is higher during information reproduction than during information recording.

According to a sixth aspect of the present invention, in the optical information recording / reproducing apparatus according to the fifth aspect, the optical information recording medium is rotated at a linear velocity at which information can be reproduced while the intensity of the light beam remains unchanged during recording.

[0018]

1 shows a first embodiment of the present invention, and FIG. 2 shows a timing chart of the first embodiment. The first embodiment is an example of a magneto-optical disk device of the non-magnetic field overwrite type. The semiconductor laser 11 is driven by a laser drive circuit 12 to emit a pulsed laser beam, and this laser beam becomes a parallel light beam by a collimator lens 13. This light beam passes through the beam splitter 14 and is condensed by the objective lens 15 to be applied to a magneto-optical recording medium 16 composed of a magneto-optical disk having an easy axis of magnetization in a direction perpendicular to the surface of the recording film, thereby forming a light spot. Is formed. The magneto-optical recording medium 16 is rotationally driven by a motor.

When information is recorded digitally, the magneto-optical recording medium 16 is heated to near the Curie temperature by the light spot, and the heated portion forms an inverted magnetic domain due to the leakage flux due to the magnetization of the surrounding portion. The temperature of the portion heated by the light spot on the magneto-optical recording medium 16 drops as the laser light is no longer applied to the magneto-optical recording medium 16, but at that time, the inversion magnetic domain also becomes small and has a constant size. Calm down. This constant magnitude is the magnetic characteristics of the magneto-optical recording medium 16 such as coercive force, saturation magnetization, domain wall energy, and perpendicular anisotropy, laser light power, irradiation time, thermal diffusivity of the magneto-optical recording medium 16, It is a value determined by the relative speed of the spot and the magneto-optical recording medium 16. In this way, marks of a certain size are formed on the magneto-optical recording medium 16.

The recording control circuit 17 modulates the clock signal 18a from the oscillator 18 with the data signal 16a to be recorded, and the laser driving circuit 12 drives the semiconductor laser 11 by the modulation signal. Therefore, the magneto-optical recording medium 1
In 6, the mark is recorded so that the data signal is recorded.

Further, when the laser beam is irradiated again to the approximately same place where the mark is recorded on the magneto-optical recording medium 16,
At that location, the temperature rises to near the Curie temperature as in the recording of the mark, and an inverted magnetic domain having a size including the already recorded mark is formed. After that, the laser light is no longer applied to the magneto-optical recording medium 16 at that location, the temperature drops, and the inversion magnetic domain shrinks, so that a mark is formed as in the case of recording the mark. The position where the mark is formed on the magneto-optical recording medium 16 is determined not by the position where the mark is first formed but by the position where the laser beam is irradiated later.

That is, the mark can be moved by irradiating the magneto-optical recording medium 16 with a laser beam at a substantially same place where the mark is already recorded. Therefore, in the magneto-optical recording medium 16, the first recorded information is completely erased and new information is written.

In this embodiment, since it is not necessary to apply a special magnetic field to the formation of the reversed magnetic domain on the magneto-optical recording medium 16, the structure of the device can be simplified to reduce the size of the device, reduce the cost, and transfer information. The speed of can be measured. In addition, there is essentially no unerased mark, and high-quality and highly reliable information can be magnetically recorded.

Further, the recording control circuit 17 phase-modulates the clock signal 18a from the oscillator 18 with the data signal 16a to be recorded as shown in FIG.
The laser drive signal 17a is output to the laser drive circuit 12 as a, and the laser drive signal 17a is phase-modulated back and forth according to the data signal 16a with respect to the clock signal 18a. That is, when the value of the data signal 16a is at the high level, the laser drive signal 17a occurs immediately before the fall of the clock signal 18a, and when the value of the data signal 16a is at the low level, the laser drive signal 17a is at the fall of the clock signal 18a. It occurs immediately after. As a result, the position of the mark 16a recorded on the magneto-optical recording medium 16 is modulated back and forth depending on the presence or absence of the data signal 16a.
a is phase-modulated and recorded on the magneto-optical recording medium 16.

The magneto-optical recording medium 16 is irradiated with the laser light from the objective lens 15 as described above, and the reflected light is reflected by the beam splitter 14 via the objective lens 15. The reflected light from the beam splitter 14 is λ / 2.
(Λ is the wavelength of the laser beam) The light enters the polarizer 20 formed of a polarization beam splitter through the plate 19. The transmitted light of the polarization beam splitter is detected by the photodetector 22 via the lens 21, and the reflected light of the polarization beam splitter is detected by the lens 2
3 is detected by the photodetector 24.

The output signals of the photodetectors 22 and 24 are the subtractor 2
The difference is obtained by 5 and a reproduction processing circuit 26 is formed as a reproduction signal.
Further, the adder 27 detects the track on the magneto-optical recording medium 16 by adding the output signals of the photodetectors 22 and 24 and outputs the track detection signal to the servo control system 2.
Output to 8. This servo control system 28 uses the objective lens 13
The optical spot on the magneto-optical recording medium 16 is aligned with the track by performing the tracking operation by controlling the actuator for driving the optical disc in the direction perpendicular to the track on the magneto-optical recording medium 16 by the track detection signal from the adder 27.

When reproducing the data signal recorded on the magneto-optical recording medium 16, the laser driving circuit 12 drives the semiconductor laser 11 by a laser driving signal of a constant level to emit a laser beam, and the adder 27 Thus, a reproduction signal 27a corresponding to the mark 16a recorded on the track on the magneto-optical recording medium 16 is obtained. The reproduction processing circuit 26 slices the reproduction signal 25a from the adder 27a at a predetermined level 26a, samples with a sampling pulse 26b, and holds the data signal 26c.

When the data signal 16b is overwritten on the magneto-optical recording medium 16, the above-mentioned data signal 16b is used.
Similarly to the case of recording a, the recording control circuit 17 causes the oscillator 18
Data signal 16 to record the clock signal 18a from
The phase is modulated by b and output to the laser drive circuit 12 as a laser drive signal 17b, and the laser drive signal 17b causes the laser drive circuit 12 to drive the semiconductor laser 11 to irradiate the magneto-optical recording medium 16 with pulsed laser light. To be done. The position on the magneto-optical recording medium 16 to which the laser beam is irradiated is only slightly offset from the position of the previously recorded old mark 16a, and the old mark 16a moves to the laser beam irradiation position. It is recorded as a new mark 16b. That is, in the magneto-optical recording medium 16, the old mark 16a is replaced by the new mark 16b, and the data signal is overwritten.

The position of the domain wall on the magneto-optical recording medium 16 can be moved by changing the intensity or pulse width (irradiation time) of the laser beam. That is, the domain wall on the magneto-optical recording medium 16 has a high intensity of laser light, or when the irradiation time of the laser light is long, it moves in the direction in which the reversed magnetic domain spreads, and conversely the intensity of the laser light is low. When the irradiation time of the laser light is short, the reversed magnetic domain moves in the direction of narrowing. This is because when the temperature of the magneto-optical recording medium 16 rises high due to the irradiation of the laser beam, the region of the reversed magnetic domain expands, and when the temperature of the magneto-optical recording medium 16 drops, its temperature distribution becomes gentle, and the reversed magnetic domain region once expanded. This is because the position of the magnetic domain wall of is substantially fixed.

In the present embodiment, information can be multivalued and recorded on a general magneto-optical recording medium which records information as a change in reflectance on the surface of the magneto-optical recording medium due to holes, dents and phase changes. The recording density of the magnetic recording medium can be dramatically improved. Next, a case of recording information on the magneto-optical recording medium 16 in an analog manner will be described. As shown in FIG. 3, the magneto-optical recording medium 16 has a recording portion (land portion: information track) 29 and a non-recording portion (groove portion) 30 arranged concentrically or spirally, and the laser light 31 from the objective lens 15 is arranged. The information recording portion 3 due to the phase change due to the formation of the light spot 32 by the irradiation of
Recorded as 3.

As shown in FIG. 5, the track detection signal (track error signal) from the adder 27 is almost constant, and the recording control circuit 17 digitizes the analog signal to be recorded at the multi-valued stage number n and controls the track. It is sent to the servo control system 28 as an offset. The servo control system 28 adds the track detection signal (track error signal) from the adder 27 and the track control offset from the recording control circuit 17, and the signal makes the objective lens 13 orthogonal to the track on the magneto-optical recording medium 16. The optical spot on the magneto-optical recording medium 16 moves on the track according to the track control offset by performing the tracking operation by controlling the actuator driven in the direction. The semiconductor laser drive circuit 12 drives the semiconductor laser 12 at a constant level, and an information recording section 33 corresponding to the track control offset is formed in the recording section 29 of the track on the magneto-optical recording medium 16 so that the signal becomes analog. Will be recorded.

When reproducing information from the magneto-optical recording medium 16, the semiconductor laser driving circuit 12 drives the semiconductor laser 12 at a constant level, and the servo control system 28 adds the adder 27.
The tracking operation is performed by controlling the actuator without offset by the track detection signal (track error signal) from the. Therefore, as shown in FIG. 4, the light spot 32 moves on the recording portion (information track) 29 of the track on the magneto-optical recording medium 16, and the reproduction from the subtractor 25 as shown by the solid line in FIG. Signal is obtained,
This reproduction signal is output through the reproduction processing circuit 26.

In the second embodiment of the present invention, the track error signal from the adder 27 is input to the reproduction processing circuit 26 instead of the output signal of the subtractor 25 in the first embodiment. The tracking operation is performed without offset,
The track error signal from the adder 27 has fluctuations as shown by the broken line in FIG. This fluctuation is due to the fact that the information recording section 33 corresponding to the track control offset is formed in the recording section 29 of the track on the magneto-optical recording medium 16, and the width of the information recording section 33 is an amount proportional to the track control offset. Becomes Therefore, the fluctuation of the track error signal from the adder 27 corresponds to the information recorded in the recording section 29 of the track on the magneto-optical recording medium 16, and is processed by the reproduction processing circuit 26 to have an appropriate polarity. It is output as record information.

FIG. 9 shows an optical system of another third and fourth embodiment of the present invention, and FIG. 6 shows a part thereof. In the third and fourth embodiments, two tracking semiconductor lasers are used in addition to the information recording / reproducing semiconductor laser 23 at the time of reproducing information in the first and second embodiments. These two tracking semiconductor lasers are provided on both sides of the information recording / reproducing semiconductor laser 23, and are driven by the semiconductor laser drive circuit 12 only when reproducing information to output a laser beam of constant power. Laser light from the tracking semiconductor laser and the information recording / reproducing semiconductor laser 23 passes through the collimating lens 13, the beam shaping prism 34, the lens 35, the beam splitter 14, the polarizing prism 36, and the objective lens 15 and is placed on the magneto-optical recording medium 16. The recording portion 29 and the non-recording portion 30 of the track are formed to form light spots S1 to S3, and the reflected light thereof is the objective lens 1
5, the light is received by the photodetectors 39 to 41 through the polarization prism 36, the beam splitter 14, and the lenses 37 and 38.

The non-recording portion 30 is composed of a coating layer having a reflectance different from that of the recording portion 29, and has a higher reflectance than the recording portion 29. Laser light from the information recording / reproducing semiconductor laser 23 is applied to the recording portion 29 to form a light spot S2.
The reflected light is detected by the light detector 40. Also, 2
Laser light from one tracking semiconductor laser is applied to the coating layers 30 on both sides of the recording unit 29 to form light spots S1 and S3, and the reflected light is detected by the photodetector 3.
It is detected by 9,41.

The output signal of the photodetector 40 is the reproduction processing circuit 2
6 and the output signals of the photodetectors 39 and 41 are added by the adder 27 to form a track error signal. The servo control system 28 performs a tracking operation by the track error signal from the adder 27. Since the tracking operation uses the coating layer 30 in which no information is recorded, the tracking error signal does not cause offset or fluctuation due to the recording signal. Therefore, more accurate signal reproduction can be performed.

FIG. 7 shows the locus of the light spot on the magneto-optical recording medium 16 in the above embodiment. In the above embodiment, the maximum frequency of the movable band of the light spot on the magneto-optical recording medium 16 in the tracking direction (magneto-optical recording medium 1
When the movement of the recording unit 29 on 6 is converted to a sine wave), f is the number of multilevel information steps, and d is the effective recording diameter of the optical spot on the magneto-optical recording medium 16. Since the outer edge of the recording portion 29 on the medium 16 needs to draw a sufficiently gentle curve with respect to the diameter of the light spot in order to obtain sufficient resolution, the envelope y = of the light spot as shown in FIG. A · sin (2πft) should be drawn.

That is, in order to record information with sufficient resolution, it is necessary to send the magneto-optical recording medium 16 in the recording direction at such a speed that the light spots are at least adjacent to each other. Therefore, the relationship between the linear velocities V of the information tracks at the time of information recording is 2nd / T = 2n because the period T with respect to f is T = 1 / f and the moving distance in one period is 2nd.
df, and V ≧ 2ndf. Therefore, in each of the other embodiments of the present invention, in each of the above embodiments, V> = 2ndf is set when information is recorded. Therefore, information can be recorded with high accuracy. However, the linear velocity V is applied only at the time of recording, and it is advantageous that the linear velocity V at the time of reproducing information is higher than that at the time of recording information in order to improve the data transfer rate.

In general, the emission intensity of a semiconductor laser is higher when recording information than when reproducing information. If the energy of the laser beam applied to the same area per unit time can be adjusted by the linear velocity of the magneto-optical recording medium, the information can be reproduced while the semiconductor laser emits light at the power for normal information recording during information reproduction. Is possible. Therefore, in each of the other embodiments of the present invention, in each of the above embodiments, the difference between the linear velocity of the magneto-optical recording medium 16 during information reproduction and the linear velocity of the magneto-optical recording medium 16 during information reproduction is appropriately adjusted. Information is recorded and reproduced while the semiconductor laser 11 is turned on with the same intensity of the light spot by setting. As a result, a simple device without a mechanism for switching the emission intensity of the semiconductor laser 11 can be realized.

[0040]

As described above, according to the first aspect of the invention, the offset corresponding to the information to be recorded is added to the tracking control signal at the time of information recording, and the tracking operation is performed by this tracking control signal, and at the time of information reproduction. Since the tracking control means for performing the tracking operation without the offset is provided, the information can be multi-valued and recorded on a general optical information recording medium, and the information recording density can be dramatically improved. it can.

According to the second aspect of the present invention, a constant offset is added to the tracking control signal at the time of information recording, and the tracking control signal corresponds to the information to be recorded while performing the tracking operation to the optical information recording medium. Since the means for modulating the intensity of the light beam and detecting the information track on the optical information recording medium at the time of information reproduction and reading the information from the fluctuation included in the track detection signal are provided, the information is recorded on the optical information recording medium in an analog manner. Can be recorded, and the information recording density can be dramatically improved.

According to the third aspect of the invention, an optical information recording medium having a coating layer having a reflectance different from that of the information tracks is formed between the information tracks, and the information should be recorded at the time of recording the information. Since the tracking control means adds an offset corresponding to the information to the tracking control signal to perform the tracking operation by the tracking control signal and performs the tracking operation without the offset at the time of reproducing the information, the information can be reproduced more accurately. it can.

According to the fourth aspect of the invention, the maximum frequency f of the movable band of the light spot on the optical information recording medium in the tracking direction, the number of multilevel information n, and the light on the optical information recording medium. Since the relation between the diameter d of the spot and the linear velocity v of the information track at the time of information recording is configured such that v> = 2ndf, the information can be recorded with high accuracy.

According to the fifth aspect of the invention, since the linear velocity of the information track is set to be higher when the information is reproduced than when the information is recorded, the information transfer rate can be improved.

According to the sixth aspect of the invention, since the optical information recording medium is rotated at the linear velocity at which information can be reproduced while the intensity of the light beam remains unchanged during recording, the intensity of the light beam can be reduced. A simple device without a switching mechanism can be realized.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a timing chart of the first embodiment.

FIG. 3 is a diagram for explaining an information recording operation of the first embodiment.

FIG. 4 is a diagram for explaining an information reproducing operation of the first embodiment.

FIG. 5 is a diagram for explaining a third embodiment of the present invention.

FIG. 6 is a diagram for explaining another embodiment of the present invention.

FIG. 7 is a diagram for explaining another embodiment of the present invention.

FIG. 8 is a timing chart of a conventional device.

FIG. 9 is a perspective view showing an optical system of another embodiment of the present invention.

[Explanation of symbols]

 11 semiconductor laser 16 magneto-optical recording medium 17 recording control circuit 26 reproduction processing circuit 28 servo control system

Claims (6)

[Claims] 1. An optical information recording / reproducing apparatus for recording / reproducing information by condensing a light beam by an objective lens while performing a tracking operation on an optical information recording medium, which corresponds to information to be recorded at the time of recording information. An optical information recording / reproducing apparatus comprising: a tracking control means for performing the tracking operation by the tracking control signal by adding the offset to the tracking control signal and performing the tracking operation without the offset when reproducing the information. 2. An optical information recording medium is recorded with information by performing a tracking operation on the optical information recording medium and condensing a light beam by an objective lens to deform the surface of the optical information recording medium. On the other hand, in an optical information recording / reproducing apparatus which collects a light beam by an objective lens while performing a tracking operation and obtains information from the reflected light from the optical information recording medium, a constant offset is added to a tracking control signal during information recording. The tracking control signal modulates the intensity of the light beam to the optical information recording medium according to the information to be recorded while performing the tracking operation, and detects the information track on the optical information recording medium at the time of reproducing the information. An optical information recording / reproducing apparatus comprising means for reading information from a fluctuation included in a track detection signal. 3. An optical information recording / reproducing apparatus for recording / reproducing information by converging a light beam by an objective lens while performing a tracking operation on the optical information recording medium, wherein an information track is used as the optical information recording medium. A coating layer with different reflectance is formed between the information tracks.When recording information, an offset corresponding to the information to be recorded is added to the tracking control signal to perform the tracking operation by this tracking control signal. An optical information recording / reproducing apparatus comprising a tracking control means for performing a tracking operation without offset during information reproduction. 4. The optical information recording / reproducing apparatus according to claim 1, 2 or 3, wherein the maximum frequency f of a movable band of the optical spot on the optical information recording medium in the tracking direction and the number of information multilevel steps. An optical information recording / reproducing apparatus, characterized in that the relation of n, the diameter d of the light spot on the optical information recording medium, and the linear velocity v of the information track at the time of information recording is such that v> = 2ndf. 5. The optical information recording / reproducing apparatus according to claim 4, wherein the linear velocity of the information track is higher when the information is reproduced than when the information is recorded. . 6. The optical information recording / reproducing apparatus according to claim 5, wherein the optical information recording medium is rotated at a linear velocity at which information can be reproduced while the intensity of the light beam is kept at the recording state during reproduction. A characteristic optical information recording / reproducing apparatus.