JPH02203424A - Optical information recording medium, method and device for optical information recording/reproducing - Google Patents

Abstract

PURPOSE:To improve the recording density of a recording medium and at the same time to attain the high speed recording/reproducing operations by recording the information within an information track formed in the moving direction of an optical head with use of the information bits having the directivity in the crossing direction of the information track. CONSTITUTION:An information track 14 includes 8 information bits 0 - 7 in the width direction of the track 14, and a train of these bits 0 - 7 is formed with the directivity secured in the direction A against the track width direction. Thus one information unit is obtained. Then many pieces of such information bit trains are formed in parallel with each other. Then the scan is carried out by the light beam spots within the track 14 in the crossing direction of the track 14. Thus the information is recorded via the information bit train and then can be reproduced. As a result, the recording density is improved for an optical information recording medium and at the same time the information can be recorded and reproduced at a high speed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical information recording medium for optically writing or reading information, and an optical information recording/reproducing method and apparatus using the medium. .

[Background of prior art and invention]

Conventionally, optical information recording media for optically writing or reading information have been of read-only type and write-once type.

#1 Replaceable type is used. These media may be in the form of a disk, a card, or the like.

In optical information recording and reproducing devices that use these optical information recording media, it is important to have control technology that allows a light beam spot of a desired diameter to follow a track, and recording and reproducing technology that enables high-density recording and high-speed reading. It's technology.

The above control technology includes an m-line groove method in which guide grooves are formed concentrically, spirally or in parallel on a recording medium and information pits are formed between the guide grooves, and a servo control technique in which information pits are formed between the guide grooves. A sample in which the area and data area are separated, and during recording and reproduction, tracking and focusing servo and information recording and reproduction are performed in a time-sharing manner, so that these two types of signals do not leak into other signals. A servo type has been proposed.

On the other hand, as for the above-mentioned recording and reproducing technology, in addition to the general one in which information pits are formed in one row in the direction of the information track, recently, in order to improve the recording density, there are multiple pits in the information track that differ in the width direction of the information track. It is known that an information pit is formed at the position of .

For example, in Japanese Patent Application Laid-Open No. 63-214919,
An information recording medium as shown in the figure is described. That is, each track Ti, T2, T3 has two pit positions in the width direction P'x, P', and a pit row is formed at each position according to the information signal. This recorded information is reproduced by simultaneously scanning information pit rows at two positions within one track with one light beam spot.
The information of each pit row is reproduced based on the difference in the amount of light incident on two photodetectors arranged corresponding to each pit.

However, the above-mentioned publication only describes optically reproducing recorded information on a recording medium as shown in Figure 8, that is, a read-only type recording medium, and optically reproduces information in the form as shown in Figure MS8. There is no description of application to recordable or rewritable recording media.

By the way, the present applicant converts recorded information into a combination of the presence or absence of information pits, the center position of the pits in the track width direction, and the width of the pits in the track width direction, and enables the same track to be covered with a relatively small light beam spot. We proposed a method of optically recording information by changing the tracking position and scanning multiple times. To reproduce the information recorded by this method, a relatively large light beam spot is used to scan the information track only once, and the information pits are determined by comparing the sum and difference of the amounts of light incident on each light receiving section of the split photodetector. This is done by detecting the combination of the presence or absence of the pit, the center position of the pit in the track width direction, and the width of the pit in the track width direction. Here, by making the wavelength of the recording light beam shorter than the wavelength of the reproduction light beam, it becomes possible to perform both recording and reproduction using the same optical system, and the information pit is set to about 17a of the reproduction light beam spot. High-density recording can be performed. In this way, it has become possible to provide write-once type and rewritable type recording media with improved recording density.

[Problems to be Solved by the Invention] However, in the optical information recording and reproducing method proposed by the applicant, the same track only needs to be scanned once during reproduction, so data can be read out at high speed. However, when recording, it is necessary to scan the same track multiple times in the direction of the track, and since the scanning is performed by moving the recording medium relative to the optical head, it is difficult to increase the speed, and speeding up of recording is still insufficient. No, no.

Therefore, an object of the present invention is to increase the recording density of a recording medium and enable high-speed recording and reproduction in optical information recording and reproduction.

[Means to solve the problem] According to the invention, the above objectives are achieved.

An optical system, characterized in that information is recorded in an information track formed along a direction of relative movement with respect to an optical head, with information pits or information pit rows with directionality in a direction transverse to the direction of the information track. information recording medium.

In addition, the optical information recording medium is irradiated with a light beam in the form of a spot, and the intensity of the light beam is changed according to the information while scanning the information track in a direction transverse to the information track direction with the light beam spot. , the scanning in the direction transverse to the information track direction is performed on the same information track by changing the position relative to the information track direction.

An optical information recording method, characterized in that information is recorded with an information pit or an information pit row with directionality in a direction transverse to the direction of the information track, and information is recorded with directionality in a direction transverse to the direction of the information track. A light beam is irradiated in a spot shape onto an optical information recording medium on which information is recorded by pits or information pit rows, and the light beam spot scans an information track in a direction transverse to the information track direction. An optical information reproducing method characterized in that information is reproduced by performing scanning on the same information track while changing its position in the information track direction.

This can also be achieved by an apparatus for carrying out the optical information recording method or the optical information reproducing method described above.

[Example 1] A specific example of the present invention will be described below with reference to one drawing.

FIG. 1 is a schematic diagram showing a first embodiment of a recording format of an optical information recording medium of the present invention.

In FIG. 1, 14 is an information track.

The reader direction is in the B direction. Guide grooves 13a and 1311+ are used for tracking servo and the like.

Timing marks are provided at appropriate positions on the guide groove, and starting positions for a series of information recording are set based on the marks. There are eight information pit positions θ to 7 in the track width direction in the information track 2 14. Information pit rows are formed with directionality in the direction A, which is slightly inclined with respect to the track width direction, thereby forming one information unit. 15 is the center line of the information pit row. A large number of such information pit rows are formed in parallel. Each information pit row is composed of a reference information pit 16 formed at recording position NO among the eight information pit positions and an information pit 17 formed at any of recording positions 1 to 7 (however, recording position If In some cases, information pits are not formed in the bits 7 to 7), thereby realizing 8-value recording (3 bits in binary).

FIG. 2 is a schematic diagram showing a second embodiment of the recording format of the optical information recording medium of the present invention. In this figure, the same parts as in FIG. 1 are given the same reference numerals.

In FIG. 2, 18 is an information pit having directionality in the input direction. Reference numeral 15 indicates the center line of the information pit, that is, in this embodiment, a long and narrow information pit is formed from the recording position MO to any one of recording positions Ht to 7.
8-value recording is realized depending on the length of the information pit.

This embodiment is based on the reference information pit 16 of the embodiment shown in FIG.
This corresponds to a form in which the information pits 17 to 17 are connected to form one information pit.

FIG. 3 is a schematic diagram showing a third embodiment of the recording format of the optical information recording medium of the present invention. In this figure, the same parts as in FIG. 1 are given the same reference numerals.

In this embodiment, the information track 14 has nine information pit positions 0 to 8 in the track width direction. Each information pit row is composed of a reference information pit (19) formed at recording position 0 of the nine information pit positions and information pits (19) appropriately formed at each of recording positions 1 to 8.
However, there are cases in which no information pits are formed at recording positions 1 to 8), thereby realizing 8-bit recording.

In the embodiments shown in FIGS. 1 to 3 above, the arrangement pitch of each information pit with respect to the recording position or the arrangement pitch of adjacent information pit rows is set slightly larger than the diameter (or convergence) of the information pits. If the information pits can be detected as information pits, the arrangement pitch can be further reduced.

FIG. 4 is a diagram showing an embodiment of an optical head optical system in an optical information recording/reproducing apparatus using the optical information recording medium of the above embodiment.

In FIG. 4, reference numeral 1 denotes a semiconductor laser, and light emitted from the semiconductor laser passes through a collimating lens 2 and a beam shaping prism 3 to become a parallel beam of light, and enters an optical deflection element 4. As the optical deflection element, an element using an ultrasonic transducer using an acousto-optic effect can be used. The light emitted from this element is the 0th order diffracted light (transmitted light) and the 1st
The diffraction angle of the first-order diffracted light is determined by the frequency of electric power applied to the ultrasonic transducer, and by rapidly changing the frequency, the first-order diffracted light can be scanned.

The 0th-order diffracted light and the 1st-order diffracted light that exit the optical deflection element 4 pass through a beam splitter 5, pass through an objective lens 6, and are sent to a recording medium 7.
Spots are formed at spatially separated locations on the top. Here, the 0th-order diffracted light is made to enter the recording medium 7 almost perpendicularly, and the optical system and the recording medium are arranged so that the 1st-order diffracted light is scanned in the track width direction by the operation of the optical deflection element 4. 7 is set. If the NA of the objective lens 6 is 0.55 and the focal length is about 4 mm, it is possible to scan the 1st-order diffracted light on the recording medium 7 by about ±151 Lm with the 0th-order diffracted light as the center, within the allowable range of aberrations. It is possible. In this case, the size of the light beam spot is about 1 gm.

The reflected light from the recording medium 7 passes through the objective lens 6, is reflected by the beam splitter 5, passes through the condensing lens 8 and the cylindrical lens 9, and forms a spot on the photodetector 311θ.

The recording medium 7 is moved along the information track direction by a driving means (not shown).

FIG. 5 is a diagram showing the light receiving section of the photodetector 10.

Reference numeral 11 denotes a four-division light receiving section that receives the light beam spot 4G corresponding to the O-th new party. The 0th order diffracted light is used to obtain a servo error signal.

The focus error signal can be obtained by the conventional astigmatism method, and the tracking error signal can be obtained by the conventional push-pull method.

Reference numeral 12 denotes a light receiving section that receives a light beam spot 41 corresponding to the first-order diffracted light. The first-order diffracted light is for detecting data signals. The first-order diffracted light is transmitted to the optical deflection element 4.
The light receiving section 1z is formed with a predetermined length in a direction optically corresponding to the scanning direction, so that it can receive light within the entire scanning range.

When recording information, the recording medium 7 is moved relative to the optical head along the information track direction by a driving means (not shown). At this time, tracking servo and focusing servo are performed as described above in order to cause the optical beam spot of the desired diameter by the O-th new beam to follow the guide groove of the recording medium 7. In addition, the optical deflection element 4
The first-order diffracted light is scanned in the width direction of the information track.

At this time, since the recording medium 7 is moving in the direction opposite to the direction B, the beam spot of the first-order diffracted light is scanned on the recording medium in the direction A, which forms a slight angle with the track width direction. .

In an element using the acousto-optic effect, the intensity of the first-order diffracted light is reduced to 0.
It is possible to make the intensity greater than the intensity of the next diffracted light. The intensity of the first-order diffracted light is changed according to the recorded information, and high intensity for information pit recording and low intensity for information pit non-recording are selectively realized. Along with this, the intensity of the 0th order diffracted light also changes, but it is possible to set the emission intensity level of the semiconductor laser 1 so that recording does not occur on the recording medium 7 depending on the 0th order even when the intensity is high. can.

Note that the recording is performed while operating the optical deflection element 4 with reference to the time when the timing mark of the guide groove is detected by the light beam spot of the 0th order diffracted light.

When reproducing information, tracking servo and focusing servo similar to those during recording are performed. and,
The light emission intensity level of the semiconductor laser 1 is set to a level that does not cause recording on the recording medium 7, and as in the case of recording, the time when the timing mark of the guide groove is detected by the light beam spot generated by the new party next time is used as a reference. The optical deflection element 4 is operated to scan an information pit or an information pit row with a light beam spot of the first-order diffracted light, and a reproduced signal is obtained from the light receiving section 12 of the photodetector 10.

In the optical head shown in FIGS. 4 and 5, a polarizing beam splitter is used as the beam splitter 5, and an analyzer is placed in front of the light receiving section 12 of the photodetector lO.
By arranging a means for applying a magnetic field to the recording medium 7, etc., and having a configuration similar to that of the magneto-optical recording and reproducing method used on a boat, the recording and reproducing method of the embodiment described above can be changed to the magneto-optical recording and reproducing method. can also be applied.

FIG. 6 is a schematic diagram showing a fourth embodiment of the recording format of the optical information recording medium of the present invention. Above 1st to 3rd
The embodiment is a recording medium of continuous groove type, but this embodiment is a recording medium of sample servo type.

In FIG. 6, 20 is an information track.

The longitudinal direction is in the B direction. The information track has a configuration in which a servo area 21 and a data area 22 are separated, and one information track has many sets of the servo area and data area arranged in succession. Servo area 21
is composed of a tracking area 23, a focusing area 24, and a timing pit 25. The tracking area 23 is made up of a plurality of servo pits arranged along the information track direction, provided that the servo pits are arranged in a staggered manner alternately with respect to the servo pit center in the information track direction.

The focusing area 24 consists of a uniform reflective surface. The timing pit 25 is a pit for timing when recording and reproducing information. In the data area 22, information pit rows or information pits similar to those in the embodiments shown in FIGS. 1 to 3 are formed with directionality in the input direction slightly inclined with respect to the track width direction. 26 indicates the center line of these information pits and information pit rows.

As the optical head of the apparatus used for recording and reproducing information on the information recording medium of this embodiment, those shown in FIGS. 4 and 5 above can be used. Here, as the recording medium 7 moves in the information track direction, the beam spot by the 0th order diffracted light scans the center of the servo pit, and the servo area 2
In step 1, tracking servo and focusing servo are performed, and the tracking and focusing positions are kept in sync until the next servo area is reached.

When recording information, similar to the embodiments shown in FIGS. 1 to 3 above,
A drive means (not shown) moves the recording medium 7 relative to the optical head along the information track direction. At this time, tracking servo and focusing servo are performed as described above. Further, the formation of information pits or information pit rows in the data area 22 is performed by operating the optical deflection element 4 based on the time when the timing pit in the servo area 21 is detected by the optical beam spot generated by the O-th new party. The optical deflection element changes the intensity of the first-order diffracted light to selectively achieve high intensity for recording information pits and low intensity for not recording information pits.
The next diffracted light is scanned in the width direction of the information track. On this occasion,
Since the recording medium is moving in the opposite direction to the direction B, the beam spot of the first-order diffracted light is scanned on the recording medium in the direction of incidence that forms a slight angle with the track width direction.

When reproducing information, tracking servo and focusing servo similar to those during recording are performed. and,
The emission intensity level of the semiconductor laser 1 is set to a level that does not cause recording on the recording medium 7, and as in the case of recording, the timing pit in the servo area 21 is detected with the light beam spot of the 0th order diffracted light as a reference. , the optical deflection element 4 is operated to scan the information pit or the information pit row with the optical beam spot of the first-order diffracted light, and the optical detector 10
A reproduction signal is obtained from the light receiving section 12 of.

As described above, in this embodiment, the recording and reproduction of information is performed in the first
This can be done in the same manner as in the embodiment shown in FIGS.

FIG. 7 is a schematic diagram showing a fifth embodiment of the recording format of the optical information recording medium of the present invention, and this embodiment is also a sample servo type recording medium similar to the embodiment shown in FIG. 6 above. be.

In FIG. 7, 27 is an information track.

The longitudinal direction is in the B direction. The information track has a configuration in which a servo area 28 and a data area 29 are separated, and one information track has many sets of the servo area and data area arranged in succession. Servo area 28
is composed of a tracking area 30, a focusing area 31, and a timing pit 32. The tracking area 30 consists of a plurality of servo pits arranged along the information track direction, provided that the servo pits are arranged in a staggered manner with alternating shifts with respect to the servo pit center in the information track direction.

The focusing area 31 consists of a uniform reflective surface. The timing pit 32 is a pit for timing when recording and reproducing information. In the data area 29, information pit rows or information pits similar to the embodiments shown in FIGS. 1 to 3 are formed with directionality in the input direction slightly inclined with respect to the track width direction. 33 indicates the center line of these information pits and information pit rows.

This embodiment differs from the embodiment shown in FIG. 6 above in that the center of the servo pit is formed to coincide with the center of the track.

As the optical head of the device used for recording and reproducing information on the information recording medium of this embodiment, an optical head similar to that shown in FIGS. 4 and 5 above can be used. However, in this embodiment, As the photodetector 10, it is possible to use one that does not have the light receiving section 11 and has the light receiving section 12 divided into four parts and arranged symmetrically with respect to the optical axis.

As described above, in an element using the acousto-optic effect, it is possible to make the intensity of the first-order diffracted light greater than the intensity of the zero-order diffracted light, and the O-th order new phase can be almost eliminated.

In this embodiment, only the first-order diffracted light is used. When the beam spot of the first-order diffracted light scans the servo area 28 as the recording medium 7 moves in the information track direction, the frequency of the optical deflection element 4 is fixed constant and the scanning of the first-order diffracted light in the A direction is stopped. In this state, the beam spot of the #1st-order diffracted light scans the center of the servo pit. Thus, tracking servo and focusing servo are performed in the servo area 28, and the tracking and focusing positions are maintained until the primary servo area is reached.

When recording and reproducing information, the timing pit 32 is detected by the photodetector 12, and using this as a trigger, the optical deflection element 4 starts the deflection operation, and the information pit row or Forming information pits or reading out the information pit string or information pits.

When scanning of the data area 29 is finished and scanning of the next servo area is started, the beam spot of the first-order diffracted light is immediately fixed at the center of the track, and the above-described operation is repeated.

In this embodiment, if the center of the scanning range of the first-order diffracted light in the track width direction is set in a direction substantially perpendicular to the recording medium 7, that is, in the optical axis direction of the objective lens 6, the scanning range of the first-order diffracted light is symmetrical with respect to the optical system and near the optical axis, so it is possible to relax the aberration conditions of the optical system.

In addition to the above-mentioned acousto-optic effect elements, such light beam scanning in the track width direction can be performed using galvanometer mirrors, wavelength-tunable semiconductor lasers, and prisms with different reflection angles depending on the wavelength of the light. This can be carried out using a combination of optical elements such as the following.

The above 6th r1! It is possible to apply the information recording/reproduction of the embodiment J and the embodiment of FIG. 7 to the magneto-optical recording/reproduction method, as described with respect to the embodiment of FIGS. 1 to 3 above.

Note that the information recording medium of the present invention may not only have linear information tracks, such as a card shape, as in the above embodiments, but also may have a spiral or concentric information track, such as a disk shape. .

[Effects of the Invention] As explained above, according to one aspect of the present invention, a light beam spot scans an information track in a direction transverse to the information track direction, and the scanning is performed by determining a position in the same information track with respect to the information track direction. By changing the direction, information can be recorded by information pits or information pit rows with directionality in a direction transverse to the direction of the information track, and furthermore, recorded information in such a form can be reproduced.
This increases the recording density of the optical information recording medium and enables high-speed recording and reproduction.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, FIG. 3, FIG. 6, and FIG. 7 are all schematic diagrams showing the recording format of the optical information recording medium of the present invention. FIG. 4 is a diagram showing the optical head optical system in the optical information recording/reproducing apparatus of the present invention, and FIG. 5 is a diagram showing the light receiving section of the photodetector. FIG. 8 is a schematic diagram showing the recording format of a conventional optical information recording medium. l: Semiconductor laser, 2: Collimating lens, 3: Beam shaping prism, 4: Optical deflection element, 5: Beam splitter, 6: Objective lens, 7: Recording medium, 8: Condensing lens, 9 Nijilintorical lens, lO : Photodetector, 1 l, 12 : Light receiving section, 13
a, 13b: Guide groove, 14.20, 27: Information track, 18, 17, 18, 19: Information pit. 40.41: Light beam spot.

Claims (11)

[Claims] (1) Information is recorded in the information track formed along the direction of relative movement with respect to the optical head by information pits or information pit rows with directionality in a direction transverse to the direction of the information track. An optical information recording medium. (2) A light beam is irradiated onto the optical information recording medium in the form of a spot, and the light beam spot scans within the information track in a direction transverse to the information track direction while changing the intensity of the light beam according to the information. , performing scanning in the direction transverse to the information track direction on the same information track while changing the position with respect to the information track direction, and recording information by information pits or information pit rows with directionality in the direction transverse to the information track direction. An optical information recording method characterized by: (3) An optical information recording device, characterized in that the optical information recording method according to claim 2 is performed. (4) It has an optical head that irradiates a light beam in the form of a spot onto an optical information recording medium and moves the light beam spot relatively in the direction of the information track of the recording medium, and the optical head has the direction of the information track. 4. The optical information recording device according to claim 3, further comprising means for scanning the light beam spot in a transverse direction. (5) The optical information recording device according to claim 4, wherein the means for scanning the light beam spot in a direction transverse to the information track direction includes an optical diffraction element using an acousto-optic effect. (6) Light beam spot scanning in a direction transverse to the information track direction is performed using the first-order diffracted light of the optical diffraction element, and a tracking error signal and a focusing error signal are generated using the zero-order diffraction light of the optical diffraction element. The optical information recording device according to claim 5, wherein the optical information recording device is detected. (7) A light beam is irradiated in a spot shape onto an optical information recording medium on which information is recorded by information pits or information pit rows with directionality in a direction transverse to the direction of the information track, and the light beam spot is used to track information. 1. An optical information reproducing method, characterized in that scanning is performed in a direction transverse to the information track direction within the same information track, and the scanning is performed in the same information track while changing the position with respect to the information track direction to reproduce information. (8) An optical information reproducing apparatus, characterized in that the optical information reproducing method according to claim 7 is carried out. (9) It has an optical head that irradiates a light beam in the form of a spot onto an optical information recording medium and moves the light beam spot relatively in the direction of the information track of the recording medium, and the optical head has the direction of the information track. 9. The optical information reproducing apparatus according to claim 8, further comprising means for scanning the light beam spot in a transverse direction. (10) The optical information reproducing apparatus according to claim 9, wherein the means for scanning the light beam spot in a direction transverse to the information track direction includes an optical diffraction element using an acousto-optic effect. (11) Light beam spot scanning in a direction transverse to the information track direction is performed using the first-order diffracted light of the optical diffraction element, and a tracking error signal and a focusing error signal are generated using the zero-order diffraction light of the optical diffraction element. The optical information reproducing device according to claim 10, wherein the optical information reproducing device is detected.