JP2604871B2 - Optical disk and optical disk device - Google Patents

Description

The present invention relates to an optical disk having a read-only area and a writable area, and realizes an optical disk having a read-only area and a writable area on one disk substrate. In an optical disc having a read-only area and a writable area, an inner peripheral part has a read-only area in which information is recorded by a mark length recording method, and an outer peripheral part has twice the recording frequency in the mark length recording method. It is a writable area in which information is recorded / reproduced by a mark position recording method of a recording frequency, and the rotation control of the mark length recording method and the mark position recording method is performed at the same rotational angular velocity. .

[Industrial applications]

The present invention relates to an optical disc having a read-only area and a writable area.

[Conventional technology]

An optical disc is a recording medium that records and reproduces information by irradiating a laser beam or generating a magnetic field as necessary. Depending on its use form, there are three types: a read-only type, a write-once type, and a rewritable type.

A read-only optical disk is a read-only disk in which a reflective film made of a thin metal film such as aluminum is formed on a transparent substrate such as glass or polycarbonate resin molded into a disk shape, and information is recorded on the substrate in an uneven shape. Optical disk. In the write-once optical disc, a recording film made of a material that easily sublimates, such as tellurium (Te), is formed on the substrate, and information is formed in the recording film in the form of a hole by irradiating a laser beam. This is an optical disk that can be written only once, and detects information based on the presence or absence of holes. further,
As rewritable optical disks, those utilizing the magneto-optical effect (MO), phase change, and the like are known at present. The MO type optical disk has a perpendicularly magnetized magnetic film (perpendicular magnetized film) formed on a substrate, and the magnetic film is heated by irradiating a strong laser beam and a magnetic field is applied by a magnetic head or an auxiliary magnetic field coil. To record information in accordance with the magnetization direction. Signal reproduction is performed by irradiating weak laser light with the external magnetic field removed and detecting the angle of the plane of polarization of the reflected light.

This utilizes the so-called Kerr effect, in which the angle of the plane of polarization of the reflected light varies depending on the direction of the magnetic field of the magnetic domain, or the Faraday effect, in which the plane of polarization of light rotates when passing through a magnetic material. is there. In the phase change type, a special recording film in which two phase changes between an amorphous phase and a crystal phase or between a crystal phase and a crystal phase due to a temperature change are formed on a substrate. A signal for recording is utilized by utilizing the property that the reflectance of light is different depending on whether it is in a crystalline state, a first crystalline state, or a second crystalline state.
It is for regenerating.

Of the three types of optical disks, the read-only optical disk has the advantage that it can be copied in large quantities, and is used for digital audio disks, video disks, and the like.

Write-once optical disks have a long service life, and there is little risk of erroneous erasure of signals after a single write.Therefore, storage devices such as document files and magnetic tapes, image data files, and rewritable optical disks Used for backup purposes.

Further, the rewritable optical disk is used for an external storage device of a computer or the like because it can be repeatedly rewritten.

[Problems to be solved by the invention]

By the way, in the above-mentioned conventional optical disks, all of the recordable areas formed on the substrate or the recording film on the substrate are all
An optical disk that is used as either a read-only memory or a writable memory and has both a read-only area and a writable area on the same surface has not yet been marketed.

For example, write-once optical disks have a large capacity, easy random access and mass copying, and are inexpensive.
It is considered to be used as a disk storing a dictionary or font pattern of a word processor, or as a disk storing a computer program or an operation manual.

However, since the write-once optical discs described above are read-only and are manufactured in a dedicated factory, the user can use his or her own fonts such as kanji in the word processor dictionary or font pattern supplied with the write-once optical disc. A dictionary cannot be enriched by registering a pattern as an external character, or additionally registering words and idioms in the dictionary according to the user's work.

Programs are often patched to add functionality or to fix bugs in the program. The above patch is generally applied to a short program in many cases.

For this reason, when the program is supplied by the write-once disc, the user cannot rewrite the data on the write-once optical disc. The cost of purchasing a new write-once optical disc is imposed due to a program correction.

Also, creating a new write-once optical disc every time a program is modified imposes a heavy burden on the program supplier and is not realistic.

For this reason, it is considered that demand for an optical disk having a writable area in which a user can arbitrarily write information in addition to a read-only area will increase in the future.

In the above-described optical disc, for example, a use form in which items that do not need to be rewritten, such as mathematical formulas, are recorded in a read-only area, and calculation results and processing results are recorded in a writable area is also conceivable.

By the way, two types of recording methods of a mark length recording method and a mark position recording method are known as a recording method of an optical disk for recording information by forming irregularities on a substrate.

FIG. 6 is an explanatory diagram of a mark length (mark lergth) recording method. In this recording method, the presence / absence of the edge 4 of the recording pit 2 formed by the irradiation of the laser beam corresponds to the signal of “1” and “0”, respectively. Correspondingly, signal 6 is recorded.

That is, the edge 3 where the scanning laser beam enters the recording pit 2 from the disk surface 1 or the edge 4 which exits from the recording pit 2 to the disk surface 1 corresponds to the signal of “1”, and the disk surface 1 or the recording pit without the edge 4 The plane in 2 corresponds to the signal of “0”.

That is, information is reproduced by detecting whether or not the edge 3 or 4 of the recording pit 2 exists at the irradiation position of the reading laser beam corresponding to the clock 5.

On the other hand, FIG. 7 is an explanatory view of a mark position recording method. When a signal of "1" is recorded at a position corresponding to the clock 15, the recording pits 12 are irradiated by laser light. Are formed, and when the signal of "0" is recorded, the recording pit 12 is not formed.

As described above, in the case of the mark position recording method, information is read by detecting the presence or absence of the recording pit 12 at a position corresponding to the clock signal 15.

Comparing the above two recording methods, the mark length recording method has an advantage that the recording density is twice as large as that of the mark position recording method because recording is performed using the edges 3 and 4 of the hole (recording pit 2). is there.

However, in the case of the mark length recording method, since the edges 3 and 4 of the pit 2 are detected in synchronization with the clock signal 5, the position control for accurately detecting the edges 3 and 4 of the recording pit 2 becomes complicated.

For this reason, the above-described mark length recording system is generally adopted for a conventional read-only optical disk, and the mark position recording system is generally adopted for a writable optical disk.

In other words, in the case of a read-only optical disk, a mark length recording method is employed because unevenness can be formed with high positional accuracy in advance, and the optical disk rotation control is performed by CLV (Constant Linear).
Velocity) method.

On the other hand, writable optical disks use the mark position recording method because it is difficult to accurately control the recording pit positioning. The optical disk rotation control is performed using the CAV (Constant Angular Velocity) method. ing.

In the CLV method, since the linear velocity of a track to be recorded and reproduced becomes constant for all tracks, the number of recording bits per track increases as the distance from the disk increases, and a high storage capacity can be realized. However, there is a disadvantage that the rotation control of the spindle motor for rotating the optical disk is complicated.

On the other hand, the CAV method has advantages in that since the rotation of the spindle motor and the recording / reproducing frequency are constant, control is easy, the control circuit system is simple, and the spindle motor can be downsized. However, since the storage capacity per track is determined by the number of marks (information amount) that can be recorded on the innermost track, there is a disadvantage that the storage capacity of the entire optical disc is reduced as compared with the CLV method. ing.

An object of the present invention is to realize an optical disk having a read-only area and a writable area in one disk substrate.

[Means and actions for solving the problem]

That is, according to the present invention, two areas, a read-only area and a writable area, are provided on one optical disc, and a read-only area for only reading information can form unevenness with high positional accuracy, and can record information at a high recording density. The information is recorded by a mark length recording method capable of recording information, and the information is recorded by a mark position recording method in a writable area where information can be rewritten.

Then, the read-only area is arranged on the inner periphery of the optical disc, the writable area is arranged on the outer periphery of the optical disc, and the recording frequency for recording information in the writable area is set to twice the recording frequency in the read-only area. ing.

As described above, since the CAV system, which facilitates the rotation control, is employed, information is recorded / reproduced, so that when used as a peripheral device of a computer, the access speed can be increased. Also, in order to solve the disadvantage of the CAV method, that is, the information recording density decreases as the information recording density becomes more outward in the radial direction, the inner peripheral portion has a higher recording density in the mark length recording method. A read-only area that is easy to form and a writable area where information is recorded and reproduced by the mark position recording method suitable for the writable area on the outer periphery are arranged to reduce the recording density, which is a drawback of the mark position recording method. By setting the recording frequency for recording information in the write area to twice the recording frequency of the read-only area, the recording density of the writable area is made equal to that of the read-only area.

Further, the read-only area and the writable area may be arranged alternately on concentric circles in the radial direction of the optical disk. In this case, for example, the read-only area records information by a mark length recording method. In the writable area, information is recorded and reproduced by a mark position recording method.

Then, for example, the read-only area and the writable area are alternately arranged in the order of the read-only area and the writable area from the innermost side, and the recording frequency of the writable area is twice the recording frequency of the read-only area. If the recording of information in the two areas is performed at the same rotational angular velocity, the access can be speeded up and the recording density can be increased for the same reason as described above.

Further, the read-only area and the writable area are arranged alternately as described above, and the rotational angular velocity when recording information in the writable area by the mark position recording method is such that the information is read from the read-only area. While the rotation frequency is made slower than the rotation angular velocity at the time of reading, and based on the rotation angular velocity, the recording frequency at the time of recording information in the writable area is changed by the recording capacity per track of the writable area to the read-only area. It is set so as to be equal to the storage capacity per track, and the rotational angular velocity when reading information from the writable area is the same as the rotational angular velocity when reading information from the read-only area.

By lowering the rotation angular velocity in this manner, deterioration of recording sensitivity caused by a decrease in the amount of laser light irradiated when recording information at a high rotation angular velocity,
This can be prevented when information is recorded in the writable area.

Further, in this case, since the rotational angular velocity at the time of reproducing information is constant in both the read-only area and the writable area, high-speed access at the time of reading information is possible.

Furthermore, as described above, the read-only area and the writable area are arranged on concentric circles in the radial direction,
When information is recorded in the writable area by the mark position recording method, the rotation control is performed by a multi-stage CAV method in which the rotation control is variable according to the radial position (radial area), and the recording frequency is adjusted in accordance with the rotational angular velocity. Perform variable control.

The variable control of the recording frequency is performed, for example, so that the recording capacity per track of the information recorded in the writable area is equal to the storage capacity per track in the corresponding read-only area. In this case, for example, the rotational angular velocity when reading information from the read-only area and the rotational angular velocity when reading information from the writable area are the same.

With the above arrangement, the storage capacity per track of the read-only area and the writable area can be made the same, and the rotational angular velocity at the time of reading information can be made constant at the same speed in the two areas. Therefore, high-speed access is possible.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of an optical disc 20 according to a first embodiment of the present invention.

The optical disc 20 is formed on a transparent substrate such as glass having a radius of 5 inches, plastic such as polycarbonate resin, or the like.
For example, a photosensitive member such as TbFeCo, TbFe, and GdFeCo is formed on the entire surface of the transparent substrate by a sputtering method, an evaporation method, or the like. The light-sensitive recording member performs thermomagnetic recording when a high intensity laser light spot is irradiated, and reflects the laser light when a low intensity laser light spot is irradiated. Reflecting film.
Accordingly, by irradiating a spot with a high-intensity laser beam and always applying a weak magnetic field from the outside, the light-sensitive recording member can rewrite information by a light modulation method. In the light modulation method, when information has already been recorded, the existing information is erased once, and new information is recorded (note that the photosensitive recording member is a base film, an upper base film or Protected by a protective film, etc.).

As shown in the figure, the optical disk 20 has an inner peripheral portion used as a read-only region 22 where only information can be read, and an outer peripheral portion outside the inner peripheral portion as a writable region 24 where information can be rewritten. used.

More specifically, in the read-only area 22, information is recorded by the mark length recording method, and in the writable area 24, information is recorded by the mark position recording method.

In the present embodiment, as shown in Table 1 below, the area from the radial position 35 mm to 70 mm on the innermost circumference is the read-only area 22.
And an area from a radial position of 70 mm to 105 mm is allocated to the writable area 24. In the read-only area 22 and the writable area 24, the number of revolutions of the optical disk 20 when recording information is the same as 1800 rpm, and the recording (bit) frequency is 3.3 MHz in the read-only area 22. In the writable area 24, the frequency is 6.6 MHz.

Recording of information in the writable area 24 is performed at a rotation speed of 1800.
CAV (Constant Angular Velocit)
y) The method is performed.

Next, FIG. 2 shows the recording format of the read-only area 22 and the writable area 24.

In the read-only area 22, information is previously formed by pits (holes) 30 on the substrate, and the length (pit length) of the pits 30 is 1 μm at a radial position of 35 mm and 75 mm at a radial position.
Is 2 μm. This is because in the read-only area 22, since information is recorded by the CAV method with a rotation speed of 1800 rpm, the pit length becomes longer toward the outer periphery.

On the other hand, at the time when the laser beam spot is supplied to the user, the writable area 24 has a guide groove provided so that the laser light spot always maintains a fixed position, and a track number and a sector number for identifying a sector position. Written
This is a pre-formatted form in which only the ID section and the like are formed. The length of the magnetic domain (or phase change area) 40 corresponding to the pit 30 in the read-only area is 1 μm immediately outside the radial position of 70 mm, and 1.5 μm at the outermost radial position of 105 mm.
μm.

This is because both the read-only area 22 and the writable area 24
The number of revolutions for recording information is the same as 1800 rpm, and the frequency for recording information (recording frequency) is 6.6 MHz in the writable area 24 and twice the 3.3 MHz that is the recording frequency of the read-only area 22. It is because. As described above, the writable area 24 records information by the mark position recording method, but the recording density of the mark position recording method is one of the mark length recording methods performed in the read-only area 22. / 2, the recording frequency of the writable area 24 (6.6 MHz) is changed to the recording frequency of the read-only area 22 (3.3 MHz).
Hz), the recording density per track of the read-only area 22 and the writable area 24, that is, the recording capacity of one track is the same.

Also, the optical disk 20 for reading (reproducing) information is used.
The rotation speed of the read-only area 22 and the writable area 24 is the same 1800 rpm as during recording and reproduction,
Therefore, the reproduction clock of the read-only area 22 and the writable area 24 is 6.6 MHz.

Next, FIGS. 3A and 3B are schematic diagrams showing the format of the sector of the read-only area 22 and the writable area 24, respectively.

As shown in FIG. 2A, the sector 100 of the read-only area 22 has an ID composed of an address section 111, an R / W identification signal 112, and the like.
It comprises a section 110, a gap 120 in which information for absorbing rotation fluctuation of the optical disc 20 is not recorded, and a data section 130 including a synchronization signal 131, a data area 132 and the like.

The address section 111 is information for identifying the address of a sector including a track number and a sector number.
The R / W identification signal 112 is a signal for identifying whether this sector is a sector in the read-only area 22 or a sector in the write-only area 24.

The synchronization signal 131 is a signal for reading data recorded in the data area 132 in synchronization with a clock, and the data is recorded in the data area 132.

The sector 100 is recorded on the substrate in the form of irregularities.

The sector 200 of the writable area 24 is shown in FIG.
As shown in the figure, the configuration is the same as that of the sector 100 in the read-only area 22 described above, and the address part 211 which is the identification information of the address of the sector 200 and that this sector 200 is a sector in the writable area 24 ID section 210 including R / W identification signal 212, gap 220 similar to gap 120,
And a data section 230 including a synchronization signal 231 similar to the synchronization signal 131 and a data area 232 in which data is recorded.

Writing to the sector 200 is performed by forming domains magnetically. Reproduction is performed by irradiating the magnetic domain with a spot of a laser beam having a low linearly polarized light intensity.

Next, FIG. 4 (a) is a diagram showing an example of an optical disk drive circuit for recording / reproducing information using the optical disk 20 having the above configuration.

In the figure, a CPU 301 controls each circuit block in a circuit in accordance with a command transmitted from a host system such as a host computer via a drive interface, and transmits data transmitted from the host system. Control such as writing to the sector of the optical disc 20 or reading data designated by the host system from the sector of the optical disc and transmitting the data to the host system via the drive interface is performed.

The optical head 302 is a unit that collects laser light from a semiconductor laser such as a laser diode, irradiates the target position on the optical disc 20, performs recording, and converts reflected light into an electric signal to reproduce information. And is composed of an optical system and a drive system.

The optical system is a mechanism for converging a laser light spot on the optical disc 20 and detecting a relative displacement between the laser light spot and a target position on the optical disc 20, and includes a semiconductor laser, lenses (coupling).・ Lens, condenser lens, objective lens, prisms (beam splitter,
Knife edge, prism), quarter wave plate, photodiode. The drive system carries out focusing control for causing the objective lens to follow the shake of the disk surface and tracking control for following the track shake to keep the relative positional relationship between the target position on the disk medium and the laser light spot always constant. Drive mechanism for
It is mainly composed of magnets, coils, and support members.

The data encoded by the mark length modulation recorded on the optical disc 20 is output from the optical head 302 and converted into a corresponding electric signal, and is transmitted to the switch 303, the mark length recording decoder 304, and the mark position recording decoder 305. Will be transferred.

The optical disk 20 is rotated by a spindle motor (not shown). A rotation control circuit for controlling the rotation of the spindle motor is also included in the optical disk drive circuit. And this rotation control circuit is CP
Controlled by U301.

The disk drive circuit includes a focusing servo system for maintaining the vicinity of the laser beam waist on the recording surface of the optical disk 20, a seek servo system for moving the beam spot to a target track, and a beam servo for transferring the beam spot to the target track of the optical disk 20. It also has servo control system circuits such as a tracking servo system for following the servo control.

By the way, the mark position recording encoder 404 is
The write data Y output from 1 is synchronized with a clock of 6.6 MHz added from the clock 402 to generate a binary waveform train Z with mark position modulation, and the generated binary waveform train Z is used as a laser diode. Output to a driver 406 (hereinafter abbreviated as LD driver 406).

The LD driver 406, based on the waveform train Z,
The laser light emission of the laser diode in 02 is controlled.
That is, when a signal corresponding to “1” is input,
The laser diode is controlled so as to emit a high-intensity laser beam, and when a signal corresponding to "0" is input, the laser beam is controlled so as to remain at a low intensity level.

The switch 303 and the switch 307 are connected to the optical head 302.
Mode for reading information from the read-only area 22 (hereinafter referred to as RO
A mode in which the optical head 302 reads information from the writable area 24 (hereinafter referred to as a RAM area).
Switch that switches and outputs signals input from two input terminals in accordance with each mode (expressed as an area read mode).

The switch 303 is in the ROM area read mode,
The mark length-modulated encoded data in the read-only area 22 read by the optical head 302 is modulated, while the mark position in the write-only area 24 read by the optical head 302 is modulated in the RAM area read mode. The encoded data is output to the PLL 306. Further, the mark length-modulated encoded data read in the ROM area read mode and the mark position modulated encoded data read in the RAM area read mode are respectively supplied to the mark length recording decoder 304 and the mark position. Output to the recording decoder 305.

The PLL 306 generates a synchronization signal corresponding to the basic period of the encoded data input via the switch 303.
This is a cked Loop, and outputs the generated synchronization signal to the mark length recording decoder 304 and the mark position recording decoder 305.

The mark length recording decoder 304 and the mark position recording decoder 305 demodulate the input coded data into a data bit string based on the synchronization signal added from the PLL 306 and output it to the switch 307.

When the switch 307 is in the ROM area read mode,
The demodulated data bit string output from the mark length recording decoder 304 is output to the CPU 301 while the demodulated data bit string output from the mark position recording decoder 305 is output to the CPU 301 in the RAM area read mode.

The CPU 301 receives data input via the switch 307.
The bit string is transmitted to the host computer via the drive interface.

Further, in the ROM area read mode or the RAM area read mode, the CPU 301 causes the pit to be read or the magnetic domain to be read to be irradiated with a laser beam of weak intensity via the LD driver 406, respectively. To control the laser diode.

Next, the operation of reading the data from the read-only area 22 or the writable area 24 of the optical disk 20 will be described with reference to FIGS. 4 (a) and 4 (b).

Normally, when reading, switches 303 and 307
M area read mode is set.

Operation when reading the relevant sector from the read-only area 22 of the optical disk 20 When the CPU 301 receives address information (track number and sector number) of data to be read from the host computer, the CPU 301 rotates the optical disk 20 via the rotation control unit at a rotation speed of 1800 rpm. To read the ID portion 110 of each sector 100 of the track indicated by the track number specified by the address information by irradiating the laser diode of the optical head with a weak laser beam through the LD driver 406. . This ID part
110 is read by the optical head 302 and the mark length recording decoder
304, via switch 307. It is determined by the R / W identification signal whether the sector indicated by the address information of the address section 111 when the ID section 110 is read is a sector in the read-only area 22 or a sector in the writable area (S1). ), If it is identified as a read-only area (S2), its RO
One sector of the M area is read (S3). That is, when the sector 100 is detected while sequentially reading the ID portion, the data area 132 of the sector 100 is read via the optical head 302, the mark length recording decoder 304, and the switch 307.

Operation for Reading the Sector from the Writable Area 24 of the Optical Disc 20 When the CPU 301 receives the address information (track number and sector number) of the data to be read from the host computer, the CPU 301 rotates the optical disc 20 via the rotation control unit at a rotation speed of 1800 rpm To read the ID section 210 of each sector 200 of the track indicated by the track number specified by the address information by irradiating the laser diode with a low intensity from the laser diode in the optical head via the LD driver 406. . This ID part
Reading of the data 210 is performed via the optical head 302, the mark position recording decoder 305, and the switch 307. Whether the sector indicated by the address information at this time is a sector in the read-only area 22 or a sector in the writable area 24 is determined by the R / W identification signal (S1).
After determining that the sector is within the sector (S2), the switch 303 and the switch 307 are set to the RAM area read mode after reading the ID section 210 (S4). Then, when the sector 200 is detected while sequentially reading the ID section, the data area 232 of the sector 200 is read via the optical head 302, the mark position recording decoder 305, and the switch 307 (S5). After reading the sector, switch 303 and switch 307 are turned on.
Return to the ROM area read mode (S6).

Operation for Writing Data to Sectors in Writable Area 24 of Optical Disc 20 When CPU 301 receives address information (track number and sector number) of data to be written from the host computer, it rotates optical disc 20 via the rotation control unit. By rotating at 1800 rpm, the ID section 210 of each sector 200 of the track indicated by the track number specified by the address information is read by irradiating a laser beam of low intensity from the laser diode in the optical head via the LD driver 406. put out. This ID part
Reading of the data 210 is performed via the optical head 302, the mark position recording decoder 305, and the switch 307. Whether the sector indicated by the address information at this time is a sector in the read-only area 22 or a sector in the writable area 24 is determined by the R / W identification signal, and the sector in the writable area 24 is determined. Is determined, the mark position recording encoder 40
4. The information is written to the data area 232 of the sector 200 of the writable area 24 via the LD driver 406 and the optical head 302. Writable area by R / W identification signal 24
If it is determined that the sector is not within the sector, writing is not performed.

Next, FIG. 5 shows the configuration of an optical disc 400 according to a second embodiment of the present invention.

As shown in the figure, in the second embodiment, the read-only area 410 and the writable area 420 are alternately arranged from the innermost circumference of the optical disc 400.

In the read-only area 410, information is recorded by a mark length recording method, and in the writable area 420, information is recorded by a mark position recording method.

Subsequently, Table 2 below shows recording forms (radial position, rotation speed, recording frequency) of the first applied example of the optical disc 400 of the second embodiment.

As shown in Table 2 above, the read-only area 410 is located at a radial position of the optical disc 400 of 30 mm to 35 mm, 40 mm to 45 mm, and 50 mm.
They are arranged concentrically with a width of 5 mm in the radial direction at intervals of 5 mm in the radial direction with m to 55 mm. The writable area 420 is located at a radius position of the optical disc 400 of 35 mm to 40 mm, 45 mm to 50 mm, and 5 mm.
It is arranged at a distance of 5 mm to 60 mm, like the read-only area 410, with an interval of 5 mm in the radial direction and a width of 5 mm in the radial direction.

Then, in both the read-only area 410 and the writable area 420, the rotation control of the optical disc 400 at the time of information reproduction / recording is performed by the CAV method in which the rotational angular velocity is constant, that is, the rotational speed is 3600 rpm. The recording frequency when recording information is:
3.3 MHz read-only area 410, 6.6 M writable area 420
Hz.

That is, also in the first application example of the second embodiment, the recording frequency of the writable area 420 is changed to the read-only area 4.
The recording frequency is twice the recording frequency of 10 and the two areas 410,
To make the storage capacity per track the same in 420,
That is, the same storage density is provided in the two areas 410 and 420.

Thus, the read-only area 410 and the writable area 420
In the case of writing new information relating to information recorded at a radial position of 30 mm in the read-only area into an arbitrary sector of the writable area, the optical head is used in the first embodiment. It is necessary to move the optical head to at least a radius position of 70 mm, and it takes time to access. However, in the case of the first application example of the second embodiment, the optical head is moved to a minimum position of a radius position of 35 mm. High-speed access is possible because you only need to move to

That is, in the application example 1, since the writable area 420 and the read-only area 410 are alternately arranged, new information on the information recorded in the read-only area 410 is located at a radial position as close to the radial direction as possible. Writing to the writable area 420 can be performed, and the access time can be reduced.

Next, Table 3 below shows recording modes of a second application example of the optical disc 400 of the second embodiment.

As shown in Table 3 above, in this second application example,
The arrangement of the read-only area 410 and the writable area 420
Same as the first application example, but the writable area
Only when writing or erasing information to 420
The rotational speed is set to 2400 rpm so that the rotational angular velocity is lower than in the first application example.

This is to improve the disadvantage that when the rotational angular velocity is high, the intensity of the laser spot per unit area decreases, and as a result, the recording sensitivity decreases. As described above, the number of revolutions when writing or erasing information in the writable area 420 is reduced to 2400 rpm, and the recording frequency at that time is reduced to 4.4 MHz in accordance with this. And the same storage capacity per track.

The number of rotations for reading information is set in the read-only area 41.
Both 0 and the writable area 420 are set to 3600 rpm, and the rotation control of information reading is exactly the same as in the first application example. Further, as described above, since the recording density of the mark length recording method is twice the recording density of the mark position recording method as described above, the recording frequency for reading the information is The frequency is set to 6.6 MHz which is twice the reproduction frequency at the time of reading the possible area 420.

Next, Tables 4 and 5 show recording modes of a third application example of the optical disc 400 of the second embodiment. The information recording is performed under the conditions shown in Tables 4 and 5.

Table 4 below shows a recording form of the writable area 420, and Table 5 shows a recording form of the read-only area 410.

As shown in the radial positions in Tables 4 and 5, the arrangement of the read-only area 410 and the writable area 420 is the same as in the first and second application examples.

As shown in Table 4 above, the number of revolutions at the time of writing / erasing information in the writable area 420 is such that the linear velocity is 20 m / s at the radial positions of 40 mm, 50 mm, and 60 mm. Radial position, 35mm-40mm, 45mm-50mm, 55mm-60mm respectively
It is set to 4777,3822,3185rpm.

In accordance with the rotation speed, the recording frequency in the writable area is set to 8.8 (8.7) so that the pit length (magnetic domain length) at the radial position of 35 mm, 45 mm, and 55 mm is 1 μm.
5) MHz, 9.0 MHz, 9.2 (9.17) MHz. The number of rotations for reading information from each of the writable areas 420 is 5
35mm ~ 40mm, 45mm for reading at a constant speed of 400rpm
The frequency (reproduction frequency) when reading information from each writable area 420 of 50 mm to 55 mm and 55 mm to 60 mm is 9.9 MHz, 1
2.7MHz and 15.5MHz.

Further, as shown in Table 5, the rotation speed of the read-only area 410 is set to 5400 rpm so as to be the same as the rotation speed of the writable area 420, and the recording frequency of the read-only area 410 corresponds to the corresponding (adjacent outer peripheral portion). 5.0 MHz (radial position 3) so as to be half of the recording frequency of the writable area 420
0mm to 35mm), 6.4MHz (radial position 40mm to 45mm), 7.8MHz
(Radial position 50mm to 55mm).

As described above, by changing the rotational angular velocity at the time of writing / erasing information in the writable area 420 in several steps, it is possible to reduce the fluctuation of the recording sensitivity in each writable area 420. In the first and second application examples,
Since the number of rotations at the time of writing / erasing information is constant in all the writable areas 420, the rotational linear velocity becomes higher at the outer peripheral portion, and the recording sensitivity decreases at the outer peripheral portion. The third application example solves this drawback.

In the above embodiment, the writable area is formed by the recording film for recording information by the light modulation method. However, the present invention is not limited to this. It is also possible to form it with another material such as a changeable optical memory material.

Further, the rotation speed and the recording frequency used in the present embodiment are as follows.
The value is not limited to the above-mentioned value, and an appropriate value according to the application can be freely set.

〔The invention's effect〕

Information is recorded in advance, and is provided with two areas, a read-only area in which information can only be read and a writable area in which information can be rewritten. In this case, the information can be reliably prevented from being rewritten, and the user can freely use the writable area as a work area, so that it can be used for various purposes and has a large practical effect.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an optical disk according to a first embodiment of the present invention, FIG. 2 is a diagram showing a recording format of a read-only area and a writable area of the first embodiment, and FIGS. FIG. 4B shows a sector configuration diagram of a read-only area and a writable area, respectively. FIG. 4A shows an optical disk drive circuit for controlling reading and writing of information using the optical disk in the first embodiment. FIG. 4 (b) is a flowchart illustrating the operation of the disk drive circuit shown in FIG. 4 (a), FIG. 5 is a configuration diagram of an optical disk according to a second embodiment of the present invention, FIG. 6 is an explanatory diagram of a mark length recording method, and FIG. 7 is an explanatory diagram of a mark position recording method. 20: optical disk, 22: read-only area, 24: writable area.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Seiya Ogawa 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (56) References JP-A-63-237220 (JP, A) JP-A-62- 137744 (JP, A) JP-A-62-121932 (JP, A)

Claims (8)

(57) [Claims] 1. An information storage area in which information is stored using a mark length recording method in an inner peripheral area as a read-only area, and a recording area using the mark length recording method in an outer peripheral area as a writable area. An optical disc having an information storage area in which information is stored using a mark position recording method with a recording frequency higher than a recording frequency, wherein the read-only area and the writable area have the same recording density. . 2. An information storage area using a mark length recording method as a read-only area and an information storage area using a mark position recording method as a writable area. An optical disk characterized in that the areas of the mark position recording system are provided alternately on concentric circles from the inner peripheral side to the outer peripheral side in the radial direction. 3. The optical disk according to claim 1, wherein the recording frequency of the storage area according to the mark position recording method is twice as high as the recording frequency of the storage area according to the mark length recording method. 4. An information storage area using a mark length recording method as a read-only area and an information storage area using a mark position recording method as a writable area having a higher recording frequency than the area of the mark length recording method. When at least the read-only area and the writable area are configured to be accessible to an optical disc having the same recording density, and when accessing the area of the mark position recording method and the area of the mark position recording method An optical disc device comprising: a rotation control unit for controlling the rotation of the optical disc at the same rotational angular velocity. 5. An information storage area using a mark length recording method as a read-only area and an information storage area using a mark position recording method as a writable area having a higher recording frequency than the area of the mark length recording method. At least a rotational angular velocity at the time of performing information write access to the mark position recording method area, and a rotational angular velocity at the time of performing information read access to the mark length recording method area. The rotation control of the optical disc is performed so as to be slower than that, and the rotational angular velocity at the time of performing the information read access to the area of the mark position recording method is the rotational angular velocity at the time of performing the information read access to the area of the mark length recording method. No rotation control means is provided for controlling the rotation of the optical disk so as to be equal to the rotation angular velocity. An optical disc device characterized by the following: 6. The optical disc, wherein information storage areas according to the mark length recording method and the mark position recording method are provided alternately concentrically from an inner peripheral side to an outer peripheral side in a radial direction. When information is recorded by the mark position recording method, the rotation control is performed by a multi-stage CAV method that varies according to the radial position, and further, the recording frequency is variably controlled according to the rotational angular velocity at that time. 6. The optical disk device according to claim 4, further comprising frequency control means. 7. The mark length recording method according to claim 1, wherein said recording frequency control means, when recording information in said mark position recording method, corresponds to a storage capacity per information track recorded in an area of said mark position recording method. 7. The optical disc apparatus according to claim 6, wherein the recording frequency is variably controlled so that the storage capacity per information track in the area is the same. 8. An optical disk having at least an information storage area using a mark length recording method as a read-only area and an information storage area using a mark position recording method as a writable area is configured to be accessible. Discriminating means for discriminating whether the accessed area is a mark length recording area or a mark position recording area; and a demodulation system and a mark position of the mark length recording area based on the discrimination result of the discriminating means. Switching means for switching a transfer route of read data between a recording system demodulation system and a recording system demodulation system.