JPH08190720A - Information processor - Google Patents

Abstract

PURPOSE: To provide a information processor capable of increasing recording capacity of an optical disk in a sample servo system. CONSTITUTION: A servo clock is generated by a 1st clock generating means 9a by rotating the optical disk 1 at a constant angular velocity and regarding a reflected light signal from servo areas arranged at constant angular intervals in the circumferential direction as a reference signal, and servo control (11) is performed on an optical means based on this servo clock. Thus, stable servo operation is carried out. Then, data is recorded and reproduced by selecting (10 and 12) a recording and reproducing clock of a frequency which is higher in accordance with a track positioned toward the outer circumferential side in the radial direction of the optical disk based on recording and reproducing clocks of plural frequencies generated by a 2nd clock generating means 9a-d in synchronization with the reference signal, thus enhancing recording density to increase the recording capacity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for reproducing a digital signal recorded on a disk-shaped recording medium, and more particularly,
The present invention relates to an apparatus for increasing the recording capacity of a recording medium such as an optical disk used as an external storage device of a computer.

[0002]

2. Description of the Related Art Heretofore, in this type of optical disk apparatus, a tracking system is often employed in which a guide groove is provided on the disk in advance and control is performed so that the light beam is positioned above the guide groove. The control error signal in this case is continuously obtained by detecting the diffraction light by the guide groove from the reflected light of the light beam, and is called a continuous servo method. In this continuous servo system, there is a problem that the difference in the shape of the guide groove and the reflectance affects the error signal and deteriorates the tracking accuracy. Also, during recording, a larger amount of light beam is emitted than during reading, so the amount of reflected light also increases proportionally. In such a case, consideration should be given to obtaining an error signal correctly and performing control. Is needed.

On the other hand, in the sample servo system, a guide groove is not used as means for obtaining servo information, but a servo area and a data (information) area are divided on a track and a servo area and a data area are alternately formed. And control is performed so that the light beam passes over this servo area. The control error signal is slightly deviated in the servo area in opposite directions centering on the track position.
The set (two) pits are recorded in advance, and are obtained by detecting the difference in the amount of reflected light when the light beam passes through both pits. As described above, according to the sample servo method, there is no influence of the guide groove, and the control error signal is obtained only in the servo area. Further, in this area, only the operation for obtaining the servo information is always performed. Some of the problems of the continuous servo system are solved, such as the effect of increasing the amount of laser light does not occur. Regarding this sample servo system, SP I E, Proceedings, Optical Mass Data Storage I
I, Vol. 695 (1986) pp. 239-246.
Page (SPIE, Proceedings, Optical Mass DataS
torageII, vol. 695 (1986) pp239-2
46).

On the other hand, in an information recording / reproducing apparatus using an optical disk, a magnetic disk, or the like, a larger capacity apparatus is required in accordance with an increase in the amount of information to be handled. For that purpose, the recording density on the disk is improved. There is a need. The so-called C.I. A. In the V (Constant Angular Velocity) method, the pit period is limited at the innermost circumference where the linear velocity is the slowest. Therefore, a margin is generated toward the outer periphery, and, for example, the recording density is reduced to で は at the outer periphery having a diameter twice as large as the innermost periphery. Thus, C.I. A.
V. In the method, the recording capacity of the disc is not fully utilized, resulting in waste.

On the other hand, the C.I.
L. V. In the (Constant Linear Velocity) method, the recording density is the same from the inner circumference to the outer circumference, and the maximum recording capacity can be obtained. However, C.I. L.
V. In this method, the number of rotations of the disk must be changed according to the track position, and the access time is C.I. A. V. However, there is a problem as a data recording / reproducing apparatus for a computer that requires random access and high-speed access. Therefore, as one of the methods aimed at eliminating the disadvantages of both types, there is a device that divides a disk into a plurality of regions in the radial direction and sets different rotation speeds so that the recording density is increased in each region. It is described in JP-A-61-17223. Japanese Patent Application Laid-Open No. Sho 61 (1994) discloses an apparatus for increasing the recording capacity by dividing the area into a plurality of areas and changing the pit period in each area while keeping the rotation speed constant.
No. 175968.

[0006]

The above prior arts all relate to an optical disk device of a continuous servo system, and do not take into consideration an optical disk device of a sample servo system. The sample servo method uses a so-called embedded clock method in which a clock pit recorded in the servo area is detected and clock reproduction is performed based on this. Since this reproduced clock serves as a reference for all operations including the servo, it is necessary to always obtain a stable clock. Further, since the cycle of obtaining the servo information affects the servo characteristics, it is necessary to make the cycle constant. However, if the number of revolutions or the recording data cycle is changed depending on the area on one disk, the cycle of servo information changes at the same time and the servo characteristics also change, so the problem of having to switch the servo characteristics also arises. is there.

An object of the present invention is to provide an information reproducing apparatus for reproducing information on a disk-shaped information recording medium by a sample servo system in which a recording capacity is increased without changing a sampling period of servo information.

[0008]

DISCLOSURE OF THE INVENTION It is an object of the present invention to provide a disc-shaped information recording / reproducing medium in which information areas and servo areas are alternately arranged on the same track and servo areas are arranged at regular angular intervals. Drive means for rotating the optical disk at a constant angular velocity, optical means for irradiating the information recording / reproducing medium with a light beam and detecting reflected light from the information recording / reproducing medium, and servo from the reflected light signal in the servo area detected by the optical means. In an information reproducing apparatus including a servo means for controlling servo means by obtaining servo information based on a clock,
Using the reflected light signal from the servo area as a reference signal, the first clock reproducing means for generating a servo clock in synchronization with the recording cycle of the servo information in the servo area and the reproduction time interval of the servo information area are equally divided, And a second clock regeneration means for generating clocks of different frequencies synchronized with the reference signal, and which frequency clock is used among the plurality of clocks generated by the second clock regeneration means. The control means for instructing, the recording means for recording the information in the information area based on the clock selected by this means, and the reproducing means for reproducing the information based on the clock selected by the control means are provided. It is achieved by

[0009]

The first clock reproducing means always reproduces a clock having a constant frequency by using predetermined information (clock pit) in the servo area as a reference signal. Using this clock, servo information is detected and a stable servo operation is performed. Similarly, the second clock reproducing means uses the clock pit in the servo area as a reference signal, but changes the reproduced clock frequency according to the track position. This makes it possible to change the information recording density according to the radial track position while keeping the rotational speed of the information recording medium (disk) constant.

That is, when recording data on the disc, for example, recording is performed based on the clock of the frequency instructed by the control means from the reproduction clock generated by the second clock reproduction means. For example, by increasing the clock frequency toward the outer periphery,
The recording density on the disc can be improved, and the recording capacity can be increased. Then, the data in the data area is reproduced based on a clock having the same frequency as the clock designated by the control means at the time of the recording.

[0011]

EXAMPLE An example of the present invention will be described with reference to FIG. Although FIG. 1 is a block diagram of an optical disk device according to the sample servo system using the present invention, parts not involved in the description of the features and operations of the present invention are not shown. In the figure, 1 is an optical disk, 2 is a disk motor, 3 is an optical pickup device, 4 is a laser driver, 5 is a preamplifier, 6 is a peak detection circuit, 7 is a modulation circuit, 8 is a demodulation circuit, and 9a to d are clock reproduction. Circuit, 10 is a selection circuit, 1
Reference numeral 1 is a tracking error detection circuit, and 12 is a control circuit. The optical disk 1 is rotated by a disk motor 2 at a constant angular velocity.

Writing / reading of data to / from the disk is performed by the optical pickup 3. The write data is subjected to a predetermined modulation by the modulation circuit 7 and then input to the laser driver 4, where the laser diode is driven and converted into the intensity of the light beam. Data is recorded on the optical disc 1 by changing the reflectance of light according to the intensity of the irradiated light beam and leaving the change of reflectance even after the light beam passes. In reading, the laser diode emits a weak light beam that does not cause a change in reflectance as in writing, and the reflected light when the light beam is applied to the optical disc 1 is detected by a photodetector to detect the reflectance. The difference in the amount of reflected light due to the difference is converted into an electric signal. The detected signal is amplified by the preamplifier 5 and then demodulated by the demodulation circuit 8 to restore the original data.

In order to realize data recording / reproducing with such a light beam, a light beam is accurately irradiated onto a previously set track on an optical disk.
So-called tracking control is necessary. In the sample servo system, servo areas and data areas are alternately arranged as shown in FIG. 2, and servo information such as tracking control is obtained only from the servo areas. Therefore, the servo information is obtained not as a continuous signal but as a discrete signal.
The tracking error information is obtained by the light amount difference between the first tracking pit 21 and the second tracking pit 22 when the light beam passes through the servo area. That is, since the two tracking pits are recorded on both sides of the center line of the track with an equal distance offset, when the irradiation position of the light beam deviates from the center of the track, the tracking pits on the deviated side are formed. The amount of reflected light of the track pit increases and the amount of reflected light of the tracking pit on the opposite side decreases. When the light beam irradiates the center of the track correctly, the reflected light amounts of both tracking pits are the same. Therefore, the amount and direction of tracking deviation can be discriminated by the difference between the amounts of reflected light of both tracking pits and the polarity, and tracking control is performed by controlling the light beam so as to cancel it.

In order to realize the tracking control by such a sampling method, a clock signal for accurately extracting the reproduction signal from the tracking pit is required. To obtain the clock signal, the clock pit 2 which is the third bit of the servo area signal shown in FIG.
Obtain from 3. A clock that equally divides the clock pits by a predetermined number is generated based on the reproduction signal of the clock pits obtained for each servo area. By forming the above-mentioned tracking pit in advance so that the reproduced signal can be obtained at a position synchronized with this clock signal,
The reproduction signal of the tracking pit can be accurately extracted.

As described above, the sample servo method is characterized in that a clock synchronized with the rotation of the disk is used. This clock is used not only for obtaining servo information but also for recording and reproducing data in a data area. .

The larger the number of servo information in one round of the disk, the better the servo characteristics can be obtained, but the data area becomes small and the recording capacity decreases. Conversely, if the number of servo areas is reduced, sufficient servo characteristics cannot be obtained. 1800 rp
The appropriate number when rotating at m is 1 per disk
It is 000 to 2000 pieces. In order to record and reproduce data by moving the pickup randomly from the inner circumference to the outer circumference of the disk, it is necessary that the intervals on the time axis of the servo areas be constant over the entire area of the disk. Therefore, the servo areas are linearly arranged from the center of the disk toward the outer circumference at regular intervals. Even if the pickup is moved in the radial direction of the disk, a reproduction signal in the servo area is obtained at a constant interval, so that a constant servo characteristic is always obtained, and a tracking operation can be performed immediately at the moving destination, so that high-speed access can be realized.

However, the fact that the servo area is constant on the time axis, that is, the reproduction time interval of the servo area is constant, requires that the above-mentioned clock be constant, and as a result, the same clock is used. Since the recording and reproduction of data also have a fixed period, the recording density is reduced toward the outer periphery of the disk.

Therefore, in the present invention, the recording density of data can be increased by making the clock for servo signal detection and the clock for data recording / reproduction different. FIG. 3 shows an example of an optical disc according to the present invention. In this optical disc 1, servo areas are arranged radially from the center of the disc, and when rotated at a constant rotation, a reproduction signal is obtained at a constant time interval. On the other hand, the data area is divided into four areas as shown in the figure, and recording and reproduction are performed at different clocks. However, the dividing lines in the figure are imaginary for the sake of explanation, and the tracks are continuous even at the boundary between the regions.

An example of division of each area is shown in FIG. Each area is 5
The data is divided into 000 tracks, the area a is 32 sectors per revolution, and if the data area sandwiched by the servo areas is 1 segment, the data recorded during this is 1
6 bytes, recording clock frequency is 11.456 MHz
Is. This clock frequency is the same as the clock for detecting the servo signal, and is a clock that divides the clock pits into 270 equal parts based on the clock pits described above. Area b has 39 sectors per round, 20 bytes per segment, and recording clock frequency is 13.9526M.
The frequency becomes Hz, and this frequency is obtained by equally dividing 338 between clock pits. Similarly, areas c and d are also set as shown in the figure, and the recording clock frequencies correspond to 405 equal parts and 473 equal parts of clock pits, respectively. The recording capacity is 43.25 MByte, which is 1.35 times as large as 320 MByte when the entire area is recorded with the setting a. The clock frequency is generated by the four clock recovery circuits 9a to 9d in FIG. Clock recovery circuit a is 1
1.1456MHz, clock recovery circuit b is 13.95
26MHz, clock recovery circuit c is 16.1874M
Hz and the clock recovery circuit d generate 19.5254 MHz, respectively. Each clock output is input to the selection circuit 10, and the clock generated by the clock reproduction circuit a is input to the tracking error detection circuit 11 and used for extracting the tracking pit reproduction signal. Each clock input to the selection circuit 10 is composed of a microprocessor or the like according to a track number for recording / reproducing.
One clock is selected by the selection signal output from the input circuit and input to the modulation circuit and the demodulation circuit.

The clock recovery circuits 9a to 9d are so-called PLL (Phase Locked Loop) shown in FIG.
Locked loop) circuit. This PLL
The circuit includes a phase comparator 91, a low-pass filter 92, a voltage-controlled oscillator 93, and a frequency divider 94. Voltage control is performed so that the phase of the output of the frequency divider 94 matches the phase of a reference signal input from the outside. The oscillation frequency and phase of the oscillator 93 are controlled. Therefore, the output of the voltage controlled oscillator is a clock signal whose frequency is a value obtained by multiplying the reference signal by the frequency division ratio of the frequency divider 94, and whose phase is always a constant value with respect to the reference signal. In this example, the reference signal is a clock pit which is the third pit in the servo area described above,
The output clock signals are the above-mentioned four types of clock signals. For example, in the clock recovery circuit a, the frequency divider 9
4 is 270, and the voltage controlled oscillator 93 generates 11.456 MHz at the center value of the control voltage.
The oscillation frequency control element is adjusted. Clock recovery circuit b
Similarly, a predetermined frequency division ratio and oscillation frequency are set in the case of .about.d.

FIG. 6 shows the relationship between the reproduced signal and the clock on the actual optical disk. A to d in FIG.
They correspond to the areas a to d in FIG. 3, respectively. Reference numeral 23 is a clock pit, and 25a to 25d are head pits of the data area. Since the clocks are generated in synchronization with the clock pits, the phases of all the clocks are aligned at this point, but thereafter, the frequencies are different, so that there is a phase shift between the clocks. The start position of the data area is set at a certain interval or longer (time distance) in order to prevent the additional write data from affecting the clock pit. Similarly, the interval between the end point of the data area and the first tracking pit is also maintained at a certain interval or more. As shown in FIGS. 3 and 4, when the area is equally divided into four areas, the areas b, c, and d are 1.25 times and 1.5, respectively, based on the area a.
A 1.75 times recording capacity can be obtained. When the total number of clocks is 270, the allocation of the servo area and the data area between one segment in the area a is 30 clocks in the servo area and 240 clocks in the data area (15 clocks × 16).
Byte). When the same distribution ratio is applied to region b, 1.
25 times, the total number of clocks is 337.5 clocks, the servo area is 37.5 clocks, and the data area is 300 clocks. However, since the frequency division ratio of the clock recovery circuit needs to be an integer, the number of clocks that can be taken is 337 or 338. In the former case, the servo area is 37
0.5 clock shorter than the original length
The interval between the clock pit and the data pit or the first tracking pit and the data pit described above becomes shorter than in the case of the area a. In the latter case, the servo area has 38 clocks, and there is no problem with the interval with the data area, but the pit interval of the first track in area b is shorter than the first part of area a, that is, the innermost circumference of the disk. I will end up. A solution to this problem is realized by shifting the start point of the area b around the outer circumference. Inner circumference radius 30m
In the case where recording and reproduction are performed at a pitch of 1.5 μm on a disc having an outer circumference of 60 mm and an outermost radius of 60 mm, this can be achieved by shifting the start point of the area b by 0.57 mm from the point of 37.5 mm. The number of tracks in this portion is 57, and the recording capacity is reduced by this amount, but this is not a problem from the viewpoint of the total capacity. Which of the three methods is adopted is determined by the margin setting of the entire optical disk device. In the regions c and d, the clock frequency is determined based on the same concept.

A second embodiment of the optical disk device according to the present invention is shown in FIG. In the figure, the same components as those in FIG. 1 are denoted by the same reference numerals. In this example,
It has two clock recovery circuits. The operation will be described assuming that the optical disks of FIGS. 3 and 4 are used. The first clock reproducing circuit 9 generates a clock 11.1456 MHz for detecting a tracking pit, and the second clock reproducing circuit 9'is a control device. Four kinds of clocks are generated by 12 selection signals. Second clock recovery circuit 9 '
FIG. 8 shows a configuration example of the above. The frequency dividing ratio variable frequency divider 95 is set to divide by 270, 338, 405 and 473 by a selection signal. The oscillating element of the voltage controlled oscillator 93 is adjusted so as to oscillate the center frequency of 4 frequencies at the center value of the control voltage.
The clock recovery circuit as a whole must have a pull-in range that covers all four frequencies. Next, FIG. 9 shows a second configuration example of the second clock recovery circuit. In this example, not only the division ratio but also the center frequency of the voltage controlled oscillator is switched by the selection signal, so that the switching element 96 switches the oscillation element. Each oscillating element is adjusted so that one of the four frequencies becomes the center frequency. The clock recovery circuit in this case does not need to have a wide pull-in range as in the embodiment of FIG.

The embodiment of FIG. 7 can reduce the number of clock recovery circuits as compared with the embodiment of FIG. But,
The access speed decreases because the synchronous operation of the clock recovery circuit is performed every time the area boundary is crossed. In addition, continuous recording and reproduction beyond the boundary cannot be performed.

As described above, according to this embodiment, in the optical disk of the sample servo system, the capacity can be increased without changing the servo characteristics. Also,
If the clock frequency is not switched using this apparatus, recording and reproduction of an optical disk to which the present invention is not applied can be performed without any problem.

Although the present embodiment has been described using numerical values in the case of dividing into four regions as an example, the gist of the present invention is not limited to the number of divisions and the numerical values described above. And various combinations are possible.

[0026]

According to the present invention, the recording capacity of the optical disk by the sample servo method can be increased without affecting the servo circuit.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment according to the present invention.

FIG. 2 is a waveform diagram of a reproduction signal of an optical disc.

FIG. 3 is a schematic diagram showing area division of an optical disc.

FIG. 4 is a diagram illustrating a numerical example in the case of performing four-region division.

FIG. 5 is a configuration diagram of a clock recovery circuit.

FIG. 6 is a waveform diagram when divided into four regions.

FIG. 7 is a configuration diagram of a second embodiment according to the present invention.

FIG. 8 illustrates a first clock recovery circuit according to the second embodiment.
It is a block diagram of the Example of.

FIG. 9 is a second clock recovery circuit according to the second embodiment.
It is a block diagram of the Example of.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 optical disk 3 optical pickup 7 modulation circuit 8 demodulation circuit 9a-9d clock reproduction circuit 10 selection circuit 11 tracking error detection circuit 12 control device 91 phase comparator 92 low pass filter 93 voltage controlled oscillator 94 frequency divider

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[Procedure amendment]

[Submission date] July 21, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

[Title of the Invention] information processing apparatus

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for processing a digital signal recorded on a disk-shaped information medium having information recorded thereon, and more particularly to an information medium such as an optical disk used as an external storage device of a computer. The present invention relates to a device that realizes an increase in recording capacity.

[0002]

2. Description of the Related Art Heretofore, in this type of optical disk apparatus, a tracking system is often employed in which a guide groove is provided on the disk in advance and control is performed so that the light beam is positioned above the guide groove. The control error signal in this case is continuously obtained by detecting the diffraction light by the guide groove from the reflected light of the light beam, and is called a continuous servo method. In this continuous servo system, there is a problem that the difference in the shape of the guide groove and the reflectance affects the error signal and deteriorates the tracking accuracy. Also, during recording, a larger amount of light beam is emitted than during reading, so the amount of reflected light also increases proportionally. In such a case, consideration should be given to obtaining an error signal correctly and performing control. Is needed.

On the other hand, in the sample servo system, a guide groove is not used as means for obtaining servo information, but a servo area and a data (information) area are divided on a track and a servo area and a data area are alternately formed. And control is performed so that the light beam passes over this servo area. The control error signal is slightly deviated in the servo area in opposite directions centering on the track position.
The set (two) pits are recorded in advance, and are obtained by detecting the difference in the amount of reflected light when the light beam passes through both pits. As described above, according to the sample servo method, there is no influence of the guide groove, and the control error signal is obtained only in the servo area. Further, in this area, only the operation for obtaining the servo information is always performed. Some of the problems of the continuous servo system are solved, such as the effect of increasing the amount of laser light does not occur. Regarding this sample servo system, SP I E, Proceedings, Optical Mass Data Storage I
I, Vol. 695 (1986) pp. 239-246.
Page (SPIE, Proceedings, Optical Mass DataS
torageII, vol. 695 (1986) pp239-2
46).

On the other hand, in the information processing apparatus using such as an optical disk or a magnetic disk, but devices of larger capacity than with the amount of information increases to handle has been demanded. For this purpose,
It is necessary to improve the recording density on the disc. The so-called C.I. A. In the V (Constant Angular Velocity) method, the pit period is limited at the innermost circumference where the linear velocity is the slowest. Therefore, a margin is generated toward the outer periphery, and, for example, the recording density is reduced to で は at the outer periphery having a diameter twice as large as the innermost periphery. Thus, C.I. A. V. In the method, the recording capacity of the disc is not fully utilized, resulting in waste.

On the other hand, the C.I.
L. V. In the (Constant Linear Velocity) method, the recording density is the same from the inner circumference to the outer circumference, and the maximum recording capacity can be obtained. However, C.I. L.
V. In this method, the number of rotations of the disk must be changed according to the track position, and the access time is C.I. A. V. However, there is a problem as a data recording / reproducing apparatus for a computer that requires random access and high-speed access. Therefore, as one of the methods aimed at eliminating the disadvantages of both types, there is a device that divides a disk into a plurality of regions in the radial direction and sets different rotation speeds so that the recording density is increased in each region. It is described in JP-A-61-17223. Japanese Patent Application Laid-Open No. Sho 61 (1994) discloses an apparatus for increasing the recording capacity by dividing the area into a plurality of areas and changing the pit period in each area while keeping the rotation speed constant.
No. 175968.

[0006]

The above prior arts all relate to an optical disk device of a continuous servo system, and do not take into consideration an optical disk device of a sample servo system. The sample servo method uses a so-called embedded clock method in which a clock pit recorded in the servo area is detected and clock reproduction is performed based on this. Since this reproduced clock serves as a reference for all operations including the servo, it is necessary to always obtain a stable clock. Further, since the cycle of obtaining the servo information affects the servo characteristics, it is necessary to make the cycle constant. However, if the number of revolutions or the recording data cycle is changed depending on the area on one disk, the cycle of servo information changes at the same time and the servo characteristics also change, so the problem of having to switch the servo characteristics also arises. is there.

An object of the present invention is to provide an information processing apparatus for reproducing information of a disc-shaped information Honakadachi body by the sample servo method having increased recording capacity without changing the sample period of the servo information .

[0008]

The above object is to drive a disc-shaped information medium in which information areas and servo areas are alternately arranged on the same track and the servo areas are arranged at constant angular intervals at a constant angular velocity. means and,該情optical means for detecting the reflected light from該情Honakadachi body irradiates a light beam to Honakadachi body, servo information based on the reflected light signal of the servo area detected by the optical means in the information processing apparatus including a servo means for controlling the optical means to obtain,
The reflected light signal from the servo area as a reference signal, a first clock generating means for generating a servo clock in synchronism with the recording period of the servo information of the servo area, the servo
Aliquoted detection time interval realm, and a second clock generating means for generating said reference signal a plurality of different frequencies synchronized with the clock, a plurality of which are generated by said second clock generating means Control means for instructing which frequency of the clock is to be used, and processing of information in the information area based on the clock selected by the control means.
It is achieved by including a processing means for processing .

[0009]

The first clock generating means always reproduces a clock having a constant frequency by using predetermined information (clock pit) in the servo area as a reference signal. Using this clock, servo information is detected and a stable servo operation is performed. Similarly, the second clock generating means uses the clock pit in the servo area as a reference signal, but changes the reproduction clock frequency according to the track position. This allows information
While maintaining Honakadachi body rotational speed (disk) to be constant,
It is possible to change the information recording density according to the track position in the radial direction.

That is, in recording data on the disk, for example, recording is performed based on a clock of a frequency designated by the control means from among reproduction clocks generated by the second clock generation means. For example, by increasing the clock frequency toward the outer periphery,
The recording density on the disc can be improved, and the recording capacity can be increased. Then, the data in the data area is reproduced based on a clock having the same frequency as the clock designated by the control means at the time of the recording.

[0011]

EXAMPLE An example of the present invention will be described with reference to FIG. FIG. 1 is a configuration diagram of an information processing apparatus using an optical disk according to a sample servo method using the present invention, but does not show parts that are not involved in the description of features and operations of the present invention. In the figure, 1 is an optical disk, 2 is a disk motor, 3 is an optical pickup device, 4 is a laser driver, 5 is a preamplifier, 6 is a peak detection circuit, 7 is a modulation circuit, 8 is a demodulation circuit, and 9a to 9d are clock reproduction. Circuit, 10
Is a selection circuit, 11 is a tracking error detection circuit, and 12 is a control circuit. The optical disk 1 is rotated by a disk motor 2 at a constant angular velocity.

Writing / reading of data to / from the disk is performed by the optical pickup 3. The write data is subjected to a predetermined modulation by the modulation circuit 7 and then input to the laser driver 4, where the laser diode is driven and converted into the intensity of the light beam. Data is recorded on the optical disc 1 by changing the reflectance of light according to the intensity of the irradiated light beam and leaving the change of reflectance even after the light beam passes. In reading, the laser diode emits a weak light beam that does not cause a change in reflectance as in writing, and the reflected light when the light beam is applied to the optical disc 1 is detected by a photodetector to detect the reflectance. The difference in the amount of reflected light due to the difference is converted into an electric signal. The detected signal is amplified by the preamplifier 5 and then demodulated by the demodulation circuit 8 to restore the original data.

In order to realize data recording / reproducing with such a light beam, a light beam is accurately irradiated onto a previously set track on an optical disk.
So-called tracking control is necessary. In the sample servo system, servo areas and data areas are alternately arranged as shown in FIG. 2, and servo information such as tracking control is obtained only from the servo areas. Therefore, the servo information is obtained not as a continuous signal but as a discrete signal.
The tracking error information is obtained by the light amount difference between the first tracking pit 21 and the second tracking pit 22 when the light beam passes through the servo area. That is, since the two tracking pits are recorded on both sides of the center line of the track with an equal distance offset, when the irradiation position of the light beam deviates from the center of the track, the tracking pits on the deviated side are formed. The amount of reflected light of the track pit increases and the amount of reflected light of the tracking pit on the opposite side decreases. When the light beam irradiates the center of the track correctly, the reflected light amounts of both tracking pits are the same. Therefore, the amount and direction of tracking deviation can be discriminated by the difference between the amounts of reflected light of both tracking pits and the polarity, and tracking control is performed by controlling the light beam so as to cancel it.

In order to realize the tracking control by such a sampling method, a clock signal for accurately extracting the reproduction signal from the tracking pit is required. To obtain the clock signal, the clock pit 2 which is the third bit of the servo area signal shown in FIG.
Obtain from 3. A clock that equally divides the clock pits by a predetermined number is generated based on the reproduction signal of the clock pits obtained for each servo area. By forming the above-mentioned tracking pit in advance so that the reproduced signal can be obtained at a position synchronized with this clock signal,
The reproduction signal of the tracking pit can be accurately extracted.

As described above, the sample servo method is characterized in that a clock synchronized with the rotation of the disk is used. This clock is used not only for obtaining servo information but also for recording and reproducing data in a data area. .

The larger the number of servo information in one round of the disk, the better the servo characteristics can be obtained, but the data area becomes small and the recording capacity decreases. Conversely, if the number of servo areas is reduced, sufficient servo characteristics cannot be obtained. 1800 rp
The appropriate number when rotating at m is 1 per disk
It is 000 to 2000 pieces. In order to record and reproduce data by moving the pickup randomly from the inner circumference to the outer circumference of the disk, it is necessary that the intervals on the time axis of the servo areas be constant over the entire area of the disk. Therefore, the servo areas are linearly arranged from the center of the disk toward the outer circumference at regular intervals. Even if the pickup is moved in the radial direction of the disk, a reproduction signal in the servo area is obtained at a constant interval, so that a constant servo characteristic is always obtained, and a tracking operation can be performed immediately at the moving destination, so that high-speed access can be realized.

However, the fact that the servo area is constant on the time axis, that is, the reproduction time interval of the servo area is constant, requires that the above-mentioned clock be constant, and as a result, the same clock is used. Since the recording and reproduction of data also have a fixed period, the recording density is reduced toward the outer periphery of the disk.

Therefore, in the present invention, the recording density of data can be increased by making the clock for servo signal detection and the clock for data recording / reproduction different. FIG. 3 shows an example of an optical disc according to the present invention. In this optical disc 1, servo areas are arranged radially from the center of the disc, and when rotated at a constant rotation, a reproduction signal is obtained at a constant time interval. On the other hand, the data area is divided into four areas as shown in the figure, and recording and reproduction are performed at different clocks. However, the dividing lines in the figure are imaginary for the sake of explanation, and the tracks are continuous even at the boundary between the regions.

An example of division of each area is shown in FIG. Each area is 5
000 is divided for each track, the region a is 32 sectors per round, configuring one segment by a servo area and a data area and other data of 16 bytes is recorded in one segment, the recording clock frequency is 11.14
56 MHz. This clock frequency is the same as the clock for detecting the servo signal, and is a clock that divides the clock pits into 270 equal parts based on the clock pits described above. Area b is 39 sectors per round, 20 bytes per segment, and recording clock frequency is 13.9.
It becomes 526MHz and this frequency is 3 between clock pits.
It will be divided into 38 equal parts. Similarly, areas c and d are also set as shown in the figure, and the recording clock frequencies correspond to 405 equal parts and 473 equal parts of clock pits, respectively. The recording capacity is 320MByte when the entire area is recorded with setting a.
43.5 MBytes, which is 1.35 times as large as that of FIG. The generation of the clock frequency is performed by the four clock generation circuits 9a to 9d in FIG. Clock generation circuit a
Is 11.1456 MHz, and the clock generation circuit b is 13.
9526 MHz, the clock generation circuit c is 16.718
4 MHz, clock generation circuit d is 19.5254 MHz
Are generated respectively. Each clock output is input to the selection circuit 10, and the generated clock of the clock generation circuit a is input to the tracking error detection circuit 11, which is used for extracting a tracking pit reproduction signal. As for each clock input to the selection circuit 10, one clock is selected by a selection signal output from a control device 12 composed of a microprocessor or the like according to a track number for performing recording and reproduction, and is supplied to a modulation circuit and a demodulation circuit. Is entered.

The clock recovery circuits 9a to 9d are so-called PLL (Phase Locked Loop) shown in FIG.
Locked loop) circuit. This PLL
The circuit includes a phase comparator 91, a low-pass filter 92, a voltage-controlled oscillator 93, and a frequency divider 94. Voltage control is performed so that the phase of the output of the frequency divider 94 matches the phase of a reference signal input from the outside. The oscillation frequency and phase of the oscillator 93 are controlled. Therefore, the output of the voltage controlled oscillator is a clock signal whose frequency is a value obtained by multiplying the reference signal by the frequency division ratio of the frequency divider 94, and whose phase is always a constant value with respect to the reference signal. In this example, the reference signal is a clock pit which is the third pit in the servo area described above,
The output clock signals are the above-mentioned four types of clock signals. For example, in the clock recovery circuit a, the frequency divider 9
4 is 270, and the voltage controlled oscillator 93 generates 11.456 MHz at the center value of the control voltage.
The oscillation frequency control element is adjusted. Clock generation circuit b
Similarly, a predetermined frequency division ratio and oscillation frequency are set in the case of .about.d.

FIG. 6 shows the relationship between the reproduced signal and the clock on the actual optical disk. A to d in FIG.
They correspond to the areas a to d in FIG. 3, respectively. Reference numeral 23 is a clock pit, and 25a to 25d are head pits of the data area. Since the clocks are generated in synchronization with the clock pits, the phases of all the clocks are aligned at this point, but thereafter, the frequencies are different, so that there is a phase shift between the clocks. The start position of the data area is set at a certain interval or longer (time distance) in order to prevent the additional write data from affecting the clock pit. Similarly, the interval between the end point of the data area and the first tracking pit is also maintained at a certain interval or more. As shown in FIGS. 3 and 4, when the area is equally divided into four areas, the areas b, c, and d are 1.25 times and 1.5, respectively, based on the area a.
A 1.75 times recording capacity can be obtained. When the total number of clocks is 270, the allocation of the servo area and the data area between one segment in the area a is 30 clocks in the servo area and 240 clocks in the data area (15 clocks × 16).
Byte). When the same distribution ratio is applied to region b, 1.
25 times, the total number of clocks is 337.5 clocks, the servo area is 37.5 clocks, and the data area is 300 clocks. However, since the frequency division ratio of the clock generation circuit needs to be an integer, the number of possible clocks is 337 or 338. In the former case, the servo area is 37
0.5 clock shorter than the original length
The interval between the clock pit and the data pit or the first tracking pit and the data pit described above becomes shorter than in the case of the area a. In the latter case, the servo area has 38 clocks, and there is no problem with the interval with the data area, but the pit interval of the first track in area b is shorter than the first part of area a, that is, the innermost circumference of the disk. I will end up. A solution to this problem is realized by shifting the start point of the area b around the outer circumference. Inner circumference radius 30m
In the case where recording and reproduction are performed at a pitch of 1.5 μm on a disc having an outer circumference of 60 mm and an outermost radius of 60 mm, this can be achieved by shifting the start point of the area b by 0.57 mm from the point of 37.5 mm. The number of tracks in this portion is 57, and the recording capacity is reduced by this amount, but this is not a problem from the viewpoint of the total capacity. Which of the three methods is adopted is determined by the margin setting of the entire optical disk device. In the regions c and d, the clock frequency is determined based on the same concept.

FIG. 7 shows a second embodiment of an information processing apparatus using an optical disk according to the present invention. In the figure, the same components as those in FIG. 1 are denoted by the same reference numerals. In this example, there are two clock generation circuits. The operation will be described assuming that the optical disk shown in FIGS. 3 and 4 is used. The first clock generation circuit 9 generates a clock of 11.456 MHz for detecting a tracking pit, and the second clock generation circuit 9 'controls the control device. Four types of clocks are generated by twelve selection signals. FIG. 8 shows a configuration example of the second clock generation circuit 9 '. The frequency division ratio variable frequency divider 95 receives signals 270, 338, 405, 4
73 division is set. The oscillating element of the voltage controlled oscillator 93 is adjusted so as to oscillate the center frequency of 4 frequencies at the center value of the control voltage. The clock recovery circuit as a whole must have a pull-in range that covers all four frequencies. Next, FIG. 9 shows a second configuration example of the second clock generation circuit. In this example, not only the division ratio but also the center frequency of the voltage controlled oscillator is switched by the selection signal, so that the switching element 96 switches the oscillation element. Each oscillating element is adjusted so that one of the four frequencies becomes the center frequency. The clock generation circuit in this case does not need to have a wide pull-in range as in the embodiment of FIG.

The embodiment of FIG. 7 can reduce the number of clock generation circuits as compared with the embodiment of FIG. But,
Each time the boundary of the area is exceeded, the synchronous operation of the clock generation circuit is performed, so that the access speed is reduced. In addition, continuous recording and reproduction beyond the boundary cannot be performed.

As described above, according to this embodiment, in the optical disk of the sample servo system, the capacity can be increased without changing the servo characteristics. Also,
If the clock frequency is not switched using this apparatus, recording and reproduction of an optical disk to which the present invention is not applied can be performed without any problem.

Although the present embodiment has been described using numerical values in the case of dividing into four regions as an example, the gist of the present invention is not limited to the number of divisions and the numerical values described above. And various combinations are possible.

[0026]

According to the present invention, the recording capacity of the optical disk by the sample servo method can be increased without affecting the servo circuit.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment according to the present invention.

FIG. 2 is a waveform diagram of a reproduction signal of an optical disc.

FIG. 3 is a schematic diagram showing area division of an optical disc.

FIG. 4 is a diagram illustrating a numerical example in the case of performing four-region division.

FIG. 5 is a configuration diagram of a clock generation circuit.

FIG. 6 is a waveform diagram when divided into four regions.

FIG. 7 is a configuration diagram of a second embodiment according to the present invention.

FIG. 8 illustrates a first example of the clock generation circuit according to the second embodiment.
It is a block diagram of the Example of.

FIG. 9 illustrates a second example of the clock generation circuit according to the second embodiment.
It is a block diagram of the Example of.

[Description of Codes] 1 optical disk 3 optical pickup 7 modulation circuit 8 demodulation circuit 9a to 9d clock generation circuit 10 selection circuit 11 tracking error detection circuit 12 control device 91 phase comparator 92 low pass filter 93 voltage controlled oscillator 94 frequency divider

[Procedure Amendment 2]

[Document name to be corrected] Drawing

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[Correction method] Change

[Correction content]

FIG.

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 7

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[Figure 7]

Claims (6)

[Claims] 1. A disk-shaped information recording / reproducing medium in which information areas and servo areas are alternately arranged on the same track and the servo areas are arranged at constant angular intervals, and the information recording / reproducing medium is rotated at a constant angular velocity. Driving means, optical means for irradiating the information recording / reproducing medium with a light beam and detecting reflected light from the information recording / reproducing medium, and servo information based on a reflected light signal of a servo area detected by the optical means. And a servo means for controlling the optical means to control the optical means, and a reflected light signal from the servo area is used as a reference signal, and the servo clock is synchronized with the recording cycle of the servo information in the servo area. And a reproduction time interval of the servo information area is equally divided,
And a second clock regeneration means for generating clocks of different frequencies synchronized with the reference signal, and which frequency clock is used among the plurality of clocks generated by the second clock regeneration means An information reproducing apparatus comprising: a control unit for instructing the above, and a reproducing unit for reproducing the information recorded in the information area based on the clock selected by the control unit. 2. The information reproducing apparatus according to claim 1, wherein the second clock reproducing means is composed of one clock reproducing circuit, and the clock reproducing circuit generates a clock having a different frequency according to an instruction from the control means. An information recording / reproducing apparatus, wherein the frequency of the clock is higher than the frequency of the servo clock. 3. The information reproducing apparatus according to claim 1, wherein the second clock reproducing means outputs a plurality of clock reproducing circuits for respectively generating the plurality of clocks. And a selection circuit having a plurality of clocks as inputs, the selection circuit
An information reproducing apparatus for selecting one of the plurality of clocks based on an instruction from the control means, the plurality of clocks having a frequency equal to or higher than a frequency of the servo clock. 4. The information reproducing apparatus according to claim 1, wherein the control means selects one of a plurality of clocks generated by the second clock reproducing means according to a track number of the information recording medium. In addition, the information reproducing apparatus is characterized in that a higher frequency is selected for tracks on the outer peripheral side. 5. The information reproducing apparatus according to claim 1, wherein the control unit divides a track of the recording medium into a plurality of groups, and the plurality of groups of the second clock reproducing unit are divided according to the groups. Select clocks in stages,
An information reproducing apparatus, wherein a clock having the same frequency as the servo clock is selected in the innermost group, and a clock having a higher frequency is selected in the outermost group. 6. The information reproducing apparatus according to claim 1, wherein the control unit is common to all track numbers of the recording medium, and has a plurality of clocks generated by the second clock reproducing unit. An information reproducing apparatus, characterized in that one of the above is selected.