JP3474183B2 - Disk-shaped recording medium and recording / reproducing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing apparatus having a disk recording medium, and more particularly to a large capacity disk file apparatus.

[0002]

2. Description of the Related Art A CAV (Constant Angular Velocity) method, in which a disc is rotated at a constant angular velocity for recording / reproduction, and a disc is rotated at a constant linear velocity, are used for recording / reproducing information on / from an optical disc or the like. CLV
(Constant Linear Velocity) method.

The former allows stable recording / reproduction, but has a problem that the recording density is low and that the quality of signals on the inner and outer circumferences is different. On the other hand, the latter can increase the recording density, but has a problem that the access speed is slow because the rotation speed of the disk is changed at the time of access.

Conventionally, as a means for solving such a problem, for example, one disclosed in Japanese Patent Laid-Open No. 61-131236 has been proposed. The method disclosed in the publication discloses that the recording clock frequency is switched according to the linear velocity of a track on a recording medium rotating at a constant angular velocity so that the recording pit lengths or recording domain lengths on the inner and outer circumferences are constant over the entire recording area. Is supposed to do.

Other related devices for switching the recording clock frequency between the inner and outer circumferences are, for example, JP-A-60-177404 and JP-A-60-117448.
The methods described in these two publications increase the recording / reproducing clock frequency for each of a plurality of tracks as the recording position moves toward the outer circumference, thereby increasing the recording capacity.

As described above, in the recording / reproducing apparatus which uses the disk-shaped recording medium rotating at a constant angular velocity, the recording / reproducing frequency of the outer peripheral track is set to the line of the recording position with respect to the recording / reproducing clock frequency of the inner peripheral part. The recording pit length or the recording domain length can be made equal at the inner and outer circumferences of the recording area by increasing the speed according to the speed. Therefore, it can be expected that the recording capacity recorded on the disc can be increased.

[0007]

By the way, the above-mentioned conventional technique makes no mention of the relationship between the pit length or the recording domain length recorded on the disc-shaped medium and the recording method thereof. Similarly, it does not mention how the pit length or the domain length changes from the inner circumference to the outer circumference of the disc.

However, studies by the present inventors have revealed that these are important points to be noted in order to perform stable reproduction of information. Particularly, in a so-called pit edge recording method in which information is recorded by giving information to the leading edge and the trailing edge of pits or recording domains generated at the time of recording, the edge detection position changes due to changes in pit length and domain length. It became clear that the amount of fluctuation increases and the detection information deteriorates. This point will be described below.

First, the clock will be considered. The clock has circuit-like fluctuations. Therefore, if the fluctuation amount is substantially constant regardless of the frequency, the fluctuation amount in the clock width increases as the frequency increases.

Next, the relationship between the formation of pits and the linear velocity will be examined. According to the experiments conducted by the present inventors, the characteristics of the recording medium include the linear velocity and the temperature rise during the formation of pits.
The temperature drop gradient is different, and as the linear velocity increases, the fluctuation amount of the edge detection position of the recording pit in the read discrimination window width increases. That is, as shown in FIG. 9, when the recording clock frequency is changed so that the recording pit length is the same on the inner and outer circumferences of the recording area, the discrimination window width W
The ratio of the fluctuation amount ΔΦ to the outer circumference tends to increase from the inner circumference to the outer circumference.

As described above, in the case of recording with the same pit length, there is a problem in that, when reproducing on the outer periphery, the read margin is stricter than that on the inner periphery and stable reproduction cannot be performed.

An object of the present invention is to solve the above-mentioned problems, to ensure stable signal quality at all recording positions on the inner and outer circumferences, to perform stable reproduction, and to provide a highly reliable and large capacity information recording / reproducing system. To provide.

[0013]

In order to achieve the above object, the present invention provides a recording pit having the same recording information at a recording signal switching position according to the recording position of a disk-shaped medium rotating at a constant angular velocity. The recording clock frequency is changed so that the length or recording domain length becomes longer from the inner circumference to the outer circumference. Further, the clock frequency of the reproduction discrimination window is changed in order to maintain the high reliability of the reproduction signal in the outer peripheral portion. Further, in order to further simplify the circuit configuration, the recording / reproducing clock is switched for each zone composed of a plurality of tracks.

That is, according to the present invention, the recording area of the disk-shaped recording medium is divided into a plurality of zones which are successively adjacent in the radial direction, a recording / reproducing clock is assigned to each zone, and each zone is assigned. A recording / reproducing system for recording / reproducing data according to an assigned clock is provided.

Further, according to the present invention, as the recording position with respect to the recording area of the disk-shaped recording medium changes from the inner circumference to the outer circumference, the recording capacity of one track increases and the pits or the pits used for recording data are formed. A recording / reproducing system is provided in which the recording / reproducing clock frequency is changed so that the circumferential length of the recording domain is gradually increased.

Further, according to the present invention, there is provided a recording / reproducing apparatus for recording and / or reproducing data in the recording area by rotating the disc-shaped recording medium at a constant angular velocity, the position of the recording medium in the radial direction. According to the above, a recording area is set to multiple zones and a clock control system that controls the clock for recording and playback to be set for each zone is provided, and data is recorded by the clock assigned to each zone. There is provided a recording / reproducing apparatus having an information recording system for performing the recording and / or an information reproducing system for reproducing data by a clock assigned to each zone.

Further, according to the present invention, the recording area is divided into a plurality of zones which are successively adjacent to each other in the radial direction, and the tracks having the same rank in each zone are surrounded by pits or recording domains used for recording data. Provided is a disc-shaped recording medium in which a recording is made so that the direction length becomes longer toward the outer peripheral zone.

[0018]

According to the present invention, the disc-shaped recording medium is rotated at a constant angular velocity, and the recording capacity of one track is increased as the recording position with respect to the recording area of the disc-shaped recording medium changes from the inner circumference to the outer circumference. Data is recorded / reproduced by changing the reproduction clock frequency. As a result, it is possible to increase the recording capacity recorded on the disc even at a constant angular velocity.

At this time, the clock frequency for recording / reproducing is set so that the circumferential length of the pits or recording domains used for recording data gradually becomes longer. That is, when the signal generated by the edge of the pit or domain recorded on the disc-shaped recording medium is detected by setting the discrimination window and the data is reproduced, the variation of the appearance position of the detection signal in the discrimination window width W is detected. Ratio of quantity ΔΦ (ΔΦ
The clock frequency for recording and reproduction is changed so that / W) is suppressed within a substantially constant range on the inner and outer circumferences of the recording medium. As a result, the discrimination window width W becomes larger at the outer circumference, and the reading margin becomes sufficient even at the outer circumference, so that reading errors are reduced. Therefore, stable signal quality is guaranteed at all recording positions on the inner and outer circumferences, and stable and highly reliable reproduction is possible.

Further, according to the present invention, the recording area of the disc-shaped recording medium is divided into a plurality of zones which are successively adjacent in the radial direction, a recording / reproducing clock is assigned to each zone, and the zone is assigned to each zone. Data is recorded / reproduced by the clock. Therefore, the clock can be easily controlled with a simple circuit configuration.

In this case, the clocks for recording and reproduction for each zone may be assigned with different frequencies so that the recording capacity of one track increases toward the outer zone. Further, regarding the tracks having the same rank in each zone, the frequency may be set so that the circumferential length of the pits or recording domains used for recording data gradually becomes longer toward the outer zone. .

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic diagram of an embodiment of an optical disk device to which the present invention is applied.

The optical disk device shown in FIG.
An optical disc medium 1 having the above, a spindle motor 3 for rotationally driving the optical disc medium 1, and an optical disc medium 1
An optical head 4 for reading and writing information from and to the main head, a main control circuit 6 for controlling the entire system, a positioning control system for the optical head 4, an information recording system, and an information functioning under the control of the main control circuit 6. It comprises a reproduction system and a clock control system.

The positioning control system for the optical head 4 is
Positioning mechanism 1 for positioning the optical head 4 at a desired position
9, a positioning control circuit 18 that controls the positioning of the positioning mechanism 19, and a scale detector 20 that functions as a means for detecting the access position of the optical head 4.

The information recording system uses the data 21 to be written.
To a code 22 of a run length limited code string such as a 2-7 modulation code, and a modulated code 2
An NRZ encoder 10 that further converts 2 into an NRZ (Non Return to Zero) code 23; a pulse width setter 12 that sets a write pulse width for the NRZ code 23 including correction and sets a recording code 24; Record code 24
Based on the above, a laser driver (not shown in FIG. 1) is driven to send a laser beam to the optical head 4.

The information reproducing system binarizes a reproducing signal 27 detected by a photodetector (not shown) in the optical head 4 to obtain a reproducing code 29, and a reproducing code 29.
Synchronization code 36 and discrimination clock 3
7, a PLL circuit 35 that outputs 7, a reproduction data combining circuit 16 that combines the code 30 of the reproduction data from the synchronization code 36, and a demodulation circuit 17 that demodulates the data 31 from the code 30.

The clock control system corresponds to a basic clock oscillator 7 for generating a basic clock, a synthesizer 8 for generating a target recording / reproducing clock from the basic clock based on the set clock information, and an access position. And clock information generating means for outputting to the synthesizer 8 clock information 34 designating a recording / reproducing clock assigned to one or more tracks. The clock information generating means is configured as one function of the main control circuit 6.

As shown in FIG. 2, the optical disk medium 1 has a plurality of zones 2a to 2a which are successively adjacent in the radial direction.
The recording area 2 is divided into 2f. This each zone 2
A plurality of tracks are provided in a to 2f, and information is recorded and reproduced here. Further, the optical disc medium 1 has the zones 2a to 2f in the recording area 2.
The recording / reproducing clock frequency switching position 41 is provided every few tracks at the boundary of the
The number of 2 is the number of sectors 42 included in the inner track.
It is supposed to be increased by one from the number of.

Then, the optical disk medium 1 of this embodiment is
As will be described later, the tracks in the same order in each of the zones 2a to 2f are recorded such that the circumferential length of the pits or recording domains used for recording data becomes longer toward the outer zone.

In this embodiment, an example of using a write-once optical disc is shown.

Although not shown, the main control circuit 6 is composed of, for example, a central processing unit (CPU), a ROM for storing programs of the CPU, a RAM for storing various data, and the like. As described above, the main control circuit 6 has a function as clock information generating means of the clock control system. For this reason, the main control circuit 6 has a configuration shown in FIG.
The conversion table as shown in FIG. 15 is stored in the ROM or RA.
It is configured to be stored and held in M, and the CPU can take out the corresponding clock information 34 based on the information from the host computer 5.

The synthesizer 8 has a basic clock 6 from a basic clock oscillator 7, as shown in FIG.
The fixed frequency divider 62 that divides 1 by 1 to output the reference clock 64 and the recording / reproducing clock 32 that is the output of the synthesizer 8 according to the frequency division number set by the clock information 34 from the main control circuit 6. Variable frequency divider 6 for frequency division
3 is compared with the frequency of the variable frequency dividing clock 65 output from the variable frequency divider 63 and the reference clock 64 to detect an error, and the output signal 6
7 and a low-pass filter 68
And a VCO (Voltage Controlled Oscillator) circuit 69 that oscillates at a frequency corresponding to the voltage of the output signal 67.

The output of the VCO circuit 69 is output as the recording / reproducing clock 32 and is fed back to the variable frequency divider 63 as described above.

The modulation circuit 9 and the NRZ encoder 10
May have a circuit configuration that is normally used.

The pulse width setting unit 12 corrects the delay element 71 in which an input signal is output from a plurality of output taps with a constant delay time and the output from the output tap of the delay element 71 by the recording corrector 11. The selector 72 has a selector 72 which selects according to a command, and an AND circuit 73 which takes the logical product of the output of the selector 72 and the NRZ code 23 input to the delay element 71.

The laser driver 14 has a current switch configuration that switches depending on the value of the recording code 24, and drives the semiconductor laser 77 on and off.

The power setting unit 13 is the semiconductor laser 7 described above.
7, a transistor 75 that is connected in series to set its drive current, a resistor 76 that is connected in series with the transistor 75, and a command value from the recording corrector 11 is digital-to-analog converted, and the transistor 75 And a D / A converter 74 for setting the base potential of the.

The recording corrector 11 is constituted by including, for example, a ROM. In this ROM, the selection command of the pulse width correction amount by the selector 72 and the command value of the input bit to the D / A converter 74 are stored with the control information 33 as an address.

The binarization circuit 15, the PLL circuit 35,
The reproduction data synthesizing circuit 16 and the like may have known circuit configurations. A circuit of this type is described in, for example, Japanese Patent Laid-Open No. 63-53722.

Next, an embodiment of the information recording / reproducing system of the present invention will be described by taking the case of using the optical disk device shown in FIG. 1 as an example.

First, in explaining the recording / reproducing operation, the principle of the pit edge recording method which is the recording method adopted in the present invention will be explained.

FIG. 4 is a waveform diagram showing a process of changing a signal when data is modulated and converted into a code and recorded on a disc, and pits formed on the disc.
FIG. 5 is a waveform diagram showing the process from the reproduction of information from the pits recorded on the disc to the demodulation of the original data.

In FIG. 1, the optical disc medium 1 is rotated by a spindle motor 3 at a constant angular velocity. In this state, data reading / writing is performed.

In FIG. 1, the data 21 to be recorded is
The code 22 is modulated by the modulation circuit 9. This coding may be performed by any modulation method, and in this embodiment,
As shown in FIG. 4, the case of 2-7 modulation is shown. The code 22 is converted into the NRZ code 23 by the NRZ encoder 10.

If the NRZ code 23 is recorded on the optical disc medium 1, pits generally longer than the irradiation recording width will be formed. This is because the heat of the laser light emitted from the semiconductor laser 77 in the laser driver 14 propagates in the recording film, and even in the portion where the recording pulse light is not irradiated, the melting point of the recording film is exceeded. is there. On the contrary, depending on the relative relationship between the melting point of the recording film and the irradiation light power, it may be shorter than the NRZ code 23, on the contrary.

Therefore, in order to make the length of the formed recording pit 26 correspond to the length of the NRZ code 23, the recording code 24 whose pulse width is previously corrected (corrected short in the illustrated case) is used. Further, the power of the recording light pulse 25 is corrected according to the linear velocity of the optical disk medium to be recorded. The recording light pulse width and the recording light power are set under the control of the recording corrector 11 using the setting devices 12 and 13, respectively. In response to this, the laser driver 14
The semiconductor laser 77 is driven to form the recording pit 26. That is, the front edge and the rear edge of the formed pit correspond to "1" of the 2-7 code, and the data is recorded on the optical disc medium 1.

Next, the case of demodulating the data 31 from the recording pit 26 will be described with reference to FIG.

The amount of reflected light from the optical disk medium 1 when the laser light is irradiated changes depending on the presence / absence of the recording pit 26, and a reproduced signal 27 which is an analog signal is obtained. Two
The binarizing circuit 15 binarizes the reproduced signal 27 using a certain slice level 28 to obtain a reproduced code 29.

As another method, the reproduction signal 27 is set to 2
It is also possible to obtain a binarized reproduction code 29 by performing the differential differentiation and detecting the zero-cross point.

A pulse corresponding to each of the rising and falling edges of the reproduced code 29 is produced, and the code 30 is obtained from both. By inputting this to the demodulation circuit 17 which performs the opposite operation to the modulation circuit 9, the data 3
1 can be reproduced.

Although the recording / reproducing clock 32 is shown in FIG. 5 in order to correspond to FIG. 4, in actuality, when the code 30 is reproduced from the reproduction code 29, P
The LL circuit 35 generates the discrimination clock 37 synchronized with the reproduction code 29 (see FIG. 1).

Here, the length of the pits formed on the optical disk medium 1 of this embodiment will be examined.

When the 2-7 modulation method is used, there are six types of recording pit lengths, but here, the length of the shortest pit will be obtained.

The total number of bits of the sector 42 of the optical disk medium 1 is Z, the track pitch is d μm, the number of tracks for switching the recording clock is N, the innermost track radius is R μm, and the number of sectors included in the innermost track is Is n, the shortest pit length l _o in the innermost track is
It is shown by the following formula.

[0056] As a result, at the i-th recording / reproducing clock switching position
Shortest pit length l _iIs as follows:

[0057] The condition that the shortest pit length is larger on the outer circumference than on the inner circumference at the position where the recording / reproducing clock frequency is switched is as follows.

N · d · n−R> 0 For example, in the optical disc medium 1 formatted with the track pitch d = 1.5 μm, N = 1024, n = 5
When 1, R = 70 mm, the pit length having the same recording information at the clock switching position can monotonically increase toward the outer circumference.

At this time, if the track pitch d, the innermost track radius R, and the number n of the sectors 42 included in the innermost track are constant, the recording pits can be changed only by changing the number N of tracks for switching the recording clock. The increasing tendency of the length can be controlled. FIG. 6 shows the transition of the shortest pit length at the position 41 at which the recording / reproducing clock 32 is switched.

On the contrary, if the shortest pit length is constant in both the inner and outer recording areas as described in Japanese Patent Laid-Open No. 61-131236, the read margin at the outer peripheral portion becomes the inner periphery. It will be stricter than the club. This phenomenon is the starting point of the present invention and will be described below.

Since the optical disc medium 1 rotates at a constant angular velocity, the linear velocity differs between the inner and outer circumferences of the recording area. For this reason, the reached temperature curve of the film surface that acts on the formation of pits when irradiated with the recording laser light differs depending on the magnitude of the linear velocity, as shown in FIG. Further, when irradiating the recording laser beam, the ultimate temperature curve of the film surface may fluctuate as shown by the dotted line in FIG. 7 due to factors such as nonuniformity of the recording film and fluctuation of linear velocity. As a result of the above variation, the pit formation position fluctuates, and the variation curve ΔΦ of the pit formation position is larger in the one where the ultimate temperature curve has a gentle gradient and the linear velocity is higher, that is, the outer peripheral part. . The same applies to the trailing edge of the formation pit.

Here, for comparison with the present embodiment, the pit length of the pit formed by the above-described conventional pit forming method will be examined.

In the prior art, as shown in FIG. 8, the frequency of the recording / reproducing clock 32 is changed in proportion to the linear velocity of the recording position so that the recording pit 26 has a constant linear density over the entire recording area. To form. Note that FIG. 8 shows the waveforms at the inner peripheral portion of the clock frequency f ₀ and the outer peripheral portion (clock frequency 2f ₀ ) having a linear velocity twice as fast as the inner peripheral portion.

As shown in FIG. 8, in this conventional technique,
Since the fluctuation amount ΔΦ of the pit length with respect to the recording pit length is larger in the outer peripheral portion than in the inner peripheral portion, after all, the discrimination clock 3
Ratio Δ of variation of detection signal position in discrimination window width W of 6
Φ / W increases. The transition of the ratio ΔΦ / W of the fluctuation amount of the detection signal position in the discrimination window width when recording is performed with the same pit length from the inner peripheral portion to the outer peripheral portion of the optical disc medium 1,
It is shown in FIG. As shown in FIG. 9, ΔΦ / W increases as the recording position moves to the outer peripheral portion, and there is a possibility that reproduction errors in the outer peripheral portion increase.

According to this embodiment, this problem is solved. Therefore, including this effect, next, according to FIG.
The recording / reproducing operation of information data will be described.

First, recording of data will be described.

The main control circuit 6 receives write data and write start position information from the host computer 5.
The main control circuit 6 converts the write start position information into a track number 46 and a sector number 47 to be accessed according to a conversion table stored in a built-in memory (not shown). The positioning control circuit 18 controls the positioning mechanism 19 so that the light spot of the optical head 4 is positioned on the track number 46 transmitted from the main control circuit 6.

As a method of positioning the optical head 4 on a target track, for example, the information of the ID portion prepared in advance in the sector 42 is used, or an external scale is provided and the positioning position is determined by the scale detector 20. Use the reading method.

Further, the main control circuit 6 obtains the clock information 34 from the converted track number 46 by the conversion table shown in FIG. 10 and sends it to the synthesizer 8.

In the synthesizer 8, the recording / reproducing clock 32 corresponding to the clock information 34 is generated from the clock information 34.
In FIG. 10, the switching position 41 of the recording / reproducing clock 32 is set for every 1024 tracks because the pit length having the same information becomes longer toward the outer periphery at the clock switching position 41, and the detection signal occupies the discrimination window width. This is because the position variation ratio (ΔΦ / W) is also smaller than when the pit length is constant. Of course, the number of tracks is not limited to this, and another number of tracks may be used as long as this condition is satisfied.

The synthesizer 8 includes a basic clock oscillator 7
The basic clock 61 generated in 1 is divided by a fixed frequency divider 62 to generate a reference clock 64. Further, the frequency division number of the variable frequency divider 63 is set by the clock information 34. The phase comparator 66 controls the frequency of the output signal 67 so that the frequency of the variable frequency-divided clock 65 that is the output and the frequency of the reference clock 64 have the same value. The output signal 67 passes through the low-pass filter 68 and V
The CO circuit 69 becomes the recording / reproducing clock 32.

By inputting the recording / reproducing clock 32 to the variable frequency divider 63, the frequency of the recording / reproducing clock 32 is kept constant. As a result, the recording / reproducing clock 32 corresponds to the corresponding recording position.

The modulation circuit 9 modulates the write data 21 received from the main control circuit 6 into code data 22 such as a 2-7 code. The NRZ encoder 10 places the code 2 on the recording / reproducing clock 32 generated by the synthesizer 8.
2 is converted into NRZ code 23.

If the NRZ code 23 is used to irradiate the laser beam for recording as described above, a recording pit length longer or shorter than that of the NRZ code 23 is formed due to the thermal diffusion characteristic of the optical disk medium. This characteristic is
Since it changes depending on the linear velocity, it is necessary to correct it to an optimum value. Further, in order to match the recording pit length with the code length of the NRZ code 23, it is also necessary to optimize the laser current for controlling the recording power of the laser.

Therefore, for the NRZ code 23, the pulse width setting unit 12 sets the pulse width including the correction, and the recording code 24 is generated. This will be described in more detail.

The converted NRZ code 23 is input to the delay element 71 of the pulse width setting unit 12. In the delay element 71, a signal with a constant delay time is output to a plurality of output taps. There is also a method of using a gate delay as the delay element.

The output from the delay element 71 is the selector 72.
Is input to the AND gate 73. One of the outputs is selected by the recording corrector 11 and input to the AND gate 73. Since the undelayed signal is input to the other side of the AND gate 73, a pulse that is shortened by the delay amount is generated. This pulse corresponds to the recording code 24 in FIGS. 1 and 4 and is input to the laser driver 14.

In the above method, the correction is made short, but conversely, when the correction is made long, the AND gate 73 is set to O.
All you have to do is change the R gate. Also, both can be used together.

On the other hand, the control of the recording light power is performed by changing the value of the current source in the laser driver 14. The laser driver 14 has a current switch configuration, and by changing the base potential of the transistor 75 that determines the current value by the D / A converter 74, light emission when the semiconductor laser 77 is turned on. You can change the power. For example, if the base potential of the transistor 75 is raised by the D / A converter 74, the emitter potential rises and the current flowing through the resistor 76 increases. Therefore, the drive current of the semiconductor laser 77 also increases and the emission power increases.

The recording corrector 11 sets the pulse width and power according to the control information 33. That is, control information 3 such as clock information 34 (or track number)
If you input 3 as the address of the built-in ROM,
As output, the corresponding correction data is output. Using this data, the selection of the pulse width correction amount by the selector 72 and the input bit to the D / A converter 74 can be designated.

Further, instead of the clock information 34 and the track number, a method of using a value from the external scale detector 20 or the number of tracks crossed from the reference radius (for example, the innermost circumference) of the disk to the present is used. Then, the position can be recognized and similar control can be performed.

By the above method, as shown in FIG.
The recording light pulse 25 is corrected to the optimum value at the recording position, and the recording pit 26 having the same length as the NRZ code 23 can be formed on the disk medium 1. Next, reproduction of data will be described.

The main control circuit 26 is the host computer 5
Further, the information on the read start position is received, the same operation as at the time of recording is performed, and the optical head 4 is positioned on the target track. The optical power of the semiconductor laser 77 is set to the reproduction level and the optical disk medium 1 is irradiated with the laser beam. As a result, the data on the medium is obtained as an optical signal and converted into a reproduction signal 27 by the photodetector in the optical head 4.
The reproduction signal 27 is output as a reproduction code 29 by the binarization circuit 15 and input to the reproduction data synthesizing circuit 16.

On the other hand, the main control circuit 6 obtains the track number 46 and the clock information 34 from the read start position information,
The clock information 34 is sent to the synthesizer 8. In the synthesizer 8, the recording / reproducing clock 32 is generated corresponding to the clock information 34 as in the recording.

In the present invention, the pit edge recording method is adopted as the data recording method. When actually adopting edge recording, the recording pits change with respect to the target length, so the data corresponding to the leading edge and trailing edge is treated as individual data and recombined is used. ing.

The leading edge pulse and the trailing edge pulse here are 2
It corresponds to the rising edge and the falling edge of the reproduction code 29 output from the digitizing circuit 15.

The PLL circuit 35 generates a discrimination clock 37 synchronized with the reproduction code 29 and a synchronization code 36. In FIG. 1, each is shown as one series, but in reality, there are two series of clocks and data corresponding to the leading edge and the trailing edge. At this time, the recording / reproducing clock 32 is VFO.
It is used as a reference clock when pulling in the (variable frequency oscillator).

The output from the PLL circuit 35 is input to the reproduction data synthesizing circuit 16. Reproduction data synthesis circuit 16
In regard to the leading edge / trailing edge synchronization code 36, the timing of synthesizing is determined by a known data (for example, SYNC pattern) detection circuit, and two series of data strings are synthesized.

After the code 30 is obtained as the output of the reproduction data synthesizing circuit 16, the demodulation circuit 17 performs the operation opposite to that at the time of modulation to obtain the data 31. This demodulation circuit 17
May be a known one.

The data reproduced by the above method is transferred from the main control circuit 6 to the host computer 5.

FIG. 10 shows a conversion table of the track number 46, the clock information 34, and the recording / reproducing clock frequency 32. In this case, the number of tracks for switching the recording / reproducing clock frequency 32 is set to every 1024, and the number of sectors 42 forming a track for each clock switching position 41 is increased by one sector as it goes to the outer circumference.

Here, the recording / reproducing clock frequency will be calculated. Assuming that the number of rotations of the optical disk medium 1 is A rpm, the number of sectors of the innermost track is n, and the total number of bits of one sector is Z, the recording / reproducing clock frequency f _{0 on} the innermost track (0 track) is as follows. become.

F ₀ = 2 × A / 60 × n × Z (Hz) Further, the recording / reproducing clock frequency f _i at the clock information _i.
Is as follows.

F _i = 2 × A / 60 × (n + i) × Z (Hz) FIG. 11 shows the track pitch d of 1.5 μm and the number n of sectors of the innermost track using the conversion table of FIG. 5
1 shows an example of the format of the optical disc medium 1 in which the innermost track radius is set to 70 mm.

FIG. 14 shows the transition of the shortest pit length of the optical disc medium 1 having the format shown in FIG.

The transition of the shortest pit length shown in FIG. 14 shows that the circumferential lengths of the pits or recording domains used for recording data gradually increase in the outer zones of tracks having the same rank in each zone. It shows that it will be. Here, the tracks having the same rank in each zone mean, for example, the tracks arranged in the same order from the inner circumferential side in each track. Specifically, it is the i-th track in each zone, for example, the 1st re-inner track.

Next, another embodiment of the recording / reproducing system of the present invention will be described.

The present embodiment is an example of increasing the recording pit length at the recording / reproducing clock frequency switching position 41 and making the recording pit length more gradual or abrupt than that of the format shown in FIG. Therefore, in the present embodiment, the number of tracks for switching the recording clock frequency is not fixed at 1024, but two kinds of different numbers of tracks are prepared and the combination is controlled. If the increase tendency of the recording pits can be suppressed more than when 1024 is fixed, the storage capacity of the optical disc medium can be increased.

That is, this embodiment is the optical disc medium 1
A zone in which the circumferential length of pits or recording domains used for recording data is shorter than the circumferential length of pits or recording domains in tracks having the same rank in adjacent zones on the inner circumferential side is mixed. It was done like this.

For example, in the optical disc medium 1 having a track pitch of 1.5 μm, three areas for switching the recording / reproducing clock on 1024 tracks are made continuous, and then an area for switching the clock on 512 tracks is provided. To do. That is, d = 1.5 μm, n = 51,
Under the condition of R = 70 mm, when N = 1024,
The pit length will be longer than that on the inner circumference side, and N = 51
When there are two, the pit length can be reduced. Therefore, the increasing tendency of the pit length from the inner peripheral portion to the outer peripheral portion can be suppressed.

The recording / reproducing apparatus realized by this embodiment can have the same structure as that of the optical disc apparatus shown in FIG. Therefore, the description will not be repeated here. In the present embodiment, the main control circuit 6 constituting the clock information generating means of the clock control system stores and holds the conversion table as shown in FIG. This point is different from the above embodiment.

FIG. 15 is a conversion table of the track number 46, the clock information 34 and the recording / reproducing clock frequency 32 for realizing the above embodiment.

FIG. 16 shows the format on the medium under the above conditions. The transition of the shortest pit length at the recording / reproducing clock switching position for the format shown in FIG. 16 shows the shape of a polygonal line graph as shown in FIG.

By switching the recording / reproducing clocks 32 with different numbers of tracks as in the above embodiment, it is possible to select a recording / reproducing clock frequency capable of stable reproduction and increase the recording capacity.

As an example, the case of switching between 1024 lines and 512 lines has been described. This is because switching by a power of 2 makes it easier to perform software processing and the processing speed can be increased. . The present invention is not limited to this.

In this embodiment, the position at which the recording / reproducing clock 32 is switched may be arbitrarily set. In this way, the increment of the recording pit length can be arbitrarily set, and the variation amount Δ of the pit length in the discrimination window width W can be set.
It is possible to make the ratio of Φ (ΔΦ / W) almost constant at any recording position on the inner and outer circumferences. Therefore, it is possible to realize a recording method of the highest density that allows stable reading with a constant reading margin at all recording positions.

FIG. 17 shows the ratio (ΔΦ / W) of the fluctuation amount of the detection signal position to the discrimination window width. As is clear from this figure, the frequency of the recording / reproducing clock is set for each zone or each track so that the pit length becomes larger as the recording position goes from the inner circumference to the outer circumference, as in the above embodiments of the present invention. If set to, (ΔΦ / W)
Can be suppressed within a substantially constant range. On the contrary, in order to set (ΔΦ / W) to be the same as the inner peripheral portion at every recording position, it is possible to know what is the shortest pit length and how much the recording / reproducing clock should be set.

In each of the above-mentioned embodiments, the write-once type optical disk in which elliptical pits are formed on the disk-shaped medium is used as the recording medium, but the present invention is not limited to this, and other optical disk media (magneto-optical / Phase change), a magnetic disk medium, a flexible disk medium, or the like can be similarly used.

Further, although the optical disk device of the above embodiment has both the recording function and the reproducing function, it may be a device having only one of the functions.

[0110]

Since the present invention is constructed as described above, it has the following effects.

Since the disk-shaped recording medium can be rotated at a constant angular velocity, the rotation time stabilization time of the disk-shaped recording medium is not required for positioning the optical head. Further, stable signal quality is guaranteed at all recording positions on the inner and outer circumferences, and at the recording / reproducing clock switching position, the ratio of the fluctuation amount ΔΦ to the discrimination window width W can be made substantially constant, and stable at all recording positions. Readable high density recording is possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing the basic configuration of an embodiment of an optical disk device to which the present invention is applied.

FIG. 2 is an explanatory diagram of a schematic format of an optical disc medium.

FIG. 3 is an explanatory diagram showing the structure of one sector.

FIG. 4 is a waveform diagram showing a data recording method.

FIG. 5 is a waveform diagram showing a data reproducing method.

FIG. 6 is a graph showing the transition of the shortest recording pit length at the recording / reproducing clock switching position.

FIG. 7 is a graph showing an ultimate temperature curve of a recording film surface.

FIG. 8 is a model waveform diagram showing a change in recording pits.

FIG. 9 is a graph showing changes in the ratio of the fluctuation amount of the detection signal position to the discrimination window width.

FIG. 10 is an explanatory diagram showing a conversion table of clock information.

11 is an explanatory diagram showing a format of an optical disc medium corresponding to the conversion table of FIG.

FIG. 12 is a block diagram showing an example of the configuration of a synthesizer.

FIG. 13 is a block diagram showing the configuration of a circuit that performs correction during recording.

FIG. 14 is a graph showing the transition of the shortest recording pit length at the recording / reproducing clock switching position.

FIG. 15 is an explanatory diagram showing a conversion table of clock information.

16 is an explanatory diagram showing a format of an optical disc medium corresponding to the conversion table shown in FIG.

FIG. 17 is a graph showing the transition of the ratio of the fluctuation amount of the detection signal position in the discrimination window width.

[Explanation of symbols]

1 ... Optical disk medium, 2 ... Spindle motor, 4 ... Optical head, 5 ... Host computer, 6 ... Main control circuit, 7 ...
Basic clock oscillator, 8 ... Synthesizer, 9 ... Modulation circuit, 10 ... NRZ encoder, 11 ... Recording corrector, 12 ... Pulse width setting device, 13 ... Power setting device, 14 ... Laser driver, 15 ... Quantization circuit, 16 ... Playback data synthesis circuit, 1
7 ... Demodulation circuit, 18 ... Positioning control circuit, 19 ... Positioning mechanism, 20 ... Scale detector, 42 ... Sector.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takeshi Maeda 1-280 Higashi Koikekubo, Kokubunji, Tokyo 1-280, Central Research Laboratory, Hitachi Ltd. Central Research Laboratory (56) Reference JP-A-1-269250 (JP, A) JP-A-61-208642 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B 20/10 G11B 7/007

Claims (3)

(57) [Claims] 1. A storage area having a plurality of tracks,
It is divided into multiple zones that are radially adjacent to each other.
For recording the data on the innermost track
Circumference of the shortest pit or shortest recording domain used
The length in the direction becomes longer toward the outer peripheral zone,
As you move to the outer zone,
Recorded in increasing numbers, at the innermost circumference of one of the zones
The number of sectors of the existing track is 51.
A disk-shaped recording medium to collect. 2. A plurality of tracks having a plurality of sectors
The recording area is divided into multiple zones that are adjacent in the radial direction.
And the sector number of each sector is recorded.
Of the plurality of zones , in the recording medium having
The header part of the sector of the
The shortest pit to record or the circumference of the shortest recording domain
The length of the direction becomes longer toward the outer zone,
Number of sectors on each track as you go to the outer zone
Is recorded to increase at the innermost circumference of any one of the plurality of zones.
The number of sectors of the existing track is 51.
A disk-shaped recording medium to collect. 3. A plurality has a track having a plurality of sectors, is partitioned into a plurality of zones which recording area radially adjacent the respective sector, a recording of a recording medium having a header portion that sector number is recorded In the reproducing apparatus , the recording medium has a shortest pit for recording the sector number or a shortest recording domain in the circumferential direction in the header portion of the sector of the track in the innermost periphery of each of the plurality of zones. The length is recorded so as to increase in the outer zone and increase in the number of sectors of each track in the outer zone, and the length is recorded in the innermost periphery of any one of the plurality of zones. the number of tracks that the sector is 51, the recording and reproducing apparatus, from the header portion of the tracks belonging to the plurality of zones, the sector number Recording and reproducing apparatus, characterized in that the raw.