JP2004171782A - Disk-type recording medium and recording and reproducing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information recording and reproducing system in which stable signal quality is guaranteed at all recording positions of inner and outer peripheries, and which has high reliability and a large capacity. <P>SOLUTION: A recording region of a disk-type recording medium 1 is sectioned to a plurality of zones 2a-2f being adjacent successively in the radial direction, a clock for recording and reproducing is allotted for every zone of zones 2a-2f, recording/reproducing of data is performed by clocks allotted for every zone of zones 2a-2f. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a recording / reproducing device having a disk-shaped recording medium, and more particularly to a large-capacity disk file device.

For recording and reproducing information on an optical disk or the like, a CAV (Constant Angular Velocity) method in which the disk is rotated at a constant angular velocity to perform recording and reproduction, and a CLV (Constant Linear Velocity) in which the disk is rotated at a constant linear velocity to perform recording and reproduction. ) Method.

The former has the problems that recording and reproduction can be performed stably, but the recording density is low, and the quality of signals on the inner and outer circumferences is different. On the other hand, the latter can raise 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, for solving such a problem, for example, one disclosed in Japanese Patent Application Laid-Open No. 61-131236 has been proposed. According to the method described in the publication, the recording clock frequency is switched according to the linear velocity of a track on a recording medium rotating at a constant angular velocity, and the recording pit length or the recording domain length on the inner and outer circumferences is made constant in the entire recording area. Is supposed to.

Other devices that switch the recording clock frequency between the inner and outer circumferences include, 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 periphery, thereby increasing the recording capacity.

As described above, in the recording / reproducing apparatus using the disk-shaped recording medium rotating at a constant angular velocity, the recording / reproducing frequency in the outer peripheral track is changed according to the linear velocity of the recording position with respect to the inner peripheral recording / reproducing clock frequency. By increasing the height, the recording pit length or the recording domain length can be made equal at the inner and outer circumferences of the recording area.
Thus, it can be expected that the recording capacity recorded on the disc can be increased.

JP-A-61-131236 JP-A-60-177404 JP-A-60-117448

Incidentally, the above-mentioned conventional technique does not mention at all the relationship between the pit length or the recording domain length recorded on the disk-shaped medium and the recording method. Also,
Similarly, it does not mention how the pit length or the domain length changes from the inner circumference to the outer circumference of the disk.

However, it has been clarified by the present inventors that these are important points to be noted in performing stable reproduction of information. In particular, in a so-called pit edge recording method in which information is provided at the leading edge and trailing edge of a pit or a recording domain generated at the time of recording, that is, in a pit edge recording method, the edge detection position is determined by a change in pit length or domain length. It has been clarified that the fluctuation amount increases and the detection information deteriorates. Hereinafter, this point will be described.

First, consider the clock. The clock has a circuit fluctuation. Therefore, assuming that the fluctuation amount is substantially constant irrespective of the frequency, the fluctuation amount in the clock width increases as the frequency increases.

Next, the relationship between pit formation and linear velocity will be discussed. According to experiments performed by the present inventors, as a characteristic of a recording medium, the temperature rise and fall gradients during pit formation differ depending on the linear velocity. As the linear velocity increases, the edge of the recording pit occupying the read discrimination window width increases. The result that the fluctuation amount of the detection position increased was obtained. That is, as shown in FIG. 9, when the recording clock frequency is changed so as to have the same recording pit length on the inner and outer circumferences of the recording area, the ratio of the fluctuation amount ΔΦ to the discrimination window width W is It tends to increase from the circumference to the outer circumference.

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

SUMMARY OF THE INVENTION It is an object of the present invention to provide a highly reliable and large-capacity information recording / reproducing method which solves the above-mentioned problems and ensures stable signal quality at all recording positions on the inner and outer peripheries to perform stable reproduction. It is in.

In order to achieve the above object, according to the present invention, a recording pit length or a recording domain length having the same recording information at a recording signal switching position is set from an inner circumference according to a recording position of a disk-shaped medium rotating at a constant angular velocity. The recording clock frequency is changed so as to become longer toward the outer circumference. In addition, the clock frequency of the reproduction discrimination window is changed in order to maintain 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 that are sequentially adjacent in the radial direction, and a clock for recording and reproduction is assigned to each zone, and assigned to each zone. A recording / reproducing method for recording / reproducing data by a clock is provided.

Further, according to the present invention, 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, the recording capacity of one track increases, and the pits or recording domains of the pits or recording domains used for recording data are increased. A recording / reproducing method for recording / reproducing data by changing a recording / reproducing clock frequency so that the circumferential length gradually increases is provided.

Further, according to the present invention, there is provided a recording / reproducing apparatus for recording and / or reproducing data in a recording area by rotating a disk-shaped recording medium at a constant angular velocity, wherein the recording / reproducing apparatus is arranged in accordance with a radial position of the recording medium. Information recording for setting a recording area to a plurality of zones, providing a clock control system for controlling a clock for recording and reproduction to be set for each zone, and recording data with a clock assigned to each zone A recording / reproducing apparatus provided with a system 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 sequentially adjacent in the radial direction, and the circumferential length of a pit or a recording domain used for data recording for tracks having the same rank in each zone. However, there is provided a disk-shaped recording medium on which the data is recorded so as to become longer as it goes to the outer peripheral zone.

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

Since the disc-shaped recording medium can be rotated at a constant angular velocity, the rotation speed of the disc-shaped recording medium does not need to be stabilized for positioning the optical head. In addition, stable signal quality is guaranteed at all recording positions on the inner and outer circumferences, and the ratio of the fluctuation amount ΔΦ to the discrimination window width W can be made almost constant at the recording / reproducing clock switching position, and stable at all recording positions. Readable high-density recording can be performed.

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

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

The optical disk apparatus shown in FIG. 1 includes an optical disk medium 1 having a recording area 2, a spindle motor 3 for rotating the optical disk medium 1, an optical head 4 for reading and writing information from and on the optical disk medium 1, and an entire system. A main control circuit 6 to be controlled and a positioning control system, an information recording system, an information reproduction system, and a clock control system for the optical head 4 functioning under the control of the main control circuit 6 are provided.

The positioning control system for the optical head 4 functions as a positioning mechanism 19 for positioning the optical head 4 at a target position, a positioning control circuit 18 for performing positioning control on the positioning mechanism 19, and a unit for detecting an access position of the optical head 4. And a scale detector 20.

The information recording system modulates the data 21 to be written into a code 22 of a run length limited code sequence such as a 2-7 modulation code, for example, and further modulates the modulated code 22 into an NRZ (Non Return to Zero). NRZ encoder 10 for converting to code 23;
A pulse width setting device 12 for setting the write pulse width including the correction for the RZ code 23 to set the recording code 24, and driving a laser element (not shown in FIG. 1) based on the recording code 24. And a laser driver 14 for sending laser light to the optical head 4.

The information reproducing system synchronizes the reproduction code 29 with a binarization circuit 15 for binarizing a reproduction signal 27 detected by a photodetector (not shown) in the optical head 4 to obtain a reproduction code 29, and 36 and a PLL circuit 35 for outputting a discrimination clock 37
And a reproduction data synthesizing circuit 16 for synthesizing the reproduction data code 30 from the synchronization code 36, and a demodulation circuit 17 for demodulating the data 31 from the code 30.

The clock control system includes 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, Alternatively, it is provided with clock information generating means for outputting to the synthesizer 8 clock information 34 specifying a recording / reproducing clock assigned to each of two 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 disc medium 1 has a recording area 2 partitioned into a plurality of zones 2a to 2f that are sequentially adjacent in the radial direction. Each zone 2a ~
A plurality of tracks are provided in 2f, where information is recorded and reproduced. The optical disc medium 1 includes, in the recording area 2, each of the zones 2a to 2a.
At the boundary of f, a recording / reproducing clock frequency switching position 41 is provided every several tracks,
At the position 41, the number of the sectors 42 is increased by one from the number of the sectors 42 included in the inner track.

The optical disk medium 1 according to the present embodiment includes the zones 2a to 2a as described later.
For tracks having the same rank in f, recording is performed such that the circumferential length of pits or recording domains used for data recording becomes longer toward the outer peripheral zone.

  In this embodiment, an example is shown in which a write-once optical disc is used.

The main control circuit 6 includes, for example, a central processing unit (CPU), a CP (not shown).
It has a ROM for storing the U program, a RAM for storing various data, and the like. As described above, the main control circuit 6 has a function as clock information generation means of a clock control system. For this reason, the main control circuit 6 stores a conversion table as shown in FIGS. 10 and 15 described later in a ROM or a RAM, and, based on information from the host computer 5, causes the CPU to Information 34
Is configured to be able to be taken out.

For example, as shown in FIG. 12, the synthesizer 8 has a fixed frequency divider 62 for dividing the basic clock 61 from the basic clock oscillator 7 and outputting a reference clock 64, and a recording / reproducing clock which is an output of the synthesizer 8. 32, the main control circuit 6
A variable frequency divider 63 that divides the frequency according to the frequency division number set by the clock information 34 from the CPU, compares the frequency of the variable frequency divided clock 65 output from the variable frequency divider 63 with the reference clock 64. And a low-pass filter 68, and a VCO (Voltage Controlled Oscillat) that oscillates at a frequency corresponding to the voltage of the output signal 67.
or) circuit 69.

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

The modulation circuit 9 and the NRZ encoder 10 may have a commonly used circuit configuration.

The pulse width setting unit 12 selects a delay element 71 in which an input signal is output from a plurality of output taps with a certain delay time and an output from the output tap of the delay element 71 in accordance with a correction command of the recording corrector 11. And an AND circuit 73 that calculates 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 according to the value of the recording code 24, thereby driving the semiconductor laser 77 on and off.

The power setting unit 13 is connected in series with the semiconductor laser 77, and sets a driving current for the transistor 75, a resistor 76 connected in series with the transistor 75, and a command value from the recording corrector 11. And a D / A converter 74 for performing analog conversion and setting the base potential of the transistor 75.

The recording corrector 11 includes, for example, a ROM and the like. This ROM contains
A command to select a pulse width correction amount by the selector 72 and a command value of an input bit to the D / A converter 74 are stored using the control information 33 as an address.

The binarizing circuit 15, the PLL circuit 35, the reproduced data synthesizing circuit 16 and the like may each have a known circuit configuration. For this type of circuit,
For example, it is described in JP-A-63-53722.

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

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

FIG. 4 is a waveform diagram showing a process of signal change when data is converted into a code by modulation and recorded on a disk, and pits formed on the disk. Fifth
The figure is a waveform diagram showing the process of reproducing information from pits recorded on a disk and demodulating it to original data.

In FIG. 1, an optical disk medium 1 is rotated at a constant angular velocity by a spindle motor 3. In this state, data reading and writing are performed.

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

By the way, if this NRZ code 23 is recorded on the optical disc medium 1,
Generally, pits longer than the irradiation recording width are formed. This is because the heat of the laser light emitted from the semiconductor laser 77 in the laser driver 14 propagates through the recording film,
This is because a state where the melting point of the recording film is exceeded occurs even in a portion where the recording pulse light is not irradiated. On the other hand, depending on the relative relationship between the melting point of the recording film and the irradiation light power, the NRZ code may be shorter than the NRZ code.

Therefore, in order to make the length of the recording pit 26 formed correspond to the length of the NRZ code 23, the recording code 24 whose pulse width has been corrected (shortened in the illustrated case) in advance.
Is used. Further, the power of the recording light pulse 25 is corrected according to the linear velocity of the optical disk medium on which recording is performed. The setting of the recording light pulse width and the recording light power is performed under the control of the recording corrector 11 using the respective setting devices 12 and 13. In response to this, the laser driver 14 drives the semiconductor laser 77 so that the recording pit 26
Is formed. That is, the leading edge and the trailing edge of the formed pit are represented by 2-
Data is recorded on the optical disc medium 1 corresponding to the 7 code "1".

Next, a case where the data 31 is demodulated from the recording pit 26 will be described with reference to FIG.

The reflected light from the optical disk medium 1 when irradiating the laser beam is
, The light amount changes depending on the presence or absence of the signal, and a reproduction signal 27 which is an analog signal is obtained. The reproduction signal 27 can be binarized by the binarization circuit 15 using a certain slice level 28 to obtain a reproduction code 29.

As another method, the reproduction signal 27 can be differentiated by the second order, its zero cross point can be detected, and a binarized reproduction code 29 can be obtained.

Pulses corresponding to the rising and falling edges of the reproduced code 29 are generated, and a code 30 is obtained from both. The data 31 can be reproduced by inputting this to the demodulation circuit 17 which performs the reverse operation of the modulation circuit 9.

In FIG. 5, the recording / reproducing clock 32 is described to correspond to FIG. 4. However, when the code 30 is reproduced from the reproducing code 29, the PLL is actually used.
The circuit 35 generates the discrimination clock 37 synchronized with the reproduction code 29 (see FIG. 1).

Here, the length of the pit formed on the optical disc medium 1 of the present embodiment will be examined.

When the 2-7 modulation method is used, there are six types of recording pit lengths. Here, the shortest pit length 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, and the innermost track radius is R.
[mu] m, and the number of sectors included in an inner circumference track top is n, the shortest pit length l _o of the innermost track is shown by the following equation.

l _o = 2π · (R + 0 · N · d) · 1.5 / Z · (n + 0)
(Μm)
Thus, the shortest pit length l at the i-th recording / reproducing clock switching position
_i is as follows.

l _i = 2π · (R + i · N · d) · 1.5 / Z · (n + i)
(Μm)
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.

NdnR> 0
For example, a formatted optical disk medium 1 with a track pitch d = 1.5 μm
In the case where N = 1024, n = 51, and R = 70 mm, the pit length having the same recording information at the clock switching position can monotonically increase toward the outer periphery.

At this time, assuming that 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 pit length increases only by changing the number N of tracks for switching the recording clock. Can control trends. FIG. 6 shows the transition of the shortest pit length at the position 41 where the recording / reproducing clock 32 is switched.

On the other hand, assuming that the shortest pit length is constant in both the inner and outer recording areas as described in JP-A-61-131236, the read margin at the outer periphery is larger than that at the inner periphery. It becomes severe. This phenomenon is a starting point of the present invention, and will be described below.

Since the optical disk medium 1 is rotating at a constant angular velocity, the linear velocities are different between the inner and outer circumferences of the recording area. For this reason, the temperature curve of the film surface which affects the formation of pits when the recording laser beam is irradiated is different 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 the non-uniformity of the recording film or fluctuation of the linear velocity. As a result of the above fluctuation, the pit formation position fluctuates, and the temperature curve has a gentle gradient and the linear velocity is larger, that is, the fluctuation amount ΔΦ of the pit formation position is larger in the outer peripheral portion. . The same can be said for the trailing edge of the formed pit.

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

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

As shown in FIG. 8, in this prior art, 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, the detection occupying the discrimination clock 36 in the discrimination window width W is eventually detected. The ratio ΔΦ / W of the fluctuation amount of the signal position increases. FIG. 9 shows 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 circumference to the outer circumference of the optical disc medium 1. Ninth
As shown in the figure, 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 the present embodiment, this problem is solved. The recording / reproducing operation of the information data will now be described with reference to FIG.

  First, data recording 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 at 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 sector 42
Use the information of the ID part created in advance, or provide an external scale,
A method of reading the positioning position with the scale detector 20 is used.

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

The synthesizer 8 generates a recording / reproducing clock 32 corresponding to the clock information 34 from the clock information 34. In FIG. 10, the switching position 41 of the recording / reproducing clock 32 is set 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 occupying the discrimination window width. This is because the ratio of the position variation (ΔΦ / W) is also smaller than when the pit length is fixed. Of course, the present invention is not limited to this, and if this condition is satisfied, another number of tracks may be used.

The synthesizer 8 divides the frequency of the basic clock 61 generated by the basic clock oscillator 7 with 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 output frequency of the variable frequency-divided clock 65 and the frequency of the reference clock 64 have the same value. The output signal 67 passes through a low-pass filter 68 and becomes a recording / reproducing clock 32 in a VCO circuit 69.

The frequency of the recording / reproducing clock 32 is kept constant by inputting the recording / reproducing clock 32 to the variable frequency divider 63. As a result, the recording / reproducing clock 32
Depends on 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 converts the code 22 into an NRZ code 23 on the recording / reproducing clock 32 generated by the synthesizer 8.

As described above, if the laser beam is irradiated by the NRZ code 23 and recorded,
Due to the thermal diffusion characteristic of the optical disk medium, a recording pit length longer or shorter than the NRZ code 23 is formed. Since this characteristic changes with the linear velocity,
It is necessary to correct to the optimal 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, the pulse width of the NRZ code 23 is set by the pulse width setting unit 12 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 device 12. In the delay element 71, a signal with a fixed delay time is output to a plurality of output taps. Note that there is a method using a gate delay as the delay element.

The output from the delay element 71 is input to the selector 72, and one of the outputs is selected by the recording corrector 11 and input to the AND gate 73. AND gate 7
Since the other signal of No. 3 receives a signal that has not been delayed, a pulse shorter 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, correction is made short, but conversely, when correction is made long, A
It is only necessary to change the ND gate 73 with the OR gate. Moreover, 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 emits light when the semiconductor laser 77 is turned on by changing the base potential of a transistor 75 for determining a current value by a D / A converter 74. Power can be changed. For example, if the base potential of the transistor 75 is increased by the D / A converter 74, the emitter potential increases, and the current flowing through the resistor 76 increases.
Therefore, the driving current of the semiconductor laser 77 also increases, and the light emission power increases.

The recording corrector 11 sets the pulse width and the power based on the control information 33. That is, control information 33 such as clock information 34 (or track number) is
When input is made as an address of a built-in ROM, corresponding correction data is output as an 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.

Also, instead of the clock information 34 and the track number, an external scale detector 20 is used.
Alternatively, the same control can be performed by recognizing the position using the method using the value from the above, or using the number of tracks that have traversed from the reference radius (for example, the innermost circumference) of the disk to the present.

By the above method, as shown in FIG. 4, 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, data reproduction will be described.

The main control circuit 26 receives information on the read start position from the host computer 5, performs the same operation as during recording, and positions the optical head 4 on the target track. The optical disc medium 1 is irradiated with laser light by setting the emission power of the semiconductor laser 77 to the reproduction level. As a result, the data on the medium is obtained as an optical signal, and is converted into a reproduction signal 27 by a photodetector in the optical head 4. The reproduction signal 27 is output as a reproduction code 29 by the binarization circuit 15 and is input to the reproduction data synthesis 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, and sends the clock information 34 to the synthesizer 8. Synthesizer 8
In response to the clock information 34, the recording / reproducing clock 32
Occurs.

In the present invention, a pit edge recording method is adopted as a data recording method.
When actually using 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 a method of re-synthesizing is used. ing.

The leading edge pulse and the trailing edge pulse here correspond to the rising edge and the falling edge of the reproduction code 29 output from the binarization 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 in one series, but actually, it is two series of clocks and data corresponding to the leading edge and the trailing edge. At this time, the recording / reproducing clock 32 is used as a reference clock at the time of pulling in a VFO (Variable Frequency Oscillator).

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

After obtaining the code 30 as the output of the reproduction data synthesizing circuit 16, the demodulating circuit 17
Performs the operation opposite to that at the time of modulation to obtain data 31. This demodulation circuit 17
Known ones may be used.

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

FIG. 10 shows a track number 46, clock information 34, recording / reproducing clock frequency 3
2 is a conversion table. In this case, the recording / reproducing clock frequency 32
Are switched every 1024 tracks, and the number of sectors 42 constituting a track is increased by one sector at each clock switching position 41 toward the outer circumference.

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

f ₀ = 2 × A / 60 × n × Z (Hz)
Further, the recording and 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 an example of the format of the optical disc medium 1 in which the track pitch d is set to 1.5 μm, the number of sectors n of the innermost track is set to 51, and the innermost track radius is set to 70 mm using the conversion table of FIG. It is shown.

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 indicates that, for tracks having the same rank in each zone, the circumferential length of pits or recording domains used for data recording gradually increases toward the outer circumferential zone. Is showing. here,
Tracks having the same rank in each zone are, for example,
The tracks are arranged in the same order from the innermost side. Specifically, it is the i-th track in each zone, for example, the first re-inner track.

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

This embodiment is an example in which the recording pit length at the recording / reproducing clock frequency switching position 41 is increased and the recording pit length is made gentler or steeper than that of the format shown in FIG. Therefore, in this embodiment, the number of tracks for switching the recording clock frequency is not fixed to 1024, but two types of different numbers of tracks are prepared.
Control is performed by a combination thereof. If the tendency to increase the number of recording pits can be suppressed as compared with the case where the number of recording pits is fixed to 1024, the storage capacity of the optical disk medium can be increased.

That is, in this embodiment, the circumferential length of a pit or a recording domain used for recording data on the optical disc medium 1 is the same as that of a pit or a recording domain in a track having the same rank in an adjacent zone on the inner circumferential side. Zones shorter than the length in the direction are mixed.

For example, in the optical disk medium 1 having a track pitch of 1.5 μm, 1024
In this track, three areas for switching the recording / reproducing clock are consecutive, and thereafter,
It is assumed that an area for switching clocks is provided in 512 tracks. In other words, under the conditions of d = 1.5 μm, n = 51 and R = 70 mm, when N = 1024, the pit length is longer than that on the inner circumferential side, and when N = 512, the pit length is longer. Can be reduced. Therefore, the tendency of the pit length to increase 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 configuration as the optical disk apparatus shown in FIG. Therefore, the description will not be repeated here. In this embodiment, the conversion table as shown in FIG. 15 is stored and held in the main control circuit 6 constituting the clock information generating means of the clock control system. This point is different from the above embodiment.

FIG. 15 shows a track number 46 and clock information 3 for realizing the above embodiment.
4 is a conversion table of 4 and a recording / reproducing clock frequency 32.

FIG. 16 shows a format on a medium under the above conditions. First
The transition of the shortest pit length at the recording / reproducing clock switching position for the format shown in FIG. 6 shows a shape of a line graph as shown in FIG.

As in the above embodiment, by switching the recording / reproducing clock 32 with different numbers of tracks, a recording / reproducing clock frequency capable of performing stable reproduction can be selected, and the recording capacity can be increased.

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

In the present embodiment, the position at which the recording / reproducing clock 32 is switched may be further set arbitrarily. In this way, the increment of the recording pit length can be arbitrarily set, and the ratio (ΔΦ / W) of the fluctuation amount ΔΦ of the pit length to the discrimination window width W is made substantially constant at any of the inner and outer recording positions. Becomes possible. Accordingly, it is possible to realize a recording method of the highest density that can read stably with a constant read margin at all recording positions.

FIG. 17 shows the ratio (ΔΦ / W) of the variation of the detection signal position to the discrimination window width. As is clear from this figure, the frequency of the recording / reproducing clock is changed for each zone or track so that the pit length increases 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 to a substantially constant range. Conversely, (ΔΦ /
In order to set W) to be the same as the inner circumference, what is the shortest pit length,
It shows how much the recording / reproducing clock should be set.

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

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

  The following effects can be obtained in the above embodiment.

The present invention provides a recording / reproducing apparatus for rotating a disk-shaped recording medium at a constant angular velocity so that the recording capacity of one track increases 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. Data recording / reproduction is performed by changing the clock frequency. As a result, even at a constant angular velocity, the recording capacity to be recorded on the disc can be increased.

At this time, the clock frequency for recording / reproducing is set so that the circumferential length of a pit or a recording domain used for data recording gradually increases. That is, when a discrimination window is set to detect a signal generated by a pit or a domain edge recorded on a disc-shaped recording medium and data is reproduced, the discrimination window width W
The recording / reproducing clock frequency is changed so that the ratio (ΔΦ / W) of the variation ΔΦ of the occurrence position of the detection signal in the above (ΔΦ / W) is kept 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 periphery, the read margin is sufficient at the outer periphery, and read 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 can be performed.

Further, the present invention divides a recording area of a disk-shaped recording medium into a plurality of zones which are sequentially adjacent in the radial direction, allocates a recording / reproducing clock to each zone, and uses a clock allocated to each zone. Record / reproduce data. Therefore, clock control can be easily performed with a simple circuit configuration.

In this case, the recording / reproducing clock for each zone may be assigned with a different frequency so that the recording capacity of one track increases toward the outer peripheral zone. Further, for the tracks having the same rank in each zone, the frequency may be changed and set so that the circumferential length of a pit or a recording domain used for data recording gradually increases toward the outer circumferential zone. .

FIG. 1 is a block diagram showing a basic configuration of an embodiment of an optical disk device to which the present invention is applied. FIG. 3 is an explanatory diagram of an outline format of an optical disk medium. FIG. 3 is an explanatory diagram showing a configuration of one sector. FIG. 4 is a waveform chart showing a data recording method. FIG. 4 is a waveform chart showing a data reproducing method. 7 is a graph showing a transition of the shortest recording pit length at a recording / reproducing clock switching position. 4 is a graph showing an attained temperature curve of a recording film surface. FIG. 3 is a model waveform diagram showing a change in a recording pit. 6 is a graph showing a change in the ratio of the amount of change in the detection signal position to the discrimination window width. FIG. 4 is an explanatory diagram showing a conversion table of clock information. FIG. 11 is an explanatory diagram showing a format of an optical disk medium corresponding to the conversion table in FIG. 10; FIG. 2 is a block diagram illustrating an example of a configuration of a synthesizer. FIG. 2 is a block diagram illustrating a configuration of a circuit that performs correction at the time of recording. 7 is a graph showing a transition of the shortest recording pit length at a recording / reproducing clock switching position. FIG. 4 is an explanatory diagram showing a conversion table of clock information. FIG. 16 is an explanatory diagram showing a format of an optical disk medium corresponding to the conversion table shown in FIG. 9 is a graph showing a change in a ratio of a variation amount of a detection signal position to a discrimination window width.

Explanation of reference numerals

DESCRIPTION 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 ... Value circuit, 16 ... Reproduction data synthesis circuit, 17 ... Demodulation circuit, 18 ... Positioning control circuit, 19 ... Positioning mechanism, 20
... scale detector, 42 ... sector.

Claims (3)

A recording area having a plurality of tracks is divided into a plurality of zones which are radially adjacent to each other, divided into each zone, and the shortest pit or shortest recording used for data recording is performed on tracks having the same rank in each zone. The length of the domain in the circumferential direction becomes longer as it goes to the outer peripheral zone, and the number of sectors in each track is recorded so as to increase as it goes to the outer peripheral zone. The circumferential length of the shortest pit or shortest recording domain used for recording is the shortest pit used for data recording on the outermost track of the zone adjacent to the inner circumference side, or the shortest recording domain. Shorter than the circumferential length,
The number of tracks belonging to a first zone of the plurality and the number of tracks belonging to a second zone separated from the first zone by a plurality of zones in an outer peripheral direction are the same,
A disk-shaped recording medium, wherein the number of sectors of a track existing in any one of the plurality of zones is 51. A recording medium comprising a plurality of tracks having a plurality of sectors, a recording area divided into a plurality of zones radially adjacent to each other, and each of the sectors having a header portion in which a sector number is recorded.
In each of the plurality of zones, the header portion of the sector of the track in the same rank has a circumferential length of the shortest pit or shortest recording domain for recording the sector number that becomes longer as it goes to the outer peripheral zone. In addition, the number of sectors in each track is recorded so as to increase as it goes to the outer peripheral zone, and the circumferential length of the shortest pit or shortest domain for recording a sector number in the track at the innermost circumference of each zone. Is shorter than the circumferential length of the shortest pit or shortest recording domain used for recording the sector number on the outermost track of the zone adjacent to the inner circumference,
The number of tracks belonging to a first zone of the plurality and the number of tracks belonging to a second zone separated from the first zone by a plurality of zones in an outer peripheral direction are the same,
A disk-shaped recording medium, wherein the number of sectors of a track existing in any one of the plurality of zones is 51. Recording or reproduction of a recording medium having a plurality of tracks having a plurality of sectors, a recording area divided into a plurality of zones radially adjacent to each other, and each of the sectors having a header for recording a sector number. In the recording and playback device that performs
In the recording medium, the circumferential length of the shortest pit or the shortest recording domain for recording the sector number in the header portion of the sector of the track in the same rank in each of the plurality of zones is equal to the outer circumference. The number of sectors in each track is longer and longer, and the number of sectors in each track is recorded so as to increase in the outermost zone.The shortest pit or the shortest pit for recording the sector number in the innermost track of each zone is recorded. The circumferential length of the domain is shorter than the circumferential length of the shortest pit or shortest recording domain used for recording the sector number in the outermost track of the zone adjacent to the inner circumference,
The number of tracks belonging to a first zone of the plurality and the number of tracks belonging to a second zone separated from the first zone by a plurality of zones in an outer peripheral direction are the same,
The number of sectors of the track existing in any one of the plurality of zones is 51,
The recording and reproducing apparatus reproduces the sector number from a header of a track belonging to the plurality of zones.

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