JP3622767B2 - Disc-shaped recording medium and recording / reproducing apparatus - Google Patents

Description

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

For recording / reproducing information with respect to an optical disk, etc., a CAV (Constant Angular Velocity) system in which the disk is rotated at a constant angular velocity and recording / reproduction is performed, and a CLV (Constant Linear Velocity) in which the disk is rotated at a constant linear velocity is performed. ) Method.

The former can be stably recorded and reproduced, but has a problem that the recording density is low, and the quality of the signals on the inner and outer circumferences is different. On the other hand, although the latter can increase the recording density, there is a problem that the access speed is slow because the rotational speed of the disk is changed during access.

Conventionally, as a solution to such a problem, for example, one described in Japanese Patent Application Laid-Open No. 61-131236 has been proposed. The method described in this publication changes the recording clock frequency according to the linear velocity of the track on the recording medium rotating at a constant angular velocity, and the recording pit length or recording domain length of the inner and outer circumferences is constant in the entire recording area. Is supposed to do.

As other devices for switching the recording clock frequency on the inner and outer circumferences, for example, JP-A-60-177404 and JP-A-60-117448 can be cited. The systems described in these two publications increase the recording capacity by increasing the recording / reproducing clock frequency for each of a plurality of tracks as the recording position goes to the outer periphery.

As described above, in a recording / reproducing apparatus using a disk-shaped recording medium rotating at a constant angular velocity, the recording / reproducing frequency in the outer peripheral track corresponds to the linear velocity at the recording position with respect to the recording / reproducing clock frequency in the inner peripheral portion. Accordingly, the recording pit length or recording domain length can be made equal on the inner and outer circumferences of the recording area.
This can be expected to increase the recording capacity recorded on the disc.

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

By the way, the above conventional technique does not mention anything about the relationship between the pit length or recording domain length recorded on the disc-shaped medium and the recording method. Also,
Similarly, there is no mention of how the pit length or domain length changes from the inner periphery to the outer periphery of the disc.

However, it has been clarified by the present inventors that these are important points to be noted in order to stably reproduce information. In particular, in the so-called pit edge recording method in which information is recorded by providing information at the leading edge and trailing edge of a pit or recording domain generated at the time of recording, the edge detection position is changed by changing the pit length or domain length. It became clear that the amount of fluctuation increased and the detection information deteriorated. This point will be described below.

First, consider the clock. The clock has circuit 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 pit formation and linear velocity is examined. According to the experiments by the present inventors, as the characteristics of the recording medium, the rise and fall gradients at the time of pit formation differ depending on the linear velocity, and as the linear velocity increases, the edge of the recording pit occupies the read discrimination window width The result was that the amount of fluctuation of the detection position increased. That is, as shown in FIG. 9, when the recording clock frequency is changed so as to have the same recording pit length at the inner and outer circumferences of the recording area, the ratio of the variation amount ΔΦ to the discrimination window width W is It tends to increase from the periphery to the periphery.

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

An object of the present invention is to solve the above-mentioned problems and provide a high-reliability and large-capacity information recording / reproducing system capable of stable reproduction by ensuring stable signal quality at all recording positions on the inner and outer circumferences. There is.

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

In other words, according to the present invention, the recording area of the disc-shaped recording medium is divided into a plurality of zones that are sequentially adjacent in the radial direction, and a recording / reproducing clock is assigned to each zone, and assigned to each zone. A recording / reproducing system 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 periphery to the outer periphery, the recording capacity of one track increases, and the pit or recording domain used for data recording There is provided a recording / reproducing method for recording / reproducing data by changing the clock frequency for recording / reproducing so that the circumferential length is gradually increased.

Furthermore, 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 disc-shaped recording medium at a constant angular velocity, and according to the radial position of the recording medium. An information recording system comprising a clock control system for controlling a recording area to set a plurality of zones and setting a recording / reproducing clock for each zone, and for recording data by a clock assigned to each zone There is provided a recording / reproducing apparatus comprising 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 that are sequentially adjacent in the radial direction, and the circumferential length of the pits or recording domains used for data recording for tracks in the same order in each zone. However, a disc-shaped recording medium is provided which is recorded so as to become longer as it goes to the outer peripheral zone.

Since the present invention is configured as described above, the following effects can be obtained.

Since the disk-shaped recording medium can be rotated at a constant angular velocity, the rotational speed stabilization time of the disk-shaped recording medium is not required 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 substantially constant at the recording / reproducing clock switching position, so that it is stable at all recording positions. Readable high-density recording can be performed.

  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 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 that rotationally drives the optical disk medium 1, an optical head 4 that reads / writes information from / to 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 that function under the control of the main control circuit 6 are configured.

The positioning control system for the optical head 4 functions as a positioning mechanism 19 that positions the optical head 4 at a target position, a positioning control circuit 18 that performs positioning control with respect to the positioning mechanism 19, and means for detecting the access position of the optical head 4. The scale detector 20 is provided.

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

The information reproduction system synchronizes the reproduction code 29 with the binarization circuit 15 that binarizes the reproduction signal 27 detected by the photodetector (not shown) in the optical head 4 to obtain the reproduction code 29, and synchronizes the synchronization code. 36 and a PLL circuit 35 that outputs a discrimination clock 37
A reproduction data synthesizing circuit 16 that synthesizes a reproduction data code 30 from the synchronization code 36, and a demodulation circuit 17 that demodulates 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, and 1 corresponding to the access position. Alternatively, it comprises clock information generating means for outputting to the synthesizer 8 clock information 34 designating a recording / reproducing clock assigned to every two or more tracks. The clock information generation unit is configured as a function of the main control circuit 6.

As shown in FIG. 2, the optical disk medium 1 has a recording area 2 partitioned into a plurality of zones 2a to 2f that are successively adjacent in the radial direction. Each zone 2a ~
A plurality of tracks are provided in 2f, where information is recorded and reproduced. In addition, the optical disk medium 1 has zones 2 a to 2 in the recording area 2.
At the boundary of f, there is a recording / reproducing clock frequency switching position 41 every several tracks,
At the position 41, the number of sectors 42 is increased by one from the number of sectors 42 included in the inner track.

As will be described later, the optical disc medium 1 of the present embodiment has zones 2a to 2 as described below.
The tracks in the same order in f are recorded such that the circumferential lengths of the pits or recording domains used for data recording become longer toward the outer zone.

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

The main control circuit 6 is, for example, a central processing unit (CPU), CP, although not shown.
It has a ROM for storing U programs, 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 stores and holds conversion tables such as those shown in FIG. 10 and FIG. 15 to be described later in the ROM or RAM, and based on information from the host computer 5, the CPU controls the corresponding clock. Information 34
It is comprised so that it can take out.

For example, as shown in FIG. 12, the synthesizer 8 divides the basic clock 61 from the basic clock oscillator 7 and outputs a reference clock 64, and a recording / reproducing clock that is an output of the synthesizer 8. 32 to the main control circuit 6
The variable frequency divider 63 that divides the frequency according to the frequency division number set by the clock information 34 from the clock frequency, and the frequency of the variable frequency divided clock 65 output from the variable frequency divider 63 and the reference clock 64 are compared. The phase comparator 66 that controls the output signal 67 so as to match the two, 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) a circuit 69.

The output of the VCO circuit 69 is output as the recording / reproducing clock 32 and 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 from 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 according to a correction command from the recording corrector 11. And an AND circuit 73 that 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 according to the value of the recording code 24, and thereby drives the semiconductor laser 77 on and off.

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

The recording corrector 11 includes, for example, a ROM. In this ROM,
A command for selecting 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 binarization circuit 15, the PLL circuit 35, the reproduction data synthesizing circuit 16, and the like can 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 system of the present invention will be described by taking as an example the case of using the optical disc apparatus shown in FIG.

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

FIG. 4 is a waveform diagram showing a process of signal change and pits formed on the disk when data is modulated and converted into a code and recorded on the disk. 5th
FIG. 4 is a waveform diagram showing the process from reproducing information from the pits recorded on the disc to demodulating the 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 is read and written.

In FIG. 1, data 21 to be recorded is modulated into a code 22 by a modulation circuit 9. This encoding 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 into the NRZ code 23 by the NRZ encoder 10.

By the way, if this NRZ code 23 is recorded on the optical disk medium 1,
In general, 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 in the recording film,
This is because a state exceeding the melting point of the recording film occurs even in a portion not irradiated with the recording pulse light. 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.

Accordingly, in order to make the length of the formed recording pits 26 correspond to the length of the NRZ code 23, the recording code 24 in which the pulse width is corrected in advance (shortened in the case of illustration).
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 by control from the recording corrector 11 using the setting devices 12 and 13. In response to this, the laser driver 14 drives the semiconductor laser 77 to record pits 26.
Is formed. That is, the front edge and the rear edge of the formed pit are represented by 2-
Corresponding to “1” of 7 codes, data is recorded onto the optical disk medium 1.

Next, the 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 irradiated with the laser light is recorded in the recording pit 26.
The amount of light changes depending on whether or not there is a reproduction signal 27 as an analog signal. By the binarization circuit 15, the reproduction signal 27 can be binarized using a certain slice level 28 to obtain a reproduction code 29.

As another method, it is also possible to obtain a binarized reproduction code 29 by second-order differentiation of the reproduction signal 27 and detecting its zero cross point.

From the rising and falling edges of the reproduction code 29, corresponding pulses are generated, and the code 30 is obtained from both. By inputting this to the demodulating circuit 17 that performs the reverse operation of the modulating circuit 9, the data 31 can be reproduced.

In FIG. 5, the recording / reproducing clock 32 is shown to correspond to FIG. 4, but in actuality, when reproducing the code 30 from the reproduction code 29, the PLL is reproduced.
The circuit 35 generates a 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 considered.

When the 2-7 modulation method is used, there are six types of recording pit lengths. Here, the length of the shortest pit is 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.
When μm and the number of sectors included in the innermost track are n, the shortest pit length l _o in the innermost track is expressed 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 at the outer circumference than at the inner circumference at the position where the recording / reproducing clock frequency is switched is as follows.

N · d · n-R> 0
For example, an optical disc medium 1 formatted with a track pitch d = 1.5 μm.
If N = 1024, n = 51, and R = 70 mm, the pit length having the same recording information at the clock switching position can be monotonously increased toward the outer periphery.

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

On the other hand, if 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 the starting point of the present invention, and will be described below.

Since the optical disk 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, as shown in FIG. 7, the ultimate temperature curve of the film surface acting on the pit formation when the recording laser beam is irradiated varies depending on the magnitude of the linear velocity. When the recording laser light is irradiated, the ultimate temperature curve on the film surface may fluctuate as shown by the dotted line in FIG. 7 due to non-uniformity of the recording film, fluctuation of the linear velocity, or the like. As a result of the above fluctuations, the pit formation position fluctuates, the ultimate temperature curve has a gentle gradient, the linear velocity is higher, that is, the outer peripheral portion has a larger pit formation position fluctuation amount ΔΦ. . The same applies to the trailing edge of the formation pit.

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

As shown in FIG. 8, the prior art changes the frequency of the recording / reproducing clock 32 in proportion to the linear velocity at the recording position to form the recording pits 26 so that the linear density is constant over the entire recording area. . FIG. 8 shows waveforms at the inner periphery of the clock frequency f ₀ and the outer periphery (clock frequency 2f ₀ ) having a linear velocity twice that of the inner periphery.

As shown in FIG. 8, in this prior art, since the variation amount ΔΦ of the pit length with respect to the recording pit length is larger at the outer peripheral portion than at the inner peripheral portion, the detection occupies the discrimination window width W of the discrimination clock 36 after all. The ratio ΔΦ / W of the fluctuation amount of the signal position is increased. FIG. 9 shows the transition of the ratio ΔΦ / W of the variation amount of the detection signal occupying the discrimination window width when recording with the same pit length from the inner periphery to the outer periphery of the optical disc medium 1. 9th
As shown in the figure, ΔΦ / W increases as the recording position goes 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. Then, including this action, the information data recording / reproducing operation will 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 on the track number 46 transmitted from the main control circuit 6.

As a method of positioning the optical head 4 on the target track, for example, the sector 42 is used.
Use the information of the ID part created in advance in the inside or provide an external scale,
A method of reading the positioning position with the scale detector 20 is used.

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.

The synthesizer 8 generates a recording / reproducing clock 32 corresponding to the clock information 34. In FIG. 10, the switching position 41 of the recording / reproducing clock 32 is set at every 1024 tracks because the pit length having the same information increases toward the outer periphery at the clock switching position 41, and the detection signal occupies the discrimination window width. This is because the rate of change in position (ΔΦ / W) is also smaller than when the pit length is constant. Of course, the number of tracks is not limited to this, and other numbers of tracks may be used as long as this condition is satisfied.

The synthesizer 8 divides the basic clock 61 generated by the basic clock oscillator 7 by the fixed frequency divider 62 and generates a reference clock 64. Further, the frequency dividing 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 becomes the recording / reproducing clock 32 in the VCO circuit 69.

Further, the recording / reproducing clock 32 is input to the variable frequency divider 63 so that 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 2-7 code. The NRZ encoder 10 converts the code 22 into the NRZ code 23 on the recording / reproducing clock 32 generated by the synthesizer 8.

As described above, when recording is performed by irradiating the NRZ code 23 with laser light,
Due to the thermal diffusion characteristics of the optical disk medium, a recording pit length longer or shorter than that of the NRZ code 23 is formed. Since this characteristic changes with linear velocity,
It is necessary to correct to an optimum value. Further, in order to make the recording pit length coincide 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 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 this delay element 71, a signal with a fixed delay time is output to a plurality of output taps. There is also a method using a gate delay as the delay element.

The output from the delay element 71 is input to the selector 72, and any output is selected by the recording corrector 11 and input to the AND gate 73. AND gate 7
Since the non-delayed signal is input to the other of 3, a pulse 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, A
It is only necessary to change the OR gate of the ND gate 73. Moreover, both can also be used together.

On the other hand, the recording light power is controlled by changing the value of the current source in the laser driver 14. The laser driver 14 has a current switch configuration, and the light emission when the semiconductor laser 77 is turned on by changing the base potential of the transistor 75 that determines the current value by the D / A converter 74. You can change the power. 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 drive current of the semiconductor laser 77 is also increased, and the light emission power is increased.

The recording corrector 11 sets the pulse width and power according to 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 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, an external scale detector 20 is used.
The position can be recognized and the same control can be performed using the method using the value from the above or the number of tracks crossing from the reference radius (for example, 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 a 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 and performs the same operation as in recording to position the optical head 4 on the target track. The light emission power of the semiconductor laser 77 is set to a reproduction level, and the optical disk medium 1 is irradiated with laser light. 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 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
The recording / reproducing clock 32 corresponds to the clock information 34 as in the recording.
Is generated.

In the present invention, a pit edge recording system is adopted as a data recording system.
And in actually adopting edge recording, the recording pit changes with the target length, so the data corresponding to the leading and trailing edges is handled as individual data and recombined. 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.

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

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 at the leading edge and the trailing edge by a detection circuit of known data (for example, a SYNC pattern).
Two series of data strings are synthesized.

After obtaining the code 30 as the output of the reproduction data synthesis circuit 16, the demodulation circuit 17
The data 31 is obtained by performing the reverse operation to that at the time of modulation. The demodulation circuit 17
A well-known thing may be sufficient.

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

FIG. 10 shows track number 46, clock information 34, recording / reproducing clock frequency 3
2 shows a second conversion table. In this case, the recording / reproducing clock frequency 32
The number of tracks to be switched is set to every 1024, and the number of sectors 42 constituting the track is increased by one sector at each clock switching position 41 as it goes to the outer periphery.

Here, the recording / reproducing clock frequency is obtained. Arpm the rotational speed of the optical disk medium 1, and the number of sectors innermost tracks n, 1 sector the total number of bits of Z, the recording and reproducing clock frequency f ₀ at 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 disk medium 1 using the conversion table of FIG. 10 and setting the track pitch d to 1.5 μm, the innermost track number n to 51, and the innermost track radius to 70 mm. 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 the circumferential lengths of the pits or recording domains used for data recording gradually increase toward the outer peripheral zone for tracks in the same rank in each zone. It shows. here,
Tracks in the same order in each zone are, for example, in each track,
It means tracks arranged in the same order from the inner side. Specifically, it is the i-th track of each zone, for example, the first re-inner track.

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

The present embodiment is an example in which the recording pit length increases at the recording / reproducing clock frequency switching position 41 and is made more gradual or abrupt than 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,
It controls by the combination of them. The storage capacity of the optical disk medium can be increased if the tendency to increase the number of recording pits can be suppressed as compared with the case where the number is fixed at 1024.

That is, in this embodiment, on the optical disc medium 1, the pits or recording domains in the tracks in which the circumferential lengths of the pits or recording domains used for data recording are in the same order in the adjacent zones on the inner circumference side are recorded. Zones that are 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
Three consecutive areas for switching the recording / reproducing clock in one track, and then
It is assumed that an area for switching clocks is provided for 512 tracks. That is, under the conditions of d = 1.5 μm, n = 51, and R = 70 mm, when N = 1024, the pit length is increased from the inner circumference side, and when N = 512, the pit length Can be reduced. Therefore, the tendency for the pit length to increase from the inner periphery to the outer periphery 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, description is not repeated here. In this embodiment, the main control circuit 6 constituting the clock information generating means of the clock control system stores and holds a conversion table as shown in FIG. 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 and a recording / reproducing clock frequency 32 conversion table.

FIG. 16 shows the format on the 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 the 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 that can be stably reproduced can be selected, and the recording capacity can be increased.

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

In the present embodiment, the position for switching the recording / reproducing clock 32 may be arbitrarily set. In this way, the increment of the recording pit length can be arbitrarily set, and the ratio (ΔΦ / W) of the pit length fluctuation amount ΔΦ to the discrimination window width W can be made substantially constant at any recording position on the inner and outer circumferences. Is possible. Therefore, a recording method with the highest density that can be read stably with a constant read margin at all recording positions can be realized.

FIG. 17 shows the ratio (ΔΦ / W) of the fluctuation amount of the detection signal position in the discrimination window width. As is apparent from this figure, the frequency of the recording / reproducing clock is set for each zone or for each track so that the pit length increases as the recording position increases from the inner periphery to the outer periphery as in the above embodiments of the present invention. If set to (ΔΦ / W)
Can be kept within a substantially constant range. Conversely, at any recording position, (ΔΦ /
To set W) to be the same as the inner circumference, what is the shortest pit length,
You can see how much the recording / reproduction clock should be set.

In each of the above-described embodiments, a write-once optical disk that forms elliptical pits on 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-magnetic and phase change). In the case where a magnetic disk medium, a flexible disk medium, or the like is used, the same can be applied.

The optical disk apparatus of the above embodiment has both the recording function and the reproduction function, but may be an apparatus having only one of the functions.

  The effects obtained in the above embodiment are as follows.

The present invention provides a recording / reproducing device that rotates a disc-shaped recording medium at a constant angular velocity and increases the recording capacity of one track as the recording position of the disc-shaped recording medium changes from the inner circumference to the outer circumference. Data is recorded / reproduced by changing the clock frequency. Thereby, the recording capacity recorded on the disc can be increased even at a constant angular velocity.

At this time, the recording / reproducing clock frequency is set so that the circumferential length of the pit or recording domain used for data recording is gradually increased. 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 data is reproduced, the discrimination window width W
The clock frequency for recording / reproducing is changed so that the ratio (ΔΦ / W) of the fluctuation amount ΔΦ of the appearance position of the detection signal in FIG. As a result, the discrimination window width W is larger at the outer periphery, and a read margin is sufficient at the outer periphery, thereby reducing reading errors. 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.

The present invention also divides the recording area of the disk-shaped recording medium into a plurality of zones that are sequentially adjacent in the radial direction, and assigns a recording / reproduction clock to each zone, and uses the clock assigned to each zone. Record / play data. Therefore, the clock control can be easily performed with a simple circuit configuration.

In this case, the recording / reproducing clock for each zone may be allocated with a different frequency so that the recording capacity of one track increases as it goes to the outer zone. Further, with respect to 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 data recording gradually increases toward the outer zone. .

1 is a block diagram showing a basic configuration of an embodiment of an optical disc apparatus to which the present invention is applied. Explanatory drawing of the outline | summary format of an optical disk medium. Explanatory drawing which shows the structure of 1 sector. The wave form diagram which shows the data recording method. The wave form diagram which shows the data reproduction method. The graph which shows transition of the shortest recording pit length in a recording / reproducing clock switching position. The graph which shows the ultimate temperature curve of a recording film surface. The model waveform figure which showed the fluctuation | variation of the recording pit. The graph which shows transition of the ratio of the variation | change_quantity of the detection signal position which occupies for the discrimination window width. Explanatory drawing which shows the conversion table of clock information. Explanatory drawing which shows the format of the optical disk medium corresponding to the conversion table of FIG. The block diagram which shows an example of a structure of a synthesizer. The block diagram which shows the structure of the circuit which correct | amends at the time of recording. The graph which shows transition of the shortest recording pit length in a recording / reproducing clock switching position. Explanatory drawing which shows the conversion table of clock information. Explanatory drawing which shows the format of the optical disk medium corresponding to the conversion table shown in FIG. It is a graph which shows transition of the ratio of the variation | change_quantity of the detection signal position which occupies for the discrimination window width.

Explanation of symbols

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 setter, 13
DESCRIPTION OF SYMBOLS ... Power setter, 14 ... Laser driver, 15 ... Value conversion 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 adjacent to each other in the radial direction, and the shortest pit or the shortest recording used for data recording is divided into each zone and tracks in the same order in each zone. The circumferential length of the domain is recorded so as to increase as it goes to the outer zone, and the number of sectors of each track increases as it goes to the outer zone,
The number of sectors included in a track belonging to any one of the plurality of zones is one more than the number of sectors included in a track belonging to a zone adjacent to the inner circumference side,
The number of tracks belonging to the first zone of the plurality is the same as the number of tracks belonging to the second zone separated from the first zone by a plurality of zones in the outer circumferential direction,
The disc-shaped recording medium according to claim 1, wherein the number of sectors of the track existing in any one of the plurality of zones is 51. In the recording medium having a plurality of tracks having a plurality of sectors, the recording area is divided into a plurality of zones adjacent in the radial direction, and each sector has a header portion in which a sector number is recorded,
The circumferential length of the shortest pit or the shortest recording domain in which the sector number is recorded becomes longer in the header portion of the sector of the track in the same order in each of the plurality of zones as it goes to the outer peripheral zone. And the number of sectors in each track is recorded so as to increase toward the outer zone,
The number of sectors included in a track belonging to any one of the plurality of zones is one more than the number of sectors included in a track belonging to a zone adjacent to the inner circumference side,
The number of tracks belonging to the first zone of the plurality is the same as the number of tracks belonging to the second zone separated from the first zone by a plurality of zones in the outer circumferential direction,
The disc-shaped recording medium according to claim 1, wherein the number of sectors of the track existing in any one of the plurality of zones is 51. Recording or reproduction of a recording medium having a plurality of tracks each having a plurality of sectors, the recording area being partitioned into a plurality of zones adjacent in the radial direction, and each sector having a header portion in which a sector number is recorded In a recording / reproducing apparatus that performs
The recording medium has a circumferential length of a shortest pit or a shortest recording domain for recording the sector number in the header portion of the sector of the track in the same order in each of the plurality of zones. As it goes to the zone, it becomes longer and the number of sectors in each track is recorded to increase as it goes to the outer zone,
The number of sectors included in a track belonging to any one of the plurality of zones is one more than the number of sectors included in a track belonging to a zone adjacent to the inner circumference side,
The number of tracks belonging to the first zone of the plurality is the same as the number of tracks belonging to the second zone separated from the first zone by a plurality of zones in the outer circumferential direction,
The number of sectors of the track existing in any one of the plurality of zones is 51;
The recording / reproducing apparatus reproduces the sector number from a header portion of a track belonging to the plurality of zones.

Images