JP2001110060A - Optical disk and information recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk capable of performing a timing control with excellent jitter, keeping a recording positional precision high and increasing the recording capacity without providing futile buffer area, and to provide an information recorder. SOLUTION: Groove tracks G and adjacent land tracks L are spirally and alternately formed on the optical disk 1, the groove track G is subjected to a wobbling processing, and gap parts GP are arranged at every prescribed interval on the groove track G. This interval is defined as N times (N is natural number) of a period of a SYNC pattern inserted at a recording time, and the length Lg of the gap part GP is made shortened than the length of the SYNC pattern. Thus, the gap part GP is detected to perform the timing control, thereby recording the recording data with the high positional precision.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk for recording digital data, and more particularly to an optical disk on which predetermined pre-information is recorded on an optical disk in advance and an information recording apparatus for recording data on the optical disk. It is.

[0002]

2. Description of the Related Art Conventionally, as a preformatting technique for an optical disc such as a CD or a DVD, wobbling of a recording track is generally adopted.
That is, the recording track is meandered by a wobble signal of a constant frequency, and for example, predetermined pre-information is recorded in advance by FM modulation or the like. When recording on an optical disk, the wobble signal is extracted and used for performing a reliable recording operation, for example, as a synchronization reference for timing control or reading out pre-information such as necessary address information.

[0003]

However, in the above-described method of wobbling an optical disk as in the above-mentioned conventional method, in order to minimize the influence on the reproduction of information pits in a recording track, the frequency of the information pit train is reduced. A wobble signal having a low frequency sufficiently distant from the band is used, and the amplitude of the wobbling must be reduced. Therefore, the extracted wobble signal has a low S / N. For example, when the wobble signal is used as a reference for timing control, the recording position of the recording data cannot be accurately specified due to an increase in jitter. There is a risk of being destroyed by overwriting. As a countermeasure, it is necessary to provide a buffer area for recording dummy data at the end of recording on the optical disc in consideration of a shift in a recording position when performing additional recording later. Had become.

Accordingly, the present invention has been made in view of such a problem, and as a preformatting technique for an optical disc, a synchronization timing is detected with good jitter without affecting reproduction of recorded data, and a recording position is detected. It is an object of the present invention to provide an optical disc and an information recording apparatus capable of recording with high accuracy without providing a useless buffer area.

[0005]

According to a first aspect of the present invention, there is provided an optical disk in which a recording data sequence is formed at predetermined intervals on a recording track having a predetermined height on an information recording surface. An optical disc on which recording data is recorded by inserting a sync pattern for delimiting, wherein gaps are formed at intervals of N times (N is a natural number) of the predetermined interval with respect to the recording track. Is
An area having a length sufficiently shorter than the length of the sync pattern is formed at a height different from the predetermined height.

According to the present invention, a gap portion whose height is changed to a partially concave or convex shape is periodically formed at intervals of N times the interval of a sync pattern to be inserted in a recording track of an optical disk. I do. The length of the gap portion is sufficiently shorter than the length when the sync pattern is recorded. When recording data on an optical disc formed in this manner, for example, by using a tangential push-pull signal, a detection signal corresponding to a gap portion can be easily obtained, and the above-described periodicity can be used as a synchronization reference. it can. Therefore, if the length and height of the gap portion are appropriately set, the detection signal of the gap portion has a high S / N and can suppress the jitter, so that the position accuracy at the time of recording is improved and a useless buffer area is provided. It is not necessary. In addition, since the sync pattern can be arranged so as to match the position of the gap, it does not overlap with the recording data, and good reproduction performance can be maintained.

The optical disk according to the second aspect is the first aspect.
In the optical disc described in (1), predetermined pre-information is recorded in the gap portion in advance.

According to the present invention, predetermined pre-information can be stored in advance depending on the presence or absence and the shape of the gap by using the gap portion acting as described above. Useful information can be preformatted with high positional accuracy.

The optical disk according to the third aspect is the optical disk according to the first aspect.
Alternatively, in the optical disk according to claim 2, a recording track having a first height on an information recording surface and a guide track having a second height different from the first height are adjacent to each other on the optical disk. And the gap portion is formed at the second height.

According to the present invention, the optical disc has a cross-sectional structure in which the recording track and the guide track have different heights, and the gap is formed simply by making a part of the recording track the height of the guide track. The optical disk preformatted as described above can be provided by a simple manufacturing method.

The optical disk according to the fourth aspect is the optical disk according to the first aspect.
In the optical disc described in the above, in the recording track,
Wobbling is performed based on a wobble signal of a constant frequency.

According to the present invention, wobbling is performed on the recording track of the optical disc, and a wobble signal can be extracted upon reading. The above-described gap portion and wobbling are used together, and the characteristics of the optical disc are utilized while utilizing the respective features. Can be subjected to a complex preformat.

The optical disk according to the fifth aspect is the optical disk according to the fourth aspect.
3. The optical disk according to claim 1, wherein the wobble signal is modulated by address information.

According to the present invention, it is possible to obtain address information by extracting a wobble signal from wobbling applied to a recording track. For example, if the above-mentioned gap portion is used as a reference for synchronization detection, it can be used for an optical disk. On the other hand, when the recording data is accurately recorded, it can be processed usefully and rationally.

According to a sixth aspect of the present invention, there is provided an information recording apparatus for recording data on an optical disk according to any one of the first to fifth aspects, wherein the recording track is irradiated with a light beam. Reading means for outputting a read signal based on reflected light, timing control means for detecting the gap portion based on a signal pattern of the read signal, and outputting a timing signal synchronized with the detection timing; and Recording means for performing a recording operation of the recording data by inserting a sync pattern at every predetermined interval as a synchronization reference.

According to the present invention, when recording data on the optical disk of the present invention, a read signal based on the reflected light of the light beam applied to the recording track is output,
A gap is detected based on the signal pattern, and a timing signal synchronized with the detection timing is output. Synchronized by the timing signal, a sync pattern is inserted into the recording data at predetermined intervals so as to match the position of the gap portion, and the recording operation is performed. Therefore, the gap portion can be easily detected based on the fluctuation of the reflected light level of the optical disk, and further, the timing signal can be maintained with higher accuracy than when it is obtained based on, for example, wobbling, and the positional accuracy of the recorded data can be improved. Becomes Further, it is not necessary to consider the buffer area at the end of recording, and the recording capacity for the optical disk can be increased.

According to a seventh aspect of the present invention, in the information recording apparatus according to the sixth aspect, the reading means outputs a tangential push-pull signal as the read signal, and the timing control means The gap portion is detected based on the tangential push-pull signal.

According to the present invention, a tangential push-pull signal is output by taking the difference between the detection signals in the forward and rearward regions in the traveling direction based on the reflected light of the light beam applied to the optical disk. A gap portion is detected from a change in the signal pattern, and the above-described timing control is performed. Therefore, a tangential push-pull signal can be easily obtained using a general four-split detector, and the recording operation on the optical disk of the present invention can be performed with a simple configuration.

According to an eighth aspect of the present invention, in the information recording apparatus of the sixth or seventh aspect, the recording means records the sync pattern as a space.

According to the present invention, when recording the recording data on the optical disk, the sync pattern is inserted as a space at the position of the gap. Therefore, no recording mark is formed around the gap, avoiding mutual interference,
It is possible to improve both the reading performance of the recording mark and the performance of detecting the gap.

An information recording apparatus according to a ninth aspect of the present invention is the information recording apparatus according to any one of the sixth to eighth aspects, further comprising a clock signal generating means for generating a clock signal based on the timing signal. It is characterized by the following.

According to the present invention, a clock signal is generated using, for example, a PLL circuit based on a timing signal synchronized with the detection timing of the gap portion of the optical disk. Therefore, an accurate clock signal corresponding to the high positional accuracy of the gap can be supplied to each unit during the recording operation.

According to a tenth aspect of the present invention, in the information recording apparatus according to any one of the sixth to eighth aspects, the number of rotations of a spindle motor that rotationally drives the optical disk based on the timing signal is controlled. It is characterized by further comprising spindle control means for controlling.

According to the present invention, the timing signal synchronized with the detection timing of the gap portion of the optical disk is used as a reference for controlling the rotation speed of the spindle motor. Therefore, the rotation speed of the spindle motor can be accurately and stably controlled according to the high positional accuracy of the gap portion, and the recording performance of the optical disc is improved.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the structure of the disk surface of the optical disk according to the present embodiment. In FIG. 1, tracks are sequentially formed spirally from the inner circumference of the disc to the outer circumference of the disc on the optical disc 1, and a groove track G as a recording track for recording recording data and a guide track adjacent to the groove track G are formed. Are alternately formed. The height of the groove track G on the disk surface and the land track L
Are different from each other, and the groove track G has a convex shape and the land track L has a concave shape when viewed from the light beam irradiation side.

The groove tracks G meander at a constant pitch on the disk surface, and are so-called wobbling. Further, since the groove track G meanders, the adjacent land track L also meanders in a similar pattern. When the groove track G is traced by a light beam, a radial push-pull signal obtained from a quadrant detector described later includes a wobble signal having a constant wobble frequency. for that reason,
A wobble frequency can be extracted and used as a reference frequency, or wobbling FM-modulated with predetermined pre-information can be applied to the optical disc 1 to extract pre-information upon reading. For example, it is possible to carry address information of the optical disc 1 as pre-information.

In this embodiment, as shown in FIG. 1, a gap GP is provided at a predetermined position of the groove track G. The gap portion GP is a region in which a portion having a length Lg on the groove track G is formed not at the height of the groove track G (the portion indicated by oblique lines in FIG. 1) but at the height of the land track L. That is, with respect to the groove track G, the gap portion G is concavely formed along the track direction.
P is formed. Since the gap GP serves as a reference for timing control when reproducing the optical disc 1 as described later, it is necessary to provide the gap GP at regular intervals in the groove track G. Further, the position where the gap GP is provided needs to be separated from the recording mark in order to minimize the influence on the reproduction performance of the recorded data. As described above, in the present embodiment, the gaps GP are arranged so as to match the sync pattern for detecting the break of the recording data, but this will be described in more detail later.

FIG. 2 is a block diagram showing a schematic configuration of an information recording / reproducing apparatus for writing and reading recording data to / from the optical disc 1 according to the present embodiment. Here, a case of an information recording / reproducing apparatus capable of writing and reading recording data to and from the optical disc 1 according to the DVD format will be described. Further, a case where the above wobbling is performed on the optical disc 1 and address information is recorded will be described.

The information recording / reproducing apparatus shown in FIG. 2 comprises an optical pickup 10, a signal generator 11, a data demodulator 12
, An address decoder 13, a system control unit 14,
It comprises a data modulation section 15, a timing control section 16, a laser drive section 17, a spindle control section 18, and a spindle motor 19. The system control unit 14 has an external host PC (Personal Compute
r) is connected, and the recording data is input / output to / from the information recording / reproducing apparatus.

In FIG. 2, the pickup 10 includes a semiconductor laser 10a for irradiating a light beam onto a groove track G of the optical disk 1, and a four-divided detector 10b for receiving a reflected light from the optical disk 1 and outputting a detection signal. In. Further, the pickup 10 includes optical forms such as a collimator lens and an objective lens (not shown). Since the semiconductor laser 10a is used for both the recording operation and the reproducing operation, it can be driven with optimum power for each.

Here, the four-divided detector 1 will be described with reference to FIG.
The divided shape of 0b will be described. In the present embodiment, as described later, the RF signal Srf, the radial push-pull signal Srpp, and the tangential push-pull signal S
Since it is necessary to generate three of tpp, the four-divided detector 10b having a four-divided light-receiving surface is used. As shown in FIG. 3, the quadrant detector 10b is divided into four regions A, B, C, and D by a dividing line in the disk radial direction and a dividing line in the track tangential direction. Areas A and B correspond to the outer circumference of the disk, areas C and D correspond to the inner circumference of the disk, and areas B and C correspond to the front side in the light beam traveling direction, and areas A and D correspond to the rear side in the light beam traveling direction. ing.

Returning to FIG. 2, the signal generator 11 outputs an RF signal Srf, a radial push-pull signal Srpp, and a tangential push-pull signal Stp based on the detection signals of the respective divided areas output from the four-divided detector 10b.
Generate p. Specifically, the detection signals of the divided areas A, B, C, and D of the four divided areas 10 are respectively Sa, Sb, and S.
Expressed as c and Sd, the RF signal Srf is generated as Srf = Sa + Sb + Sc + Sd by taking the sum of these.

The radial push-pull signal Srpp
Corresponds to the difference between the reflected light levels on the outer peripheral side and the inner peripheral side in the disk radial direction, and is generated by Srpp = (Sa + Sb)-(Sc + Sd).

The tangential push-pull signal Stpp corresponds to the difference between the reflected light levels on the front and rear sides in the track tangential direction, and is generated by Stpp = (Sa + Sd)-(Sb + Sc).

The data demodulation unit 12 demodulates the recording data recorded on the optical disc 1 based on the RF signal Srf output from the signal generation unit 11. In the case of supporting the DVD format, the RF signal Srf is 8-1
6 Perform demodulation and deinterleaving to demodulate the recording data.

The address decoder 13 comprises a signal generator 11
The wobble signal is extracted based on the radial push-pull signal Srpp output from the device, and the address information is read. That is, since the wobbling meandering pattern involves a shift in the disk radial direction, the radial push-pull signal Srpp directly includes a wobble signal component, and it is possible to determine address information from the modulation pattern of the wobble signal. it can.

The system control unit 14 includes the data demodulation unit 12
And the address information from the address decoder 13 to control the operation of the entire information recording / reproducing apparatus. The system control unit 14 includes a CPU (not shown)
M, ROM, and the like, and executes a control program while inputting and outputting data to and from the host PC.

The data modulating unit 15 includes a system control unit 14
Generates a modulation signal based on the recording data supplied from the
Output to the timing control unit 16. In the case of the DVD format, modulation is performed by forming an ECC block, performing interleaving, 8-16 modulation, and scrambling.

The timing control section 16 includes the signal generation section 11
Push-pull signal St output from
pp, the gap G on the groove track G
A timing control signal is generated using P as a reference for the timing control, and thereby the operation timing of the laser drive unit 17 and the spindle control unit 18 is controlled. In this embodiment,
Assume that the timing control unit 16 generates and outputs a synchronization detection signal as a timing signal. The timing control unit 16 includes a synchronization detection circuit and a PLL.
Details of the configuration and operation will be described later.

The laser driver 17 is provided with a semiconductor laser 10a.
Output a drive signal whose pulse timing is controlled by the timing control unit 16 to irradiate a light beam from
The semiconductor laser 10a is driven. During a reproducing operation, a driving signal corresponding to the reproducing power is output, and during a recording operation, a driving signal corresponding to the recording power is output.

The spindle controller 18 supplies a control signal whose timing has been controlled by the timing controller 16 to a spindle motor 19. Then, the spindle motor 19 drives the optical disc 1 to rotate based on the control signal. On the other hand, a rotation pulse is output from the spindle motor 19 in accordance with the rotation of the optical disc 1, and the spindle control unit 1
8 is fed back.

Next, the arrangement of the gap GP on the optical disc 1 according to the present embodiment and the operation waveform near the gap GP will be described with reference to FIG. In FIG. 4, the waveform pattern of the recording signal, the configuration of the groove track G, the waveform pattern of the RF signal Srf, and the waveform pattern of the tangential push-pull signal Stpp are compared and shown at a common timing from the top.

At the first stage of recording on the optical disk 1, no recording mark has been formed on the groove track G, and a gap portion GP having a length Lg has been formed at a predetermined position. When recording is started in this state, the gap G is determined based on the tangential push-pull signal Stpp.
The position of P is determined, and a recording signal shown in FIG. 4 is generated in synchronization with the position of P. This recording signal includes 1 as a sync pattern centered on the determined position of the gap GP.
4T space is included. That is, a space having a width of 14 channel bits is periodically inserted to separate recording data. The length Lg of the gap GP is considerably shorter than the length corresponding to the 14 channel bit width of the sync pattern.

As shown in FIG. 4, the recording signal includes a first pulse preceding the sync pattern and a second pulse subsequent to the sync pattern. A recording mark M1 corresponding to the second pulse and a recording mark M2 corresponding to the second pulse are formed. On the groove track G, no recording mark is formed in a range between the recording mark M1 and the recording mark M2, and a gap GP having a length Lg is arranged near the center of the recording mark. That is, the gap portion GP is arranged to be separated to some extent from the preceding and succeeding recording marks M1 and M2.

Here, the optical disk 1 according to the present embodiment
The reason for making the gap GP of the groove track G coincide with the vicinity of the center of the sync pattern is as follows.
First, a sync pattern is a pattern inserted to divide a sync frame, which is a processing unit of recording data, and its arrangement is periodic. Therefore, the sync pattern overlaps with the arrangement of the gap GP used as a reference for timing control. Because it is easy. Secondly, in the DVD format, the 14T space of the sync pattern has the longest space length, and the gap GP can be arranged away from the recording mark to suppress the influence on the reproduction performance.
Note that the gap portion GP may be provided for all the sync patterns.
The gap portion GP may be provided at a cycle of N times (N is a natural number) the appearance cycle of the sync pattern, such as every third or every third pattern.

When the groove track G on which the recording marks M1 and M2 and the gap GP are formed is traced and reproduced, the detection signal from the four-divided detector 10b is processed by the signal generation unit 11 as shown in FIG. An RF signal Srf having a simple waveform pattern is obtained. In the case of the RF signal Srf, the level is large at a position where the recording marks M1 and M2 are not present, and is low at a position where the recording marks M1 and M2 are formed. At the position corresponding to the sync pattern, the level of the RF signal Srf is kept large. As a result, the data demodulation unit 12 performs demodulation processing in response to the RF signal Srf, so that the recording data corresponding to the recording marks M1 and M2 can be demodulated.

Here, as shown in FIG.
The influence of P on the level fluctuation of the RF signal Srf is reduced. Actually, the level of the RF signal Srf slightly changes due to the change in the level of the reflected light at the gap GP. However, since the length Lg of the gap GP is sufficiently smaller than that of the 14T space, the S / N ratio is reduced. The level fluctuation is within the allowable range. Thus, the RF signal S
From the viewpoint of securing the S / N of rf, the length L of the gap portion GP
g is desirably set to a value not exceeding, for example, 2T to 3T. However, since it is necessary to generate a change pattern in the tangential push-pull signal Stpp as described later, it cannot be extremely shortened.

On the other hand, during the recording operation, the four-part detector 10
When the detection signal from b is processed by the signal generator 11, FIG.
A tangential push-pull signal Stpp having the waveform pattern shown in FIG. Before the recording mark is formed on the groove track G, since only the gap GP is formed, the waveform pattern changes in an inverted S shape at the position of the gap GP. This is because when the light beam traces the gap GP, the gap G
This is due to the fact that the reflected light amount level is reduced because P is at the height of the land track L, while the timing of light reception level reduction is shifted between the preceding areas B and C and the following areas A and D. That is, at first, the light receiving levels of the regions B and C decrease, and (Sa + Sd)> (Sb + Sc)
And the tangential pull signal Stpp increases in the positive direction. Subsequently, the light receiving levels of the areas A and D decrease,
Since (Sa + Sd) <(Sb + Sc), and the tangential push-pull signal Stpp decreases in the negative direction, an inverted S-shaped pattern as shown in FIG. 4 is obtained. Therefore, by detecting the inverted S-shaped pattern in the tangential push-pull signal Stpp, it becomes possible to perform timing control based on the gap GP.

Next, the configuration and operation of the timing control section 16 of the information recording / reproducing apparatus according to the present embodiment will be described with reference to FIGS. FIG. 5 is a block diagram illustrating a configuration of a main part of the timing control unit 16. FIG. 6 is a timing chart of each unit of the timing control unit 16, and FIG.
FIG. 8 is a diagram illustrating an example of a circuit configuration of a synchronization detection circuit included in the timing control unit 16, and FIG. 8 is a diagram illustrating operation waveforms of the synchronization detection circuit in FIG.

As shown in FIG. 5, the timing controller 16
Includes a synchronization detection circuit 101, a phase comparator 102, a control circuit 103, an oscillator 104, and a frequency dividing circuit 105.

The synchronization detection circuit 101 receives the tangential push-pull signal Stpp,
, The above-mentioned inverted S-shaped pattern at the position is detected, and a synchronization detection signal is output. Note that the synchronization detection circuit 10
The specific circuit configuration of 1 will be described later. In addition, the phase comparator 102, the control circuit 103, the oscillator 104, and the frequency dividing circuit 105 integrally form a PLL circuit.

In FIG. 5, the synchronization detection signal from the synchronization detection circuit 101 is compared in phase by a phase comparator 102 with a frequency-divided signal obtained by dividing the recording clock by N. Then, the control circuit 102 generates a control signal whose control amount changes according to the degree of the phase error of the phase comparator 102, and outputs the control signal to the oscillator 104. Oscillator 104 according to a control signal
Is variably controlled and output as a recording clock. On the other hand, the recording clock is frequency-divided by N by the frequency dividing circuit 105, and the frequency-divided signal is divided by the phase comparator 10 as described above.
2 is supplied. As a result, a recording clock having N times the frequency of the synchronization detection signal is output, and the phase of the recording clock can always be matched with the synchronization detection signal. When a sync pulse is output for each sync frame in the DVD format, N = 1488 may be set.

Here, the timing control unit 1 will be described with reference to FIG.
The operation waveforms of the six units will be described. In FIG. 6, a tangential push-pull signal Stpp, a synchronization detection signal,
It shows a frequency-divided signal and a recording clock, and shows the relationship between the respective phases. FIG. 6A shows the case where the phase of the recording clock is advanced, FIG. 6B shows the case where the phase of the recording clock is appropriate, and FIG. 6C shows the case where the phase of the recording clock is delayed. I have. FIG. 6 shows a case where the frequency division number N of the frequency dividing circuit 105 is 8 for simplicity.

In FIGS. 6A to 6C, the tangential push-pull signal Stpp includes a gap GP.
, A waveform portion of the above-described inverted S-shaped pattern corresponding to the above appears periodically. In the synchronization detection signal from the synchronization detection circuit 101, the generation timing of each pulse coincides with the vicinity of the center of the inverted S-shaped pattern of the tangential push-pull signal Stpp. That is, the detection frequency of the gap GP matches the frequency of the synchronization detection signal, and N times the frequency becomes the frequency of the recording clock.

As shown in FIG. 6A, when the phase of the recording clock is advanced, the rising timing of the frequency-divided signal divided by N in the frequency dividing circuit 105 is earlier than the synchronization detection signal. On the other hand, as shown in FIG. 6C, when the phase of the recording clock is delayed, the rising timing of the frequency-divided signal is later than the synchronization detection signal.

When the phase of the recording clock is shifted as shown in FIG. 6A or FIG. 6C, the phase of the recording clock is adjusted based on the operation of the PLL circuit. As a result, finally, as shown in FIG. 6B, the rising edge of the frequency-divided signal and the synchronization detection signal have the same timing, and the recording clock is output while maintaining the frequency and phase stably. Therefore, by writing recording data on the optical disk 1 using this recording clock, a recording mark can be formed at an appropriate recording position.

Next, the synchronization detection circuit 101 included in the timing control section 16 will be described with reference to FIGS. As shown in FIG. 7, the synchronization detection circuit 101 is a circuit that outputs one pulse each time the gap portion GP is detected as described above, and includes two comparators 201 and 202.
, A falling edge detector 203, a one-shot pulse generator 204, and a gate circuit 205.

One end of each of the comparators 201 and 202 receives the tangential push-pull signal Stpp. The other end of the comparator 201 has a zero level Z of the tangential push-pull signal Stpp.
, And a predetermined threshold value TH is input to the other end of the comparator 202. As shown in FIG. 8, the level of the portion without the gap GP is zero level Z with respect to the tangential push-pull signal Stpp.
Is set as In addition, S is larger than zero level Z,
A predetermined level within a range smaller than the peak of the character pattern is set as the threshold TH.

At this time, as shown in FIG. 8, the output signal C1 from the comparator 201 goes high in the first half of the S-shaped pattern and goes low in the second half. On the other hand, in other portions, the output signal C1 is undefined because the level of the zero level Z and the level of the tangential push-pull signal Stpp match (the portion indicated by oblique lines in FIG. 8). On the other hand, since the output signal C2 from the comparator 202 sets the threshold value TH to a level larger than the zero level Z, the output signal C2 is at a high level in a narrow range in the first half of the S-shaped pattern. It becomes low level in the part.

The falling edge detector 203 detects a falling edge in the signal waveform of the output signal C1 from the comparator 201 and outputs a pulse train P1. Therefore, the pulse train P1 includes a pulse Pc near the center of the S-shaped pattern and a large number of pulses that are generated randomly in a portion where the output signal C1 is undefined.

The one-shot pulse generator 204 outputs a gate pulse P2 having a high level by the pulse width of the time T0 at the falling timing of the output signal C2 from the comparator 202. Here, the time T0 needs to be set to a range that includes only the output timing of the pulse Pc from the falling edge detector 203 and does not include other pulses.

The gate circuit 205 selectively passes the pulse train P1 from the falling edge detector 203 based on the gate pulse P2 from the one-shot pulse generator 204 and outputs it as a synchronization detection signal. That is,
The gate is opened during the period when the gate pulse P2 is at the high level for the time T0, the output pulse from the falling edge detector 203 is output, and the gate is closed during the other periods.
Suppress output. Thereby, the gate circuit 2
Since the synchronization detection signal output from 05 has the same timing as the center of the S-shaped pattern and outputs only the pulse Pc, the gap GP can be used accurately as a synchronization reference.

Next, with reference to FIG. 9, the accuracy of the recording clock generated corresponding to the above-described synchronization gap GP will be described in comparison with a conventional recording clock generated based on wobbling. FIG. 9A shows a comparison of the jitter generated in the recording clock in the conventional case, and FIG. 9B shows a comparison of the jitter generated in the recording clock in the present embodiment. In FIG. 9, for simplicity,
The case where the frequency division number N = 24 is shown.

In the case of FIG. 9A, a recording clock is generated based on the wobble signal included in the radial push-pull signal Srpp. First, the radial push-pull signal Srpp is converted into a binary signal, and then the recording clock is obtained by comparing the phase of the recording clock with the frequency-divided signal obtained by dividing the recording clock by M. Here, the radial push-pull signal S
The frequency and phase of the recording clock are controlled in synchronization with the zero cross point of rpp. However, as shown in FIG. 9A, since the noise level of the radial push-pull signal Srpp is considerably large, the jitter in the vicinity of the zero-cross point of the binarized signal increases, and the jitter of the frequency-divided signal also increases. . As a result, jitter occurs over several cycles in the recording clock.

This is because the wobbling performed on the groove track G may overlap with the information pit, and it is necessary to suppress the influence on the reading of the recording data.
This is because the wobble frequency is set sufficiently smaller than the frequency band of the information pit row and the amplitude of the wobbling is made very small.

On the other hand, in the case of this embodiment, FIG.
As shown in FIG. 9B, the jitter of the vicinity of the S-shaped pattern of the tangential push-pull signal Stpp and the corresponding synchronization detection signal and the corresponding frequency-divided signal are much smaller than those in FIG. I have. As a result, the jitter of the recording clock can be sufficiently reduced to less than one cycle. This is because the gap portion GP is formed so as to coincide with a sync pattern having no recording marks around it, so that the size can be made approximately the same as the shortest recording mark, and the frequency is high and the amplitude is sufficiently secured. And a rapidly changing tangential push-pull signal Stpp
Is obtained.

As described above, when the recording clock is generated based on the gap GP as in the present embodiment, the difference in the magnitude of the jitter between FIG. 9A and FIG. Compared to the case of generating based on the frequency, the frequency and phase can be controlled more accurately, and the recording data can be written with higher accuracy. Therefore, recording data can be recorded at an accurate recording position on the optical disk 1, and there is no need to provide a buffer area for additional recording.

Next, FIG. 10 is a diagram showing a main configuration when the present invention is applied to generation of a control signal in the spindle control section 18 of the information recording / reproducing apparatus according to the present embodiment.
As shown in FIG. 10, the spindle control unit 18 is configured to include a cycle detection unit 301, a subtraction circuit 302, and a control circuit 303.

In FIG. 10, the cycle detector 301 includes:
The period of the synchronization detection signal output from the synchronization detection circuit 101 of the timing control unit 16 is detected. That is, one cycle corresponding to the detection interval of the gap GP is counted by an external reference clock (not shown), and the count value is output. The subtractor 302 subtracts a preset reference count value from the count value output from the cycle detection unit 301 and outputs the result. The control circuit 303 includes the subtractor 30
A control signal whose control amount changes according to the value output from 2 is generated and output to the spindle motor 19.

For example, when the rotation speed of the spindle motor 19 increases, the detection period of the gap GP decreases, and the count value output from the period detection unit 301 decreases. As a result, the output from the subtractor 302 becomes a negative value. Becomes vice versa,
When the rotation speed of the spindle motor 19 decreases, the detection period of the gap GP increases, and the count value output from the period detection unit 301 increases. As a result, the output from the subtractor 302 becomes a positive value. Therefore, if the control circuit 303 is provided with such a characteristic that the number of revolutions is decreased when the input value is negative and the number of revolutions is increased when the input value is positive, the number of revolutions of the spindle motor 19 is constant in synchronization with the reference clock. Is kept.

Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention. Hereinafter, a case where the present invention is modified and applied will be specifically described.

In the above embodiment, the gap portion GP of the groove track G is formed at the height of the land track L. However, the present invention is not limited to this. The height of the gap portion GP is set within the detectable range. The height may be different from the height.

In the above embodiment, the case where the synchronization detection signal is generated based on the gap GP formed in the groove track G has been described. However, the present invention is not limited to this. For example, pre-information such as address information is carried in the gap GP. In addition, it may be readable at the time of the recording operation. In this case, pre-information may be recorded based on the presence or absence of the gap GP and the height of the gap GP.

In the above embodiment, the case where the gap portion GP is formed in the groove track G and wobbling is performed has been described, but the gap portion G is formed in the groove track G.
The present invention can be applied even when only P is formed and no wobbling is performed.

[0076]

As described above, according to the present invention,
A gap is formed periodically in the recording track of the optical disk, and the sync pattern is arranged so as to match the position of the gap during recording. And the recording position accuracy can be kept high, and the recording capacity of the optical disc can be increased without providing a buffer unit.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of a disk surface of an optical disk according to an embodiment.

FIG. 2 is a block diagram illustrating a schematic configuration of an information recording / reproducing apparatus according to the embodiment.

FIG. 3 is a diagram illustrating a divided shape of a four-divided detector.

FIG. 4 is a diagram showing an arrangement of gap portions and operation waveforms in the vicinity of the gap portions according to the embodiment.

FIG. 5 is a block diagram illustrating a main configuration of a timing control unit.

6A and 6B are timing charts of various parts of the timing control unit. FIG. 6A shows a case where the phase of a recording clock is advanced.
FIG. 4B is a diagram illustrating a case where the phase of the recording clock is appropriate, and FIG. 4C is a diagram illustrating a case where the phase of the recording clock is delayed.

FIG. 7 is a diagram illustrating an example of a circuit configuration of a synchronization detection circuit.

FIG. 8 is a diagram showing operation waveforms of the synchronization detection circuit.

9A and 9B are diagrams for comparing and explaining the accuracy of a recording clock based on a gap portion and the accuracy of a recording clock based on wobbling, wherein FIG. 9A shows jitter occurring in a conventional wobbling-based recording clock, and FIG. FIG. 6 is a diagram illustrating jitters generated in a recording clock according to the embodiment.

FIG. 10 is a diagram showing a main configuration in a case where the present invention is applied to generation of a control signal in a spindle control unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical disk 10 ... Optical pick-up 10a ... Semiconductor laser 10b ... 4 division | segmentation detector 11 ... Signal generation part 12 ... Data demodulation part 13 ... Address decoder 14 ... System control part 15 ... Data modulation part 16 ... Timing control part 17 ... Laser drive part 18 Spindle control unit 19 Spindle motor 101 Synchronization detection circuit 102 Phase comparator 103 Control circuit 104 Oscillator 105 Frequency divider circuit 201, 202 Comparator 203 Falling edge detector 204 One shot pulse generator 205 gate circuit 301 period detector 302 subtractor 303 control circuit G groove track L land track GP gap section Srf RF signal Srpp radial push-pull signal Stpp tangential push-pull signal

Claims (10)

[Claims] 1. An optical disc for recording recording data by inserting a sync pattern for dividing a recording data sequence at predetermined intervals into a recording track having a predetermined height on an information recording surface. Gap portions are formed at intervals of N times (N is a natural number) of the predetermined interval with respect to the track, and the gap portion has an area having a length sufficiently shorter than the length of the sync pattern different from the predetermined height. An optical disc characterized by being formed at a height. 2. The optical disc according to claim 1, wherein predetermined pre-information is recorded in the gap portion in advance. 3. A recording track having a first height on an information recording surface and a guide track having a second height different from the first height are formed adjacent to each other on the optical disc, 3. The optical disk according to claim 1, wherein a gap portion is formed at the second height. 4. The optical disk according to claim 1, wherein the recording track is wobbled based on a wobble signal of a constant frequency. 5. The optical disk according to claim 4, wherein said wobble signal is modulated by address information. 6. An information recording apparatus for recording recording data on an optical disk according to claim 1, wherein the recording track is irradiated with a light beam, and a reading signal is output based on reflected light. Means, a timing control means for detecting the gap portion based on the signal pattern of the read signal, and outputting a timing signal synchronized with the detection timing; Recording means for performing a recording operation of the recording data by inserting the recording data. 7. The read means outputs a tangential push-pull signal as the read signal, and the timing control means detects the gap portion based on the tangential push-pull signal. The information recording device according to claim 6. 8. The information recording apparatus according to claim 6, wherein the recording unit records the sync pattern as a space. 9. The information recording apparatus according to claim 6, further comprising a clock signal generating unit that generates a clock signal based on the timing signal. 10. The information according to claim 6, further comprising a spindle control unit that controls the number of revolutions of a spindle motor that rotationally drives the optical disk based on the timing signal. Recording device.