JPS6220147A - optical disk device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Technical field] The present invention relates to an optical disc device.

[Prior Art] In recent years, there has been a proposal to use an optical disk device that uses an optical disk formed of a photoreactive recording material into a disk shape as a storage medium as an auxiliary storage device of a computer system.

The schematic structure of such an optical disc is shown in Fig. 9 and Fig. 1.
Shown in Figure 0.

In the figure, an optical disc 1 includes a base material 2, a disc material made of a transparent material such as acrylic resin, on which a single recording track TR is spirally formed, on which a preformatted area (described later) according to a recording format is formed. 3, and a spacer 5 that connects the base material 2 and the disk material 3 via an air gap 4, and the surface of the disk material 3 on the side of the air gap 4 is coated with a photoreactive recording material with a uniform thickness to store, for example, data. The wavelength of the laser beam used for recording and reproduction is 1/8. Reference numeral 6 denotes a spindle hole into which a spindle of a motor (not shown) for rotationally driving the optical disk 1 is inserted.

An example of the signal format of the recording track TR is shown in FIGS. 11(a) and 11(b).

In the figure, a plurality of sectors SC consisting of a preformat area PF, a data area DF, and a gap GPI separating the preformat area PF and data area DF are consecutively set in the recording track TR, separated by a gap GP2. .

In addition, the preformat area PF includes a preamble consisting of a synchronization signal for matching circuit conditions, that is, a bit synchronization signal BS for synchronizing the pit clock of the data write/read circuit with the generation timing of recording data, and this preformat area PF. A sector synchronization signal SS consists of a bit string (pattern) with a sharp autocorrelation for detecting a sector SC, and a sector address SA for identifying a sector SC.

The bit synchronization signal BS forming the preamplifier is a PLL (PLL) for extracting a pit clock and data using a read signal from an optical pickup unit that irradiates the optical disc 1 with a laser disc and detects reflected light.
A signal is used that allows the locking loop (locked loop) circuit to be properly locked. For example, a signal that changes the state of the read signal with a minimum inversion period (i.e.,
The recording state becomes a repetition of the minimum pit (small hole) length.
O1,0101...''.

Further, the data area DF consists of a plurality of pieces of data to which a frame synchronization signal FS is attached and forms a frame, and a preamble (bit synchronization signal BS) attached to the beginning of these data. Note that the frame synchronization signal FS consists of a sharp autocorrelation pattern similar to the sector synchronization signal SS. - As shown in FIG. 12, such a preformat area PF is formed at the time of manufacturing the optical disc 1,
Further, a portion corresponding to the data area DF is formed as a data groove DG, which is a guide groove capable of guiding the optical pickup. Further, the pits forming the preformat area PF have a depth of 174 wavelengths of the laser beam, and the data grooves DG are formed at a depth of 178 wavelengths of the laser beam.

Therefore, by forming pits with a laser beam on the photoreactive recording material in the data groove DG, which is the data area DF, when data is recorded, the reflected light level of the recorded portion will be the same as that of the preformat area PF. The light level is the same as the optical level, and the data recording state can be determined based on this.

By the way, when recording data on the optical disc 1, the bit synchronization signal BS in the preformat area PF is read and a pit clock is detected.

A sector synchronization signal SS is detected based on the pit clock, and a sector address SA is detected based on the detection timing of this sector detection signal SS.

If the sector address SA indicates the target sector, the timing of the beginning of the data area OF is determined from the detection timing of the sector address SA, and the data area DF is transferred to the frame synchronization signal following the bit synchronization signal BS. It is completed by alternately recording FS and frame data.

When reproducing data recorded in this way, first, the bit synchronization signal BS in the preformat area PF is read to detect the pit clock, the sector synchronization signal SS is detected based on the pit clock, and the sector synchronization signal BS is detected. Sector address SA is detected based on the detection timing of signal SS.

If the sector address SA indicates the target sector, the bit synchronization signal BS at the beginning of the data area OF is detected from the detection timing of the sector address SA, and the pit clock is restarted based on this bit synchronization signal BS. To detect.

Next, a frame synchronization signal FS is detected based on this pit clock, and frame data is determined based on the detection timing.

In this way, the preformat area PF and the data area D
F is formed asynchronously, and when reproducing recorded data, the beginning of the data area DF is determined based on the pit clock of the preformat area PF, which causes the following inconvenience. Ta.

That is, the optical disc 1 is rarely used fixedly in one drive device, and in many cases, it is used while being attached to and detached from the drive device. Therefore, when the optical disc l is attached to the attachment/detachment mechanism, eccentricity may occur in the optical disc l due to errors, etc., and this eccentricity may cause the optical disc l to
There are rotational fluctuations.

Therefore, the state of rotational fluctuation of the optical disc 1 may change between when data is recorded and when data is reproduced, and if the difference in rotational fluctuation is large, the frame synchronization signal FS is transmitted in the data area DF. This results in the inconvenience that the recorded frame data cannot be reproduced. Furthermore, when a burst error occurs in the data area DF, the frame synchronization signal FS cannot be detected in the data area DF, and the recorded frame data cannot be reproduced.

Furthermore, in the PLL circuit that constitutes the pit synchronization circuit that detects the pit clock from the pit synchronization signal BS, if the rotational fluctuation is large as described above, the center of the eye pattern of the signal waveform and the sampling timing will deviate greatly. It has become impossible to sample data in an optimal state, resulting in the inconvenience of increased pit errors.

[Objective] The present invention has been made to solve the above-mentioned disadvantages of the conventional technology, and an object of the present invention is to provide an optical disc device that can suppress rotational fluctuations of an optical disc and realize data recording and reproduction with high reliability. It is said that

[Structure] In order to achieve the above-mentioned object, the present invention forms servo tracks on which servo data is recorded, consisting of pit rows at predetermined intervals, at intervals corresponding to the width of the data track on which the data is recorded, and a reading means for reading data, and a recording/reproducing means for recording and reproducing data on the data track, and according to an output signal of the reading means,
It controls the rotation of the optical disk and the tracking of the reading means and recording/reproducing means.

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

FIG. 1 shows how signal pits are formed on an optical disc 1 according to an embodiment of the present invention.

In this way, the optical disc 1 has a recording track T along from the start point to the end point of the set recording track TR.
A servo track S configured by continuously arranging pits PT at predetermined intervals with a track interval that can form R.
Only T is formed.

Therefore, as shown in FIG. 2, the portion of the surface of the disc material 3 of the optical disc 1 on the air gap 4 side, where the recording track TR is formed, is flat without any unevenness. In addition, in FIG. 2, 0 indicates a photoreactive recording material layer, and the thickness of this photoreactive recording material layer OM is determined by the laser beam (
(described later) is set to about 178 wavelengths. Note that the laser beam for recording and reproducing data on the optical disc 1 is incident on the flat surface of the disc material 3, that is, the surface on which the photoreactive recording material layer OM is not laminated.

Further, the interval between pits PT of the servo track ST corresponds to, for example, the repetition frequency of the minimum pit length of the recording signal, that is, the reference frequency when the optical disc I is rotationally driven at a predetermined speed (in this case, at a predetermined linear speed). The depth is set to be approximately 174 times the wavelength of the laser beam. FIG. 3 shows an optical disk drive device according to an embodiment of the present invention.

In the figure, a laser beam output from a semiconductor laser element 10 that generates a laser beam for recording and reproducing data on an optical disk 1 is converted into parallel light via a coupling lens 11.

The laser beam is split into two by the diffraction grating 12, and after passing through the half mirror 13,
Images are formed on the recording track TR and servo track ST formed on the optical disc 1 by the objective lens 15 via the four-wavelength plate 14, respectively.

The laser beams reflected from the recording track TR and servo track ST of the optical disc 1 are 1
The light is reflected by the half mirror 13 through the /4 wavelength plate 14 and focused onto the light receiver 17 by the condenser lens 16 .

As shown in FIG. 4, this light receiver 17 has two
A light-receiving element 17a has a divided light-receiving surface and generates a light-receiving signal for forming a focusing error signal and reproduced data, which detects the deviation of the focus of the laser beam with respect to the recording track TR, and a light-receiving element 17a that is divided into two in the horizontal direction. It has a surface and is composed of a light receiving element 17b for forming a rotation signal for detecting the rotation status of the optical disc 1 and a tracking error signal for detecting the positional deviation of the laser beam with respect to the servo track and the recording track. The reflected light from the recording track TR is imaged on the light receiving element 17a, and the reflected light from the servo track ST is imaged on the light receiving element 17b.

Then, the output signal of the light receiving element 17a is transmitted to the recording track T.
It is added to a data reproducing section 18 for reproducing R recorded data, and a focusing control section 19 that executes focusing control to accurately focus the laser beam on the recording track TR. Note that, in this way, the focusing control is performed on the recording track T that is closer to the laser beam.
Therefore, even if the output of the semiconductor laser element 10 during data recording is approximately 10 times the output during reproduction, sufficient energy is supplied to the servo track ST to form pits ( data recorded on the servo track TR will not be destroyed.

Further, the output signal of the light receiving element 17b is sent to the rotation control unit 20 as a frequency signal fc that indicates the rotation state of the optical disc 1.
It is also added to a tracking control section 21 that accurately positions the laser beam on the recording track TR.

The rotation control unit 20 includes a reference frequency generator 22,
A reference frequency signal fr having the same frequency as the frequency signal fc when the optical disc 1 is rotating at a predetermined speed is added, and the one-rotation control unit 20 makes the error between the reference frequency signal fr and the frequency signal fc zero. Thus, the signal Sr output to the drive motor 23 that drives the optical disc 1 is adjusted.

Note that since the laser beam output from the semiconductor laser element 10 during data recording is modulated by the recording data, the frequency signal fc obtained from the light receiving element 17b at this time becomes an intermittent signal. Also, the rotation control of the motor 23 by the rotation control section 20 can be sufficiently achieved.

Further, the semiconductor laser drive section 24 drives the semiconductor laser element 10 in response to a drive signal LDV output from a recording/reproduction control section (not shown).

For example, when recording data on an optical disk l, a signal obtained by modulating the recorded data using a predetermined method is added as the drive signal LDV, so that the laser beam output from the semiconductor laser element 10 is driven by the recorded data. This recorded data is directly modulated onto the optical disc 1.
recorded in In addition, when reading data from the optical disc 1, the drive signal Ll)V is 111 at the time of data recording.
This signal has a constant level of about 0, and thereby the laser beam output from the semiconductor laser element 10 has a constant level of about 1710 when recording data.

When recording data on the optical disc 1 with the above configuration,
First, in order to efficiently and reliably record and reproduce data on the recording trunk TR of the optical disc 1, the recording track TR is formatted into the recording format shown in FIGS. 11(a) and 11(b), for example.

Note that the formatting process and the data recording and reproducing process described below are performed by the above-mentioned recording and reproducing unit or a corresponding control unit.

In that case, using a predetermined frequency as the reference frequency for the bit rate of recording data, various synchronization signals, sector addresses, etc. recorded in the preformat area PF are transmitted from the beginning of the recording track TH at intervals corresponding to the length of one sector. It will be formed sequentially.

At that time, the focusing control unit 19 focuses the laser beam on the recording track TR based on the signal output from the light receiving element 17a, and at the same time, the focusing control unit 19 focuses the laser beam on the recording track TR based on the signal output from the light receiving element 17b. Control unit 2
0 controls the rotational speed of the motor 23 to a predetermined value, and the tracking control section 21 positions the laser beam on the servo track ST and the recording track TR.

In this way, since the pit rate when recording the preformat area PF and the speed of the portion of the optical disc 1 that is irradiated with the laser beam are always maintained in a constant relationship, the recording track TR has the servo track ST.
A preformat area PF is recorded based on the pit PT recorded in .

Next, when recording data on the recording track TR formatted in this way, a sector address is extracted from the data in the preformat area PF output from the data reproducing unit 18, and it matches the sector address of the target sector. When the drive signal LD corresponding to the recording data
V is output to the semiconductor laser drive section 24 at the same bit rate as the preformat area PF.

As a result, the relationship between the bit rate when recording data and the speed of the portion of the optical disc 1 that is irradiated with the laser beam is adjusted to the data area DF of the recording track TR.
and preformat area PF are the same. Therefore, when reproducing data, it is possible to apply the bit rate set in the preformat area PF to the data area DF as is, and it is possible to shorten the pit synchronization signal etc. set at the beginning of the data area DF. result,
Data recording efficiency on the optical disc 1 is improved.

Further, during data recording and reproduction, the rotation control unit 20 always controls the motor 23 so that the linear velocity of the portion of the optical disc 1 irradiated with the laser beam is constant based on the light reception signal based on the reflected light from the servo track ST. is controlled, rotational unevenness does not occur, and data errors due to jitter and wump can be prevented.

Furthermore, in this embodiment, the recording format of the optical disc 1 can be set arbitrarily.

This has the advantage that the user can appropriately create a recording format that is optimal for the field of use. Furthermore, by using unique pattern signals for the sector synchronization signal in the preformat area PF and the frame synchronization signal in the data area DF, it is possible to make the data recorded on the optical disc 1 unreadable by others. The confidentiality of information can be maintained.

By the way, when using optical disc 1 with different models of optical disc devices,
In order to make the data recorded on the optical disc 1 reproducible, the recording format of the optical disc 1 may be unified. In this case, the data in the preformat area PF may be formed in advance when the optical disc 1 is manufactured.

An example of the optical disc 1 in which the preformat area PF is formed in advance in this way is shown in FIGS. 5 and 6. In these figures, the same or corresponding parts as in FIGS. 1 and 2 are given the same reference numerals.

In the figure, in the recording track TR, pit rows corresponding to the data in the preformat area PF are formed at intervals of one sector and at the same depth as the pits PT of the servo track ST (in this case, 174 wavelengths of the laser beam). ing.

The mechanism for recording and reproducing data on this optical disc 1 is the same as described above, so its explanation will be omitted. However, as a matter of course, with this optical disc 1, there is no need to execute the process of forming a preformat area PF on the optical disc 1.

Now, when data corresponding to the preformat area PF is recorded in advance on the recording track TR of the optical disc 1 in this way, the depth of the pit in the preformat area PF formed on the recording track TR is as described above. It is set to the same value as servo track ST.

Therefore, the level of the light reception signal output from the light receiving element 17a is different between the preformat area PF and the data area DF, and this causes the preformat area PF to
It is possible to obtain the effect that the data reproducing unit 18 can distinguish between the data in F and the data in the data area DF.

By the way, since the conditions for reproducing data in the preformat area PF and data area DF recorded on the same recording track TR are different, the data reproducing unit 18 has different conditions when reproducing data in the preformat area PF. It is necessary to change the threshold value for identifying the level of the light-receiving signal of the light-receiving element 17a when reproducing the data in the data area DF.

Usually, such a threshold is output as a voltage signal from a level holding circuit with a time constant, etc. Therefore, when changing the threshold, the voltage signal held in this level holding circuit is changed to a level corresponding to the threshold. At this time, it takes some time until the level of this voltage signal is changed due to the time constant of this level holding circuit.

Therefore, in the above-mentioned recording format, it is necessary to set a gap between the preformat area PF and the data area DF in accordance with the time required to change the level of the holding voltage signal in this level holding circuit. Since the time is longer than the bit rate of the recorded data, the length of the gap is large, resulting in a disadvantage that the recording efficiency of the optical disc 1 is deteriorated.

Still another embodiment of the present invention for solving such inconveniences will be described next.

FIG. 7 shows the servo track ST and recording track TR on the optical disc 1 according to this embodiment.

In the figure, the servo track ST includes a recording track T.
A preformat area PF is formed at a position corresponding to one sector interval of H.

FIG. 8 shows an apparatus for driving such an optical disc 1 to record and reproduce data. In this figure, the same parts and corresponding parts as in FIG. 3 are denoted by the same reference numerals, and the explanation thereof will be omitted.

In the figure, the light reception signal output from the light receiving element 17a of the light receiver 17 is applied to the focusing control section 19 and the data reproducing section 31 for reproducing data in the data area DF, and the output of this data reproducing section 31 is shown in FIG. The reproduced data DAI is applied to one input terminal of the switch 32.

Further, the light reception signal output from the light receiving element 17b of the light receiver 17 is applied to the one rotation control section 20, the tracking control section 21, and the data reproduction section 33 for reproducing the data of the preformat area PF. Reproduction data DA2 output from the reproduction section 33 is applied to the other input terminal of the switch 32.

The switch 32 selects either the reproduced data DAI or DA2 and outputs it to the recording/reproducing controller according to the selection signal SEL output from the recording/reproducing controller 6. Therefore, the recording/reproducing unit , until the sector address corresponding to the target sector is detected, the selection signal SE is used to input data in the preformat area PF.
When the reproduction data DA2 is selected by the switch 32 by setting L to logic level L and the sector address corresponding to the target sector is detected, from the point in time when a time corresponding to the length of the gap described later has elapsed from the detection timing, The drive signal LDV corresponding to the recording data is output in the same manner as in the above embodiment, and the recording data is recorded in the data area DF of the sector detected at that time.

In addition, when reproducing data, when the recording/reproducing section detects a target sector in the same manner as when recording data, it sends a 1 selection signal S to input data in the data area DF of that sector.
EL is set to logic level H, and the switch 32 selects the reproduced data DAI.

In this way, the preformat area PF and the data area D
Since the data of F is reproduced by separate data reproducing units 31 and 33, the threshold value for identifying the received light signal is fixed to each data reproducing unit 31 and 33.
After reproducing the preformat area PF, the data area O
There is no need for time to change the threshold value as described above before reproducing F, and in this case, it is sufficient to provide a gap corresponding to a very short time for switching the switch 32.

Therefore, preformat area PF and data area D
The length of the gap set between F can be significantly shortened, and as a result, the recording efficiency of the optical disc 1 can be improved.6 In each of the above embodiments, the optical disc 1 is Although the case where the optical disc 1 is driven at a constant angular velocity has been described, the present invention can be similarly applied to a case where the optical disc 1 is driven at a constant angular velocity. In this case, since a large number of concentric recording tracks are formed on the optical disk, one servo track is formed in each gap between the recording tracks.

Furthermore, the format of the recording track TR, the format of the servo track ST, etc. are not limited to the embodiments described above.

Further, in the embodiments described above, the case where the optical disk is driven at a constant linear velocity has been described, but the present invention can be similarly applied to a case where the optical disk is driven at a constant angular velocity. In that case, since many recording tracks are formed concentrically on the optical disk, the servo track is
One recording layer is formed in each gap between the recording tracks.

Furthermore, a groove having a predetermined depth, for example, 1/8 wavelength of a laser beam, is formed in the disk material 3 on the entire surface of the optical disk 1 in correspondence with the recording track TR, and the light receiving device receives the reflected light from this groove. Tracking control can also be performed based on the light reception signal of the element 17a.

[Effects] As described above, according to the present invention, servo tracks on which servo data is recorded, which are composed of pit rows at predetermined intervals, are formed at intervals corresponding to the width of the data tracks on which data are recorded, and the servo trunk a reading means for reading data, and a recording/reproducing means for recording/reproducing data on the data track, and an output signal of the reading means controls rotation of the optical disk and tracking of the reading means and the recording/reproducing means. This makes it possible to suppress rotational fluctuations of the optical disc during data recording and reproduction.

As a result, even if the eccentricity of the optical disc changes and the rotational fluctuation changes between when data is recorded on the optical disc and when data is reproduced from the optical disc, data can be reproduced properly without any problems. This provides the advantage that data can be recorded and reproduced on and from an optical disc with high reliability.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a recording state of an optical disc according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line A-A in FIG. FIG. 4 is a block diagram showing an example of an optical disc drive device, FIG. 4 is a plan view showing an example of a light receiver, FIG. 5 is a plan view showing a recording state of an optical disc according to another embodiment of the present invention, and FIG. B- in Figure 5
7 is a plan view showing a recording state of an optical disc according to still another embodiment of the present invention; FIG. 8 is an example of an optical disc drive device according to still another embodiment of the present invention; FIG. A block diagram, FIG. 9 is a plan view showing an example of an optical disk, FIG. 10 is a sectional view showing an example of an optical disk, and FIGS. 11(a) and (b) are conventional examples of the recording format of an optical disk. FIG. 12 is a plan view showing the recording state of a conventional optical disc. 1... Optical disk, ST... Servo track, T
R... Recording track, 10... Semiconductor laser element,
11... Coupling lens, 12... Diffraction grating,
13...Half mirror-514...1/4 wavelength plate, 1
5... Objective lens, 16... Condensing lens, 17...
- Light receiver, 17a, 17b" - Light receiving element, 18.:H,
33.-Data reproducing section, 19.. Focusing control section, 20.. Rotation control section, 21.. Tracking control section, 23.. Motor, 24.. Semiconductor laser drive section, 32.. Switcher. Agent Patent Attorney Crest 1) Seito Yoto (Likt/)Toichi Figure 3 Figure 4 ○ (Rishiri ○(°') 'i---(=) o ○ (,)! 111 +- +Q: 1-+, Q: V> to L/) to Figure 9 Figure 70 Ak TH

Claims (1)

[Claims] In an optical disk device of a data recording format, a preformat area in which a sector synchronization signal for detecting the start of a sector and a plurality of consecutive sector addresses for identifying sectors are placed in front of each data area of an optical disk. , a reading means for forming in advance on an optical disk servo tracks on which servo data consisting of pit rows at predetermined intervals are recorded at predetermined intervals corresponding to the width of the data track on which the data is recorded, and reading data on the servo tracks; An optical disc comprising a recording/reproducing means for recording and reproducing data on a data track, and controlling rotation of the optical disc and tracking of the reading means and the recording/reproducing means based on an output signal of the reading means. Device.