JPS60256926A - Optical disc recorder - Google Patents

Abstract

PURPOSE:To reduce the time required for servo write of a servo write type disc especially by deflecting an optical beam at plural angles in time division so as to form plural tracks during one revolution of the disc. CONSTITUTION:The disc 3 is turned stably via a PLL6 and a motor 4 under the control of a controller 18. On the other hand, the light from the laser 13 is subjected to intensity modulation by an EO modulator 12, inputted to an AO deflector 11, n-set of frequencies having an interval of DELTAf outputted from a variable frequency oscillator 11 is received in time series, the light is deflected by a deflection angle proportional to the frequency of an input signal 21 and the optical spot 7 is formed on the disc via the mirror 10, the lens 9 and the lens 8 and then recording is attained. Since plural tracks are formed at the same time during one revolution of the disc 3, the time required for servo write is decreased to one over several to several tens in the servo write type optical disc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a write/read type optical disc recording device, and particularly to a servo write type optical disc recording device.゛ [Background of the Invention] Currently, write-readable optical disks in general use have guide grooves (pre-groups) and header information (track addresses,
Sector addresses, etc.) are written, and data bits are written and read based on this information. Currently, discs with header information and guide grooves are reproduced using a type of mold called a stamper, using a method similar to that used for general audio records.
Manufacturing is taking place. A disk manufactured by this method is called a replica disk. Replica disks have relatively good productivity, but because they involve a type of pressing process, it is difficult to reduce disk eccentricity, and the track shape is inevitably distorted compared to the original. Since these eccentricities and distortions in track shape have a negative effect on tracking and data reading, it is desirable that they be absent, especially in optical disk devices that require high reliability.

As a method to solve this problem, a servo write method used in magnetic disk drives and the like can be considered. This method uses a light beam to write pregroup and header information on each disc, and although the above two problems are solved, two new problems arise. The first problem is that servo writing takes a lot of time. For example, an optical disc with a diameter of 30 cm has about 50,000 tracks on one side, so if you were to perform servo writing by rotating the disc at 600 revolutions per minute, it would take more than 80 minutes for each disc. As a result, productivity drops significantly.

The second problem is that in current general optical discs, the header information pits have a depth of λ/4, and the pre-group has an uneven (phase) structure having two depths of λ/8. The reason for this is that the tracking error signal detection method is Pu5h.
-It uses a diffraction method called the Pu1l method, but for the pre-group part, a depth of λ/8 is optimal, and for the header part, the modulation depth for data reading is maximum at a depth of λ/4. be. However, such a two-stage deep structure is difficult to fabricate using a servo light device using a light beam.

Since the solution to the first problem is the subject of the present invention and will be described in detail later, the solution to the second problem will be described here first.

Applicants have already proposed a recording/reproducing optical disc that does not use pre-groups. This method is disclosed in Japanese Patent Application Laid-Open No. 58-91537 or Japanese Patent Application No. 57-14112.
Although it is detailed in No. 1, I will give an overview of it. FIG. 1 shows the track structure of this system, in which one or more pits 2 are arranged intermittently on a track 1 in advance to form an area a. Following area a, area b (initially nothing is written) is provided for recording data bits later.

One sector is already formed between the area a and the area, and a track is formed by connecting a large number of such sectors. When recording data bits, tracking is performed based on tracking information obtained from pit 2 written in advance in area a, and data bits are recorded in area 2 while holding the tracking information obtained from area a. Here, the ratio of area a to one sector is, for example, 5 to
The time required for the optical spot to pass through 11 sectors during data recording is, for example, 100 μsec.
It is of the order of magnitude.

Here, the method for detecting tracking information from the pits written in area a is not the Pu5h Pu1l method, but the heterodyne method. Various circuit systems have been proposed for this detection method, for example, Japanese Patent Laid-Open No. 58-9
This method is described in detail in Japanese Patent Publication No. 1538, Japanese Patent Application Laid-open No. 52-93222, and the like. In this heterodyne system, the pit is λ
/4 uneven structure (phase structure) also has a shading structure (amplitude structure)
However, it has the advantage of providing tracking information.

Therefore, even if the area a is written in advance by servo writing on the disk as described above, tracking information can be obtained from these pits 2. Therefore, by using this tracking information detection method, the second problem mentioned above can be solved.

However, the first problem, that is, the time required for servo writing, remains a problem even with the applicant's recording/reproducing optical disc system that does not use a pregroup.

[Purpose of the invention]

In view of the above-mentioned points, an object of the present invention is to provide an optical disk recording device that can reduce the time required for servo writing, particularly in a servo write type optical disk, from one to several tenths of the time.

[Summary of the invention]

In order to achieve the above object, the present invention is characterized in that a plurality of tracks are formed simultaneously during one rotation of the disk by time-divisionally deflecting a light beam into a plurality of angles using an optical deflection device. .

[Embodiments of the invention]

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

FIG. 2 shows an embodiment of an optical disc recording apparatus according to the present invention. The apparatus is composed of an optical system, a rotation system for rotating the disc 3 to be recorded, a feeding system for intermittently transporting the optical system in the radial direction of the disc, a control device 18 for controlling these elements, etc. be done. The optical system 14 includes a laser 13 serving as a light source for pit recording, and an EO modulator 13 for modulating the light intensity of the laser beam. It is composed of an AO deflector 11 for deflecting a light beam, lenses 8 and 9, and the like. The rotation system is for stably rotating the disk, and is composed of a motor 4, an encoder 5, etc., and is preferably controlled by PLL (phase locked loop). The feed system includes a ball screw 15, a step motor 16, and the like.

An output from a variable frequency oscillator 17 is connected to the AO deflector 11. The variable frequency oscillator 17 can also be of the PLL frequency synthesizer type that synthesizes a predetermined frequency from one reference frequency, but if higher speed is required, a configuration as shown in Fig. 3 may be used. Good. In the configuration shown in FIG. 3, n oscillators 25 with fixed frequencies are used with a frequency difference of Af, and the control signal 2
3 allows the switching circuit 26 to select only one of these frequencies. By using the switching circuit 26 as an electric switch, the switching time can be on the order of nanoseconds. 24 is an amplifier.

FIG. 4 shows the shape of a track group when servo writing is performed using the device shown in FIG. 2, and FIG.
The relationship between the signal 21 applied to the deflector 11 and the signal 20 applied to the EO modulator 12 is shown.

Further, FIG. 5(b) shows the relationship between the signal 21 and the pulse train 19 applied to the step motor 16 in a more compressed time axis than in FIG. 5(a).

The pattern to be servo written is 1 as shown in Figure 1.
Among the sectors, there is only area a, and the time AT required to pass through area a is the time T required to pass through one sector.
It is 5% to 10% of On the other hand, in the AO deflector 11, the frequency f of the input signal 21 and the optical deflection angle have a proportional relationship in a certain frequency range. Therefore, as shown in Fig. 4, after recording one area a of a certain track, the input frequency of the AO deflector is increased (or decreased) by Af to deflect the light beam and record area a of the adjacent track. do. what if,
Assuming that 6T is 1/n of T, area a can be recorded over a maximum of n tracks during time T by repeating the above operation.

Therefore, if the time required for one rotation of the disk is NT, it takes 9 minutes for one rotation of the disk, that is, n
It becomes possible to servo write N sectors. In addition,
Since the tracks created by the apparatus shown in FIG. 2 are concentric tracks, the pulse motor is driven to move the optical head in the radial direction by 99 minutes each time the disk rotates, and the recording operation is repeated again.

In this embodiment, the EO modulator 12 is used to modulate the light intensity, but it is not necessary to use this modulator. For example, it is also possible to modulate the intensity of the deflected light by amplitude modulating the signal 21 applied to the AO deflector 11 at the frequency f. Therefore, by AM-modulating the signal 20 and superimposing it on the signal 21, the light intensity can be modulated without using the EO modulator 12. Furthermore, it is not necessary to use the AO deflector 11 as the deflector, and the same effect can be obtained by deflecting the mirror 10 using a piezo, for example.

Next, another embodiment will be described in which the present invention can be used to perform servo writing even faster. In this embodiment, the configuration of the device is almost the same as that in FIG. 2, but the AO deflector 11
The signals added to the signal are slightly different from those shown in FIG. In this embodiment, as shown in FIG. 6, f01fl? . . . m signals with f□-1 as the reference frequency are synthesized and input. However, adjacent frequency differences are always separated by nAf. By doing this, servo writing can be performed using m light beams at intervals of 9 minutes for n tran, so servo writing can be performed at a speed m times faster than in the previous embodiment. becomes possible. In this case, the distance the head is sent by the step motor for each rotation of the disk is n.
It goes without saying that the -m tran is 9 minutes long.

〔Effect of the invention〕

As described above, according to the present invention, in an apparatus that uses a light beam to write a track consisting of alternating pit rows and blank areas, the pit row area has a length of 1/'n of the sector length. If so, it becomes possible to write in 1/n time compared to writing one track at a time. For example, the diameter is 30cm, the track pitch is 1.
In the case of 6 μm, there are approximately 50,000 tracks on one disk surface, and if it were to be written at a disk rotation speed of 600 rpm, it would take 83 minutes. However, n=10
If this is the case, the present invention enables servo writing in about 8 minutes. Furthermore, as described in the second embodiment, if a plurality of (m) light beams are used, this time can be further shortened to 1/m, which has a very large effect on the servo write type optical disk.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the track configuration of an optical disc, FIG. 2 is a diagram showing the configuration of an embodiment of the present invention, FIG. 3 is a diagram showing an example of the configuration of the variable frequency oscillator 17 in FIG. 2, and FIG. The figure shows the track shape when track recording is performed according to the present invention, FIG. 5 shows the signals applied to the apparatus shown in FIG. 2, and FIG.
FIG. 3 is a diagram representing a signal applied to an O deflector. 1...Track, 2...Bit, 3...Disk, 4...Motor, 5...Encoder, 6...PL
L circuit, 7... light spot, 8, 9... lens, 1
0...Mirror, 11...AO deflector, 12...E
O modulator, 13... Ar laser, 14... Optical head section (moving section), 15... Ball screw, 16... Step motor, 17... Variable frequency oscillator, 18...
・Control device, 19...Pulse motor input, 20...
Modulation signal, 21...AO input signal No. 4 Figure 5 (b), q Jlfllll= ・-・m

Claims (1)

[Claims] 1. In a device that uses a light beam to write a track consisting of pit rows and blank areas arranged alternately along the direction of rotation on a rotating surface, the light beam is time-divided at multiple angles using a light deflection device. An American disk recording device characterized by forming a plurality of tracks during one rotation of the disk by deflecting the disk.