JPH0341626A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To enable a track servo capable of coping with a beam shift by performing a tracking control with a sum signal of a 1st track error signal and a low band component of an output of a filter circuit to position a spot of a main beam into a pregroup. CONSTITUTION:The 1st track error signal corresponding to a symmetry of a reflected light pattern of reflected light of the main beam from a disk 101 is detected in the whole area having the pregroup by a 1st track error signal detecting means 103. Then, a 2nd track error signal is obtained by detecting a difference in quantity of light between two beams of reflected light of two subbeams of + or - primary diffracted light from the disk 101 by a 2nd track error signal detecting means 104 in an ID area only. Then, the tracing control is performed by a control means 106 with the sum signal of the 1st track error signal and the low band component of the output of the filter circuit 105 in order to position the spot of the main beam into the pregroup. By this method, the tracking servo capable of coping with a beam shift and a disk inclination can be performed.

Description

[Detailed Description of the Invention] [Summary] Regarding an optical information recording and reproducing device that records and reproduces information on an optical disk using three light beams, when a stable and highly reliable track error signal i is detected. In order to enable track servo that is resistant to beam shifts, a pregroove is formed in advance at the manufacturing stage, and
An information signal is recorded by a main beam spot in an area other than the ID area of the pregroove on a disc that has 10 areas in which the track number and sector number are recorded in advance in a part of the pregroove. In an optical information recording device for reproducing data, one beam of light is used as the main beam, and the spot of the main beam is used as the center of the optical information recording system for reproducing the disc. In the opposite direction, L1 next JJr
A spot forming means for forming a spot by a sub-beam of light and for forming each spot by moving autonomously in the width direction of the rack; a first track error signal g detecting means for detecting a first track error signal in the entire area of the pregroove; and two reciprocal light beams from the disk by the two beams of the lower first-order diffracted light. a second track error signal detection means for detecting a difference in plasticity only in the ID region to obtain a second track error signal; and a filter circuit for filtering only low-frequency components of the second track error signal. , a signal that is the sum of the first track error signal and the output low-frequency component of the filter circuit, and is used to perform tracking control so that the spot of the main beam falls on the pre-groove (Cl b"l). It will come true.

[Industrial application field]

The present invention relates to an optical information recording/reproducing device 1, in particular an optical information recording/reproducing device SX'J! in which information is recorded/reproduced onto a disk using three light beams. Regarding 1.

Optical information recording and reproducing devices such as Image Noisle and De-T-1 Mentophylsystem 6 are gaining acceptance in the market due to their high recording density and good handling of the recording medium. Furthermore, recently, a replaceable type that applies the principle of magneto-optical recording has been put into practical use, and its field of application is expected to expand from workstations to external storage v1 of parts-pull computers.

It is important for such an optical information recording/reproducing device to be able to stably perform track servo even if there is eccentricity of the disk.

[Conventional technology]

FIG. 4 shows a configuration diagram of an example of a conventional optical information recording/reproducing device. In the figure, a diverging light emitted from a semiconductor laser 11 as a light source is made into parallel light by a collimating lens 12, and then enters an objective lens 15 via a beam splitter 13 and a reflecting mirror 14.
A tiny spot is irradiated onto the surface.

At this time, the objective lens 15 is de, the f-screw 16 is shaken,
It is necessary to always irradiate the spot on a predetermined track by following the eccentric component, and for this purpose, an Akubo L-eater (not shown) is used to enable the spot to move independently in the focus and track 1 directions. It is equipped with

The spot on the disk 16 travels back along the same optical path as the reflected light, enters the beam splitter 13, is reflected there, and then passes through the condenser lens 17 and enters the beam splitter 18, where it is reflected. A part of the light beam is transmitted through the beam splitter 18 and the rest is reflected.
The output detection 1 of the 1° photodetectors 19 and 20 which is incident on 0 and photoelectrically converted is number 0 and 11110.
21 and subtracted by differential amplifiers S22 and S23, respectively. The information signal g from the disk 16 is sent to the adder 2
The focus error signal G3 and the track error signal g are taken out from the differential amplifiers 22 and 23, respectively.

Next, a method of generating the focus error G3 and the track error signal described above will be explained. FIG. 5 shows the principle of spot one noise detection (hereinafter referred to as SSD method) as an example of a focus error detection method. When the object lens 15 moves away from the objective lens 15, the light-receiving area becomes a person as shown in FIG. As shown in FIG. 8, the light-receiving area of the middle light-receiving section B and the upper and lower light-receiving sections A.

The sum of the light-receiving areas (light sensitivity) of C is WL.

Therefore, by obtaining the difference between the sum of the outputs of the light receiving sections A and C of the photodetector 19 and the output of the central light receiving section B using the differential amplifier 22, the special focus error as shown in FIG. 5(D) can be avoided. (C can be detected.

-73', 1 ~ As one of the easy error signal detection methods,
A push-pull method is known that uses a guide groove called a pregroove that is pre-rolled on the disk 16. This light is focused by the objective lens 15 and placed on the disk 1.
When the spot formed on the disc 16 is at the center of the pregroove, as shown by So in FIG. However, the spots in Figure 6 (A) and (C
) As shown in FIG.
Alternatively, as shown in 26a'' and 26b'', there is a method of showing different symmetries depending on the track deviation h@. .

As a result, the reflected light from the disk 16 is received by the 2 minute υ1 photodetector, and the difference in light output is taken! - A rack error signal can be generated.

Further, as another example of the track error signal detection method, there is a three-beam method. This is the collimating lens 12 in Figure 4.
Is there a diffraction grating in the optical path between the beam splitter 13 and the beam splitter 13? 24
Insert the
A tracking error signal is detected by comparing the reflected light intensity of the first-order diffracted light.

That is, as shown in FIG. 7, the spot 28o of the 110th-order diffracted light using the 3-beam method is arranged on the information bit string of the disk 16, and each spot 28o of the +1st-order diffracted light and the -1st-order diffracted light
8, 1.28-1 are arranged in front and behind the spot 28o in the longitudinal direction of the track, and slightly shifted in opposite directions to each other in the track width direction G, and the reflected light of the spot 28o is detected by a photodetector. The light is received at spot 29. ,．． 2
Each reflected light of 1L1 is received by a photodetector 30.31. Then, by taking the difference between the outputs C8 of the photodetectors 30 and 31 using the XIvJ amplifier 32, a track error signal (rFs) containing track deviation information is obtained. Sj is done.

[Problem to be solved by the invention]

However, although the push-pull method described above has a simple optical system and a good signal-to-noise ratio of the resulting Gg, it uses the sensitive phenomenon of light diffraction, so it is sensitive to the pregroove shape and the optical system is The disadvantage is that it is susceptible to aberrations and disk tilt.

Therefore, the assembly required for optical heads and disks.
The gv viscosity is always strict, and there are various difficulties in maintaining compatibility between disks.

Furthermore, if a so-called beam shift occurs in which the optical axis of the reflected light does not match the incident light due to the track actuator following the eccentricity of the disk, track innoset occurs in the push-pull method, and the allowable beam shift u 1
What is 00 μm? Therefore, when accessing a wide range of tracks, it is necessary to take measures such as a two-stage servo system with a coarse access mechanism.3 The main reason why the cost of optical information recording/reproducing devices and disks cannot be reduced is that the push-pull method This is because a track error signal is obtained.

On the other hand, the three-beam method described above is a method that generates a tracking error signal from the difference in the amount of light of the ±1st-order diffracted light, and has the feature that it is not affected by beam shifts or changes in the pattern of reflected light. (Sub-beams) are placed before and after the 0th-order diffracted light (main beam) for information recording and reproduction, so for write-once (WORM) or erasable optical discs, the sub-beams are placed before and after the 0th-order diffracted light (main beam) for information recording and reproduction, so for write-once (WORM) or erasable optical discs, the preceding sub-beams and the following sub-beams There was a problem that it could not be used because the amount of light changed dynamically between the sub-beams.

The present invention was made in view of the above points, and is a stable and 4E
The objective is to detect a high track error signal of in +3 and to acquire an optical information recording/reproducing device capable of detecting a high track error signal in +3 and enabling a strong track revolution against beam jets.

[F stage for solving problems]

FIG. 1 shows a prefectural configuration diagram of the present invention9. In the same figure, 101
In the A disk, a pregroove is formed in advance at the manufacturing stage, and a part of the pregroove has an IDfn area in which track number 8 and sector number are recorded in advance. 1
02 is a spot forming means, which uses the 0th order 417 light as a main beam and the ±1st order diffracted lights as two beams, forms a spot by the main beam on the disk 101, and forms an I-
Slots 1- are formed by two sub-beams in opposite directions in each of the rack longitudinal direction and track width direction. These spots are formed so as to be movable in the direction of the track.

103 is a first track error signal detection means, 104 is a second 1-rack error signal detection means. A first track error signal depending on the symmetry is detected in the entire area of the pregroove.

Further, the second track error signal detection means 10.1
A second track error confidence is obtained by detecting the difference in photosensitivity between the two beams reflected from the disk 101 by the two beams of the first-order diffracted light only in the frn 1D region.

A filter circuit 105 converts the low frequency component of the second track error signal into a p-wave. Reference numeral 106 denotes a W control means, which performs tracking control so that the spot of the main beam is placed on the pre-groove by the sum of the first track 1-ler beam and the output low-frequency component of the filter circuit 105. do.

[Effect]

Even if the disc 101 is a write-once or erasable optical disc, there is always an area on its track where only 1 is repeated5. This area is an area called an ID area where the sector number and track number are recorded. be,.

That is, the track formed in the pregroove of the disk 101 is recorded by chronologically synthesizing several sectors as shown in FIG. 2(A). .

Sector 4. As shown in FIG. 2(B), it consists of the above-mentioned ID area 35 and data area 36, 10 areas 35 are read areas, that is, read-only areas, and the data area 36 is used for all recording, playback, and erasure. This is a possible area.

Furthermore, as shown in FIG. 2(C), the IDff1 area 35 is
Sector mark, track mark, and sector number data are recorded, and gaps are provided between them to protect the data from rotational fluctuations and the like.

This] ID area 5 is recorded in advance at the disc manufacturing stage.In the present invention, the second track error signal 104 is used to apply the so-called three-beam method to write the second track from only the ID area 1I 235. Error 6iQ is detected. However, the number of 10 regions Vi35 per revolution of the disk 101 is around 20 concave at most, and the number of rotations of the disk 101 is often between 1800 and 240.
It is 0 rpm. Therefore, the sampling frequency of the second track error signal 3 is 600) (z~800 Hz), and it is impossible to cover the track revolution band with this alone.

Therefore, in the present invention, the first track 1 is detected f.
The stage 103 detects the first track error signal using the push-pull method in the entire area where the pregroove is formed on the disc 101, and only the low frequency signal is detected by one filter circuit 1o.
By compensating with the low-frequency component of the second track error signal obtained through 5, it is possible to perform track servo that is resistant to beam jitter and disk tilt. Furthermore, recording, reproduction, and erasing of write-once and erasable optical discs, which was impossible with the three-beam method, becomes possible.

Incidentally, most of the disc inclination of the beam jet 15 is the tnla frequency component of the disc 101, so the track error signal 8. By using the first track error signal obtained by the push-pull method as the high-frequency component of , the b problem is small.

〔Example〕

FIG. 3 shows a block diagram of one embodiment of the invention.

In the figure, the same components as those in FIG. Since it is the same as the apparatus to which the beam method is applied, illustration is omitted. .

In FIG. 3, reference numerals 41a to 41d indicate respective photodetecting sections of the four-split photodetector, and numerals 42 and 43 indicate the photodetecting sections of the two-split photodetector, respectively. The reflected light from the disk of the main beam, which is 0th-order diffracted light, is incident on the photodetectors 41a to 41d, where it is photoelectrically converted.

Output detection signals from the photodetectors 41a and 41b are converted into voltage by a current-voltage conversion amplifier 44, amplified, and supplied to one input terminal of a differential amplifier 45. Further, the output detection signals of the photodetectors 41C and 41d are supplied to other input terminals of the differential amplifier 45 through the current-voltage conversion amplifier 46.

Here, when the 0th-order diffracted light (main beam) is within the pregroove, the signals at both input terminals of the differential amplifier 45 are equal; on the other hand, when it is J" away from the pregroove, the signals are The output detection signals -h of the current-voltage conversion amplifiers 44 and 46 have a higher level than the other.Therefore, the first track error signal by the push-pull method described above is extracted from the differential amplifier 45.

This first track error signal is supplied to a phase compensation circuit 47, where it is subjected to a known phase compensation circuit, and then input to a zero adder 48.

On the other hand, the reflected light from the disk of the first sub-beam, which is the +1st-order diffracted light, is incident on the photodetector 42, and the reflected light from the disk of the second sub-beam, which is the 11th-order diffracted light, is incident on the photodetector 43. is incident. Photodetectors 42 and 43
The detection signals obtained by photoelectric conversion are separately converted from current to voltage by current-to-voltage conversion amplifiers 49 and 50, amplified, and then supplied to differential amplifiers 51, respectively. This is where you can make a difference.

As a result, a second track 1 error signal is extracted from the differential amplifier 51 in accordance with the difference in light intensity between the reflected lights of the first and second sub-beams. However, during recording, the light intensity U of the reflected light of the first and second sub-beams changes dynamically, so it cannot be used as it is as a track error signal.

Therefore, in this embodiment, the output signal of the differential amplifier 51 is supplied to the sample and hold circuit 52, and the spots of the first and second sub-beams are placed on the ID area 35, which is also reproduced during recording. 10 synchronized with timing
It samples at the first rear signal and holds it until the next IO area signal is input again. As a result, there is little change in the flame of the reflected light of the first and second sub-beams, not only during playback and erasing, but also during recording. A second track error signal detected in the same manner as above is taken out from the ripple hold circuit 52.

This second track 1-ra beam is a low-pass filter (1,P
F) 53, where a low frequency component including at least the rotational frequency component of the disk is converted into one wave), and this low frequency component is supplied to the adder 48.

As a result, the first track error (
, T and the low-frequency component of the second track error signal are extracted, and this sum is amplified in power by the power amplifier 54 and then applied to the track actuator.
55 as a drive current. As a result, the objective lens is slightly displaced so as to bring the spot of the main beam into the pregroove. By this tracking control of the main beam, both the main beam and the two sub-beams are similarly displaced in the track width direction.

〔Effect of the invention〕

As described above, according to the present invention, '
; J41's track 1 error (fT) is compensated by the area component of the second track error signal using the 3-beam method, so tradding υ-bo that is resistant to beam shift and disk tilt can be performed. Furthermore, it has the advantage that it can record a wide range of information in the same way as rewriting and erasing for all writeable and erasable optical discs, which was impossible with the three-beam method.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle configuration of the present invention. FIG. 2 is a diagram showing the track configuration VA. FIG. 3 is a block diagram of an embodiment of the present invention. An example configuration diagram, FIG. 5 is an explanatory diagram of focus error detection, FIG. 6 is an explanatory diagram of the push-pull method, and FIG. 7 is an explanatory diagram of the configuration of the three-beam method. In the 1° diagram, 101 is a disk, 102 is a spot forming means; 103; first track 1ler detection means; 1(14);
105 is a filter circuit, and 106 is a second track error signal detection means. 01 Aksho and Sun Moon's J Minou! Composition F foot diagram (A) (B) (C) Fig. 5

Claims (1)

[Claims] A pregroove is formed in advance at the manufacturing stage, and
A disc (101) having an ID area in which a track number and a sector number are recorded in advance in a part of the pregroove.
On the other hand, in an optical information recording and reproducing apparatus that records an information signal in an area other than the ID area of the pregroove using a spot of a main beam and reproduces the information signal, the 0th order diffracted light is the main beam, and Spots are formed by sub-beams of ±1st-order diffracted light in mutually opposite directions in each of the track longitudinal direction and track width direction of the disk (101) with the beam spot as the center, and each spot is formed movably in the track width direction. a spot forming means (102) for detecting a first track error signal in an entire area of the pregroove according to the symmetry of a reflected light pattern of light reflected from the disk (101) by the main beam; The track error signal detection means (103) of No. 1 detects the difference in the amount of light reflected from the disk (101) by the two sub-beams of the ±1st-order diffracted light.
a second track error signal detection means (104) for detecting only in the region to obtain a second track error signal; a filter circuit (105) for filtering only the low frequency component of the second track error signal; The first track error signal and the filter circuit (10
5) control means (106) for controlling tracking so that the spot of the main beam is located in the pre-groove using a signal that is the sum of the output low-frequency component; playback device.