JPH0287334A - Optical information recording/reproducing device and information recording medium - Google Patents

Abstract

PURPOSE:To increase the recording capacity of a medium by controlling a 2nd optical means to a desired tracking position on the medium based on the deviation of a reference track detected by a 1st optical means. CONSTITUTION:The deviation of a reference tack is detected by a deviation detection sensor 22 attended with the drive of an optical disk 1 and its detection signal is outputted to a comparator 51. On the other hand, A laser beam is made incident on an opposite recording reproducing head 40 from a range finder 30 supported to an eccentric detection head 10, its reflected light is received by a range finding detection sensor 34 and outputted to an A/D converter circuit 51. The offset of a distance with respect to the deviation is calculated by a system controller 58, a seeking motor 53 is driven and an offset is controlled to be zero with respect to the deviation and the distance with the recording and reproducing head 40. Thus, highly dense recording and reproduction is attained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical information recording and reproducing device that records and/or reproduces information on an information recording medium, and particularly relates to an optical information recording and reproducing device that records and/or reproduces information on an information recording medium, and particularly when the information recording medium (hereinafter abbreviated as the medium) rotates. The present invention relates to an optical information recording and reproducing apparatus that performs a method for correcting eccentricity using two optical means and a cheek-shaped detector.

[Conventional technology]

Conventional non-contact position control methods for trucks are generally known in the following basic systems: (1) three-beam system, (2) two-beam split system, and (3) wobbling system.

In all of the above three methods, the original pickup section is moved in the radial direction of the focus direction or the track direction,
There is a sensor that detects the amount of track eccentricity, and a drive unit that drives a pickup lens etc. by focusing control using an astigmatism method, etc. These are integrated with an optical block and held by a mirror body. It is called a head and is commonly used.

Conventionally, a configuration as shown in FIG. 4 has been known as a device for this purpose. In FIG. 4, the Rade beam emitted from the Rade light source 101 is transmitted to the polarizing beam splitter 102.
, passes through the quarter-wave plate 103, and passes through the objective lens 1.
04, the light is focused onto the disk 105 and recording is performed. The light reflected from the disk 105 passes through the objective lens 104.
The light passes through the quarter-wave plate 103, the polarizing beam splitter 102, the astigmatism optical system 112, and is irradiated onto the four-split photodetector 107. In this way, an autofocus signal is obtained, and the lens driving device 110 is driven to perform autofocus.

The optical system described above is arranged on one substrate,
The recording head 108 as a whole is referred to as a recording head 108.

A head drive mechanism 109 and a head drive motor 110 move the recording head 108 in the radial direction of the disk. A motor control circuit 111 controls the motor 110 so that the recording head 108 moves at a constant speed. Also.

The disk 105 is rotated by a spindle motor 106, which is controlled by a spindle motor control circuit 107 so as to rotate at a constant angular velocity.

In this way, by feeding the recording head 108 at a constant speed and rotating the disk 105 at a constant speed, recording can be performed with a constant track interval.

Next, FIG. 5 shows an explanatory diagram of the main parts of a conventional additionally writable recording and reproducing apparatus. 201 and 202 are recording and reproducing radar beams, respectively, and are formed by separate radar beams. Information tracks are recorded by transmitting a laser beam 201 to an optical modulator 203. The light is focused onto a recording medium 207 through a beam splitter 204, a vibrating mirror 205, and an objective lens 206.

On the other hand, the reproduction radar beam 202 is connected to the beam splitter 2
08, recording medium 207 via mirror 209, beam splitter 204, vibrating mirror 205, objective lens 206
The light is focused on the recorded track above. The reflected light from the recorded field track passes through an objective lens 206, a vibrating mirror 205, a beam splitter 204, a mirror 209, and a beam splitter 208, and is irradiated onto a photodetector 200, which generates a signal containing information on the deviation between the track and the radar beam. obtain.

This signal is input to the driver 210 of the vibrating mirror 205, and the vibrating mirror 205 is moved so that the laser beam 202
Section K14 so that the recorded track is accurately tracked.

At the same time, the recording radar beam 201 is also
Move by. In this way, Ledebeam 201
It becomes possible to trace a position a certain distance away from the already recorded track on the recording medium 207, and additional writing and recording becomes possible.

In the above-mentioned conventional example, various information such as video, audio, or character signals are recorded along concentric or spiral guide grooves called pre-groups formed on the surface of the medium according to the information to be recorded. The medium surface is irradiated with an intensity-modulated light beam spot, and the recording film is evaporated or discolored by the energy thereof, thereby forming information recording bits. or,
Even during reproduction, the recorded information pits are read out along the pre-groups. Like this K
The pre-group, which is a guide groove, plays an important role during recording and/or reproduction.

[Problem to be solved by the invention]

However, today, a major development theme is how much recording capacity can be provided in a predetermined recording/playback area. Therefore, the pitch given to K and pregroup is, for example, 1.2 to 16 like LD and CD.
As the thickness becomes smaller and smaller than 6 μm, as a result, the influence of small defects or dust on the pre-group becomes a big problem. Furthermore, there is a tolerance due to machining, such as concentricity accuracy of the rotation center hole with respect to the pre-group of the medium. With the addition of precession, large precession movements often occur as a medium. In such a state, in a configuration in which AT (auto tracking) is controlled only by one optical means, as shown in the conventional example shown in FIG. 4, accurate AT control cannot be performed for the eccentricity, and Even when there is a small defect, it has the drawback that AT failure occurs, resulting in an increase in recording and reproduction error rates.

Therefore, in the conventional example shown in FIG. 5, the recording radar beam 201 and the reproducing laser beam 202 are set separately in order to correct the amount of eccentricity, and the laser beams are irradiated from two directions and transmitted through one optical block. The beam is divided into two, one for recording and the other for reproduction. therefore,
The reproducing radar beam follows along the formed pre-group (track) on the medium, and the recording radar beam is allowed to form information recording bits at a certain distance. However, this conventional example shown in FIG. 5 also follows the pre-group formed at a constant distance, and as a result, the conventional example
This will result in an AT control error similar to the one shown in the figure.

〔the purpose〕

The present invention has been made in view of the problems of the prior art described above, and its purpose is to reduce the number of pre-groups (reference tracks) provided on an information recording medium as small as possible.
It is an object of the present invention to provide an optical information recording/reproducing device that enables an increase in the recording capacity of the medium and a reduction in manufacturing costs.

[Means to solve the problem]

According to the present invention, the above object is achieved by using an information recording medium in which at least one reference track is formed at a circumferential position of the disk-shaped recording medium at a substantially constant radial distance from the disk rotation center. , an optical information recording and reproducing apparatus for recording and/or reproducing information, the apparatus comprising: a first optical means for detecting the amount of eccentricity of a reference track from the disk rotation center; and a first optical means for emitting a light beam to the information recording medium. It has a second optical means for recording and/or reproducing information by irradiating it, and a length measuring device for measuring the distance from the first optical means to the second optical means.

The second optical means is controlled to a desired tracking position on the medium based on the eccentricity of the reference track detected by the first optical means. This is achieved by an optical information recording/reproducing device.

Also, as a medium suitably used in the above device.

The present invention provides an information recording medium in which at least one reference track is formed at a circumferential position of the disk-shaped recording medium at a substantially constant radial distance from the center of Day 2 rotation of the medium.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, an embodiment according to the present invention will be described specifically and in detail based on the drawings.

FIG. 1 is a schematic diagram showing a first embodiment of the optical information recording/reproducing apparatus of the present invention, and more specifically shows a schematic configuration of an optical system used in the apparatus.

In the figure, reference numeral 1 denotes an optical disk as an information recording medium, and the optical disk rotates around an axis by a rotation mechanism (not shown). 1O corresponds to an eccentricity detection head section, which detects the movement of a reference track for eccentricity detection provided in advance on the medium surface of the optical disk 1. The optical system configuration of the eccentricity detection head 10 includes a semiconductor laser 11 as a light source, a collimator lens 12, and an wavelength plate 13.
, a polarizing beam splitter 14 , a Kaede wave plate 15 ,
A pickup lens 16, a focusing actuator 17, a non-decentered beam splitter 18, an astigmatism generating optical system 19 consisting of a combination of a spherical lens and a cylindrical lens, a focus error detection sensor 20, a condenser lens 21, It consists of an eccentricity detection sensor 22.

Reference numeral 30 denotes a length measuring device that is integrated with the eccentricity detection head 10, and has a function of measuring the distance to the recording/reproducing head, which will be described later, by using the light flux guided from the eccentricity detection head 10, as will be explained later. have The optical system of the length measuring device 30 is
a wave plate 31, a non-polarizing beam splitter 32,
First corner cube 33 and photodetector 34
The second corner cube 35, which is fixed to the recording/reproducing head 40, forms a two-beam interference type interferometric length measuring device.

40 is a recording/reproducing head, which is composed of a semiconductor laser 41 and a collimator lens 42.

Astigmatism generating optical system 4 consisting of a diffraction grating 43, a polarizing beam splitter 44, an A wavelength plate 45, a pickup lens 46, a tracking and focusing actuator 47, a spherical lens, and a cylindrical lens.
8 and a photodetector 49. Further, a corner cube 35 is fixedly installed in a part of the recording/reproducing head 40.
The distance of the recording/reproducing head 40 from the eccentricity detection head 10 is constantly measured by the length measuring device 30 using the corner cube. This recording and reproducing head 40 is for recording and reproducing information on the medium surface of the optical disc 1 using a semiconductor laser 41.

As can be seen from the description of the optical system configuration, focusing of the head is performed by an astigmatism method, and tracking is performed by a three-beam method, both of which are well-known techniques, so their description will be omitted.

Next, a method for detecting the eccentricity of the optical disc 1 using the eccentricity detection head 10 will be explained based on FIG. Semiconductor laser 1
After the light beam emitted from the light source 1 is made into a parallel light beam by a collimator lens 12, the direction is set appropriately and the direction of polarization is rotated by a wavelength plate 13. A part of the parallel light is reflected by a polarizing beam splitter. The light beam is directed toward the length measuring device 30, and the transmitted light beam passes through the arm wave plate 15 and the pickup lens 16 to form a light spot on the medium surface of the optical disk. The light beam reflected on the medium surface is returned to the pickup lens 16. After passing through the Kaede wavelength plate 15 and being reflected by the polarizing beam splitter, it reaches the non-polarizing beam splitter 18. The light is focused on the focus error sensor 20. The focus actuator 17 is driven by the focus error signal obtained from the focus error detection sensor 20 via a serger (not shown) to perform autofocus control. On the other hand, the light beam reflected by the non-polarizing beam splitter 18 forms a spot on an eccentricity detection sensor 22 provided at a position conjugate with the medium surface of the optical disk 1 by a condensing lens 21. Focus error detection is not limited to the above-mentioned method, and a known technique such as the Bushdel method may be used.

FIG. 2 is a diagram for explaining a method for detecting eccentricity of an optical disk using the eccentricity detection sensor 22. As shown in FIG.

In the figure, reference numeral 22 denotes the eccentricity detection sensor described above, and as shown in the figure, this sensor is composed of two right-angled triangular photosensors 22m and 22b arranged with their hypotenuses facing each other. The outputs from each of the photosensors 22m and 22b are taken out by a differential amplifier 23 as a differential output. A light spot 24 is focused by the condenser lens 21, and an image 25 of a reference track formed on the medium surface of the optical disk is formed within the light spot.

It is assumed that the reference tracks are previously formed concentrically on a part of the medium surface of the optical disk (for example, near the outermost periphery) by means of photolithography or the like.

In order to increase the contrast of the image 25 of the reference track and to increase the accuracy of eccentricity detection, it is desirable that the reference track be a density-type 9-turn whose reflectance is as low as possible than the medium surface. This is because by doing so, the medium surface and the light-receiving surface of the sensor for detecting eccentricity are in a conjugate relationship, so that an image with high contrast and sharp edges is formed. In the eccentricity detection head 10, only the autofocusing servo is operated, and the autotracking servo is not performed. Therefore, as shown in FIG. 2, the image 25 of the reference track moves in the direction of the arrow in FIG. 2 within the stationary source spot 24 due to the eccentricity of the single source disk.

Since the amount of eccentricity usually reaches several tens of micrometers or more, the original spot diameter on the medium surface must be made sufficiently large within the possible range so that the image 25 of the reference track does not deviate from within the optical spot 24. To achieve this, for example, the effective NA can be reduced by making the light flux incident on the pickup lens sufficiently thin, and the diameter of the imaging spot on the disk surface can be increased, or an arbitrary offset can be intentionally applied to the focus serge system. There are methods for illuminating a wide area on the surface of the medium.

FIG. 3 is a system schematic diagram of the optical information recording/reproducing apparatus of the present invention.

The optical disc 1 is fixedly connected to the rotating shaft of a spindle motor 55, and its rotation is controlled by a driver 54 via a system controller 58. optical disc 1
An eccentricity detection head 1 is supported and fixed by a frame body (not shown) at a position relative to a reference track that is formed in advance at a certain position (near the outer periphery) or formed at the time of mounting.
0 is installed.

As the optical disc 1 rotates, the amount of eccentricity of the reference track is detected by eccentricity detection sensors 22m and 22b (shown in FIG. 2), and the detected signal is input to the comparison circuit 51.

On the other hand, a laser beam that shares a light source with the eccentricity detection head 10 from the sub-length device 30 supported by the eccentricity detection head 10 enters the optical block of the opposing recording/reproducing head 40.
The reflected light is received by the length measurement detection sensor 34 in the length measurement device 30 and sent to the comparison circuit 51 after h/D conversion, and the system controller 58 calculates and processes the offset of the distance with respect to the eccentricity amount. A so-called serve loop is performed in which the seek motor 53 is driven and controlled by the seek driver 52, and the offset amount is controlled (2) with respect to the eccentric amount and the distance between the recording and reproducing head. At this time, the AT servo system 56 of the recording/reproducing head 10 is placed in a hold state by the system controller 59. The recording/reproducing head 40 with eccentricity correction like Jin is AF.
The (autofocus) serge system 56 captures the surface deviation on the surface of the optical disc 1, and a semiconductor laser or the like forms recording pits. Also, during reproduction, recorded information pits can be read out with eccentricity removed by the thermal loop, as in the above-mentioned recording. The semiconductor laser power at this time is a general method of reading the output by the system controller 58. Another method is during playback.

By installing a 3-beam system that allows only the recording/reproducing head 40 to follow the recorded information pits, the above-mentioned sir cuts the loop, and the AT is controlled by the system controller 58.
By driving the Sage system.

It is also possible to use it as a conventionally widely known reproducing head.

〔Effect of the invention〕

As explained above, the optical information recording/reproducing device of the present invention has the following features:
Since an information recording medium on which at least one reference track is formed is used, it is possible to perform high-density recording and reproduction compared to conventional information recording media, and the manufacturing cost of the medium is 4.
It can be made cheap.

Further, in the optical information recording/reproducing apparatus of the present invention, since the recording/reproducing head section is surged in synchronization with the locus of the reference track, conventional AT (auto tracking) can be made unnecessary.

Furthermore, in a state where recorded pits have been formed, it is also possible to rely on and track the recorded pits based on the commonly used (three-beam method). At this time, the eccentricity correction surge from the eccentricity detection section is turned off.

Further, in this embodiment, since a sensor having a triangular detection portion is used for detecting eccentricity, a wide dynamic range of the amount of eccentricity can be obtained. Therefore, even large eccentricities can be corrected.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the optical information recording/reproducing device of the present invention, FIG. 2 is a diagram for explaining an eccentricity detection section,
FIG. 3 is a system schematic diagram of an optical information recording/reproducing apparatus according to the present invention, and FIGS. 4 and 5 are schematic diagrams of a conventional information recording/reproducing apparatus. DESCRIPTION OF SYMBOLS 1... Optical disk, 10... Eccentricity detection head part, 3
0... Length measuring device, 40... Recording/reproducing head. Agent: Patent Attorney Yohei Yamashita

Claims (2)

[Claims] (1) At least one disc is located at a circumferential position of the disc-shaped recording medium at a substantially constant radial distance from the disc rotation center.
In an optical information recording and reproducing apparatus that records and/or reproduces information using an information recording medium on which a reference track of a book is formed, the apparatus includes a first optical information recording and reproducing apparatus that detects the amount of eccentricity of the reference track from the center of disk rotation. 1 optical means, a second optical means for recording and/or reproducing information by irradiating the information recording medium with a light beam, and a distance from the first optical means to the second optical means. and a length measuring device for measuring, and controlling the second optical means to a desired tracking position on the medium based on the eccentricity of the reference track detected by the first optical means. An optical information recording and reproducing device characterized by: (2) At least one disc is located at a circumferential position of the disc-shaped recording medium at a substantially constant radial distance from the disc rotation center.
An information recording medium on which the reference track of a book is formed.