JPS61278039A - Disk device - Google Patents

Abstract

PURPOSE:To protect information, and to execute an access at a high speed by storing the position information to which an optical axis of an optical head corresponds, after information has been recorded, or at the time of holding after information has been reproduced, moving the optical head to an unrecorded area, and moving the optical head again in accordance with the stored position information, when recording or reproduction has been restarted. CONSTITUTION:When a holding state has exceeded a prescribed time, a CPU 50 stores address information of its recording position or reproducing position in its internal memory by a reproducing signal supplied from a binarization circuit 52, decides an unrecorded area (b) or (c) being near a track number of the address information, and outputs the address information its area to a driving circuit 51. As a result, a bead spot can be irradiated in advance to the unrecorded area of an optical disk 1. When starting the reproduction or recording, the optical head moves to a recording position or a reproducing position of the previous time by driving a linear motor in accoardance with the address information recorded in the CPU 50, and information can be recorded and reproduced at a high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a disk device such as an optical disk device that records or reproduces information on an optical disk using, for example, focused light.

[Technical background of the invention and its problems] In recent years, image information such as documents that are frequently generated is photoelectrically converted by two-dimensional optical scanning, and this photoelectrically converted image information is recorded on an image recording device, or Recently, optical disk devices have been used as image recording devices in image information file devices that can search for and reproduce images as needed, and reproduce and output them as hard copies or soft copies.

Conventionally, such optical disk devices use an optical disk that records information in a spiral manner, and information is recorded or reproduced using an optical head that moves linearly in the radial direction of the optical disk using a linear motor. It has become. In such a device, after recording or reproducing information on an optical disk, the same track is irradiated with a weak laser power to reproduce the information. However, even with a weak laser power, recording information may be destroyed if the same track is irradiated for a long time.

Therefore, from the standpoint of information protection, methods can be considered such as stopping laser emission, accessing an unrecorded (no information) area with an optical head, or prohibiting laser irradiation on the same track. However, from the viewpoint of high-speed information retrieval, if the laser is turned off, the focus must be retracted, if an unrecorded area is accessed, the recording area must be accessed again, and the previous recording or playback position must be searched. However, there is a drawback that it takes extra time to record or reproduce new information.

[Object of the invention] This invention was made in view of the above circumstances, and its purpose is to protect information and provide high-speed access during the standby period after information recording or information reproduction. The aim is to provide a disk device that can do this.

[Summary of the invention] In order to achieve the above-mentioned object, the present invention provides a system that, after recording information,
Alternatively, during standby after information reproduction, the position information corresponding to the optical axis of the optical head is memorized, the optical head is moved to an unrecorded area, and when recording or reproduction is resumed, the position information corresponds to the stored position information again. The optical head is moved by the

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

1 to 4 schematically show the structure of an optical disk device of the present invention. That is, the optical disc 1 is rotated by the motor 2 at a constant linear velocity with respect to an optical head 3, which will be described later. For example, as shown in FIG. 2, the optical disc 1 has a donut-shaped recording film 1a made of a metal coating layer such as tellurium or bismuth coated on the surface of a circular substrate made of glass or plastic. There is. The recording film 1a of this optical disc 1 has a recording area a1 where information is written.
Further, there are unrecorded areas b and c, in which only address information is recorded, which are provided at the outer and inner circumferential ends of the recording area a, respectively, and in which no information is written.

An optical head 3 for recording and reproducing information is provided on the back side of the optical disc 1.

This optical head 3 is constructed as follows. That is, 11 is a semiconductor laser (light source), and a diverging laser beam is generated from this semiconductor laser 11. In this case, when writing (recording) information on the recording film 1a of the optical disc 1, Laser light whose light intensity is modulated according to the information to be recorded is generated, and when information is read out from the recording film 1a of the optical disc 1 (reproduction), laser light having a constant light intensity is generated.

The diverging laser beam generated by the semiconductor laser 11 is converted into a parallel beam by the collimator lens 13 and guided to the polarizing beam splitter 14 . The laser beam guided to this polarized beam splitter 14 is reflected by this polarized beam splitter 14, and then
The light passes through the 74-wavelength plate 15 and enters the objective lens 16,
This objective lens 16 allows the recording film 1a of the optical disc 1 to be
focused towards. Here, the objective lens 16 is supported movably in the front axis direction and in the direction perpendicular to the optical axis, and when the objective lens 16 is positioned at a predetermined position, the focused light emitted from the objective lens 16 is The beam waist of the laser beam is the recording film 1a of the optical disc 1.
The minimum beam spot is formed on the surface of the recording film 1a of the optical disc 1. In this state, the objective lens 16 is kept in focus and on track, allowing information to be written and read.

Further, the diverging laser beam reflected from the recording film 1a of the optical disc 1 is converted into a parallel beam by the objective lens 16 when focused, passes through the quarter-wave plate 15 again, and is returned to the polarizing beam splitter 14. . By reciprocating through the quarter-wave plate 15, the plane of polarization of this laser light is rotated by 90 degrees compared to when it is reflected by the polarizing beam splitter 14. The light passes through polarizing beam splitter 14 . The laser beam that has passed through the polarizing beam splitter 14 is divided into two systems by a half mirror 17, and one of the laser beams (track deviation detection system) is transmitted to one first photodetector by a first projection lens 18. irradiated on top. The first photodetector 19 includes photodetection cells 19a and 19b that convert the light imaged by the first projection lens 18 into electrical signals.

The signals outputted by these photodetection cells 19a119b are γ signal and β signal, respectively.

On the other hand, the laser beam from the other side (defocus detection system) separated by the half mirror 17 is extracted by a knife etch (light extracting member) 2Q, and only the component passing through the area separated from the optical axis is extracted, and the laser beam is transmitted to the second projection lens. After passing through 21, it is irradiated onto a second photodetector 22. The second photodetector 22 includes photodetection cells 22a and 22b that convert the light imaged by the second projection lens 21 into electrical signals. These photodetection cells 22a122b
The signals output by are α signal and β signal, respectively.
A signal is now output.

Further, as shown in FIGS. 3 and 4, the optical head 3 is fixed to a movable part 5 of a DC linear motor (moving mechanism) 4 which is composed of a movable part and a fixed part. 5 in the radial direction of the optical disc 1, that is, as shown in A
, are moved linearly in the B direction. 6 is an optical scale fixed to the movable part 5; 7 is a light emitting part 7a and a light receiving part 7;
This is a detector for detecting the position of the optical scale 6 consisting of the optical scale 6, etc., and outputs two types of detection signals having different phases according to the movement of the movable part 5 by a so-called overlapped grating detection method. The linear motor 4 is driven by adjusting the amount of current supplied to the movable coil 8 from a drive circuit 51 that is driven in response to a signal from a CPU 50, which will be described later. Reference numeral 9 denotes a magnet serving as the iron core of the movable coil 8.

Out of the above-mentioned optical head 3, the photodetection cells 19a, 1
The output of 9b is used for tracking deviation correction and reproduction signal.

Further, the outputs of the photodetection cells 22a and 22b are used for correcting force focusing (defocusing).

Further, the outputs of the photodetection cells 22a122b are supplied to amplifiers 31 and 32, respectively. The output of the amplifier 31 is supplied to a non-inverting input terminal of a differential amplifier 38. Also,
The output of the amplifier 32 is supplied to the inverting input of the differential amplifier 38.

This differential amplifier 38 detects a defocus signal (α-
β) can be obtained.

The output of the differential amplifier 38 is supplied to a waveform shaping circuit 39. This waveform shaping circuit 39 shapes the waveform of the signal supplied from the differential amplifier 38 and then outputs it to the drive circuit 40 . The drive circuit 40 includes a coil 2 that drives the objective lens 16 in a direction perpendicular to the recording surface 1a of the optical disc 1 in accordance with a signal supplied from the waveform shaping circuit 39.
By supplying a current corresponding to 4, the objective lens 1
6 to correct force focusing (defocusing).

Further, the outputs of the photodetection cells 19a and 19b are supplied to amplifiers 41 and 42, respectively. The output of the amplifier 41 is supplied to the non-inverting input terminal of a differential amplifier 45, and the output of the amplifier 42 is supplied to the inverting input terminal of the differential amplifier 45. The differential amplifier 45 is configured to obtain a tracking deviation detection signal (γ-δ) by taking the difference between the signals supplied from the amplifiers 41 and 42. The output of the differential amplifier 45 is supplied to a waveform shaping circuit 47. This waveform shaping circuit 47 shapes the waveform of the signal supplied from the differential amplifier 45 and supplies it to the drive circuit 48 . This drive circuit 48 includes a coil 2 that drives the objective lens 16 in the horizontal direction with respect to the recording surface 1a of the optical disc 1 in accordance with a signal supplied from the waveform shaping circuit 47.
By supplying a current corresponding to 3, the objective lens 1
6 to correct tracking deviation.

Further, the outputs of the photodetection cells 19a and 19b are amplified by amplifiers 41 and 42, respectively, and then supplied to an adder 46. This adder 46 is configured to obtain a video signal by summing the signals supplied from amplifiers 41 and 42.

The output of the adder 46, that is, the video signal, is supplied to a binarization circuit 52. The signal binarized by the binarization circuit 52 is supplied to the CPU 50, which will be described later, as a reproduction signal.

This CPLJ 50 is a control circuit that controls the whole, and controls the amount of current flowing through the movable coil 8 by driving and controlling the drive circuit 51 according to address information from an external device (not shown). The head 3 is moved to a corresponding predetermined position. Further, when the CPU 50 determines by an internal timer (not shown) that a predetermined period of time, for example, 5 minutes has elapsed since the recording or reproduction of information has ended, the binarization circuit 5
The address information of the recording position or reproduction position, that is, the track number and task number supplied from 2, is stored in a memory (not shown).

Further, the CPLJ 50 determines which unrecorded area b or C is closer to the track number of the address information, and outputs the address information of that area to the drive circuit 51. Thereby, the drive circuit 51 supplies a current corresponding to the above signal to the moving coil 8 of the linear motor 4.

As a result, the movable part 5 of the linear motor 4 is moved to the non-memory area b or C, so that the optical head 3
The laser beam irradiated from the recording area is irradiated onto the unrecorded area b or C.

Next, the operation in such a configuration will be explained. For example, the diverging laser beam generated by the semiconductor laser 11 is converted into a parallel beam by the collimator lens 13 and guided to the polarizing beam splitter 14 . The laser beam guided to this polarizing beam splitter 14 is reflected by this polarizing beam splitter 14, and then 1/
The light passes through the four-wavelength plate 15 and enters the objective lens 16, and is focused by the objective lens 16 toward the recording film 1a of the optical disc 1.

In this state, when recording information, bits are formed on tracks on the optical disk 1 by irradiation with a high-intensity laser beam (recording beam), and when reproducing information, bits are formed on tracks on the optical disk 1. Laser light L (reproduction beam light) is irradiated. The reflected light from the optical disc 1 for this reproduction beam is converted into a parallel light beam by the objective lens 16,
The light passes through the quarter-wave plate 15 again and is returned to the polarizing beam splitter 14. As the laser beam travels back and forth through the quarter-wave plate 15, the plane of polarization of this laser beam is rotated by 90 degrees compared to when it is reflected by the polarizing beam splitter 14, and the plane of polarization is rotated by this 90 degrees. The laser light passes through a polarizing beam splitter 14.

The laser beam that has passed through the polarizing beam splitter 14 is divided into two systems by a half mirror 17, and one of the laser beams 1 (track deviation detection system) is transmitted to a first photodetector 19 by a first projection lens 18. On the other hand, the laser light from the other side (defocus detection system) separated by the half mirror 17 is extracted by a knife etch (light extracting member) 20, so that only the component passing through the area separated from the optical axis is extracted. , passes through the second projection lens 21 and is irradiated onto the second photodetector 22. Therefore, signals corresponding to the irradiated light are output from the photodetection cells 20a, 20b, 19a, and 19b. The signals are fed to amplifiers 31.32.41.42, respectively.

A normal focusing operation in such a state will be explained. That is, the signals from the amplifiers 31 and 32 are respectively amplified by differential amplifiers 33 and 34 and supplied to a differential amplifier 38. Then, the differential amplifier 38
is the detection signal from the photodetection cell 22a and the photodetection cell 22
A defocus detection signal (α-β) obtained by taking the difference with the detection signal from b is output to the waveform shaping circuit 39.

Then, the waveform shaping circuit 39 shapes the waveform of the supplied signal and outputs it to the drive circuit 40. Thereby, the drive circuit 40 supplies a predetermined current to the coil 24 in accordance with the signal from the waveform shaping circuit 39, and drives the objective lens 16 in the vertical direction to perform force shifting. As a result, the beam spot formed by the objective lens 16 can be set at the optimum position relative to the focus position.

Also, normal tracking operation will be explained. That is, the signals from the amplifiers 41 and 42 are sent to the differential amplifier 4.
5. Then, the differential amplifier 45 outputs a tracking deviation detection signal (γ-δ) obtained by taking the difference between the detection signal from the photodetection cell 19a and the detection signal from the photodetection cell 19b. And the above signal is
The waveform is shaped by a waveform shaping circuit 47 and then supplied to a drive circuit 48 . As a result, the drive circuit 48 can control the waveform shaping circuit 47.
A predetermined current is supplied to the coil 23 according to a signal from the
Tracking is performed by driving the objective lens 16 in the horizontal direction. As a result, the beam spot formed by the objective lens 16 can be set at the optimum position relative to the tracking position.

Also, during playback, the same behavior occurs as during playback when recording,
Moreover, tracking and force tsusing are now performed.

When the predetermined time (5 minutes) has elapsed in the standby state during recording or playback as described above, the CPU 50 uses the playback signal supplied from the binarization circuit 52 to read the address information of the recording position or playback position. It is stored in an internal memory (not shown).

Further, the CPU 50 determines which unrecorded area b or C is closer to the track number of the address information, and outputs the address information of that area to the drive circuit 51. Thereby, the drive circuit 51 supplies a current corresponding to the above information to the moving coil 8 of the linear motor 4, and
Move the movable part 5 of the slider 4 to the unstored area b or C. As a result, the laser beam emitted from the optical head 3 is emitted onto the unrecorded area b or C.

In this case, the force correction by the optical head 3 continues to be performed.

As a result, the beam spot produced by the objective lens 16 can be irradiated onto the unrecorded area b or C of the optical disc 1. Thereby, recorded information can be protected.

When reproducing information or recording information next time, the linear motor 4 is driven in accordance with the address information stored in the CPU 50 to move to the previous recording position or reproduction position. At this time, since the correction of the force twisting is still being performed, the user can immediately move to the access position without having to retract the force twisting. Therefore, information can be recorded or reproduced immediately from the previous recording or reproduction position, that is, at high speed.

In the above embodiment, a case has been described in which a knife is used to detect defocus, but the present invention is not limited to this, and a detection signal for defocus may be obtained by an astigmatism method. Moreover, although the case where the photodetector is composed of two photodetection cells has been described, the present invention is not limited to this, and the present invention can be similarly implemented using a photodetector having another structure.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to provide a disk device that can protect information and perform high-speed access during standby after information recording or information reproduction. .

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing the configuration of a disk device showing an embodiment of the present invention, FIG. 2 is a diagram showing a disk according to the invention, and FIGS. 3 and 4 are diagrams showing an optical head and a linear motor. It is a figure showing an example of composition. DESCRIPTION OF SYMBOLS 1... Optical disk (disc), 3... Optical head, 4... Linear motor, 11... Light source (semiconductor laser), 16... Objective lens, 19.22... Photodetector, 19a, 19b, 22a, 22b--Photodetection cell, 23.24...Coil, 31.32.41.42-
...Amplifier, 38.45...Differential amplifier, 46...
Adder, 39.47... Waveform shaping circuit, 40.48.
...Drive circuit, 50...CPU, 51...Drive circuit, 52...Binarization circuit.

Claims (3)

[Claims] (1) In a disk device that records or reproduces data on a disk using focused light, an optical head consisting of a light source and a focusing means for focusing the light emitted from the light source onto the disk; A moving means for moving an optical head in the radial direction of the disk, a detecting means for detecting light reflected by the disk, a driving means for driving the focusing means in accordance with a detection result by the detecting means, and a data recording means. or when waiting after data playback,
A disk characterized in that it comprises a storage means for storing positional information to which the optical axis of the optical head corresponds, and a control means for moving the optical head to an unrecorded area of the disk by the moving means during the standby period. Device. (2) The disk device according to claim 1, wherein the moving means is constituted by a linear motor. (3) The disk device according to claim 1, wherein the position information is address information read from the disk.