JPH1069643A - Optical disk recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a damage preventing method not damaging data on a disk even when the disk having wavelength dependency is irradiated with a reading output by a laser beam having the wavelength of a high absorbing ratio and simultaneously an optical disk recording and reproducing device having an optical disk discriminating method capable of recognizing to be unable to read with the laser beam wavelength. SOLUTION: The optical disk K1 having the wavelength dependency in a charged reflecting ratio/absorbing ratio is rotated at a high speed with a spindle motor K3, the optical disk surface is irradiated by the laser beam with a light pickup K6 via a focusing lens operating in the vertical direction of the optical disk surface, and the laser beam reflected from the optical disk surface is measured with an A-D converter K8 to convert into an electric signal. And the size of the electric signal is measured with a micro computer K12, the energy of the irradiated laser beam is dispersed, the level of the reflecting light is detected without damaging data on the optical disk K1 and whereby the optical disk K1 is discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk recording / reproducing apparatus having a short-wavelength laser, and more particularly, to a type of optical disk which does not destroy data on the optical disk even if an optical disk having a wavelength dependency is loaded due to an erroneous operation. The present invention relates to an optical disc recording / reproducing apparatus provided with an optical disc discriminating circuit for discriminating the optical disc.

[0002]

2. Description of the Related Art Compact disc standards include 12 cm discs and 8 cm discs due to differences in outer diameter dimensions, and there are also discs whose read-only, write-once and eraseable types have been changed depending on the purpose of use. However, these optical discs have only two structural dimensions, disc diameters of 12 cm and 8 cm. Other thicknesses, hole diameters of chucking portions, distances from the reading side surface to the reflecting surface, and the like. Standards define the size of the pits on the recording surface, the readout direction, and the radial spacing. Further, the wavelength of the laser beam for writing / reading is around 780 nm, the reflectance of the disk is defined by this wavelength, and it is designed to satisfy this standard even if the material of the optical disk is changed. It was not necessary to determine the physical structure and material of the optical disc except for the recorded / unrecorded portion of the write-once disc of 12 cm / 8 cm.

First, the first method of discriminating the diameter of an optical disc is as follows. There is a difference in rotational moment between two optical discs, and discrimination can be made by detecting this difference.

[0004] As an example of this, from the stationary state of each disk, a constant rotational torque is applied, the time until reaching a predetermined rotational speed is measured in advance and set in a control program, and the optical disk is used. Each time it is replaced, the same measurement is performed to determine.

[0005] As a second method, a reflection type photocoupler is installed near a diameter of 10 cm when an optical disk is loaded in the apparatus, and reflection of the optical disk surface is detected when a 12 cm diameter disk is loaded. There is also a method of making a determination by making it possible.

[0006] Next, a method for discriminating between a recorded portion and an unrecorded portion of a write-once optical disc will be described. The unrecorded portion of the write-once optical disc is all in a reflective state and has no pits, but a groove for guiding an optical pickup. Is formed. For this reason, in the recorded part, the laser light is applied to the pits formed in the grooves from the optical pickup to detect the intensity of the reflected light and make it a data signal, but when entering the unrecorded part, the optical pickup traces the groove properly. The reflected light remains strong. By utilizing this, it is possible to determine the recorded portion and the unrecorded portion.

Here, the operation in the case of using a short-wavelength laser in the conventional optical disk reproducing apparatus to determine the type of the optical disk will be described with reference to the drawings.

FIG. 7 is a flowchart of a program processed by a microcomputer of a conventional optical disk reproducing apparatus when an optical disk is inserted. The configuration diagram of the conventional optical disc reproducing apparatus is the same as FIG.

When it is detected in step F1 (hereinafter, step is omitted) that the optical disk has been inserted, the output of the laser beam is turned on in F4, and the lens is moved up and down in the vertical direction of the optical disk surface in F5. At this time, the reflection signal from the optical disk is checked at F6, and the check is continued until the specified search time set at F7 elapses. At this time, if a reflection signal from the optical disc is detected in F6, the rotation of the spindle motor is instructed in F15, and the normal optical disc initial operation is performed.

If the reflected signal from the optical disk is not detected in F6 and the search specified time in F7 elapses, the output of the laser beam is turned off in F10 and F14
NG display ON is instructed, and NG display is continued until the optical disk is removed in F12. When the optical disk is removed, an NG display OFF instruction is provided in F13 and the process returns to the optical disk insertion check of F1.

In this method, when an optical disk having a wavelength dependence is inserted, the laser beam is absorbed by the optical disk and the reflected light is small.
Further, since the lens is moved up and down while the optical disc is stopped, the power of the racer light is concentrated on one point on the optical disc, and there is a possibility that data on the optical disc having wavelength dependency may be damaged.

[0012]

As described above, in the conventional optical disk reproducing apparatus, even if the optical disk has a wavelength dependence, the reflected light is sufficiently obtained and the wavelength of the laser light which is not absorbed by the optical disk is used. No matter what order the discs were discriminated, the discs were not damaged, and there was no problem. However, since it is necessary to use laser light having a short wavelength, there is a possibility that the disk may be damaged if the laser light is irradiated while the disk is stopped.

In recent years, an optical disk recording / reproducing apparatus has been designed to increase the data recording capacity by keeping the outer diameter and thickness of the optical disk and the hole diameter of the chucking portion the same as those of the compact disk, while keeping the optical disk surface on the recording surface side from the reflecting surface. The standard for high-density optical disks has been born with smaller distances, smaller pits, smaller readout directions, and smaller radial intervals. Further, since the size of the pits and the intervals between the pits in the reading direction and the radial direction are reduced, laser light (650 nm, 635 nm) having a shorter wavelength than that of the compact disk is used in this high-density optical disk recording / reproducing apparatus. .

However, a write-once optical disc in a compact disc has a wavelength dependence as shown in FIG.
It can be seen from the figure that there is a 4.5-fold difference in the absorptance between nm and 635 nm. That is, in a high-density optical disc recording / reproducing apparatus, even if the optical disc is a write-once compact disc, even if the output of a small laser beam for reading data on the disc with a laser beam having a wavelength of 635 nm, This means that there is a possibility that data on the optical disc may be damaged due to a recording action on the optical disc.

On the other hand, the compact disc and the high-density optical disc have the same outer diameter, thickness, and hole diameter of the chucking portion, so that they can be mechanically mounted on both recording / reproducing devices, and the same in appearance. Therefore, there is a problem in that the user may erroneously recognize and load a write-once optical disc of a compact disc into a high-density optical disc recording / reproducing apparatus, thereby damaging data on the disc.

[0016]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a disk which has a high absorptance and which is irradiated with a laser beam having a high absorptance at a readout output without damaging data on the optical disk. It is an object of the present invention to provide an optical disk recording / reproducing apparatus having an optical disk discriminating method capable of recognizing that the data cannot be read with the wavelength of the laser light at the same time.

Therefore, (1) The optical disk recording / reproducing apparatus of the present invention disperses the energy of the laser light by inserting the optical disk, rotating the optical disk at a high speed, and then irradiating the optical disk with short-wavelength laser light. The energy of the laser light irradiated per unit area is apparently reduced, preventing damage to the optical disk and measuring the amount of laser light reflected from the optical disk to determine that the optical disk is wavelength-dependent, It is characterized in that data on the optical disk is prevented from being damaged. (2) The optical disc recording / reproducing apparatus of the present invention is characterized in that the optical pickup lens reciprocates in the direction perpendicular to the optical disc surface while the optical disc is rotating at a high speed, and the laser light focus signal of the optical pickup that changes based on the reflected signal from the optical disc. If the optical disc has a wavelength dependence and the absorptance is high at the wavelength of the irradiating laser beam and there is a possibility that data on the optical disc may be damaged, a laser beam focus signal that reduces the signal is used. Utilizing the method, it is characterized in that it is determined whether or not an optical disk having wavelength dependency causes data corruption. (3) The optical disc recording / reproducing apparatus of the present invention comprises a means for rotating a loaded optical disc having a wavelength dependence of the reflectance / absorptance at a high speed, and an optical disc rotating at a high speed operating in a direction perpendicular to the disc surface. A means for applying laser light to the disk surface through a focusing lens, a means for measuring the laser light reflected on the disk surface and converting it to an electric signal, and a means for measuring the magnitude of the electric signal. In this method, the level of the reflected light from the optical disk is detected without disturbing the data on the optical disk by dispersing the energy of the laser light, and the optical disk is identified.

As described above, the present invention discriminates that a disc has a wavelength dependence by preventing damage to the optical disc and measuring the amount of reflection of laser light from the disc, thereby preventing data corruption on the disc. Is to prevent it.

In this case, a safe rotation speed of the disk for preventing the optical disk from being damaged is obtained.

FIG. 3 shows an example of the wavelength and absorptance of a laser beam in a wavelength-dependent optical disk. In the optical disk recording / reproducing apparatus of the present invention, the wavelength-dependent optical disk which can be mounted on the apparatus is not used. The absorptance (α1) at the wavelength (λ1) of the laser beam possessed and the absorptance (α2) at the wavelength (λ2) of the laser beam of the optical disc device in which the optical disc having the wavelength dependence is originally used.
When only the absorptance is considered from 2), it is necessary to be able to rotate the optical disk at a rotation speed that satisfies the following equation.

Rotation magnification of optical disk ≧ α1 (%) / α2 (%) where the rotation magnification of the optical disk in the expression is the required rotation number of the optical disk / the standard rotation number at the innermost circumference of the compact disk.

Next, since the spot diameter of the laser beam formed on the optical disc differs from the aperture ratio (NA) of the lens used and the wavelength of the laser beam, the spot diameter of the high-density optical disc recording / reproducing apparatus is φ1, and the optical disc of the compact disc is When the spot diameter of the recording / reproducing apparatus is φ2, the required rotation magnification of the optical disk is given by the difference of the spot diameter: the rotation magnification of the optical disk ≧ φ1 ² / φ2 ² Furthermore, the position of the pickup is the innermost circumference (radius r). When disc discrimination is performed at a position shifted outward by a from the position, the disc rotation magnification is: disc rotation magnification ≧ {2 (r + a) π} / 2π
r However, [pi from the above Pi, rotation ratio of the above 3 conditions are satisfied disc rotation ratio ≧ optical disc (α1 / α2) · (φ1 2 / φ
2 ² ) · [{2 (r + a) π} / 2πr] is obtained.

As a result, even if an optical disk having a high wavelength dependency is irradiated with a laser beam having a wavelength having a high absorptance, the disk rotates at a high speed. The energy per hit is less than the energy received when the laser light of the wavelength originally used is rotating at the standard speed of the disk, and the data on the optical disk is not damaged.

At the same time, the lens of the optical pickup is reciprocated in the direction perpendicular to the optical disk surface while the optical disk is rotating at high speed. At this time, the laser focus signal of the optical pickup changes based on the reflection signal from the optical disk. However, if the optical disk has a wavelength dependency, and if the absorptance of the laser light of the irradiating wavelength is high at that time, the optical focus signal from the optical disk is changed. Since the reflected light is reduced, the laser focus signal of the optical pickup becomes very small. Using this laser focus signal,
It is possible to determine whether an optical disk having this wavelength dependency causes data corruption in the optical disk recording / reproducing apparatus.

[0025]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an optical disk recording / reproducing apparatus according to an embodiment of the present invention.

K1 is an optical disk, which is intended for a compact disk and a high-density disk because they have the same outer diameter, thickness and chucking portion. K3 is a spindle motor for rotating the optical disk K1, and K2 is a disk chucking section for fixing the optical disk K2 to the spindle motor K3. An optical pickup unit K6 has a function of emitting laser light, a function of moving a lens to irradiate a laser beam to a target location on the optical disk K1, and a function of converting laser light reflected from the optical disk K1 into an electric signal. K7 is an RF amplifier
A small electric signal corresponding to the reflected signal from the optical disk K1 obtained by the optical pickup K6 is amplified. K8
Is an A / D converter, which converts analog data into digital data in order to take the light reflection signal obtained by the optical pickup K6 into a microcomputer. K12 is a microcomputer which receives various signal inputs, performs predetermined processing according to the signals, and comprehensively controls the spindle motor K3, the optical pickup K6 and the like based on the processing results. A lens vertical position control signal output from the microcomputer K12 for changing the position of the lens of the optical pickup K6 is converted to a DA converter K
The signal is converted into an analog signal by 9 and further amplified by a lens actuator amplifier K10 to add a control signal to an optical pickup K6. Further, in order to control the speed of the spindle motor K3, the rotation control signal output from the microcomputer K12 is converted into an analog signal by a DA converter K4, and further converted into a motor drive signal by a motor driver K11. And supplied to the spindle motor K3. K5 is a disk loading detection device that detects that there is a possibility that the optical disk K1 has been loaded. K
Reference numeral 13 denotes a display device for notifying the user of the status of the optical disk K1 and the optical disk recording / reproducing device.

FIG. 4 is a diagram showing the structure of a typical optical pickup unit. In the optical disk K1, the laser light emitted from the semiconductor laser light emitting unit P10 passes through the diffraction grating P7 and reaches the beam splitter P6. The laser beam that travels straight here passes through the lens P4 and forms a focal point at P3 on the optical disk. At this time, a magnet P5 is attached around the lens P4, and a focus coil P2 is arranged around the magnet P5. By giving a lens position control signal to the focus coil P2, the focus on the optical disk is adjusted. . The laser light reflected on the disk passes through the lens P4 again, and the beam splitter P
6, the light is reflected in the horizontal direction, passes through the concave lens P8 and the cylindrical lens P9, hits the photodetector P11, and is photoelectrically converted into an electric signal.

FIG. 5 is a diagram showing the shape of the image on the photodetector and the polarity of the focus error output when the distance between the optical disk and the lens of the optical pickup changes.

In this example, description will be made using an astigmatism method. The photodetector D1 is divided into four parts, and when a laser beam is incident on this detector, a voltage proportional to the area intensity of the incident light is output from each. The photodetector has a structure in which the shape of an image changes depending on the distance between the optical disk and the lens due to the action of the cylindrical lens in the pickup. FIG.
(A) shows a case where the distance between the optical disk and the lens is small, and the image shape is a vertically long ellipse like D2.
At this time, the output of the differential amplifier D5 is positive. On the other hand, FIG. 5C shows a case where the distance between the optical disk and the lens is large, and the shape of the image is a horizontally long ellipse as shown by D4. At this time, the output of the differential amplifier becomes negative. Further, when the distance between the optical disk and the lens is exactly in focus, the shape of the image on the detector becomes a circle like D3 as shown in FIG. 5B. At this time, the output of the differential amplifier becomes 0 because plus and minus are equal.

As described above, according to the astigmatism method, it is found that the focus error voltage output from the pickup changes by changing the distance between the optical disk and the lens.

FIG. 6 shows a change in the focus error voltage when the distance between the optical disk and the lens of the optical pickup is continuously changed. FIG. 6A shows a case where an optical disk such as a press disk which does not have wavelength dependency or a laser beam having a wavelength which has a sufficiently small absorptivity even if it has wavelength dependency is used. That is, since the reflection is sufficiently obtained from the optical disc, the laser light incident on the photodetector is strong, and the focus error signal is also a large signal. On the other hand, FIG. 6B shows a focus error signal when a laser beam having a wavelength with a large absorptance is irradiated on an optical disk having a wavelength dependency.
Most of the laser light is absorbed on the optical disk, and the amount of laser light returning to the photodetector is small, so that the focus error signal becomes small. The amplitude of the focus error signal of the write-once type compact disc having the wavelength dependence is smaller than the amplitude of the force error signal of the press disc without the wavelength dependence by using the laser beam having a short wavelength according to the present embodiment. As a result, a result of about 1/10 was obtained.

As described above, by operating the microcomputer in accordance with the flowchart of FIG. 2, even if the optical disk having a high wavelength dependence is irradiated with the laser beam having the high absorptance, the output at the normal read level is obtained. If so, it is possible to determine the optical disk without damaging the data on the optical disk.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG.

First, when an optical disk is mounted on the drive, it is determined in step F1 (hereinafter, steps are omitted) that the optical disk is inserted, and an optical disk rotation control signal is output in a maximum state in F2. Upon receiving this signal, the motor driver sets the spindle motor to the maximum rotation state. F
In 3, the time from the stop of the optical disk to the maximum rotation state is set in advance, and the elapse of the time is waited. Then, when the optical disk reaches the maximum rotation, the laser beam ON / OFF signal is given to the pickup in F4 to turn on the laser beam. In this state, in F5, the lens vertical position output signal is applied to the pickup, and the lens is repeatedly moved up and down. In addition, F6
Then, the focal point of the laser light on the optical disk is changed by moving the lens up and down, the reflected signal output from the pickup is amplified by the RF amplifier, and the change in the reflection state is observed. At this time, in the case of an optical disc having a wavelength dependency such as a write-once optical disc, most of the laser light output from the pickup is absorbed on the optical disc, and thus the reflected signal is very small. In the case of a press optical disc having no wavelength dependence, a sufficient reflection is obtained as compared with a write-once optical disc, so that a relatively large reflected signal is obtained. If the difference between the reflection signals is detected and a certain level or more can be detected, it is determined that the currently mounted optical disk is a press-type optical disk and that there is no possibility of data damage even if a short wavelength laser is irradiated. Then, the rotation of the spindle motor is turned off, and after waiting at a time F9 until the rotation of the optical disk is stopped, the operation shifts to a normal optical disk initial operation. The reason why the rotation of the optical disk is stopped in F9 is that there is a possibility that an accurate focusing operation cannot be performed due to the influence of surface deviation of the optical disk or the like.

On the other hand, if the reflected signal from the optical disk cannot be detected in F6, the operation is repeated for a specified time in F7, and if it cannot be detected, an optical disk having a wavelength dependency such as a write-once optical disk is used. Judging that it is mounted, immediately turns off the laser light output in F10, and turns off the spindle motor rotation in F11.
In step F14, the user is informed that there is a possibility of data corruption, and in step F12, the process waits until the optical disk is removed. When it is detected at F13 that the optical disk has been removed, a series of operations is terminated, and the operation returns to the operation of waiting for insertion of the optical disk at F1.

[0037]

As described above, in an optical disk recording / reproducing apparatus, conventionally, a disk having a wavelength dependence is irradiated with a laser beam having a short wavelength used for writing and reading of a high-density disk with energy at the time of reading. However, in the optical disk recording / reproducing apparatus having the optical disk discriminating means according to the present invention, the optical disk is rotated at a high speed. In order to reduce the energy of the laser light per unit area absorbed by the optical disc, it is possible to prevent data on the optical disc from being damaged, and at the same time, the energy of the laser light absorbed by the optical disc per unit time is the same as during normal reading. Measurement of the intensity of the laser beam reflected from the optical disk The Rukoto, it can be determined that an optical disk having wavelength dependence.

Therefore, the use of this discriminating means prevents the data on the optical disk having wavelength dependency from being damaged.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of an optical disk recording / reproducing apparatus of the present invention.

FIG. 2 is a flowchart for explaining an example of processing by a microcomputer of the optical disk recording / reproducing apparatus of FIG. 1;

3 is a graph showing an example of a change in an absorptance and a reflectance with respect to a change in a wavelength of an optical disc having wavelength dependency in the optical disc recording / reproducing apparatus of FIG. 1;

FIG. 4 is a structural diagram of a typical optical pickup.

FIG. 5 is a diagram for explaining a focus detection method of an optical pickup by an astigmatism method.

FIG. 6 is a diagram for explaining output of a focus error signal when the distance between the optical disk surface and the lens of the optical pickup is continuously changed.

FIG. 7 is a flowchart for explaining an example of processing by a microcomputer of a conventional optical disc reproducing apparatus.

[Explanation of symbols]

K1 optical disk K2 disk chucking unit K3 spindle motor K4 digital / analog converter K5 disk loading detector K6 optical pickup K7 RF amplifier K8 analog / digital converter K10 lens actuator amplifier K11 motor driver K12 microcomputer K13 display unit P2 focus coil P3 Laser light focus on optical disk P4 Lens P5 Magnet P6 Beam splitter P7 Diffraction grating P8 Concave lens P9 Cylindrical lens P10 Semiconductor laser light emitting unit P11 Photodetector D1 Photodetector D2 Image form when the distance between optical disk and lens is small D3 Distance between optical disk and lens Is the image shape at the time of just focus D4 The image shape D at the time when the distance between the optical disc and the lens is large D 5 Differential amplifier

Claims (3)

[Claims] After the optical disk is inserted, the optical disk is rotated at a high speed and then irradiated with a short-wavelength laser light, thereby dispersing the energy of the laser light, and the laser light irradiated per unit area on the optical disk. The energy is apparently reduced, the damage of the optical disk is prevented, and the amount of laser light reflected from the optical disk is measured to determine that the optical disk is wavelength-dependent. An optical disc recording / reproducing apparatus characterized in that the optical disc recording / reproducing apparatus is prevented. 2. A lens of an optical pickup is reciprocated in a direction perpendicular to an optical disk surface while the optical disk is rotating at a high speed.
The intensity of the laser light focus signal of the optical pickup, which changes based on the reflection signal from the optical disk, is measured, and the optical disk has a wavelength dependency and the absorptance is high at the wavelength of the laser light being irradiated, and the optical disk has a high absorption rate. An optical disc characterized in that, when there is a possibility of data corruption, it is determined whether or not the wavelength-dependent optical disc causes data corruption by using the laser beam focus signal whose signal is reduced. Recording and playback device. 3. A means for rotating a loaded optical disc having a wavelength dependence of reflectance / absorptance at a high speed, and a disc which passes through the optical disc rotating at a high speed in a direction perpendicular to the disc surface through a focusing lens. A means for irradiating a laser beam to the surface, a means for measuring the laser light reflected on the disc surface and converting the same to an electric signal, and a means for measuring the magnitude of the electric signal, wherein the laser light applied to the optical disc is provided. An optical disk recording / reproducing apparatus characterized in that the optical disk is discriminated by detecting the level of the reflected light from the optical disk without damaging the data on the optical disk by dispersing the energy of the optical disk.