JP2003016667A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk device which can read-out/write-in both DVD-RAM disk and DVD-R/RW disk without complicating the mechanism. SOLUTION: A plane of polarization of a laser beam emitted from a semiconductor laser device 31 is rotated by 90 deg. by a liquid crystal unit 34 and a hologram 35 divides the laser beam with the plane of polarization rotated by 90 deg. to three parts for differential push-pull. When the liquid crystal unit 34 is on by a switchover unit 27, however, the plane of polarization is not rotated by the liquid crystal unit 34 and the laser beam is transmitted through the hologram 35 as it is and works as the laser beam for push-pull. Thereby tracking detection is executed by switching over between a push-pull system and a differential push-pull system by making the liquid crystal unit 34 on/off corresponding to discrimination result of disk kinds.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc device for recording and reproducing data on various optical discs and reproducing data recorded on those optical discs.

[0002]

2. Description of the Related Art Conventionally, an optical disk device for recording data on an optical disk (medium) or reproducing data recorded on an optical disk is practically used by a laser beam output from a semiconductor laser oscillator mounted on an optical head. Has been converted.

As the above-mentioned optical disc, there are CD and CD-R.
A read-only type typified by OM, DVD-ROM, and DVD-video, a one-time write-once type typified by CD-R, DVD-R, and a rewritable type typified by an external memory of a computer. It is roughly divided into types. The rewritable type optical disc is an optical disc using a phase change recording film, and includes a CD-RW and a DVD-RAM disc and a DVD-R / W disc that are expected to replace the video market as a storage device of a computer. .

DVD-RA for DVD-RAM disc
Although the M drive has been on the market since 1998, reproduction of optical discs other than rewritable optical discs such as CD-ROM and CD-R is indispensable in response to user's request.

That is, a DVD for a DVD-RAM disk
-In the RAM drive, not only recording and reproduction on the DVD-RAM disk but also DVD-ROM, CD-R
Reproduction of OM, CD-R, and CD-RW is indispensable, and the technology unique to each company is adopted as a focus control method and a tracking control method for supporting various discs.

Here, Japanese Patent Laid-Open No. 11-1999 discloses that a common laser device and a photodetector are used while adopting different tracking control systems for different kinds of optical disks.
There is a device as shown in No. 66602.

That is, Japanese Patent Laid-Open No. 11-66062 discloses a magneto-optical disk (Advanced Storage Ma).
Gneto Optical, hereafter simply "ASMO"
Say. ) And DVD (Digital Versa)
The optical pickup device, which is used for reproducing the title disc, irradiates the disc with the laser beam and detects the laser beam reflected by the disc, uses a so-called DPP at the time of recording / reproducing the ASMO.
(Differential Push Pull) method for adjusting tracking, and DVD-ROM
When reproducing a so-called DPD (Differential Phase De) using only one beam spot
device for adjusting the tracking by means of the tection method.

In this device, the plane of polarization of the laser light is rotated by 90 ° by a liquid crystal shutter, and then the laser light is diffracted by using a polarization selective hologram to obtain three laser lights to generate an ASMO tracking signal. Further, when the disc is a DVD-ROM, a control voltage is applied to the liquid crystal shutter to rotate the plane of polarization of the laser light, and the polarization-selective hologram does not diffract the laser light, so that only one laser light is emitted from the disc. It is reflected and a tracking signal is generated based on the laser light.

The optimum method for detecting the tracking error signal of the DVD type disc and the CD type disc differs for each type, and for the CD type disc having a wide track interval, the three-spot method, which can easily and stably detect the signal, is advantageous. Yes, on the other hand, DVD-ROMs and DVDs with narrow track intervals
-For video discs, it is known that the phase difference method, which does not require adjustment of the diffraction direction of the light emitted from the light source, is advantageous as in the three-spot method.

In a rewritable DVD disc (which utilizes the difference in reflectance due to the phase change recording film), the pits are not formed, so the phase difference method cannot be used, and continuous recesses (grooves) are formed. Alternatively, a push-pull detection method that detects interference on both sides of the group using a groove that forms a convex portion (land), and a beam is divided into three beams by a grating or the like, one beam for each group and two beams for the land portion. The differential push-pull method that applies a difference to detect the difference is mainly used.

Among the optical disk tracking detection methods in such an optical disk drive apparatus, the push-pull method has been widely used for recording type optical disk apparatuses because it does not need to separate beams and can use laser light without waste. On the other hand, there is a tendency that an offset occurs due to the tilt of the medium or the shift of the lens, and the recorded pits are displaced from the center of the group. Therefore, it is necessary to automatically correct the offset.

On the other hand, in the differential push-pull method, the beams are divided into three beams and applied to the group and the land to generate push-pull signals having mutually opposite phases, and the difference between them is used to tilt the medium or shift the lens. While there is a merit that the offset can be reduced, there is a demerit that the power of the laser light is reduced because the beam is divided.

Of the recordable DVDs, the DVD-R
In the AM, data is written in both the land and the group, and when the differential push-pull method is used in the recording mode in which the power of the laser beam is large, the track adjacent to the track to be recorded is also irradiated with the sub-beam and recorded. The existing data may be erased or destroyed.

When the push-pull method is adopted for the DVD-R / RW, the push-pull signal is small due to the structural characteristics of the groove formed on the disc, so that the S / N ratio is small. The drive device is unavoidably affected by media tilt and lens shift, and therefore the drive device is forced to use the differential push-pull method.

In this way, a DVD-RAM disc and a D
Since the VD-R / RW disc is forced to adopt different tracking detection systems, it is difficult to realize a pickup device and a disc device satisfying both of them.

As disclosed in Japanese Patent Laid-Open No. 11-66602, there is a technique for switching between a phase difference (DPD) system and a differential push-pull (DPP) system, but as described above, a rewritable DVD is used. The system disc cannot use the phase difference method because no pits are formed, and the DVD-RAM cannot use the differential push-pull method because data is written in both the land and the group.

Therefore, at present, the DVD-RAM disk drive and the DVD-R / RW disk drive are sold as separate devices.
A user who wants to use both the VD-RAM disc and the DVD-R / RW disc has to purchase the DVD-RAM disc drive and the DVD-R / RW disc drive separately.

For DVD-RAM disc and DVD-R
/ RW discs and DVD-RAM discs and DVD-R / discs by using independent pickup heads
Although it is possible to realize an optical disc device compatible with both RW discs, as described above, DVD-
Since the RAM drive needs to reproduce not only rewritable optical disks such as CD-ROMs and CD-Rs, a large number of pickup heads must be mounted, which leads to an increase in cost and complexity of the mechanism, and an increase in the size of the device. Will be done.

Therefore, the DV can be reproduced without complicating the mechanism.
There is a demand for an optical disk device capable of reading / writing both a D-RAM disk and a DVD-R / RW disk.

[0020]

DISCLOSURE OF THE INVENTION The present invention provides an optical disk device capable of reading / writing both a DVD-RAM disk and a DVD-R / RW disk without complicating the mechanism as described above. Especially.

[0021]

Means for Solving the Problems In order to solve the above problems, the present invention uses a DVD-RAM as an optical disk loaded.
And DVD-R or DVD-RW, and the discriminating means determines that the optical disk is a DVD-
A first tracking unit that performs tracking detection by a push-pull method when it is determined to be RAM, and a differential push when the optical disc is determined to be a DVD-R or DVD-RW by the determination unit. A second tracking unit that performs tracking detection by the pull method and a switching unit that switches the number of light beams used for tracking detection according to the determination result by the determination unit are provided.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION An optical disk device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an optical disk device. This optical disk device records data on the optical disk 1 and reproduces data from the optical disk 1.

The above optical disk device can read data from not only DVD-RAM but also other DVD-ROM, DVD-video disk and CD, and CD-R, D
It is configured as a device capable of writing and rewriting data on VD-R and DVD-R / RW discs.

The optical disc 1 is a CD or CD-RO.
Reproduction-only type represented by M, DVD-ROM, DVD-video, 1-time write-once type represented by CD-R, DVD-R, first generation (Ver.1.0: 2.6 GB) DVD
-Various disks such as rewritable type represented by RAM and second generation (Ver.2.0: 4.7 GB) DVD-RAM, DVD-RW, and CD-RW are mounted (loaded). It has become.

The optical disk 1 is a disk substrate made of a transparent base material such as polycarbonate, and a reflective film or a recording film capable of recording and reproducing information is formed on the disk substrate.
These are D type discs and DVD type discs.

As shown in FIG. 1, an optical pickup head (PUH) 2 has an objective lens 3 as will be described later, and inside the optical pickup 2, a semiconductor laser unit for DVD system and CD system. (Not shown) is provided, and one of the semiconductor laser units is selected according to whether the loaded optical disc 1 is a DVD disc or a CD disc and is energized by the laser control unit 4 to emit a laser beam having a corresponding wavelength. To occur.

When either the DVD or CD semiconductor laser unit is selected and activated, the optical disc 1 is activated.
The laser beam corresponding to is focused on the optical disc 1 by the objective lens 3. Data is written on or reproduced from the optical disc 1 by the converged laser beam.

The laser control unit 5 has its settings set by the DVD data processing unit 5. The settings are a reproduction mode for obtaining a reproduction signal, a recording mode for recording data, an erasing mode for erasing data, and a DV.
The DVD mode in which data processing is performed on a D disc and the CD mode in which data processing is performed on a CD disc are different.

That is, in the DVD mode, the semiconductor laser unit for DVD is selected and activated, and in the CD mode, the semiconductor laser unit for CD is selected and activated. The laser beam for DVD or CD is
The laser control unit 4 energizes the semiconductor laser unit so as to generate laser beams having different power levels in the three modes of the reproduction mode, the recording mode and the erasing mode, and having the power levels corresponding to the modes. .

The DVD disk or the CD disk is carried directly or in the disk cartridge 1a and carried by the tray 7 into the apparatus so that the DVD disk or the CD disk is arranged facing the objective lens. Tray motor 7 for driving this tray 7
Is provided in the device. The loaded DVD disk or CD disk is rotatably held on the spindle motor 10 by the stamper 8 and is rotated by the spindle motor 9.

An encoder 9a is provided on the rotary shaft of the spindle motor 9. The encoder 9a is composed of a disk provided with a slit and a detector which is turned on and off by the slit, and outputs a pulse based on the rotation of the spindle motor 9. The output from the encoder 9a is output to a spindle motor control circuit (not shown) in the DVD data processing unit 5 and used for rotation control of the spindle motor 9.

The optical pickup 2, as shown in FIG.
The optical disc 1 is placed on a feed mechanism 11 driven by a feed motor 10 and moved by the feed mechanism 11 in the radial direction of the optical disc 1.

The optical pickup 2 has a photodetector (described later) for detecting a laser beam therein. This photodetector detects the laser beam reflected by the optical disc 1 and returned via the objective lens 3.

The detection signal (current signal) from the photodetector is
It is converted into a voltage signal by the current / voltage converter (I / V) 12, and this signal is converted into a reference amplifier (RF amplifier) 1
3 and the servo amplifier 14. The reference amplifier 13 outputs to the DVD data processing unit 6 a tracking error signal for reproducing the data of the header portion described later and an addition signal used for reproducing the data of the recording area. Further, from the reference amplifier 13, an addition signal as an RF signal indicating the level of the reflected light amount from the optical disc 1 is sent to the CD servo seek control and the CD
It is output to the data processing unit 16. Servo amplifier 1
The servo signals (track error signal, focus signal) from 4 are output to the DVD servo seek control unit 15 in the DVD mode and to the CD servo seek control and CD data processing unit 16 in the CD mode.

As an optical method for detecting the focus shift amount, either the astigmatism method or the knife edge method is usually adopted.

The optical disc 1 has spiral or concentric circular tracks, and information is recorded on the tracks.
Information is reproduced or recorded / erased by tracing a focused spot along this track. In order to stably trace the focused spot along the track, it is necessary to optically detect the relative displacement between the track and the focused spot.

Generally, as a method for detecting the track deviation, a phase difference detection (Differential Phase D) is performed.
detection method, push-pull (Push-Pu)
11) method and Twin-Spot method, and either method is adopted.

In the DVD mode, the optical disk device is D
A focus signal, a tracking signal and a feed signal are sent from the VD servo seek control unit 15 to a focus and tracking actuator driver and a feed motor driver 17, and the objective lenses 3 and 4 are subjected to focus servo control by the driver 17 and tracking servo control. To be done. Further, focusing is performed by adjusting the focus gain and the like based on the focus signal.

Further, the reflectance of the optical disk 1 is estimated from the level of the focus signal (supplied to the CPU 25 via the DVD servo seek control unit 15 or the CD servo seek control and CD data processing unit 16). The gain of the full addition signal, that is, the RF signal is determined. That is, the RF signal output from the I / V 12 is generated through the RF amplifier 13 as an RF signal adjusted to a constant level regardless of the reflectance of the optical disc 1.

Further, the driver 17 is responsive to the access signal.
Is supplied to the feed motor 11 to control the conveyance of the optical pickup 2.

This DVD servo seek control unit 15
Are controlled by the DVD data processing unit 6.
For example, an access signal is supplied from the DVD data processing unit 6 to the DVD servo seek control unit 15 to generate a feed signal.

Further, the spindle motor driver 18 and the tray motor driver 19 are controlled by the control signal from the DVD data processing unit 6, the spindle motor 10 and the tray motor 8 are energized, and the spindle motor 10 is rotated at a predetermined rotation speed. The tray motor 8 appropriately controls the tray.

The reproduction signal corresponding to the data of the header portion supplied to the DVD data processing unit 6 is a CP which will be described later.
Supplied to U25. As a result, the CPU 25
A sector number as an address of the header portion is judged from the reproduced signal and compared with a sector number as an address to access (record data or reproduce recorded data).

As for the reproduction signal corresponding to the data in the recording area supplied to the DVD data processing unit 6, necessary data is stored in the RAM 20, and the reproduction signal is processed by the DVD data processing unit 6 and the RAM 2 as a buffer.
SCSI interface controller and CD-
The reproduction processing signal is supplied to the ROM decoder 22 and is supplied to another device such as a personal computer via SCSI.

In the CD mode, the focus signal from the CD servo seek control and CD data processing unit 16,
The tracking signal and the feed signal are sent to the focus and tracking actuator driver and the feed motor driver 17, and the driver 17 subjects the objective lenses 3 and 4 to focus servo control and tracking servo control.

Further, the driver 17 is responsive to the access signal.
Is supplied to the feed motor 11 to control the conveyance of the optical pickup 2. The spindle motor driver 18 and the tray motor driver 19 are controlled by the CD servo seek control and the control signal from the CD data processing unit 16.
Is controlled, the spindle motor 10 is energized, and the spindle motor 10 is rotated at a predetermined rotation speed.
The reproduction signal supplied to the CD data processing unit 16 is
The data is processed by the processing unit 16 and output through the CD data output amplifier 23.

Each unit shown in FIG. 1 is controlled by the CPU 25 in accordance with the procedure stored in the ROM 24. RA
M26 is used as a memory of the CPU 25.

The ROM 24 is provided with a disc characteristic table storing the characteristic of each optical disc 1 for discriminating the type of the mounted optical disc 1 and controlling based on the discrimination result. There is. In this disc characteristic table, as characteristics of each optical disc 1, the reflectance, the wavelength of the beam, the light amount of the beam, the presence / absence of the header portion (pre-pit), the direction of the header signal (relative to Iot), the innermost zone The number of header parts (sectors) of one track (one round) in the (lead-in area 42) is registered. The optical disk device shown in FIG. 1 has a switching unit 27 for switching between the push-pull system and the differential push-pull system.

FIG. 2 shows a DVD-ROM and a DVD-RAM.
The outline of the lead-in area in the recording format of FIG. The recording formats of DVD-R and DVD-RW are almost the same as those of DVD-RAM.

As shown in FIG. 2, at the start position of the lead-in belonging to the non-rewritable embossed data zone of the DVD-ROM, a code meaning a blank (for example, 0
0H) is set in the initial zone.

The initial zone, which is the lead-in start position of the DVD-RAM, is an undefined area which may or may not have a code indicating blank.

B at a position overlapping with the above-mentioned initial zone
CA (Burst Cutting Area) -Cod
The area e is arranged. Here, the DVD-RAM disc is a BCA (Burst) disc when the disc-recording company makes the unrecorded disc in the physical standard of the DVD-RAM.
Cutting Area) -It is specified that Code can be recorded. This BCA-Code has a maximum of 18
It has an 8-byte data area and each disc is recorded so as to have a unique value. For example, a DVD-RAM
The BCA Code of the disc can be used as a unique serial number.

When reading the BCA data of this DVD-RAM disc, a unique servo system is required for BCA read, and the data in the BCA cannot be read by the focus / track servo when reading the data of the DVD-ROM. .

Radial position 2 of the disc outside the BCA
DVD-RO between 3.5mm and 23.996mm
The M, DVD-R, DVD-RW, and DVD-RAM are each provided with an embossed data zone in which control data is recorded. DVD-R, DVD-RW and DVD-RAM
In both cases, the radius of the disk is 23.5 mm to 23.996 mm
The recording method of the physical signal between them is the same embossed data zone as the DVD-ROM.

In the case of a DVD-ROM, a blank zone and a data area are arranged following the embossed data zone, and in the case of a DVD-RAM, a mirror data zone and a rewritable data zone are arranged subsequently to the embossed data zone. There is.

In the case of a DVD-RAM or the like, a rewritable data zone in the lead-in area is followed by a write-once or rewritable data zone as a user area, and a lead-out area is placed at the outermost periphery of each disc. Has been done.

In the control data zone of the embossed data zone, the type of DVD standard (DVD
-ROM, DVD-RAM, DVD-R, DVD-RW
Etc.) and part version, disc size and minimum read rate, disc structure (1 layer ROM disc. 1
Layer RAM disk, dual layer ROM / RAM disk, etc.),
Recording density, data area allocation, descriptor of burst cutting area, linear velocity condition for designating exposure amount at the time of recording, read power, peak power, bias power, information on medium manufacturing, etc. are recorded.

In other words, in this control data zone, information about the entire information storage medium such as the physical sector number indicating the recording start / recording end position and the recording power,
Information such as recording pulse width, erasing power, reproducing power, linear velocity at the time of recording / erasing, information on recording / reproducing / erasing characteristics, information on manufacturing of information storage medium such as serial number of individual disk, etc. It is recorded.

In the above rewritable data zone,
It includes a recording / reproducing area in which recording / reproducing can be performed by laser light and a reproduction-only area (header section) in which recording / reproducing is not possible by laser light. One recording / reproducing area and one reproducing-only area are paired to form a unit called a sector.

Therefore, by reading the data in these control data zones, the disk loaded in the optical disk device can be read as a DVD-ROM, a DVD-RAM, or a DVD-ROM.
It is possible to reliably identify whether it is R or DVD-RW. Also, recording / reproducing processing can be performed according to the characteristics of each medium.

DVD, DVD-RAM disk, DVD-R disk, D
As described above, the VD-RW disc has the lead-in area at the innermost circumference, the lead-out area at the outermost circumference, and the data area therebetween. In the lead-in area, a reference signal necessary for stabilizing the servo when the optical pickup is accessed, an identification signal with other media, etc. are recorded. In the lead-out area, the same reference signal as in the lead-in area is recorded. The data area is divided into sectors, which are the smallest access unit.

In the DVD-RAM disk, one sector consists of a pit row portion formed on the surface of a reflective film such as a metal thin film and an uneven portion. The pit row portion is composed of pits of 0.4 μm to 1.87 μm engraved to represent the sector address. The concavo-convex shape portion includes a concave portion (called a groove) and a convex portion (called a land), and the land and the groove are alternately formed.

A metal thin film capable of phase change is attached to the surface of each of the land and the groove. The phase change means that the state of the adhered metal thin film changes to a crystalline state and an amorphous state by irradiation with a light beam. Data can be written and rewritten in the lands and grooves by utilizing the phase change.

In the case of a DVD-RW disc, a metal thin film capable of phase change is attached to the surface of the groove, and only the groove can use the phase change to write data. In the case of a DVD-R disc, a highly sensitive organic dye film is formed on the surface of the groove, and only the groove can use the change of the dye to write data only once.

The optical pickup head 2 of the optical disk device is a CD / DVD compatible optical head, and this optical head includes a laser and an objective lens for recording / reproducing to / from a DVD, and a laser and objective for recording / reproducing to / from a CD medium. In the case of a two-lens / two-laser optical head having a lens, any one-lens / two-laser optical head having a laser and a common objective lens for reproducing CD and DVD media may be used.

The present invention realizes switching between the push-pull system and the differential push-pull system by switching the number of beams according to the type of media while using a common optical pickup head.

The structure of the optical pickup head 2 according to the first embodiment of the present invention will be described below with reference to FIGS. 3 and 4. The one shown in FIGS. 3 and 4 has two lenses /
This is a part of the two-laser optical head for recording / reproducing on / from DVD. A laser and an objective lens for recording / reproducing on / from a CD medium are not shown.

As shown in FIGS. 3 and 4, the semiconductor laser device 31 emits a laser beam for recording / reproducing to / from a DVD, and the laser beam emitted from the semiconductor laser device 31 is reflected by the half mirror 32. The light is converted into parallel light by the collimator lens 33.

The light beam collimated by the collimator lens 33 is transmitted through the liquid crystal panel 34 as a liquid crystal element, the polarization hologram 35, and the quarter-wave plate 36 to the prism 3.
7, the optical axis thereof is bent by 90 degrees, reaches the objective lens 3, and is focused on the optical disc 1 by the objective lens 3.

The light beam reflected by the optical disk 1 is the objective lens 3, the prism 37, and the quarter-wave plate 3/4.
6, the polarization hologram 35, the liquid crystal panel 34, and the collimator lens 33 to reach the photodetector 38.
A signal corresponding to the intensity of the light beam received by 8 is output.

In FIG. 3, 39 is a hologram, and 40 is a second photodetector. When detecting focus detection and tracking detection by separate detectors, the photodetector 38 detects focus detection. The performed hologram 39 is used to form an astigmatism image for focus detection. Further, the hologram 39 reflects the reflected light from the disk to form an image for tracking detection by the second photodetector 40.

Whether the focus detection and the tracking detection are detected by the common detector or the individual detectors can be appropriately selected. In the following description, the focus detection and the tracking detection are performed by the photodetector 38. Will be described.

The liquid crystal panel 34 has a structure in which TN type liquid crystal is sandwiched between two glass substrates with transparent electrodes in the optical axis direction, and when the control voltage is OFF, the polarization plane of the incident laser light is 90 degrees. Output after being rotated. Further, when the control voltage of the liquid crystal panel 34 is turned on, the incident laser light is transmitted as it is without rotating the polarization plane. The control voltage of the liquid crystal panel 34 is the switching unit 27.
Is turned on / off by.

The polarization hologram 35 functions as a hologram only for light of a predetermined polarization direction. For example, only when S-polarized light is incident, the light is divided into three and divided into a group / land of the disc. The grating is designed to shoot.

Here, the operation principle of the liquid crystal panel 34 and the polarization hologram 35 will be described with reference to FIGS. As described above, the liquid crystal panel 34 can change the polarization direction of the incident laser light by 90 degrees by turning it on and off. Further, the polarization hologram 35 functions as a hologram only for the light of the designated polarization direction.

As shown in FIG. 5, when the control voltage of the liquid crystal panel 34 is OFF, the S-polarized laser light incident on the liquid crystal panel 34 is output as P-polarized light with its polarization plane rotated by 90 °. Since the polarization hologram 35 functions as a hologram for only S-polarized light, the incident P-polarized laser light is transmitted as it is and is condensed by the objective lens 3 to form one beam spot. Irradiated on the disk, the photodetector 38 serves as a means for obtaining a tracking error signal by the push-pull method. This mode is used when recording or reproducing DVD-RAM.

FIG. 6 shows the beam spot position on the disk and the detection state by the photodetector 38 in the state shown in FIG. As shown in FIG. 6, the photodetector 38 includes four-division photodiodes a, b, c, d for the main beam (one beam) and side (sub) beams arranged on the side thereof. Photodiodes e, f, g, h
It is composed of.

As shown in FIG. 6, when one beam spot focused by the objective lens 3 is applied to the center of the track on the disc, the reflected light from the disc is 4
Images of the upper and lower sides (in FIG. 6) are formed on the divided photodiodes a, b, c, d. Therefore, among the detection signals of the four-division photodiodes a, b, c, d, (a +
A tracking error signal can be obtained from the difference signal between d) and (b + c). Further, the sum of the detection signals of the four-division photodiodes a, b, c, d becomes the reproduction signal.

In the push-pull method, it is not always 4
It is not necessary to use the divided photodiodes, and the photodiodes a and d and the photodiodes b and c may be formed as one. However, when the DPD method is used together or when the astigmatism method is used for focus error detection, a four-division photodiode is used for the main beam.

When a DPD method is applied to a DVD-ROM or a DVD video disk, (a +) is included in each detection signal of the four-division photodiodes a, b, c, d.
A tracking error signal can be obtained from the difference signal between b) and (c + d).

On the other hand, when the control voltage of the liquid crystal panel 34 is ON, the S-polarized laser light incident on the liquid crystal panel 34 is transmitted as it is without rotating the polarization plane as shown in FIG. Since 35 functions as a hologram for only S-polarized light, the incident S-polarized laser light is divided into three and condensed by the objective lens 3, and the groove on the disc and both sides The three spots on the land are irradiated with spots, and the photodetector 38 serves as a detection unit for obtaining a tracking error signal by the differential push-pull method. DVD
This mode is used when recording or reproducing -R and DVD-RW.

FIG. 8 shows the beam spot position on the disk and the detection state by the photodetector 38 in the operating state of FIG.

As shown in FIG. 8, when one beam spot focused by the objective lens 3 is applied to the center of the groove track on the disc, the reflected light from the disc is divided into four-piece photodiodes a, b, and An image of the upper and lower sides (in FIG. 8) is formed on c and d, and upper and lower sides (in FIG. 8) on the four-divided photodiodes e and f, g and h.
Form an image of the object.

Therefore, when the DPP method is used, [(a + b)-(c +
d)]-k [(ef)-(g-h)] can be calculated to obtain the tracking error signal with the offset component canceled.

Next, the operation of the optical disk device will be described with reference to FIG.

First, the tray motor 7 is controlled by the main controller 25.
When the disk 1 is loaded into the disk device by driving, the main controller 25 drives the spindle motor 9 via the motor driver 18 to rotate the disk 1 at a predetermined speed (ST1).

Next, the main controller 25 turns on the focus servo (ST2), and then the feed motor driver 1
The feed motor 11 is driven via 7 to move the optical pickup head 2 from the initial position to a predetermined radial position on the disk (ST3). This moving position is a radial position near the lead-in area (outside at the radial position) of the DVD disc.

Then, the main control section 25 includes a switching unit 27.
Then, the liquid crystal panel 34 in the optical pickup head 2 is turned on (ST4), and the generation of the tracking error signal is set to the differential push-pull mode (ST5).

In the DVD data processing unit 5, the laser control unit 4 causes the semiconductor laser device 31 in the PUH 2 to have the lowest power (or each level in the recording mode of various media) among the levels in the reproducing mode of various media. It is set to generate a laser beam with a low level of reproduction power). That is, DVD-
In the RAM, when the differential push-pull method is adopted and the high power is used, the side beam may erase the recorded data, so that the recorded data of the DVD-RAM is not erased. It is set to generate a laser beam with power.

The optical pickup head 2 is located in the vicinity of the lead-in area of the DVD disc and reads the control information recorded in the lead-in area (S
T6). If the control information cannot be read, the optical pickup head 2 is moved to the inner circumference side of the disk (ST7), and the control information is read repeatedly.

When the control information recorded in the lead-in area of the DVD type disc is read, the CPU 25 determines that the loaded disc is a DVD-ROM, a DVD video or a DVD-RA based on the disc type information in the control information.
It is determined whether the disc is an M, a DVD-R, or a DVD-RW disc.

The loaded disc is a DVD.
-If it is determined to be RAM (ST8), the main control unit 25 turns off the liquid crystal panel 34 in the optical pickup head 2 via the switching unit 27 (ST9), and generates the tracking error signal by the push-pull method. The mode is set (ST10).

The main control section 25 is a DVD-RAM.
Processing such as reproduction, recording, or erasing is performed (S
T11). Here, the laser beam for the DVD-RAM needs different levels of power in the three modes of the reproduction mode, the recording mode and the erasing mode. Therefore, based on the disc characteristic table stored in the ROM 24 and the characteristic data in the control information read from the disc, laser control is performed so that the semiconductor laser device 31 generates a laser beam having a power corresponding to each mode. Energized by unit 4.

On the other hand, the loaded disc is a DVD-
When it is determined to be R / RW (ST12), the main controller 25 does not change the liquid crystal panel 34 in the optical pickup head 2 and keeps the tracking error signal generation in the differential push-pull mode. (ST13).

The main control section 25 performs processing such as reproduction, recording, or erasing on the DVD-R / RW (ST1
4). Here, the laser beam for DVD-R / RW is
Different levels of power are required for the three modes of reproduction mode, recording mode and erasing mode. Therefore, based on the disc characteristic table stored in the ROM 24 and the characteristic data in the control information read from the disc, laser control is performed so that the semiconductor laser device 31 generates a laser beam having a power corresponding to each mode. Energized by unit 4.

When it is not determined that the DVD-RAM or the DVD-R / RW is selected, the main control unit 25 sets the P
The UH2 is switched to the CD system and the CD servo control unit 16 operates the focus control system and the tracking control system for the CD. Then, the control information recorded in the lead-in area of the disc is read, and it is determined whether the loaded disc is a CD, a CD-R, or a CD-RW (ST15).

When it is determined that the loaded disc is any one of the CD type discs, the main control unit 25 reproduces the CD, CD-R /
Processing such as reproduction, recording, or erasing for the RW is performed (ST16).

Similarly, the laser beam for CD has different levels of power in the three modes of the reproducing mode, the recording mode and the erasing mode, and the semiconductor laser is generated so that the laser beam of the power corresponding to the mode is generated. The laser unit is activated by the laser control unit 4.

When it is not possible to determine whether the loaded disc is a DVD type disc or a CD type disc, the main controller 25 drives the tray motor 7 to drive the tray motor 7 because the optical disc device cannot process. The disc 1 is ejected from the disc and the process is completed (ST1
6). In addition, when the eject button is pressed after the processing such as reproduction, recording, or erasing on the optical disk is finished, the main controller 25 similarly drives the tray motor 7 to eject the disk 1 from the disk device, and the processing is performed. When playing back various optical discs as described above,
The disc drive device has to determine what kind of optical disc is mounted. As a method for discriminating an optical disc, a method for comparing and discriminating the reflectance level of an RF signal (Japanese Patent Laid-Open No. 11-7710, etc.) and a method for judging from the level of a focus error signal (Japanese Patent Laid-Open No. 10-
340526, etc.), and a method of judging from the amplitude of the tracking error signal (Japanese Patent Laid-Open No. 10-334574).

CD, CD-ROM, DVD-ROM, D
Since an optical disk as VD-video has a high reflectance due to the formation of an AI film, it is possible to distinguish it from a DVD-RAM disk from this reflectance, but DV
When the reflectance is low and similar, such as a D-RAM, DVD-R, and DVD-RW disc, it is difficult to determine the optical disc type.

Therefore, in this embodiment, by reading the control information recorded in the lead-in area of the disc, the DVD-ROM, the DVD video, and the DVD-RA are read.
It is determined whether the disc is an M, DVD-R, DVD-RW disc or a CD disc.

In the operation procedure of the optical disc apparatus shown in FIG. 9, the optical pickup head 2 is positioned at a radial position outside the lead-in area of the DVD disc and reading is started by the differential push-pull method. It is not limited to this.

That is, reading may be started by the differential push-pull method. The operation procedure in this case will be described with reference to FIG.

First, the main controller 25 drives the tray motor 7 to load the disk 1 in the disk device, and then drives the spindle motor 9 via the motor driver 18 to rotate the disk 1 at a predetermined speed. Drive (ST2
1).

Subsequently, the main controller 25 turns on the focus servo (ST22), drives the feed motor 11 via the feed motor driver 17, and moves the optical pickup head 2 from the initial position to a predetermined radial position on the disk. (ST23). This moving position is a radial position near the lead-in area (outside at the radial position) of the DVD disc.

Then, the tracking control by the push-pull method is turned on (ST24). The optical pickup head 2 is located near the lead-in area of the DVD disc, and reads the control information recorded in the lead-in area (ST25). If the control information cannot be read or the tracking error signal is not obtained (DVD-R / RW), the optical pickup head 2 is moved to the inner circumference side of the disc (ST.
26) The reading of control information is repeated.

When the control information recorded in the lead-in area of the DVD type disc is read, the CPU 25 determines that the loaded disc is a DVD-ROM, a DVD video or a DVD-RA based on the disc type information in the control information.
It is determined whether the disc is an M, a DVD-R, or a DVD-RW disc.

Then, the loaded disc is a DVD.
-If it is determined to be a RAM (ST27), the main control unit 25 performs processing such as reproduction, recording, or erasing on the DVD-RAM (ST28). Where DVD
-The laser beam for RAM requires different levels of power in the three modes of reproduction mode, recording mode and erasing mode. Therefore, based on the disc characteristic table stored in the ROM 24 and the characteristic data in the control information read from the disc, laser control is performed so that the semiconductor laser device 31 generates a laser beam having a power corresponding to each mode. Energized by unit 4.

On the other hand, the loaded disc is a DVD-
When it is determined to be R / RW (ST29), the main controller 25 turns on the liquid crystal panel 34 in the optical pickup head 2 (ST30) and maintains the differential push-pull mode for the generation of the tracking error signal. (ST31).

Then, the main control section 25 uses the DVD-R / R
Processing such as reproduction, recording, or deletion of W is performed (ST32). Here, the laser beam for DVD-R / RW needs different levels of power in the three modes of the reproduction mode, the recording mode, and the erasing mode. Therefore, based on the disc characteristic table stored in the ROM 24 and the characteristic data in the control information read from the disc, laser control is performed so that the semiconductor laser device 31 generates a laser beam having a power corresponding to each mode. Energized by unit 4.

The loaded disk is a DVD-RAM, DVD
-If it is not determined to be either R / RW,
The main control unit 25 switches the PUH2 for the CD system,
The CD servo control unit 16 operates the focus control method and tracking control method for CD. Then, the control information recorded in the lead-in area of the disc is read, and the loaded disc is CD, CD-
It is determined whether the disc is an R disc or a CD-RW disc (ST33).

When it is determined that the loaded disc is any one of the CD type discs, the main control unit 25 reproduces the CD, CD-R /
Processing such as reproduction, recording, or deletion of the RW is performed (ST34). The laser beam for CD is in the playback mode,
The semiconductor laser unit is energized by the laser control unit 4 so that a laser beam having a power corresponding to the three modes of the recording mode and the erasing mode is generated.

When it is not possible to determine whether the loaded disc is a DVD type disc or a CD type disc, or when processing such as reproduction, recording, or erasing of the optical disc is completed, the eject button is pressed. If
The main controller 25 drives the tray motor 7 to eject the disc 1 from the disc device, and ends the process.

When writing is performed in the DVD-RAM by using the differential push-pull method, data is recorded in both the groove and the land in the DVD-RAM, and the power of the laser beam at the time of writing is at the time of reading. Since it is larger than the above, there is a possibility that the side beam erases the recorded data on the track adjacent to the track to be originally written. Also, D
In the VD-R / RW, when the push-pull method is adopted, the S / N ratio is bad and the offset is greatly affected, resulting in a large tracking shift. However, as in the first embodiment, the media type is different. By switching to the optimum tracking detection method according to the above, these problems can be solved and the DVD-RAM can be realized without complicating the mechanism.
It is possible to provide an optical disc device capable of reading / writing both discs and DVD-R / RW discs.

Further, since the liquid crystal element panel 34 and the polarization hologram 35 are used, the tracking detection method can be switched quickly without causing an optical deviation.

In the above-described first embodiment, the polarization hologram 35 is shown to function as a hologram with S polarization, but it may also function with P polarization. In that case, the operating mode is opposite to that described above.

That is, as shown in FIG. 10, the liquid crystal panel 3
When the control voltage of 4 is ON, the light beam is not divided and the tracking error signal is obtained by the push-pull method.
As shown in FIG. 11, the control voltage of the liquid crystal panel 34 is OF
In the case of F, the light beam is divided into three, and the tracking error signal is obtained by the differential push-pull method.

Furthermore, although an example in which S-polarized light is incident on the liquid crystal element has been shown above, it may be set so that P-polarized light is incident. In that case, the operating mode is opposite to that described above.

In the above embodiment, the number of beams is switched by the combination of the liquid crystal panel 34 and the polarization hologram 35. However, in the second embodiment, the number of beams can be switched by inserting / removing a grating element. Similar functions can be achieved.

That is, in the second embodiment, FIG. 11 and FIG.
2, the liquid crystal panel 34 and the polarization hologram 35
Instead, the plate 42 having the grating element 41 mounted thereon is slidably supported by the slide shaft 43 in the direction orthogonal to the optical axis of the light beam in the direction of the arrow in the figure. A driving means 44 such as an electromagnet is arranged near the plate 42, and the driving means 44 is turned on / off to move the grating element 41 in and out of the optical axis of the light beam.

Since the grating element 41 is provided with a grating so as to divide the light beam into three, when the grating element 41 is located on the optical axis of the light beam, a tracking error signal is generated by the differential push-pull method. In addition, when the grating element 41 is retracted from the optical axis of the light beam, the tracking error signal can be obtained by the push-pull method.

In the first embodiment described above, the DVD type optical head and the CD type optical head are independent, but as in the third embodiment shown in FIGS. 15 and 16,
It is also possible to use an optical head in which both the DVD system and the CD system serve as the optical system.

That is, in the third embodiment shown in FIGS. 15 and 16, the optical system is the same as in FIGS. 3 and 4, and the same parts are designated by the same reference numerals, and the description thereof will be omitted. However, by using the integrated optical unit 51 for DVD and the integrated optical unit 52 for CD,
The system can also serve as an optical system.

As shown in FIG. 16, the integrated optical unit 51 for DVD receives the reflected light from the disc returned through the laser element 51a for emitting the laser beam of 650 nm for DVD, the objective lens and the optical system. The light receiving element 51b for diffracting the reflected light from the disc and the light receiving element 5
It has a hologram 51c leading to 1b. Laser element 5
The laser light emitted from 1a passes through the half mirror 32 and is converted into parallel light by the collimator lens 33.
The prism 37 is reached through the liquid crystal panel 34, the polarization hologram 35, and the quarter-wave plate 36, where the optical axis is set to 90 °.
The objective lens 3 is bent and reaches the objective lens 3,
Is focused on the optical disc 1.

The light beam reflected by the optical disk 1 is the objective lens 3, the prism 37, and the quarter-wave plate 3/4.
6, the hologram 51 via the polarization hologram 35, the liquid crystal panel 34, the collimator lens 33, and the half mirror 32.
After reaching c, it is diffracted by the hologram 51c and received by the light receiving element 51b, and a signal corresponding to the intensity of the light beam is output.

Further, in the integrated optical unit 52 for CD,
A laser element 52a that emits a 780 nm laser beam for a CD, a light receiving element 52b that receives reflected light from the disc returned via an objective lens and an optical system, and a reflected light from the disc that is diffracted and guided to the light receiving element 52b. It has a hologram 52c.

The laser light emitted from the laser element 52a is reflected by the half mirror 32, converted into parallel light by the collimator lens 33, and reaches the prism 37 via the liquid crystal panel 34, the polarization hologram 35, and the quarter-wave plate 36. Then, the optical axis thereof is bent by 90 degrees, reaches the objective lens 3, and is focused on the optical disc 1 by the objective lens 3.

The light beam reflected by the optical disk 1 is the objective lens 3, the prism 37, and the quarter-wave plate 3/4.
6, the hologram 52 through the polarization hologram 35, the liquid crystal panel 34, the collimator lens 33, and the half mirror 32.
After reaching c, it is diffracted by the hologram 52c and received by the light receiving element 52b, and a signal corresponding to the intensity of the light beam is output.

The polarization hologram 35 has a 780 nm CD.
The laser light for DVD and the laser light for DVD of 650 nm pass through, but the laser light for DVD of 650 nm wavelength functions as a hologram for the light having a predetermined polarization direction, and the light is divided into three to make a group / land of the disk. Has been given a grating to hit the.

The operation procedure and circuit block in the third embodiment are the same as those in the first embodiment described with reference to FIGS. 1 and 5 to 10.
The description thereof is omitted because it is exactly the same as that of the first embodiment, but the liquid crystal panel 34 is turned on / off as in the first embodiment.
By turning off, it becomes possible to switch between the push-pull method and the differential push-pull method.

In the third embodiment, the liquid crystal panel 34 is used.
The configuration is such that the number of beams is switched by the combination of the above and the polarization hologram 35, but the same function can be achieved by switching by switching the element with the grating in and out as in the second embodiment. .

That is, in the fourth embodiment shown in FIG.
Instead of the liquid crystal panel 34 and the polarization hologram 35, a plate 61 having a grating element 60 mounted thereon is slidably supported by a slide shaft or the like in the direction orthogonal to the optical axis of the light beam in the direction of the arrow in the figure. Then, driving means 44 such as an electromagnet is arranged in the vicinity of the plate 61, and the driving means 44 is turned on / off to move the grating element 41 in and out of the optical axis of the light beam.

Since the grating element 60 is provided with a grating so that the light beam is divided into three parts, when the grating element 60 is located on the optical axis of the light beam (the solid line position in FIG. 17), the differential push is performed. The tracking error signal can be obtained by the pull method, and the tracking error signal can be obtained by the push-pull method when the grating element 60 is retracted from the optical axis of the light beam (the position of the dotted line in FIG. 17).

The second to fourth embodiments described above all have the same effects as the first embodiment. The third embodiment and the fourth embodiment are DVD-based and CD-based. Since the optical system is also used, the pickup head can be downsized and the push-pull method and the differential push-pull method can be switched.

According to the respective embodiments of the present invention described above, it is possible to switch between the push-pull system and the differential push-pull system without complicating the mechanism, and as a result, the DVD-RAM disc and the DVD-RAM disc can be switched. R
It is possible to provide an optical disk device capable of reading / writing both of the / RW disk.

[0137]

As described above, according to the present invention, a DVD-RAM disk and a DVD-RAM disk can be used without complicating the mechanism.
It is possible to provide an optical disc device capable of reading / writing both R / RW discs.

[Brief description of drawings]

FIG. 1 is a block diagram of an optical disk device according to a first embodiment.

FIG. 2 is a diagram showing a recording format of a DVD disc.

FIG. 3 is a perspective view showing a pickup device according to the first embodiment.

4 is a plan view of the pickup device shown in FIG.

FIG. 5 is a plan view for explaining the principle of switching the tracking method.

FIG. 6 is a plan view for explaining the principle of tracking method switching.

FIG. 7 is a diagram for explaining a tracking detection operation by a push-pull method.

FIG. 8 is a diagram for explaining a tracking detection operation in the differential push-pull method.

FIG. 9 is a flowchart for explaining an operation procedure according to the first embodiment.

FIG. 10 is a flowchart for explaining another operation procedure according to the first embodiment.

FIG. 11 is a plan view for explaining a modification example of the switching principle of the tracking method.

FIG. 12 is a plan view for explaining a modification example of the switching principle of the tracking method.

FIG. 13 is a perspective view showing a pickup device according to a second embodiment.

FIG. 14 is a plan view showing a pickup device according to a second embodiment.

FIG. 15 is a perspective view showing a pickup device according to a third embodiment.

FIG. 16 is a plan view showing a pickup device according to a third embodiment.

FIG. 17 is a plan view showing a pickup device according to a fourth embodiment.

[Explanation of symbols]

2 ... Pickup head 3 ... Objective lens 27 ... Switching unit 31 ... Semiconductor laser device 34 ... Liquid crystal unit 35 ... Hologram 38 ... Photodetector

Continued front page    F term (reference) 5D090 AA01 CC18 DD01 HH01 JJ11                 5D118 AA26 BA01 BF06 CA22 CA24                       CD03 CF03 CF14 CG02 CG04                       CG14 CG24 CG33 CG44 DA33                       DA35 DA43                 5D119 AA41 BA01 CA16 EA02 EB13                       EC45 EC48 HA21 HA65 JA23                       JA30

Claims (8)

[Claims] 1. An optical disk device for irradiating an optical disk with a light beam to record or read data, wherein the loaded optical disk is a DVD-RAM or a DVD.
-R or DVD-RW discriminating means, and first discriminating means for performing tracking detection by the push-pull method when the discriminating means discriminates that the optical disk is a DVD-RAM. The disc is DVD-R or DV by the discriminating means.
The second that performs tracking detection by the differential push-pull method when it is determined to be D-RW
The optical disc device, comprising: the tracking means and the switching means for switching the number of light beams used for tracking detection according to the discrimination result by the discrimination means. 2. The optical disk device according to claim 1, wherein the switching means divides the beam emitted from the semiconductor laser device into three parts, and a liquid crystal element provided between the polarization hologram and the semiconductor laser device. And an optical disk device characterized in that the number of beams emitted from the polarization hologram is switched by turning on / off the function of the liquid crystal element. 3. The optical disk device according to claim 2, wherein when the liquid crystal element is in an OFF state, the beam emitted from the semiconductor laser device is converted into a beam by a polarization hologram.
An optical disk device for converting a polarized beam into split beams, which is configured not to split the beam when the liquid crystal element is turned on. 4. The liquid crystal device according to claim 2, wherein the liquid crystal element is for converting a beam emitted from the semiconductor laser device into a polarized beam divided into three by a polarization hologram in an ON state. An optical disk device characterized in that the beam is not divided into three when the switch is turned off. 5. The optical disc device according to claim 1, wherein the switching means includes a polarization hologram for dividing a beam emitted from the semiconductor laser device into three, and the polarization hologram in an optical path of the beam emitted from the semiconductor laser device. An optical disk device comprising a moving means for taking in and out. 6. The optical disc loaded by the discriminating means in the optical disc apparatus according to claim 1, is a DVD-
When determining whether it is a RAM, a DVD-R, or a DVD-RW, the second tracking means performs tracking control by the differential push-pull method to read the data regarding the disk type in the optical disk. Optical disk device. 7. An optical disk device for irradiating an optical disk with a light beam to record or read data, wherein the first optical disk or the land or groove in which data is recorded on both lands and grooves formed on the optical disk. In an optical disc device in which a second optical disc in which data is recorded on one side is loaded, a laser device that emits a light beam and a light beam emitted from this laser device irradiates both the groove and the lands on both sides of the groove. So as to divide the light beam into three, a first tracking means for performing tracking control by a push-pull method using one light beam without operating the above dividing means, and the above division By operating the means, three light beams are used and the differential push-pull method is used. The second tracking means for controlling the tracking and the optical disk loaded based on the information read from the optical disk by performing the tracking control by the second tracking means when the optical disk is loaded are recorded on both the land and the groove. Means for determining whether the optical disc is the first optical disc or the second optical disc recorded on one of the land and the groove, and when the discriminating means determines that the optical disc is the first medium, Selecting means for selecting the first tracking means without operating the dividing means, and operating the dividing means for selecting the second tracking means when it is determined that the optical disk is the second medium. An optical disk device characterized by having. 8. An optical disk apparatus for irradiating an optical disk with a light beam to record or read data, wherein the first optical disk or the land or groove in which data is recorded on both lands and grooves formed on the optical disk. In an optical disc device in which a second optical disc in which data is recorded on one side is loaded, a laser device that emits a light beam, and a light beam emitted from this laser device is emitted to both the groove and the lands on both sides of the groove. Splitting means for splitting the light beam into three so as to be irradiated; first tracking means for performing tracking control by push-pull method using one light beam without operating the splitting means; The splitting means is operated and three light beams are used for the differential push-pull method. And a second tracking means for performing tracking control and an optical disk loaded based on the information read from the optical disk by performing tracking control by the first tracking means when the optical disk is loaded and recorded on both the land and the groove. Means for determining whether the optical disc is the first optical disc or the second optical disc recorded on one of the land and the groove, and when the discriminating means determines that the optical disc is the second medium, An optical disk device comprising: a selecting unit that operates the dividing unit to select the second tracking unit.