This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2005-053330, filed Feb. 28, 2005, the entire contents of which are incorporated herein by reference.
1. Field
One embodiment of the invention relates to an optical disk, such as DVD-R or DVD-RW. One embodiment of the invention further relates to an optical disk apparatus and an optical disk processing method which process such an optical disk.
2. Description of the Related Art
In recent years, various optical disks, including DVD-R and DVD-RW, have been widely used. In the recording layers of these optical disks, land tracks and groove tracks are formed alternately from the inner edge toward the outer edge. The land tracks are provided with land pre-pits (LPP) indicating the addresses of the groove tracks. To achieve higher capacity, tremendous efforts have been put into the research and development of an optical disk with a plurality of recording layers.
For example, Jpn. Pat. Appln. KOKAI Publication No. 10-289450 discloses a focus servo control method with a servo circuit which, when recording and reproducing information onto and from an optical disk with a plurality of recording layers, starts a focus search operation from the surface close to the recording and reproducing surface on the front or back side of the optical disk.
Furthermore, Jpn. Pat. Appln. KOKAI Publication No. 10-340536 discloses techniques related to a pre-pit information detecting unit capable of obtaining information precisely based on a pre-pit signal even when a noise component is superimposed on the wobble signal obtained from the tracks.
In addition, Jpn. Pat. Appln. KOKAI Publication No. 2003-317259 discloses the technique for providing an inner-periphery LPP detecting means for detecting an LPP (land pre-pit) signal obtained from the land track adjacent to the inner periphery of an information track in addition to outer-periphery LPP detecting means for detecting an LPP signal obtained from the land track adjacent to the outer periphery of the information track and acquiring rough address information with the inner-periphery LPP detecting means when the outer-periphery LPP signal cannot be detected.
A general architecture that implements the various feature of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention.
Various embodiments according to the invention will be described hereinafter with reference to the accompanying drawings. In general, according to one embodiment of the invention, an optical disk comprises a first and a second recording layer in each of which first and second tracks (or land tracks and groove tracks) are formed alternately from the inner edge toward the outer edge, the first tracks (or land tracks) of the first recording layer having pits which indicate the addresses of the second tracks of the first recording layer adjacent to the inner periphery of the first tracks of the first recording layer, the second tracks (or groove tracks [which may be virtually considered to be land tracks, referring to
A conventional optical disk, such as DVD-R or DVD-RW, has a single recording layer into or from which data is recorded or reproduced. Recently, the use of a multilayered structure of recording layers has been examined to increase the recording capacity.
FIGS. 1 to 4 schematically show the configuration of an optical disk with a plurality of recording layers according to an embodiment of the present invention.
As shown in
As shown in
Tracking on the first recording layer 1 is done from the inner edge of the optical disk toward the outer edge, whereas tracking on the second recording layer 2 is done from the outer edge toward the inner edge. The reason is that the optical disk is of the Opposite Track Path (OTP) type where the spiral direction in the first recording layer is the reversal of that in the second recording layer. For example, in the first recording layer 1, tracking is done spirally from the inside toward outside of the disk, whereas in the second recording layer, tracking is done spirally from the outside toward inside of the disk.
Referring to
As shown in
Furthermore, as shown in
Specifically, in the optical disk whose pre-pits have the same polarity in the first recording layer 1 and second recording layer 2, the pre-pit P of each recording layer indicates the address of the inner-edge-side track adjacent to the track having the pre-pit P. That is, when viewed from the track without a pre-pit P, the pre-pit P in the outer-edge-side track adjacent to the track without a pre-pit P indicates the address of the track without a pre-pit P.
The optical disk may be the reversal of that in the above explanation. Specifically, in an optical disk whose pre-pits have the same polarity in the first recording layer 1 and second recording layer 2, a pre-pit P of each recording layer may indicate the address of the outer-edge-side track adjacent to the track having the pre-pit P. That is, when viewed from the track without a pre-pit P, the pre-pit P in the inner-edge-side track adjacent to the track without a pre-pit P may indicate the address of the track without a pre-pit P.
Next, an explanation will be given of an optical disk where the polarity of the pre-pits in the first recording layer 1 is different from (or opposite to) the polarity of the pre-pits in the second recording layer 2.
As shown in
Furthermore, as shown in
Specifically, in an optical disk where the polarity of the pre-pits in the first recording layer 1 is different from the polarity of the pre-pits in the second recording layer 2, a pre-pit P in the first recording layer 1 indicates the address of the inner-edge-side track adjacent to the track with the pre-pit P, whereas a pre-pit P in the second recording layer indicates the address of the outer-edge-side track adjacent to the track with the pre-pit P. That is, when viewed from the track without a pre-pit P, a pre-pit P in the outer-edge-side track adjacent to the track without a pre-pit P in the first recording layer 1 indicates the address of the track without a pre-pit P and a pre-pit P in the inner-edge-side track adjacent to the track without a pre-pit P in the second recording layer 2 indicates the address of the track without a pre-pit P.
The optical disk may be the reversal of that in the above explanation. Specifically, in the optical disk where the polarity of the pre-pits in the first recording layer 1 is different from the polarity of the pre-pits in the second recording layer 2, a pre-pit P in the first recording layer may indicate the address of the outer-edge-side track adjacent to the track with the pre-pit P and a pre-pit P in the second recording layer 2 may indicate the address of the inner-edge-side track adjacent to the track with the pre-pit P. That is, when viewed from the track without a pre-pit P, the pre-pit P in the inner-edge-side track adjacent to the track without a pre-pit P in the first recording layer 1 may indicate the address of the track without a pre-pit P and the pre-pit P in the outer-edge-side track adjacent to the track without a pre-pit P in the second recording layer 2 may indicate the address of the track without a pre-pit 2.
The optical disk whose pre-pits have the same polarity in the first recording layer 1 and second recording layer 2 has pre-pit polarity information that indicates the pre-pits have the same polarity. Specifically, in the area A1 of the optical disk whose pre-pits have the same polarity in the first recording layer 1 and second recording layer 2, pre-pit polarity information is recorded that indicates the pre-pits in the first recording layer 1 and second recording layer 2 have the same polarity (a pre-pit always indicates the address of the outer-edge-side [or inner-edge-side] track adjacent to the track in which the pre-pit is placed).
In contrast, the optical disk where the polarity of the pre-pits in the first recording layer 1 is different from the polarity of the pre-pits in the second recording layer 2 has pre-pit polarity information that indicates the pre-pits differ in polarity between the first recording layer 1 and the second recording layer 2. Specifically, in the area A1 of the optical disk whose pre-pits differ in polarity between the first recording layer 1 and the second recording layer 2, pre-pit polarity information is recorded that indicates the polarity of the pre-pits in the first recording layer 1 is different from the polarity of the pre-pits in the second recording layer 2 (a pre-pit in the first recording layer indicates the address of the outer-edge-side [or inner-edge-side] track adjacent to the track in which the pre-pit is placed and a pre-pit in the second recording layer indicates the address of the inner-edge-side [or outer-edge-side] track adjacent to the track in which the pre-pit is placed).
Furthermore, in the area A2 on the first recording layer 1 of the same-polarity optical disk and different-polarity optical disk, recording-layer identifying information that indicates the first recording layer is recorded. Similarly, in the area A2 on the second recording layer 2 of the same-polarity optical disk and different-polarity optical disk, recording-layer identifying information that indicates the second recording layer is recorded.
With the above configuration, the optical disk apparatus which processes the optical disk can determine whether the optical disk to be processed is of the same polarity type or the different polarity type by acquiring the pre-pit polarity information recorded in the area A1. Moreover, the optical disk apparatus which processes the optical disk can determine whether the recording layer of the optical disk to be processed is the first recording layer 1 or the second recording layer 2 by acquiring the recording-layer identifying information recorded in the area A2.
Next, referring to FIGS. 5 to 7, a schematic configuration of the optical disk apparatus according to the embodiment will be explained.
As shown in
The optical pickup 10 includes a laser 11, a collimate lens 12, a polarization beam splitter (hereinafter, referred to as PBS) 13, a ¼ wavelength plate 14, an objective 15, a condenser lens 16, and a light detector 17.
First, the way the optical disk apparatus records information onto the optical disk will be explained. The modulation circuit 21 modulates recording information (data symbols) provided by the control section 35 according to a specific modulation method into a channel bit train. The channel bit train corresponding to the recording information is input to the recording and reproducing section 22. Further input to the recording and reproducing section 22 is a recording and reproducing instruction (in this case, a recording instruction) from the control section 35. The recording and reproducing control section 22 outputs a control signal to the actuator 26 to drive the optical pickup so that the optical beam may be gathered suitably at the target recording position. Furthermore, the recording and reproducing control section 22 supplies a channel bit train to the laser control circuit 23. The laser control circuit 23 converts the channel bit train into a laser driving waveform, thereby driving the laser 11. That is, the laser control circuit 23 pulse-drives the laser 11. As a result, the laser 11 emits a recording optical beam corresponding to a desired bit train. The recording optical beam emitted from the laser 11 becomes parallel light at the collimate lens 12 and enters the PBS 13 and passes through it. The beam passed through the PBS 13 passes through the ¼ wavelength plate 14 and is gathered by the objective 15 at the information recording surface (the first recording layer 1 or second recording layer 2) of the optical disk. The gathered recording optical beam is maintained in a state where the best microscopic spot is obtained on the recording surface by focus control performed by the focus control circuit 32 and actuator 26 and by tracking control performed by the tracking control circuit 34 and actuator 26.
Then, the way the optical disk apparatus reproduces the information from the optical disk will be explained. A recording and reproducing instruction (in this case, a reproducing instruction) from the control section 35 is input to the recording and reproducing control section 22. According to the reproducing instruction from the control section 35, the recording and reproducing control section 22 outputs a reproduction control signal to the laser control circuit 23. On the basis of the reproduction control signal, the laser control circuit 23 drives the laser 11. As a result, the laser 11 emits a reproducing optical beam. The reproducing optical beam emitted from the laser 11 becomes parallel light at the collimate lens 12, enters the PBS 13, and passes through the PBS 13. The light beam passed through the PBS 13 passes through the ¼ wavelength plate 14 and is gathered by the objective 15 at the information recording surface of the optical disk. The gathered reproducing optical beam is maintained in a state where the best microscopic spot is obtained on the recording surface by focus control performed by the focus control circuit 32 and actuator 26 and by tracking control performed by the tracking control circuit 34 and actuator 26. At this time, the reproducing optical beam projected on the optical disk is reflected by the reflecting film or reflective recording film at the information recording surface. The reflected light passes through the objective 15 in the opposite direction and becomes parallel light again. The reflected light then passes through the ¼ wavelength plate 14, has polarized light perpendicular to the incident light, and is reflected at the PBS 13. The beam reflected at the PBS 13 is turned into convergent light by the condenser lens 16 and enters the light detector 17. The light detector 17 is composed of, for example, a 4-quadrant photodetector. The beam entering the light detector 17 is converted photoelectrically into an electric signal, which is then amplified. The amplified signal is equalized and binarized at the signal processing circuit 24. The resulting signal is sent to the modulation circuit 25. The modulation circuit 25 modulates the signal according to a specific modulation method and outputs the reproduced data.
A focus error signal is generated on the basis of a part of the electric signal output from the light detector 17. Similarly, a tracking error signal is generated on the basis of a part of the electrical signal output from the light detector 17. The focus control signal 32 controls the actuator 28 on the basis of the focus error signal, thereby controlling the focus of the beam spot. The tracking control circuit 34 controls the actuator 28 on the basis of the tracking error signal, thereby controlling the tracking of the beam spot.
As shown in
As shown in
The difference signal S2 is a signal obtained from the pre-pit in a land track L of the first recording layer adjacent to the outer-periphery of a groove track G of the first recording layer. Alternatively, the difference signal S2 is a signal obtained from the pre-pit in a groove track G of the second recording layer adjacent to the outer-periphery of a land track L of the second recording layer.
The difference signal S3 is a signal obtained from the pre-pit in a land track L of the first recording layer adjacent to the inner-periphery of a groove track G of the first recording layer. Alternatively, the difference signal S3 is a signal obtained from the pre-pit in a groove track G of the second recording layer adjacent to the inner-periphery of a land track L of the second recording layer.
On the basis of pre-pit information obtained from the area A1 of the optical disk and recording-layer identifying information obtained from the area A2, the optical disk apparatus selects one of the difference signals S2 and S3 and reproduces the pre-pit according to the selected difference signal. Specifically, on the basis of the pre-pit polarity information and recording-layer identifying information, the optical disk apparatus determines a method of detecting pre-pits in the first and second recording layers and reproduces an address from the pre-pits in the first and second recording layers by the determined detecting method.
The optical disk apparatus irradiates the optical disk with the optical beam and detects the reflected light from the optical disk, thereby reading various pieces of information reflected in the reflected light. For example, the optical disk apparatus reads management information from a management information storage area A of the optical disk (ST1). The control section 35 of the optical disk apparatus determines the type or the like of the optical disk to be processed on the basis of the media ID included in the management information. If the optical disk to be processed is DVD-R or DVD-RW and falls under the OTP types of a plurality of recording layers (in the embodiment, two recording layer) (YES in ST2), a difference signal selecting process is carried out.
If the control section 35 of the optical disk apparatus has determined that the difference signal selecting process is necessary for the optical disk to be processed (YES in ST2), it determines on the basis of the pre-pit polarity information included in the management information whether the pre-pits in the first and second recording layers of the optical disk to be processed have the same polarity (ST3).
If the control section 35 of the optical disk apparatus has determined that the pre-pits in the first and second recording layers of the optical disk to be processed have the same polarity (YES in ST3), it selects the difference signal S2 (ST5). On the basis of the difference signal S2, the pre-pit is detected and reproduced (ST7). If the control section 35 of the optical disk apparatus has determined that the polarity of the pre-pits in the first recording layer of the optical disk to be processed is different from the polarity of the pre-pits in the second recording layer (NO in ST3), it determines on the basis of the recording-layer identifying information included in the management information which of the first recording layer and second recording layer is to be processed (ST4). If the control section 35 of the optical disk apparatus has determined that the first recording layer is to be processed (NO in ST4), it selects the difference signal S2 (ST5). On the difference signal S2, the pre-pit is detected and reproduced (ST7). If the control section 35 of the optical disk has determined that the second recording layer is to be processed (YES in ST4), it selects the difference signal S3 (ST6). On the basis of the difference signal S3, the pre-pit is detected and reproduced (ST7).
In the optical disk to be processed in the embodiment, the track of the first recording layer 1 spirals so as to do tracking from the inside of the disk to the outside, whereas the track of the second recording layer 2 spirals so as to do tracking from the outside of the disk to the inside. In the first recording layer 1 of the same-polarity optical disk, the address of a groove track G is obtained from the pre-pit in the land track L outside the groove track G. In the second recording layer 2, too, the address of a land track L is obtained from the pre-pit in the groove track G outside the land track L. In contrast, in the first recording layer 1 of the different-polarity optical disk, the address of a groove track G is obtained from the pre-pit in the land track L outside the groove track G. In the second recording layer 2, the address of a land track L is obtained from the pre-pit in the groove track G inside the land track L.
The optical disk apparatus of the embodiment changes the pre-pit detecting method on the basis of the pit polarity information and recording-layer identifying information obtained from the optical disk. This makes it possible to obtain the correct pre-pit signal and the correct address from both of the same-polarity optical disk and the different-polarity optical disk.
While in the embodiment, the output from the direct-current coupled amplifier H4 has been inverted in polarity by the polarity inverter IV, the present invention is not limited to this. For instance, the polarity of the input signal to the direct-current coupled amplifier H4 may be changed by a selector switch.
While in the embodiment, the pre-pit detecting method has been explained which determines whether to reproduce the pre-pit in the track on the inner-edge side of the target track as an address or the pre-pit in the track on the outer-edge side of the target track as an address, the present invention is not limited to the pre-pit detecting method. For instance, in HD-DVD (including HD-DVD-R and HD-DVD-RW) the formulation of whose standard has recently been in progress, track wobbles are used in place of pre-pits. In the track wobbles, addresses are reflected using phase modulation. That is, the present invention may be applied to a track wobble detecting method which determines whether to reproduce the track wobble on the inner-edge side of the target track as an address or the track wobble on the outer-edge side of the target track as an address.
While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
Number | Date | Country | Kind |
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2005-053330 | Feb 2005 | JP | national |