WO2005031721A1

WO2005031721A1 - Optical medium for data recording and optical recording apparatus capable of recording data

Info

Publication number: WO2005031721A1
Application number: PCT/KR2003/002798
Authority: WO
Inventors: Seong-Su Park; Bong-Gi Kim; Soo-Han Park; Chun-Seong Park; Tae-Youn Heo
Original assignee: Samsung Electronics Co., Ltd.
Priority date: 2003-10-01
Filing date: 2003-12-22
Publication date: 2005-04-07
Also published as: AU2003285784A1; KR100565796B1; KR20050032430A

Abstract

An optical medium for data recording and an optical recording apparatus capable of recording data. On the optical medium not recording any data, plural pits having the same size are periodically formed along a track-wise direction. The interval between neighboring pits is identical to the track-wise direction of the pit. The size of pits pre-formed on the optical medium changes according to the optical power supplied from the optical recording apparatus, and thus data are recorded on the optical recording medium. Accordingly, the pre-formed pits prevent tracking offset during the data recording and also prevent DC-offset during the data reproduction.

Description

OPTICAL MEDIUM FOR DATA RECORDING AND OPTICAL RECORDING APPARATUS CAPABLE OF RECORDING DATA

[Technical Field] The present invention relates to an optical recording medium for data recording and an optical recording apparatus capable of data recording, and more particularly, to an optical recording medium which is pre-formed with at least one pit in an unrecorded area to record data according to phase changes, and an optical recording apparatus capable of recording data.

[Description of Related Art]

An optical recording apparatus records certain data to an optical recording medium and reproduces the recorded data, in which the data recording and reproducing is performed according to reflectivity of light such as a laser beam. A compact disk player (CEP) may represent an optical recording apparatus, and a compact disk (CD), a video compact disk (VCD) and a digital video disk (DVD) may represent an optical recording medium. Referring to FIG. 1, an unrecorded, conventional and optical recording medium has a plurality of lands 110 and grooves 120. The lands 110 have similar heights to that of surface of optical recording medium, and the grooves 120 are formed between lands 110 in certain depths. When data is desired to be recorded at the optical recording medium, the optical recording apparatus forms a plurality of pits in certain sizes on the grooves 120 or lands/grooves 110 and 120 to record the data. At this time, the pit may be formed along a middle line of grooves 120, i.e., in the middle (shown in phantom) of track as shown in FIG. 2A. However, in certain conventional recording such as differential push pull (DPP) with respect to optical recording medium, the pit is formed, shifting from a middle line (shown in phantom) of track towards the land 110 as shown in FIG. 2B. In specific, tracking offset is generated on the track during data recording on a conventional pit-less optical recording medium. As such, when data is reproduced at a conventional optical recording medium, the conventional optical recording apparatus does not precisely perform tracking servo and the reproducing capability of an optical recording apparatus decreases.

[Summary of the Invention]

Accordingly, it is an aspect of the present invention to provide an optical recording medium which can prevent tracking offset generated during data recording at an optical recording medium and an optical recording apparatus capable of recording data. To solve the above-mentioned problems, in an optical recording apparatus recording data at an optical recording medium according to the present invention, a light source emits a light of a certain power to modulate a preformed pit size by phase change. The control part determines forming period of pit, and then controls the light source to emit light having various power according to the determined period and the data. The data is recorded at the optical recording medium by the above process. In specific, the optical recording medium comprises a plurality of groove wherein a pit is periodically formed along the track direction, and a plurality of lands formed between the plurality of grooves, and the control part modulates the size of pit according to a power of light to record the data on the groove. The pit is formed in the middle of groove along the track direction, and the control part controls the light source to adaptively emit a light having a power for eliminating a certain area in the pit and a light having a power for keeping a certain area as an initial status in the pit. The pit may have the same size and a plurality of pits are periodically formed in a middle of the groove, and an interval between two adjacent pits is formed to be the same as the length of pit in a direction of track. If the data is recorded at the optical recording medium, the control part compares and analyzes the period and the data and adaptively emits at least one of a light having a power for eliminating a certain area in the pit of the plurality of pits, a light having a power for keeping an initial status of the plurality of pits, and a light having a power for generating a new pit in the groove area without the pit.

[Brief Description of the Drawings]

FIG. 1 is a schematic view for showing a conventional optical recording medium before data recording; FIG. 2 A and 2B are views of an example of pits formed in grooves of FIG. 1; FIG. 3 is a view of a part of recording/reproducing layer of optical recording medium for recording data according to an embodiment of the present invention; FIG. 4A and 4B are views of an example of a part formed at the optical recording medium of FIG. 3 before data recording; FIG. 5 is a schematic block diagram of a part of an optical recording apparatus which can record data at the optical recording medium of FIG. 4. FIG. 6 is a view for explaining an embodiment of recording data at an optical recording medium wherein a pit is consecutively formed; FIG. 7 is a view for explaining an embodiment of recording data at an optical recording medium wherein a plurality of pits are in advance formed; and FIG. 8 is a flow chart for schematically explaining the data recording method of FIG. 5.

[Best Mode of the Invention]

The above objects and other features of the present invention will be more apparent by describing preferred embodiments of the present invention in greater detail below. FIG. 3 is a view that illustrates a part of recording/reproducing layer of optical recording medium for recording data according to an embodiment of the present invention; An optical recording medium according to an embodiment of the present invention records data, and has at least one recording/reproducing layer. A DND-R, a DND-RW, a DND+RW, a DVD-RAM, a DND-ROM, a CD-R, a CD-RW and a CD-ROM can be an example for the optical recording medium, but it should not be considered as limiting. In here, R means that data can be once recorded, and ±RW and RAM means that data can be re-recorded several times. Referring to FIG. 3, a recording/reproducing layer 300 of an optical recording medium according to an embodiment of the present invention comprises a plurality of lands 310, a plurality of grooves 320 and at least one pits 330. The plurality of lands have a height similar to that of surface of an optical recording medium, and are formed in grooves 310 which will be described later. This is to divide tracks, or grooves 310. The pits 330 are periodically formed in the grooves 320 along the track direction. Pits 330 are arranged along a middle line (shown in phantom) as a certain size. In detail, the pits 330 may be continuously formed along a middle line of a plurality of grooves 320 as shown in FIG. 4A. Therefore, one pit 330 is formed in one recording/reproducing layer 300. This is because a plurality of interconnected tracks are spirally formed from inner circumference to outer circumference at an optical recording medium 500a. If the pits 330 are at least two, each of pits 330 is configured in a middle line of grooves 320 in the same size as shown in FIG. 4B. The interval between two adjacent pits 330 is preferably the same as the length (d) of the pits 330 in direction of tracking. Further, the size of pre-formed pits 330 is one of 3T through 12T, however, it should not be considered as limiting. The pits 330 may be regularly formed not only in grooves 320 but also on a plurality of lands 310 along the tracking direction according to recording/reproducing characteristics of optical recording medium. The format scheme of pits 330 formed on the lands 310 is the same as that on the grooves 320. Examples of an optical recording medium comprising at least one pit 330 only on a groove 320 are a DVD-R, a DVD-RW and DVD+RW, and an example of an optical recording medium comprising at least one pit 330 in groove 320 and on land 310 is a DVD-RAM. An optical recording medium according to the present invention forms a pit 330 along a middle line (shown in phantom) of a groove 320 so as not to generate tracking offset. FIG. 5 is a schematic block diagram of a part of an optical recording apparatus of FIG. 4 which can record data at an optical recording medium. Referring to FIGS. 4 and 5, an optical recording apparatus 500 according to an embodiment of the present invention comprises an optical pick-up 510, a signal processing part 520 and a control part 530. The optical recording apparatus 500 shown in FIG. 5 records data at an optical recording medium 500a, and a compact disk player (CDP), a digital video disk player

(DVDP) and a digital video disk recorder (DVDR) can be examples thereof. Additionally,

FIG. 5 shows a block related to a data recording of the optical recording apparatus 500, with the other blocks being omitted for convenience of explanation. If the optical recording apparatus 500 is set as a recording mode, the optical recording apparatus 500 emits a laser beam to the recording/reproducing layer 300 to record data by phase changes. In specific, the optical recording apparatus 500 forms or eliminate the pits 330 for recording by using phase change. Further, if the optical recording apparatus 500 is set as a reproducing mode, the optical recording apparatus 500 emits laser beam to the optical recording medium 500a, receives the laser beam reflected from the recording/reproducing layer 300, and thereafter reproduces data recorded at the optical recording medium 500a via signal processing procedure. The optical pick-up 510 comprises a laser diode 511, a laser diode driving part 512, a beam splitter 513, a collimating lens 514, an object lens 515 and a photo diode 516. The laser diode 511 applied as a light source is driven by the laser diode driving part 512, and emits a laser beam having a certain light power. The beam splitter 513 changes a light path of laser beam emitted from the laser diode 511. The collimating lens 514 converts a laser beam having a certain radiation angle into a parallel light and outputs the parallel light. The object lens 515 condenses the laser beam outputted from the collimating lens 514 to a track of the optical recording medium 500a. In other words, the object lens 515 performs focusing servo and tracking servo by a servo control part (not shown). If the optical recording apparatus 500 is set as a reproducing mode, the laser beam reflected from the optical recording medium 500a deflects towards the photo diode 516 by the beam splitter 513. The photo diode 516 converts and outputs the deflected laser beam to a high frequency signal. The signal processing part 520 is a digital signal processor (DSP), which digitalprocesses the signal outputted from the optical pick-up 510 to output the digital video/audio signals. The control part 530 controls the optical pick-up 510 and the signal processing part

520 to reproduce data recorded at the optical recording medium 500a. If the optical recording apparatus 500 is set as a recording mode, the control part 530 controls the optical pick-up 510 to record data provided from a data source (not shown) at a recording/reproducing layer of the optical recording medium 500a. If the optical recording apparatus 500 is set as a recording mode, the method for recording data at the optical recording medium 500a according to an embodiment of the present invention will be explained hereinafter. First, the optical recording medium 500a before data recording has at least one recording/reproducing layer 300 as shown in FIG. 3. In the present invention, it will be explained with reference to an exemplary embodiment of the case recording data using the optical recording medium 500a wherein one pit 330 is in advance formed in a plurality of grooves 320 as shown in FIG.4A. If the optical recording apparatus 500 is set as a recording mode, the optical pick-up 510 performs focusing servo by the control of the control part 530, and then records data at the optical recording medium 500a by using the laser beam emitted from the laser diode 511. Because one pit 330 is already formed at the optical recording apparatus 500, the optical pick-up 510 can omit the tracking servo. This is possible because the tracking offset is prevented during data recording by the pit 330 which is in advance formed. The control part 530 determines a period pattern of the pit 330 formed at the optical recording medium 500a. The control part 530 controls the laser diode driving part 512 to emit laser beam having varying power depending on the determined period pattern and data. In detail, the control part 530 analyzes the period pattern and the data. The control part 530 generates a recording control signal comprising at least one of first and second control signals, in which the first control signal is to keep a certain area of one pit 330 and the second control signal is to eliminate a certain area of one pit 330 according to the analyzed result. The control part 530 determines which area covers a recording position of data of the one preformed pit 330 to generate a recording control signal. The recording control signal is a pulse signal to adjust a power level of laser beam, and phase-changes the recording/reproducing layer 300. The pit 330 corresponding to the data or the recording control signal is formed to a variety of sizes according to the power of laser beam. If the recording control signal is generated, the laser diode 511 emits laser beam having power corresponding to a certain interval of the recording control signal. For example, if the inputted recording control signal is the second control signal, the laser diode 511 emits laser beam of approximately 40 power for a certain time. The specific power value used here is only an exemplary purpose, and thus, it should be not considered as limiting. The beam splitter 513 deflects the emitted laser beam of a certain power in direction of the object lens 515. The object lens 515 condenses the laser beam into a middle line, i.e., to a track, of the groove 320 of optical recording medium 500a. The recording of data is performed by the above procedure. As described above, the tracking offset is not generated during data recording, and therefore, the shift of the object lens 515 for the tracking servo also does not occur. This can prevent a DC-offset caused by light amount changes generated by the shift of the object lens 515, when the data recorded at an optical recording medium 500a according to an embodiment of the present invention is reproduced. The data is recorded by phase changes. In specific, one pit 330 formed in the groove 320 is eliminated according to the power of laser beam such that the optical recording medium 500a changes the phase. FIG. 6 is a view for explaining an embodiment of data recording at an optical recording medium wherein one pit is consecutively formed. For example, as shown in (a) of FIG. 6, the case in which one pit 602 is continuously formed in a groove 610, and the data is recorded at 3T interval, will be explained hereinafter. Firstly, to record the data of 3T, the control part 53 generates a recording control signal, which maintains an initial 3T pit area 604, eliminates the next 3T pit area a' (shown in phantom) by phase changes, maintains the next 3T pit area 606 and eliminates the next 3T pit area b\ More specifically, when the data is to be recorded at the pre-formed pit 602 at 3T intervals, the recording control signal consists of 'the first control signal-→the second control signal~→the first control signal→the second control signal'. Then, the optical pick-up 510 emits the laser beam having a certain power according to a recording control signal to the optical recording medium 500a. The laser diode 511 sequentially emits the laser beam having 'the first power corresponding to the first control signal for 3T interval → the second power corresponding to the second control signal for 3T interval → the first power corresponding to the first control signal for 3T interval → the second power corresponding to the second control signal for 3T interval' according to a driving control of the laser diode driving part 512. A plurality of pits 604 and 606 are formed in the groove 610 of the optical recording medium 500a as shown in (b) of FIG. 6. The optical recording apparatus 500 capable of recording data according to an embodiment of the present invention can also record data at the optical recording medium 500a wherein a plurality of pits 330 are periodically formed as shown in FIG. 4B. When data is recorded at the optical recording medium 500a as shown in FIG. 4B, the control part 530 controls the laser diode driving part 512 to emit a laser beam having various power according to the data and the period pattern of a plurality of pre-formed pits 330. In specific, the control part 530 analyzes the period pattern and data. The control part 530 generates a recording control signal comprising at least one of third to sixth control signals based on the analysis in which the third control signal is to keep a certain area of the plurality of pits 330 formed in the recording/reproducing layer 300, the fourth control signal is to eliminate the certain area of the plurality of pits 330, the fifth control signal is to keep a area where the plurality of pits 330 are not formed and the sixth control signal is to generate a new pit in an area where the pit 330 is not formed,. In other words, the control part 530 determines whether the position to be recorded by the data belongs to a certain area of a plurality of the pre-formed pits 330, or to the pit-less area of the grooves 320. The control part 530 generates a recording control signal for recording the data at the optical recording medium 500a according to the determination result. The recording control signal is a pulse signal for adjusting a power level of laser beam. The optical pick-up 510 emits a laser beam having a certain power according to a recording control signal to the optical recording medium 500a. Data is recorded at the optical recording medium 500a by phase change. As certain area of a plurality of pits 330 formed in the groove 320 is eliminated by the power of laser beam or a new pit is formed in the groove 320, the optical recording medium 500a changes the phase. FIG. 7 is a view for explaining an embodiment of data recording at an optical recording medium wherein a plurality of pits are in advance formed; In the case of FIG. 7 (a), for example, that a plurality of pits 702, 704 and 706 having a size of 3T are formed in a groove 710 at 3T intervals, and the recording data is formed as a pit of 12T, and this will be explained hereinafter. The control part 530 generates a signal control signal such that, in order to record data, the first and second pits 702 and 704 pit areas are maintained, the first and second pit-less areas a and b (shown in phantom) are formed by phase change, and apart, or the entire part of the third pit 706 is eliminated by phase change. In specific, the recording control signal corresponding to 12T comprises 'the first control signal→ the fourth control signal → the first control signal → the fourth control signal → the second control signal'. Accordingly, the laser diode 511 sequentially emits by driving control of the laser diode driving part 512, the laser beam having 'the first power corresponding to the first control signal for 3T interval — > the fourth power corresponding to the fourth control signal for 3T interval -→ the first power corresponding to the first control signal for 3T interval ^→ the fourth power corresponding to the fourth control signal for 3T interval →the second power corresponding to the second control signal for 3T interval'. As a result, the pit 708 is formed in the groove 710 of the optical recording medium 500a as shown in FIG. 7(b) such that the data of 12T can be recorded. FIG. 8 is a flow chart for schematically explaining the data recording method of FIG. 5. Referring to FIGS. 3 to 8, at least one pit 330 to be recorded by the data is periodically formed in the groove 320 (S810). The at least one pit 330 is formed along the track. If the optical recording apparatus 500 is set as a recording mode, the optical recording apparatus 500 emits a laser beam having a certain power to the pit 330 of the recording/reproducing layer 300 (S820). If one pit 330 is formed in the groove 320 as shown in FIG. 4A in the step of S810, the laser beam having the first power for keeping a certain area in the pit 330 as an initial status, and the laser beam having the second power for eliminating a certain area of the pit 330, are adaptively emitted according to the recording data in the step of S820. Meanwhile, if a plurality of pits 330 is formed in the groove 320 as shown in FIG. 4B in the step of S810, the laser beam having the third power for keeping a certain area of a plurality of pits 330 formed in the recording/reproducing layer 300, the laser beam having the fourth power for eliminating a certain area of the plurality of pits 330, the laser beam having the fifth power for keeping a certain area of the pit-less groove 320, and the laser beam having the sixth power for generating a new pit in a pit-less area, are adaptively emitted according to the period and data in the step of S820. Accordingly, the size of pit 330 formed in the step of S810 is adjusted by the laser beam emitted in the step of S820 (S830). According to the phase change of the pit 330 by the emitted laser beam, a part of the pit 330 is eliminated such that the data can be recorded (S840). Meanwhile, to format the optical recording medium 500a recording data therein to an initial data-less state, the control part 530 generates a recording control signal to form at least one pit 330 as shown in FIG. 4 A and 4B. The laser diode driving part 512 drives the laser diode 511 to emit a laser beam to have a power corresponding to the recording control signal. The optical recording medium 500a is formatted to an initial data-less status by the above process. The pit 330 corresponding to the data formed at the optical recording medium 500a is formed and/or eliminated by the phase change such that the optical recording medium 500a is formatted as an initial status. The optical recording apparatus 500 capable of recording data according to the present invention as described above can also record data at the optical recording medium 500a with at least one pit 330 being formed in the land 310, instead of the groove 320. As described above, an optical recording medium for recording data and an optical recording apparatus capable of recording data according to the present invention in advance form in advance a pit having a certain periodity at an optical recording medium before data recording such that tracking offset can be prevented during data recording. When the recorded data is reproduced, DC-offset generated by the tracking offset can be also prevented. Since the tracking offset is not generated in data recording, tracking servo can be omitted while reproducing the data, and it can simplify an optical structure of an optical pickup such as reducing the number of sensor, provided at a photo diode and eliminating diffraction grid. As such, the optical pick-up can be manufactured at a decreased cost and the optical recording apparatus can be slim-sized. Although the preferred embodiments of the present invention have been described, it will be understood by those skilled in the art that the present invention should not be limited to the described preferred embodiment, but various changes and modifications can be made within the spirit and scope of the present invention as defined by the appended claims.

[Industrial Applicability] The present invention relates to an optical recording medium which in advance forms a pit at an optical recording medium before data recording and then records data by phase changes, and an optical recording apparatus which can record data.

Claims

[CLAIMS]

1. An optical recording medium comprising: a plurality of grooves having a pit periodically formed along a track direction; and a plurality of lands formed among the plurality of grooves to divide the tracks, wherein the size of pit is adjusted according to an externally-input optical power to record the data.

2. The optical recording medium as claimed in claim 1, wherein the pit is continuously formed in a middle of the groove along the track direction.

3. The optical recording medium as claimed in claim 1, wherein a plurality of pits periodically formed in a middle of the groove, and the interval between two adjacent pits is the same as the length in the track direction of the pit.

4. The optical recording medium as claimed in claim 1, wherein an additional pit is periodically formed in the lands along the track direction.

5. An optical recording apparatus for recording data at an optical recording medium, comprising: a light source emitting a light having a certain power to the optical recording medium such that a size of pit periodically formed at the optical recording medium is adjusted by a phase change; and a control part, after determining a forming periodicity of the pit, controlling the light source to emit lights having various power depending on the determined periodicity and the data to record the data.

6. The optical recording apparatus as claimed in claim 5, wherein the optical recording medium comprises a plurality of grooves having a pit periodically formed along the track direction; and a plurality of lands formed among the plurality of grooves to divide the tracks, wherein the control part adjusts sizes of the pit according to the light power to record the data on the groove.

7. The optical recording apparatus as claimed in claim 6, wherein the pit is continuously formed in a middle of the groove along the track direction, and the control part controls the light source to adaptively emit a light having power to eliminate a certain area of the pit and a light having power to keep a certain area of the pit as an initial status.

8. The optical recording apparatus as claimed in claim 6, wherein a plurality of pits in same size are periodically formed in a middle of the groove, and the interval between two adjacent pits is the same as the length of track direction of the pit.

9. The optical recording apparatus as claimed in claim 8, wherein, if the data is recorded at the optical recording medium, the control part compares and analyzes the periodicity and the data, and controls the light source to emit, in a certain order, at least one of a light having a power for eliminating a certain area of a corresponding pit of the plurality of pits, a light having a power for keeping an initial size of the plurality of pits and a light having a power for forming a new pit in a pit-less groove area.

10. The optical recording apparatus as claimed in claim 6, wherein an additional pit is periodically formed in the plurality of lands.

11. A method for recording data at an optical recording medium having a plurality of grooves and lands comprising: periodically forming a pit for data recording in a plurality of grooves along the track direction; after determining a forming periodicity of the pit, emitting a light having a certain power to the pit according to the determined periodicity and the data; and changing the phase of a certain area of the pit by the light emitted to record the data.

12. The method for recording data at an optical recording apparatus as claimed in claim 11, wherein pit forming step forms the pit in a middle of the groove continuously along the track direction.

13. The method for recording data at an optical recording apparatus as claimed in claim 12, wherein the light emitting step adaptively emits a light having a power for eliminating a certain area in the pit and a light having a power for keeping a certain area in the pit as an initial status.

14. The method for recording data at an optical recording apparatus as claimed in claim 11, wherein the pit forming step forms the plurality of pits in the same size in a middle of the groove with an interval between two adjacent pits being the same as the length of the pit in a direction of track.

15. The method for recording data at an optical recording apparatus as claimed in claim 14, wherein the light emitting step compares and analyzes the periodicity and the data, and emits, in a certain order, at least one of a light having a power for eliminating a certain area of the pit of the plurality of pits, a light having a power for keeping an initial status of the plurality of pits, and a light having a power for generating a new pit of the groove area without the pit.

16. The method for recording data at an optical recording apparatus as claimed in claim 11, wherein an additional pit is periodically formed in the land along the track direction.