JP2004152442A - Optical disk device and processing method of optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disc device which can enhance reading ratio to a header, and the like, by an optimum tracking offset through sampling plural offset candidate values. <P>SOLUTION: Plural offset values are arranged, centered about tracking control parts 2, 3, 21, 23 for forming a control loop based on a signal from an optical pickup 2 and performing control in tracking direction for the optical pickup, and the offset value by the tracking control part. The device comprises: a sampling part 15, which performs tracking offset respectively, corresponding to each of the plural offset values and sampling for a detection signal for the optical pickup in tracking offset; and an offset decision part 14, which decides a new offset value based on this sampling result, supplies this value to the tracking control part and makes the tracking controlled by the new offset value. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical disk device, and more particularly, to an optical disk device in which a tracking offset value is optimized by a sampling process.
[0002]
[Prior art]
Recently, as optical disks and optical disk devices have been developed and spread, the capacity of optical disks has also been increasing, and accordingly, there has been a demand for a high operation reliability of a control system of the optical disk device.
[0003]
In an optical disk device, a pickup head that irradiates a laser beam and detects reflected light is controlled in a focus direction and a tracking direction, so that the pickup head is arranged at an optimum position, and then recording and reproducing processes on the optical disk are performed. I have. For example, in the case of tracking offset control, these controls are performed by generating a track error signal corresponding to the control deviation and performing control in a direction to cancel the track error signal.
[0004]
As a related device related thereto, there is an example in which a tracking offset is corrected by an identification signal of a head portion of a sector in an optical disk of a land / groove format (for example, see Patent Document 1). However, this method cannot always improve the header reading rate. Further, the offset value sampling processing as shown in the present invention is not performed.
Therefore, in a conventional optical disk device, a disk on which header information (CAPA portion), which is a physical address, is written in a zigzag manner, such as a DVD (Digital Versatile Disc) -RAM (Random Access Memory), is written. In some cases, the tracking control system includes a DC offset other than the electrical DC offset, and the read rate of the header may decrease.
[0005]
[Patent Document 1]
JP-A-10-11762 (page 8)
[0006]
[Problems to be solved by the invention]
In a conventional optical disk device, when reading header information that is a physical address in a staggered manner like a DVD-RAM, the tracking control system includes not only an electrical DC offset but also other DC offsets. In some cases, there is a problem that the read rate of the header cannot be set to a sufficient value only by the control method for eliminating the tracking error of the conventional device.
[0007]
SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical disc apparatus that improves a reading rate of a header or the like of an optical disc by performing sampling using a plurality of offset candidate values, thereby achieving an optimum tracking offset.
[0008]
[Means for Solving the Problems]
According to the present invention, a tracking control means for forming a control loop based on a signal output from an optical pickup for detecting light reflected from an optical disk and controlling a tracking direction of the optical pickup, and an offset value by the tracking control means A plurality of offset values centered at the center, respectively, performing a tracking offset according to the plurality of offset values, and sampling means for sampling a detection signal of the optical pickup at that time; An optical disc device comprising: an offset determining unit that determines an offset value, supplies the offset value to the tracking control unit, and performs tracking control based on the new offset value.
[0009]
The present invention is not limited to the above-described structure, in which the control is performed only in the direction in which the tracking error of the conventional device is canceled. A value candidate is prepared, and offset adjustment is performed according to each offset value. At this time, the RF signal obtained from the pickup is sampled, and the read rate of the head is obtained from this. Then, the offset value with the highest header read rate is determined as the optimal offset value. The determined offset value is supplied to, for example, a tracking actuator driver of the tracking control system, and the tracking control is performed with the offset value having the highest head read rate.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an optical disc device according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an example of a schematic configuration of an optical disc apparatus according to the present invention, FIG. 2 is a diagram showing an example of a configuration of an optical system, FIG. 3 is a flowchart illustrating an example of an initial operation, and FIG. 5 is a flowchart illustrating a method for determining a tracking offset, FIG. 5 is a graph showing a relationship between an offset value F and a reading rate R, and FIG. 6 is a relationship between a header and a light spot that the optical disc apparatus according to the present invention intends to read. FIG.
[0011]
<Structure and operation of optical disk device>
First, the structure of the optical disk device according to the present invention will be described with reference to the drawings.
[0012]
(Construction)
As shown in FIGS. 1 and 2, an optical disk device according to the present invention includes an optical pickup 2 that irradiates a laser beam to a disk D driven by a disk motor 1 and receives a reflected light thereof. And an RF amplifier 3 to which the output signal is supplied. Further, it has a signal processing unit 4 to which the RF signal amplified by the RF amplifier 3 is supplied. Further, it has a tracking servo amplifier 21 and a focus servo amplifier 22 that are connected to the RF amplifier 3 and are supplied with the focus error signal FE and the tracking error signal TE. 24. The outputs of the drivers 23 and 24 are returned to the pickup 2 and supplied to a drive coil 38 in the track direction and a drive coil in the focus direction (not shown) for servo control. Further, it has a disk motor driver 27 connected to these control units, a disk motor 1 connected thereto, a feed motor driver 26 and a feed motor 25 connected thereto.
[0013]
The signal processing unit 4 includes a demodulation unit 5, a modulation unit 6, a sampling unit 15 that performs a sampling process for obtaining an optimal tracking offset value that is a feature of the present invention, and a sampling unit that is obtained by the processing of the sampling unit 15. And an offset determining unit 14 for determining an optimum tracking offset based on the result.
[0014]
Further, as shown in FIG. 2, the pickup 2 connected to the RF amplifier 3 has a four-divided detector 34 and sub-beam detectors 35 and 36, and further has a laser for generating a laser beam for irradiating the optical disk. The generator 37 includes a splitter 32 for separating generated laser light and reflected light from the optical disk D, and a compound lens 33 disposed in front of the objective lens 31 and the four-divided detector 34.
[0015]
(motion)
In the optical disc device according to the present invention having such a configuration, the processing operation of the optical disc D is performed as described below. That is, as shown in FIG. 1, a signal read by the optical pickup 2 from the disk D driven by the disk motor 1 is supplied to the RF amplifier 3. The RF amplifier 3 supplies the RF signal amplified from the output of the optical pickup 2 to the demodulation unit 5 of the signal processing unit 4. Further, the RF amplifier 3 extracts the focus error signal FE and the tracking error signal TE and supplies them to the tracking servo amplifier 21 and the focus servo amplifier 22, respectively. Further, a control signal supplied from the tracking servo amplifier 21 is supplied to the tracking actuator driver 23, and a control signal supplied from the focus servo amplifier is output to the focus actuator driver 24. The outputs of the drivers 23 and 24 are returned to the pickup 2 and supplied to a drive coil 38 in the track direction and a drive coil in the focus direction (not shown) to drive them and perform servo control in the tracking direction and the focus direction. . In the control of the tracking direction, tracking control by an optimal offset process obtained by sampling, which is a feature of the present invention described in detail below, is further performed.
[0016]
The signal processing unit 4 includes a demodulation unit 5 and a modulation unit 6. The demodulation unit 5 is detected by the optical pickup 2 and appropriately amplified by the RF amplifier 3 under the control of the control unit by the CPU 13, the RAM 11, and the ROM 12. The demodulated signal is demodulated into a reproducible signal form. The demodulated signal is supplied to an external processing device such as a host computer via the interface 8.
[0017]
The modulation unit 6 included in the signal processing unit 4 modulates a signal provided from the external host computer 10 or the like via the interface 8 into a signal form that can be recorded on the optical disc D. The modulated signal is reflected on a laser beam generated from a semiconductor laser 35 of the pickup 2 via the RF amplifier 3 and irradiates a predetermined area of the optical disk, and is recorded as reproducible information in the predetermined area. You.
[0018]
The control unit performs an operation determination by the CPU 13 according to the operation programs stored in the RAM 11 and the ROM 12, and controls the entire processing operation by referring to information from each unit. The interface 8 performs communication control regarding the interface, such as transmission and reception of various operation commands and data with the host computer 10. The operation command is exchanged between the control unit and the host computer 10 via the interface 8. However, the optical disk device may be operated by an operation panel (not shown), and is not necessarily limited to this mode.
[0019]
<Sampling process and tracking offset determination according to the present invention>
Next, a process of determining an offset by a sampling process based on a plurality of offset candidates, which is a feature of the present invention, will be described in detail with reference to the drawings.
[0020]
First, the offset error in the tracking direction that the optical disk device according to the present invention intends to eliminate will be described. FIG. 6 is a diagram showing a relationship between a header to be read by the optical disk device and a light spot. In FIG. 6, a header section 51 is formed at the time of forming a groove, and is composed of a plurality of header areas 52 composed of a plurality of pits. The center of the pit exists on the same line as the center of the amplitude of the boundary between the groove 53 and the land 54. In this case, the header portions 52 for grooves and the header portions 52 for lands are formed alternately (in a staggered manner).
[0021]
As shown in FIG. 6, tracking control of the spot S of the laser beam emitted from the pickup 2 to the header 52 of the optical disc D is not necessarily performed at the optimum position when reading the header 51. . The readout rate R of each header information of the header section 51 is the highest when offset adjustment is necessary so that it is arranged on the center of the staggered header section 52 like the spot S ′. The optical disk device according to the present invention can optimize the position of the spot S 'and improve the header reading rate by determining the optimum offset value by the sampling process described below.
[0022]
(Initial operation)
Since the offset operation by the sampling process of the optical disc device according to the present invention is performed as a part of the initial operation, the initial operation will be described first, and then the offset operation will be described in detail. In the flowchart of FIG. 3, when the power is turned on and the optical disk D is mounted on the disk tray, the control unit including the RAM 11, the ROM 12, the CPU 13, and the like detects the amount of reflected light to detect the DVD high reflection or the DVD low reflection disk. Is determined (S11). Next, the setting of the DVD-RAM 4.7G is output (S12). Next, the laser is turned on (S13). Then, an offset value is taken in the control by eliminating the tracking error signal by the tracking control loop including the pickup 2, the RF amplifier 3, the tracking servo amplifier 21, the tracking actuator driver 23, and the like (S14). This is a normal offset process that does not involve the sampling process of the present invention in the sampling unit 15.
[0023]
Further, the presence or absence of a header (CAPA) on the optical disk is determined (S15). Then, focus balance adjustment (focus adjustment) is performed (DVD-RAM 4.7G) (S16). Next, tracking balance adjustment is performed (DVD-RAM 4.7G) (S17). Next, the tracking gain is adjusted (DVD-RAM 4.7G) (S18). Then, the offset is determined by a sampling process unique to the present invention, and the details will be described later (S19). Further, the beam spot is moved to an emboss area (corresponding to the innermost periphery) (S20). Then, automatic adjustment in the emboss area is performed (S21). Then, the control data in the emboss area is read (S22).
[0024]
Here, it is finally determined that the medium is a DVD-RAM 4.7G based on the read control data (S23). If it is finally determined that the DVD-RAM is 4.7G, the DMA in the inner and outer peripheral portions is read (S24). This completes the initial processing for the DVD-RAM 4.7G (S25).
[0025]
However, if it is determined in step S23 that the DVD-RAM is 2.6G, the laser is turned off and the setting of the DVD-RAM 2.6G is output (S26). After that, the process is the same as the case of the RAM 4.7G, and the laser is turned on as in step S13, the offset is fetched as in steps S14 and S15, and the presence or absence of a header is determined (S27). Further, similarly to step S16, the focus balance is adjusted (S28). Further, similarly to step S17, the tracking balance is adjusted (S29). Further, similarly to step S18, the tracking gain is adjusted (S30). Then, similarly to step 19, the offset determination involving the sampling process unique to the present invention is performed here, and the details will be described later (S31). Then, after the RF amplitude adjustment of the header section (S32), the DMA is read as in step S24 (S33). Then, the initialization as 2.6G is completed (S34).
[0026]
(Offset determination according to the present invention)
In such initial processing, the optical disc apparatus according to the present invention provides a plurality of offset candidates around the offset reference value obtained by the offset processing by the plurality of tracking servo loops, and sequentially performs the offset processing. At this time, an RF signal or the like detected by the pickup 2 and amplified by the RF amplifier 3 is sampled, and an optimum offset value is determined based on the sampling result. Note that the sampling process of the present invention is performed in step S19 (or step S31 for a 2.6 G disk) during the above-described initial process, as an example. Even if it does, it has the same effect.
[0027]
In the flowchart of FIG. 4, first, the offset determined by the tracking servo loop including the pickup 2, the RF amplifier 3, the tracking servo amplifier 21, and the tracking actuator driver 23 is detected as a reference offset (S41). . This corresponds to the offset processing in step S14 or step S27 in the above-described initial processing. Next, this reference offset is set as a tracking offset adjustment center position P, which is a reference point, as shown in FIG. The offset process is sequentially performed on the offset values of (S42). It is preferable that the offset value candidates are prepared, for example, at ten locations. However, the present invention is not limited to this. The more the number is, the more accurate the offset value is determined, but the required time is longer.
[0028]
Then, when performing the offset processing with each offset value, the PID reading rate at each offset value is obtained and stored in the storage area (S43). Then, when the processing is completed for all the offset value candidates (S44), the offset determining unit 14 sets the offset value having the best read rate R as the final offset value, and sends the offset value to the tracking actuator. It is supplied to the driver 23 (S45). The graph of FIG. 5 shows that the center position P is not always the best reading rate R, and the offset value F 'which is the best point of the reading rate R of the header is obtained. Here, it is also preferable to determine the optimum offset value F 'based on, for example, the best point of the jitter (Jitter) without being limited to the read rate R of the header.
[0029]
Therefore, according to the present invention, it is possible to perform the optimal tracking control by obtaining the optimal offset value by the sampling process, improve the header read rate R and the like, and perform a stable processing operation. An optical disk device can be provided.
[0030]
Those skilled in the art can realize the present invention from the various embodiments described above, but it is easy for those skilled in the art to come up with various modified examples of these embodiments, and the invention has the inventive capability. The present invention can be applied to various embodiments at least. Therefore, the present invention covers a wide range not inconsistent with the disclosed principle and novel features, and is not limited to the above-described embodiments.
[0031]
【The invention's effect】
As described above in detail with reference to the drawings, according to the present invention, it is possible to perform tracking control based on an optimum offset value by sampling processing, and header information is written in a zigzag pattern like a DVD-RAM. It is possible to provide an optical disk device and an optical disk processing method capable of performing a stable operation by accurately reading address information by improving a header read rate of a loaded disk.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a schematic configuration of an optical disk device according to the present invention.
FIG. 2 is a diagram showing an example of a configuration of an optical system of the optical disc device according to the present invention.
FIG. 3 is a flowchart illustrating an example of an initial operation of the optical disc device according to the present invention.
FIG. 4 is a flowchart illustrating a method for determining a tracking offset of the optical disc device according to the present invention.
FIG. 5 is a graph showing a relationship between an offset value F and a reading rate R of the optical disc device according to the present invention.
FIG. 6 is a diagram showing a relationship between a header and a light spot to be read by the optical disc device according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Disc motor, 2 ... Optical pick-up, 3 ... RF amplifier, 4 ... Signal processing apparatus, 5 ... Demodulation part, 6 ... Modulation part, 7 ... Seek servo control unit, 8 ... I / F, 10 ... Host computer, 11 RAM, 12 ROM, 13 CPU, 14 offset setting unit, 15 sampling unit, 21 phase compensation servo amplifier, 22 focus servo amplifier, 23 actuator driver, 24 actuator driver, 25 feed motor , 26: feed motor driver, 27: disk motor driver.

Claims (6)

A tracking control unit that forms a control loop based on a signal output by an optical pickup that detects reflected light from an optical disc and controls a tracking direction of the optical pickup;
Sampling means for providing a plurality of offset values around the offset value by the tracking control means, performing a tracking offset according to the plurality of offset values, and sampling a detection signal of the optical pickup at that time,
Offset determining means for determining a new offset value based on the sampling result by the sampling means, supplying this to the tracking control means, and performing tracking control with the new offset value,
An optical disk device comprising: 2. The optical disk device according to claim 1, wherein the offset determination unit determines an offset value such that a read rate of the header sampled by the sampling unit is optimized. 2. The optical disk device according to claim 1, wherein the offset determination unit determines an offset value that optimizes jitter based on sampling by the sampling unit. A tracking control step of forming a control loop and controlling the tracking direction of the optical pickup, based on a signal output by the optical pickup that detects reflected light from the optical disc;
Providing a plurality of offset values around the offset value by the tracking control step, performing a tracking offset according to the plurality of offset values, a sampling step of sampling the detection signal of the optical pickup at that time,
An offset determining step of determining a new offset value based on the sampling result of the sampling step, supplying this to the control loop of the tracking control step, and performing tracking control with the new offset value,
An optical disk processing method comprising: 5. The optical disk processing method according to claim 4, wherein the offset determining step determines an offset value that optimizes a read rate of the header sampled in the sampling step. 5. The optical disc processing method according to claim 4, wherein the offset determining step determines an offset value such that the jitter based on the sampling in the sampling step is optimized.

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