JP2008516365A - Optical disc device having tilt correction device, and method for reading and / or writing optical disc using optical disc device having tilt correction device - Google Patents

Abstract

  An optical disc apparatus 1 having a tilt correction device that reads and / or writes data from / to the optical disc 100, and measures the tilt at the inner and outer peripheral portions of the optical disc, and the measured tilt value TILTin of the inner peripheral portion And a tilt correction curve (curves 1, 2, 3, 4, 5, 6) for determining tilt correction as a function of the radial position of the optical disc depending on the difference ΔTILTout of the tilt value TILTout of the outer peripheral portion An optical disc apparatus characterized in that at least a part of selectable curves has a shape forming a curve.

Description

  The present invention relates to an optical disc apparatus having a tilt correction device that reads and / or writes an optical disc. The tilt correction device is means for tilting the optical lens holder in order to correct tilt errors.

  The present invention also relates to an optical reading and / or optical writing method using such an optical disc apparatus.

  The optical disk device reads information from the optical disk and / or writes information to the optical disk. Such an optical disc may be, for example, a DVD, DVD + R or BD. The optical disk apparatus reads information from and / or writes information to the optical storage disk using a laser and an optical system that guides the laser to each position on the optical disk. This optical system has a lens holder having a lens. During read and / or write operations, the laser light should be placed on the track and focused on the disk. For this purpose, tracking and focusing means are used. Such an optical disc apparatus is disclosed in, for example, US Patent Application Publication No. 2003/0210628. Means for tilting the lens holder are also provided inside or attached to the lens holder. Tilting, i.e. rotating about the axis, allows improved control of the movement of the lens holder, and as a result, coincides with the optical axis between the lens in the lens holder and the optical medium to be read or written. Improve the condition. Radial tilt is one of the most important parameters related to optical disk write or read performance. Therefore, it is necessary to provide an optimal or near-optimal radial tilt during optical disc writing and reading processes. One radial tilt calibration method used today is based on jitter measurements during the write or read process. This is because calibration based on such jitter measurements gives the highest accuracy. During the writing and reading process, the tilt error is specified, the tilt correction signal is calculated from the specified tilt error, and the tilt correction signal is transmitted to the tracking means so that the tilt error is corrected. By implementing proper alignment, tilt correction is performed. One drawback of this method is that the write or read process is often forced to stop because tilt calibration must be performed. After this calibration process, the writing process or the reading process can be resumed. As a result of this known procedure, throughput is reduced. In Japanese Patent Laid-Open No. 10-222860 “Optical Disc Playback Method and Optical Disc Device”, the tilt of the disc is specified by two tilt sensors for the inner peripheral portion and the outer peripheral portion, and the intermediate tilt value is calculated for the intermediate sector of the disc. An optical disc apparatus is described in which tilt correction is performed based on measured tilts at the inner and outer peripheries.

  Although the apparatus and method described in JP-A-10-222860 has been described as eliminating the need for tilt correction during the writing and / or reading process, the inventor of the present invention has found many situations. I realized that this is not the case.

  One object of the present invention is to provide an improved optical disk apparatus and an improved optical reading and / or optical writing method using the optical disk apparatus.

  For the above purpose, the optical disc apparatus of the present invention is dependent on the difference between the measured inclination of the inner peripheral portion and the outer peripheral portion of the optical disc. A selection device for selecting an inclination correction curve for determining inclination correction as a function of the radial position, wherein at least some of the selectable curves have a curvilinear shape .

  In the apparatus and method described in Japanese Patent Application Laid-Open No. 10-222860, the inclination value is determined by linear interpolation between the inclination of the inner peripheral portion and the inclination of the outer peripheral portion. The inventor of the present invention has noticed one drawback of this known apparatus and method that the resulting correction is often far from the actual slope and may even differ in sign. In the disc and the method according to the present invention, a selection device is used that has the difference in inclination between the inner periphery and the outer periphery as one input information. One curve is selected based on the difference in the slope values. At least some of the selectable curves for tilt correction are those that form a curve as a function of radial position, ie, are not linearly dependent.

  Research has shown that the radial tilt of an optical disc has several different shapes. The radial inclination value is often a curve function of the disk radial position. When the linear function is used as in the apparatus and method of Japanese Patent Laid-Open No. 10-222860, the inclination error is often corrected only partially, and it may even increase rather than reduce the error.

  In some preferred embodiments, a single measuring device is used to measure the tilt at the inner and outer perimeters. In Japanese Patent Application Laid-Open No. 10-222860, two inclination sensors arranged on the inner peripheral portion and the outer peripheral portion are used. By using a single measuring device, tilt identification errors due to differences between sensors, such as differences in temperature, accuracy and / or bias error, can be avoided, thus increasing the accuracy of tilt correction. For example, using a tilt calibration based on jitter allows the use of a single measuring device.

  In some preferred embodiments, the selection device is selected from a slope value, rotation speed, operation type, disk type, humidity, temperature, average laser power, and operation time at either the inner or outer periphery. To have at least one additional input information.

  Even though the slope values at the inner and outer perimeters are specified, the curve showing the dependence of the slope as a function of the radial position may depend at least in part on one or more additional parameters. The selection device may be in the form of an algorithm embedded in the program code.

  In some preferred embodiments, the selection device has at least one additional input due to temperature and / or humidity. These parameters have a non-negligible effect on the slope curve. This embodiment is best combined with an embodiment where the device includes a single measuring device for measuring the tilt at the inner and outer perimeters.

  In a further embodiment, the disc device is characterized in that it has means for specifying the tilt at the median circumference of the disc to determine the curve parameters.

  In these embodiments, depending on the case, the inclination in the middle portion of the disk is specified. This specification is used to specify the curve parameters, that is, the degree of bending of the curve that specifies the slope between the inner periphery and the outer periphery.

  In these embodiments, in some cases, the shape of the curve is re-determined by measuring the slope value at the middle periphery. This enables more accurate tilt correction. Basically, this procedure can be equated with a gauging procedure in which the values for one or more curves are gauged, and in some cases the slope value in the intermediate sector is measured.

  Preferably, the means for specifying the inclination in the middle peripheral part is a single measuring device for the inclination in the inner peripheral part and the outer peripheral part. By using the same equipment and techniques for all tilts, any problems due to differences in measurement techniques or equipment are avoided.

  Within the concept of the invention, the term “selection device” and similar terms are to be understood in a broad sense, for example, any piece of hardware (such as a selection device), performing the selection function described above. Any circuit or sub-circuit designed to do, any piece of software designed or programmed to perform a selection operation according to the present invention (a computer program or sub-program or set of computer programs, including algorithms or program codes) ), Or any combination of one or a combination of hardware and software pieces operating as such, and should not be limited to the exemplary embodiments given below Absent. One program may be a combination of a plurality of functions.

  One method according to the present invention is a method for performing writing or reading on an optical disk using an optical disk device, in which inclination values at the inner and outer peripheral portions of the optical disk are measured, and the measured inner and outer peripheral portions are measured. Depending on the difference in inclination value, an inclination correction curve for determining inclination correction as a function of the radial position of the optical disc is selected, and at least a part of the selectable inclination correction curves is a curved line. The tilt correction curve selected during writing or reading of the optical disc is the method used for tilt correction.

  In some preferred embodiments, the above method according to the present invention may be combined with any of the steps described above in connection with the apparatus according to the present invention (eg input of other parameters such as temperature). .

  Hereinafter, the above and other aspects of the present invention will be described with reference to embodiments. The figure is not drawn to scale. Throughout the drawings, identical elements are designated with identical reference numerals.

  FIG. 1 schematically shows a device known from US 2003/0210628.

  FIG. 1 shows tilt correction by detecting jitter during reproduction of the optical disc 100.

  When reading of the optical disc 100 is started by the optical disc apparatus 1, the controller 106 monitors the jitter of the reproduction data at a constant time interval. While the optical disc 100 is being read, the jitter changes constantly. The optical pickup 101 reads the recording signal from the optical disc 100, and the reproduction signal detector 104 detects only the reproduction signal from the signals read by the optical pickup 100. The jitter detector 105 detects the jitter amount of the reproduction signal detected by the reproduction signal detector 104, and the detected jitter amount is input to the controller 106. The amount of jitter detected from the optical disc 100 at a certain time interval during playback of the optical disc 100 is compared with the reference jitter amount stored in the storage unit. When the detected jitter amount is larger than the reference jitter amount, a signal for minimizing the jitter amount is transmitted to the tilt driving IC 107, and the tilt driving IC 107 operates the tilt driving device 103 that tilts the guide 102.

  One drawback of this known apparatus and method is that the write or read process is often forced to stop because tilt calibration must be performed. After this calibration process, the writing process or the reading process can be resumed. As a result of this known procedure, throughput is reduced.

  In Japanese Patent Laid-Open No. 10-222860 “Optical Disc Playback Method and Optical Disc Device”, the tilt of the disc is specified by two tilt sensors for the inner peripheral portion and the outer peripheral portion, and the intermediate tilt value is calculated for the intermediate sector of the disc. An optical disc apparatus is described in which tilt correction is performed based on measured tilts at the inner and outer peripheries.

  Although the apparatus and method described in JP-A-10-222860 has been described as eliminating the need for continuous tilt correction during the writing and / or reading process, the inventor of the present invention I realized that in many situations this is not the case.

  FIG. 2 shows the measured tilt for various DVD + R discs as a function of the radial position of the disc. The curve shown is the curve showing the slope for the three DVD + R devices as a function of the radial position, and the dotted line shows the linear interpolation between the slope value of the inner circumference and the slope value of the outer circumference. ing.

  FIG. 2 shows that linear interpolation in many parts of the disc gives a fairly decent slope value. The uncompensated tilt error, i.e. the difference between the curve and the dotted line, is often larger than the curve value, and for the DVD + R_2 curve and the DVD + R_1 curve, even the sign is erroneous in a significant part. This means that applying gradient correction according to linear interpolation exacerbates the problem rather than solving the gradient problem. Thus, even with this known apparatus and method, there is still a need to use continuous radial tilt correction with disadvantages (eg, tilt correction described in US 2003/0210628). Often done.

  In the apparatus and method according to the present invention, the difference between the tilt value at the inner periphery and the tilt value at the outer periphery of the disk is measured, and the result of the measured difference in tilt in the radial direction depends on ΔTILT = TILTin−TILTout. Thus, the curve shape is selected. The device in this example includes a selection device that is generally in the form of a flowchart of the slope prediction algorithm shown in FIG.

  Depending on the difference in measured slope values, prediction curves 1 to 6 are selected in this example (not a limiting example). At least some of these curves are curves that are not linearly dependent. With respect to a linearly dependent curve, that is, a straight line connecting the start point and the end point, the definition itself of the start point value TILTin and the end point value TILTout determines the curve, and therefore it is not necessary to select the curve.

  In addition to the slope difference ΔTILT, the selection device may have more additional input information that affects the selection of the curve. These additional input information may influence the value of x or y, i.e. the cut-off value for determining the selection of the curve, e.g. the degree of bending or to one or more of the curves 1 to 6 It may affect the parameters of the curve, such as the introduction of higher order coefficients, or may affect both of these parameters.

  In some embodiments, the slope TILTin at the inner circumference and the slope TILTout at the outer circumference are measured using a single measuring device or measurement procedure. In Japanese Patent Application Laid-Open No. 10-222860, two inclination sensors arranged on the inner peripheral portion and the outer peripheral portion are used. Using a single measuring device avoids tilt identification errors due to sensor-to-sensor differences such as temperature, accuracy, and / or bias error differences, increasing tilt correction accuracy while reducing cost Is done. For example, using a tilt calibration based on jitter allows the use of a single measuring device.

  In some embodiments, one piece of additional input information is a slope value at either the inner periphery or the outer periphery.

  Of course, if the selection device has two pieces of input information, the measured value at the inner periphery and the measured value at the outer periphery, and the curve is selected depending on the set of these values (TILTin; TILTout) Such forms are within the scope of the present invention as claimed. This is because the resulting curve depends on both values and therefore inherently depends on the combination of the difference in slope and the slope value at either the inner or outer circumference. is there.

  The selection of the curve may be a quantized selection. That is, in some embodiments, there is a limited number of separate curves (one or more curves; for example, six curves as in the example above), one of which is a slope It is selected depending on the difference value ΔTILT and possibly further input information. Alternatively, the curve may be selected by a parameter depending on input information. Mixed forms may also be used. For example, for small difference values Δtilt, a linearly dependent curve is selected, and for somewhat larger differences, a standard two-way such that the parameter does not depend on the values of ΔTILT, TILTin and / or TILTout. A higher order curve shape with higher order parameters depending on ΔTILT, TILTin and / or TILTout, and / or additional input information is selected for a larger Δtilt. TILTin and TILTout may be measured in different ways.

  For a written / ROM disc, the slope as a function of jitter can be measured inside and outside the disc during the startup phase of the disc.

  For blank recordable / rewritable discs, the measurement of the inner / outer radial tilt is performed, for example, during an OPC (Optimum Power Control or Calibration) procedure before writing data on the disc. Can be implemented in The OPC procedure is a known procedure in which test writing is performed in the test area at the start and end.

  We start OPC at the recording speed inside the disc. First, OPC is performed, and writing is performed on at least three tracks using laser power from the first OPC. Subsequently, radial tilt calibration is performed on the center track of the three written tracks. After tilt calibration, power must be recalibrated due to tilt changes. This procedure is repeated outside the disc. This results in good radial tilt values on the inside and outside of the disc.

  Another method that is sometimes used, especially for blank disks, is the square of the radial error signal (ie, push-pull signal). Such a method can also be used within the technical scope of the present invention to obtain tilt values at the inner and outer perimeters of the disc. However, compared to OPC procedures, these methods often give relatively low accuracy slope values.

  Although the present invention has been described above with reference to specific embodiments for describing the present invention, these embodiments should not be construed as limiting the present invention. The present invention may be implemented as hardware, firmware or software, or a combination thereof. Some embodiments are within the scope of the following claims.

  As an example, the selection device has at least one further input for temperature and / or humidity. These parameters have a non-negligible effect on the slope curve. This embodiment is best combined with an embodiment where the apparatus includes a single measuring device for measuring the inner and outer slopes.

  In another embodiment, the disk device is a device configured to perform a gauging procedure in which a slope at the median circumference of the disk is established to determine the curve parameters.

  In the concept of the present invention, it is understood that the terms “inner circumference” and “outer circumference” are not necessarily strictly interpreted as referring to only the innermost and outermost parts of the disc. I want to be. “Inner perimeter” refers to the beginning of the disc or a portion close to the start, and “outer perimeter” refers to the end of the disc or the portion close to the end. These parts need not be the exact start and end of the track, but may be.

  The present invention is embodied in each of the novel features and combinations thereof. Any reference signs should not be construed as limiting the claim. The word “comprising” or “comprising” does not exclude the presence of elements other than those listed in a claim. The word “one” preceding an element does not exclude the presence of a plurality of such elements. The drawings and embodiments are presented by way of example and do not limit the scope of the claims. For example, although the coil is wound on the holder in the figure, there may be an embodiment in which the coil is provided on the attached foil by printing or other techniques.

Schematic perspective view of an optical disc apparatus according to the prior art Graph showing the slope value as a function of radius position Flowchart illustrating the slope prediction algorithm

Claims (5)

An optical disk device having a tilt correction device for reading and / or writing to an optical disk,
A measuring device for measuring the inclination of the inner and outer peripheral parts of the optical disc;
A selection device that selects a tilt correction curve that determines tilt correction as a function of the radial position of the optical disc, depending on the measured difference in tilt between the inner and outer perimeters;
An optical disc apparatus, wherein at least a part of the selectable curves has a curved shape.   The selection device is selected from at least one of the inclination value, the rotation speed, the operation type, the disk type, the humidity, the temperature, the average laser power, and the operation time in either the inner periphery or the outer periphery. 2. The optical disc apparatus according to claim 1, further comprising two additional input information.   2. The optical disk apparatus according to claim 1, further comprising a single measuring device that measures inclinations in the inner peripheral portion and the outer peripheral portion.   2. The optical disc apparatus according to claim 1, further comprising means for specifying an inclination in a middle portion of the disc in order to determine a curve parameter. A method of writing or reading an optical disc using an optical disc device,
The inclination values at the inner periphery and the outer periphery of the optical disc are measured,
Depending on the difference between the measured slope values of the inner and outer perimeters, a tilt correction curve is selected that determines tilt correction as a function of the radial position of the optical disc,
At least a part of the selectable inclination correction curves is a shape forming a curve,
The method wherein the selected tilt correction curve is used for tilt correction during writing or reading of the optical disc.

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