Patent application number | Description | Published |
20080205246 | OPTICAL HEAD AND OPTICAL DISK DEVICE - An interference type optical head and an optical disk device that can easily adjust an optical path length difference of a couple of lights, ensure higher signal amplification effect, and are suitable for reduction in size are provided in order to improve a regeneration signal quality with amplification of signal in the case where reflectivity of each layer must be lowered and relative noise for the signal increases because read speed is high in a multilayer optical disk. In view of essentially improving an S/N ratio of the regeneration signal in high-speed rotation of a multilayer disk, a plurality of interference phases are generated and an optical system for differential calculation has been reduced in size with an angular selective polarization conversion element in the optical disk device for amplifying the signal with interference of the light not radiated to the disk with the reflected light from the disk. Moreover, adjustment of reflection mirror angle of the reference light is no longer required by using a corner cube prism as the reference light reflection mirror and highly accurate signal detection can also be realized with a simplified structure. | 08-28-2008 |
20080205255 | Optical disk - The invention provides an optical disk that enables high-speed reproduction of address signals. A wobble address system for optical disk supports various types of synchronization, such as phase synchronization, bit synchronization, word synchronization, etc., to be established easily with high detection reliability with the use of an self-orthogonal code. Thus, the invention provides a method for easily synchronizing an address signal, i.e., high-speed reproduction of the address signal. Further, by virtue of an efficient modulation system of the address signal and redundancy thereof, it becomes possible to detect address information with high reliability. This capability is particularly effective in optical recording/reproduction with a blue light source whose signal light quantity and reproduction quality are prone to reduce. Moreover, other additional data of the address data is preserved in the wobbles, which provides medium information to a rewritable optical disk without using embossed pits such that a high-reliability disk (with enhanced security) is realized with a low cost and easily. | 08-28-2008 |
20080219109 | INFORMATION RECORDING AND RETRIEVAL METHOD, AND ITS APPARATUS - Provided is a recording and retrieval apparatus for a multi-layer optical disk. A multi-layer optical disk in which a plurality of recording layers and a single servo layer are combined to form a set is used. A spot for the servo layer and a spot for the recording layers are turned on in a time-sharing manner. Servo signal detection areas are formed discretely in the servo layer. The servo signal detection areas and data recording areas are provided so as not to overlap each other when viewed from the spot incident side. Thus, separation of data from each of the layers can be done by even a single photodetector without interference. | 09-11-2008 |
20080273450 | Optical disk - The invention provides an optical disk that enables high-speed reproduction of address signals. A wobble address system for optical disk supports various types of synchronization, such as phase synchronization, bit synchronization, word synchronization, etc., to be established easily with high detection reliability with the use of an self-orthogonal code. Thus, the invention provides a method for easily synchronizing an address signal, i.e., high-speed reproduction of the address signal. Further, by virtue of an efficient modulation system of the address signal and redundancy thereof, it becomes possible to detect address information with high reliability. This capability is particularly effective in optical recording/reproduction with a blue light source whose signal light quantity and reproduction quality are prone to reduce. Moreover, other additional data of the address data is preserved in the wobbles, which provides medium information to a rewritable optical disk without using embossed pits such that a high-reliability disk (with enhanced security) is realized with a low cost and easily. | 11-06-2008 |
20080291562 | RECORDING METHOD FOR RECORDING DATA ON A RECORDING MEDIUM - If a large minimum data unit for recorded data is used to record a small data amount of management information, the recording time is long, and furthermore when a WO (write once) is used as the recording medium, the number of recording operations which can be performed is restricted. | 11-27-2008 |
20080291791 | RECORDING METHOD FOR RECORDING DATA ON A RECORDING MEDIUM - If a large minimum data unit for recorded data is used to record a small data amount of management information, the recording time is long, and furthermore when a WO (write once) is used as the recording medium, the number of recording operations which can be performed is restricted. | 11-27-2008 |
20080291792 | RECORDING METHOD FOR RECORDING DATA ON A RECORDING MEDIUM - If a large minimum data unit for recorded data is used to record a small data amount of management information, the recording time is long, and furthermore when a WO (write once) is used as the recording medium, the number of recording operations which can be performed is restricted. | 11-27-2008 |
20080291812 | Optical disk - The invention provides an optical disk that enables high-speed reproduction of address signals. A wobble address system for optical disk supports various types of synchronization, such as phase synchronization, bit synchronization, word synchronization, etc., to be established easily with high detection reliability with the use of an self-orthogonal code. Thus, the invention provides a method for easily synchronizing an address signal, i.e., high-speed reproduction of the address signal. Further, by virtue of an efficient modulation system of the address signal and redundancy thereof, it becomes possible to detect address information with high reliability. This capability is particularly effective in optical recording/reproduction with a blue light source whose signal light quantity and reproduction quality are prone to reduce. Moreover, other additional data of the address data is preserved in the wobbles, which provides medium information to a rewritable optical disk without using embossed pits such that a high-reliability disk (with enhanced security) is realized with a low cost and easily. | 11-27-2008 |
20080297935 | RECORDING METHOD FOR RECORDING DATA ON A RECORDING MEDIUM - If a large minimum data unit for recorded data is used to record a small data amount of management information, the recording time is long, and furthermore when a WO (write once) is used as the recording medium, the number of recording operations which can be performed is restricted. | 12-04-2008 |
20080316876 | Optical disk - The invention provides an optical disk that enables high-speed reproduction of address signals. A wobble address system for optical disk supports various types of synchronization, such as phase synchronization, bit synchronization, word synchronization, etc., to be established easily with high detection reliability with the use of an self-orthogonal code. Thus, the invention provides a method for easily synchronizing an address signal, i.e., high-speed reproduction of the address signal. Further, by virtue of an efficient modulation system of the address signal and redundancy thereof, it becomes possible to detect address information with high reliability. This capability is particularly effective in optical recording/reproduction with a blue light source whose signal light quantity and reproduction quality are prone to reduce. Moreover, other additional data of the address data is preserved in the wobbles, which provides medium information to a rewritable optical disk without using embossed pits such that a high-reliability disk (with enhanced security) is realized with a low cost and easily. | 12-25-2008 |
20090040897 | Reproducing signal measuring method, signal reproducing apparatus, and optical recording medium - Regarding a signal recorded with a first frequency in a recording area on a specific first recording layer and a signal recorded with a second frequency different from the first frequency in a recording area on a second recording layer which might cause interlayer crosstalk in relation to the first recording layer, a reproducing signal measurement method for a multilayer optical recording medium having at least three recording layers includes reproducing the signal recorded in the recording area on the first recording layer, separating signals recorded respectively with the first and second frequencies, discriminating signal amplitude of the first frequency and a maximum value in signal amplitude of the second frequency, and calculating a signal amplitude ratio between them to measure interlayer crosstalk contained in the signal reproduced from the recording area on the first recording layer. Thus, the interlayer crosstalk quantity caused by unnecessary light can be measured quantitatively. | 02-12-2009 |
20090086602 | OPTICAL INFORMATION REPRODUCING METHOD, OPTICAL INFORMATION REPRODUCING APPARATUS AND OPTICAL INFORMATION RECORDING MEDIUM - Reproduction on an optical recording medium having plural information layers involves the problem of distortion occurring due to interlayer crosstalk and hence deterioration in the quality of a readout signal. At a predetermined radius, a correction coefficient for correcting the amount of fluctuation components is calculated from a readout signal with distortion due to the interlayer crosstalk, and then is stored. The stored correction coefficient is used to eliminate crosstalk components and to correct readout signal fluctuation during reproduction on a predetermined area. In this way, the original readout signal without interlayer crosstalk components can be obtained, so that good-quality reproduction characteristics can be achieved. | 04-02-2009 |
20090279412 | Information Recording Media, A Method For Recording/Reproducing Information, An Apparatus For Recording/Reproducing Information - An information recording medium includes a plurality of layers for recording or reproduction of information by irradiation, wherein each of the layers includes an emboss portion and wobble portion including wobbles of a first frequency and a second frequency that is different from the first frequency. The first frequency is constant in each of the plurality of layers, and a different signal is obtained from the wobbles of the first and second frequencies in each of the plurality of layers. | 11-12-2009 |
20090285071 | RECORDING METHOD, RECORDING MEDIUM, AND RECORDING SYSTEM - An information recording medium and an optical recording system allow target information (such as an ad) to be displayed without requiring changes in hardware or physical specifications. The recording medium comprises a recording-limited area in which recording is made possible by canceling the limit after an instruction is issued for displaying the target information. | 11-19-2009 |
20090316539 | OPTICAL HEAD AND OPTICAL DISK APPARATUS - There are provided an interference type optical head and an optical disk apparatus, which have a signal amplification effect and which can be manufactured in sizes comparable to conventional optical heads. In an optical disk apparatus that performs signal amplification by making a light, which is used as a reference light without being irradiated on an optical disk and, interfere with reflected light from the optical disk, a corner cube prism that reflects the reference light is mounted on the same actuator as an objective lens. Further, there is provided a movable portion that adjusts the optical path length of the interfering light in accordance with the kind of optical disk being read and the recording layer being read. A wedge prism may be used for the movable portion, and a spherical aberration correction lens and an optical path length adjusting component may be moved integrally. Thus, a stable amplification effect may be obtained while keeping the overall size comparable to conventional apparatuses. | 12-24-2009 |
20100017679 | RECORDING AND REPRODUCING DATA TO/FROM A RECORDING MEDIUM HAVING A USER DATA AREA AND AN INFORMATION AREA FOR STORING INFORMATION ABOUT THE RECORDING MEDIUM - If a large minimum data unit for recorded data is used to record a small data amount of management information, the recording time is long, and furthermore when a WO (write once) is used as the recording medium, the number of recording operations is restricted. To solve the above problems, the present invention records data in a management area in units smaller than ordinary units for recorded data to suitably record information in a limited management area and thereby efficiently use the user data area. At that time, the present invention simplifies interleave processing usually applied to ordinary recorded data, and performs the simplified interleave processing on a data structure (for data of small size) of the present invention so as to ensure the signal processing compatibility between the ordinary data and data having the data structure according to the present invention. | 01-21-2010 |
20100142354 | OPTICAL PICKUP DEVICE - In an optical pickup capable of removing inter-layer crosstalk, a dark line that may appear in a central portion of a beam is removed. Thereby, an error in a data signal is reduced. Reflected light from a multi-layer disc is split into two parallel bundles with a splitting optical system in a way that the light is split at a central line. Thereby, when reflected light from a target layer is focused, the reflected light is not influenced from an attenuation element provided on an optical axis. | 06-10-2010 |
20100188961 | Optical Disc Apparatus - An optical disc apparatus includes a laser diode, a first optical component which branches beams from the laser diode into a first beam and a second beam, an objective lens which focuses the first beam on an optical information recording medium, an actuator which drives the objective lens in an optical axis direction, a reference mirror provided in an optical path of the second beam, an optical path length varying unit which varies an optical path length of the second beam, a first photo detector, a second photo detector, a second optical component which branches beams obtained by combining the first beam which is reflected by the optical information recording medium and the second beam which is reflected by the reference mirror and which makes the branched beams incident on the first and second photo detectors, and a signal processing part. | 07-29-2010 |
20100214896 | MULTILAYERED OPTICAL DISC AND ITS RECORDING METHOD - In an optical disc having N (N is an integer larger than or equal to 3) information recording layers of rewritable or recordable type, each of the information recording layers includes an test area to adjust conditions for recording and reproduction and the test areas are arranged so that the radial positions thereof overlap those of other layers. Recording test is performed only to an area smaller than or equal to 1/N of the test area of each layer and any other area is always unrecorded (write inhibited). | 08-26-2010 |
20100226239 | MULTILAYER OPTICAL DISC - A multilayer optical disc which has three or more recording layers and enables easy positioning of a focused beam spot onto a particular recording layer in which a BCA is disposed. An inter-layer distance between a particular recording layer and a recording layer adjacent to the particular recording layer is larger than the other inter-layer distances in which, at the focused beam spot positioning, the focused beam spot traverses the said adjacent recording layer earlier than the other recording layer adjacent to the particular recording layer. | 09-09-2010 |
20100271921 | OPTICAL INFORMATION RECORDING MEDIUM, OPTICAL INFORMATION RECORDING/REPRODUCING DEVICE AND OPTICAL INFORMATION RECORDING/REPRODUCING METHOD - A holographic recording medium in which information can be reproduced by phase conjugate beam without requiring a mirror for obtaining the phase conjugate beam and its driving part and recording density is not reduced. The recording medium includes a recording layer in which an interference pattern is recorded and a light absorption/transmission layer which can be reversibly changed to be in a first state where signal beam and reference beam passed through the recording layer are absorbed at the time of recording of information and a second state where the reference beam is transmitted at the time of reproduction of information, and the reference beam transmitted through the light absorption/transmission layer is reflected by a reflection layer to produce the phase conjugate beam. | 10-28-2010 |
20100309764 | MULTILAYERED OPTICAL DISK AND ITS RECORDING METHOD - To provide a recording method of a multilayered optical disk having three or more recording layers, for performing recording while securing sufficient test areas without reducing user data areas, and while suitably controlling the power of laser beam irradiated onto each of the layers. The method uses an optical disk which has at least a first recording layer and a second recording layer located on the side nearer to the light incident surface than the first recording layer, and which respectively has a first test area configured by a plurality of segments in the first recording layer and a second test area configured by a plurality of segments in the second recording layer. Further, the method is configured such that there is defined beforehand a predetermined radial distance L corresponding to relative precision of radial positions between the plurality of layers and the optical spot diameter, and that when an arbitrary segment in the second test area is test-recorded, a segment in the first test area, the radial distance of which from the recorded test area in the second test area is within the range of the predetermined radial distance L, is set as a segment in which the test recording is not performed. Thereby, even in the case where the radial positions of the test areas of the plurality of layers are substantially overlapped with each other, it is possible to precisely perform the learning of optical power. For this reason, it is possible to use and arrange the test areas of the plurality of layers without waste. Further, the learning of recording power can be performed without receiving the influence of the recorded state of the other layers, so that the accuracy of the learning of recording power can be improved. Thereby, it is possible to improve the quality of recording and the reliability of recorded data. | 12-09-2010 |
20100329097 | MULTILAYERED OPTICAL DISC AND ITS RECORDING METHOD - Information about a variation ratio of the recording power sensitivity, which varies depending on whether another recording layer is recorded or unrecorded, is recorded onto a disc control information area (DI) in advance. Moreover, based on this recording-power-sensitivity variation information, recording-power compensation is performed. The corresponding recording-power compensation method is classified into three types: (1) type in which the recording is performed by judging the recorded/unrecorded states of another layer, (2) type in which, instead of judging the recorded/unrecorded states of another layer, the recording is performed using an intermediate power of the optimum powers for both of the recorded/unrecorded states, and (3) combination of (1) and (2). | 12-30-2010 |
20110002204 | POWER ADJUSTMENT METHOD, INFORMATION WRITE METHOD AND INFORMATION WRITE MEDIUM - A write power adjustment method makes it possible to set optimum write power with high precision. Trial writing is conducted by using write power Pw,m (where m is an integer) of a plurality of kinds, and a modulation M,m associated with each write power is calculated. Optimum asymptotic power Pasy-opt is calculated by performing predetermined computation by using reference asymptotic power Pasy-ref and reference write start power Pws-ref which are previously determined for each medium. An evaluated value S,m=M,m×(Pw,m−Pasy-opt) is calculated by using the optimum asymptotic power Pasy-opt. Write power Pw that makes the evaluated value S equal to zero when applying straight line approximation to a relation between the write power Pw,m and the evaluated value S,m is calculated as optimum write start power Pws-opt. And optimum write power Pw-opt is found by performing predetermined computation on the optimum write start power Pws-opt. | 01-06-2011 |
20110043943 | MICROWAVE ASSISTED MAGNETIC RECORDING HEAD AND MICROWAVE ASSISTED MAGNETIC RECORDING APPARATUS - With respect to microwave assisted magnetic recording, high-density information recording is performed by forming a favorable write magnetic domain on a recording medium. The recording medium is placed in a magnetically resonant state by generating a microwave, and information is recorded. A recording medium | 02-24-2011 |
20110080815 | OPTICAL RECORDING AND REGENERATING APPARATUS - The present invention achieves an optical recording and regenerating apparatus focusing two opposed beams of light at a same place in an optical recording medium to record a standing wave generated by interference of the two beams of light. In the apparatus, phase information is recorded in the optical recording medium by a phase modulating means for modulating phase of one of the two beams of light. The generation reference light generated from a light source is allowed to interfere with regenerated light generated by projecting one of the two beams of light onto the optical recording medium to generate three or more beams of interfering light having different interference phases are simultaneously generated. The three or more beams of interfering light are then detected, and the phase modulated by the phase modulating means is demodulated from an output of the detector. | 04-07-2011 |
20110090770 | THERMAL-ASSISTED-MAGNETIC-RECORDING HEAD AND MAGNETIC RECORDING SYSTEM USING THE THERMAL-ASSISTED-MAGNETIC-RECORING HEAD - Provided is a thermal-assisted-magnetic-recording head capable of directing, to a magnetic recording medium, light in which the spot size is reduced to submicron order with high total optical propagation efficiency. A light coupling unit that guides light emitted from the light source into a magnetic head and a high-refractive-index core that couples with the light guided by the light coupling unit to lead the light to an air bearing surface are arranged in the magnetic head. The light coupling unit includes a plurality of thin-film-like cores that are separated from each other by a clad material. An upper part of the high-refractive-index core is placed between two thin-film-like cores. | 04-21-2011 |
20110141867 | OPTICAL INFORMATION RECORDING/REPRODUCING APPARATUS AND OPTICAL INFORMATION REPRODUCING APPARATUS - In a system of detecting an interference light with a light not irradiated onto an optical disc to increase the S/N ratio, it is difficult to stably acquire a reproduced signal with a simple configuration. Since the recording density is not improved, an improvement in transfer rate is difficult. In an optical information recording/reproducing apparatus where two optical beams face each other and are focused at the same place of a recording medium to record a standing wave developed by interference of the two optical beams, a phase difference of the two optical beams is modulated in a multiple stage and recorded. During reproduction, an interference light of a reproduced light from the recording medium and another reproduction reference light is detected as a reproduced signal, and a phase servo control stabilizing the phase of interference during reproduction by using a low frequency component of the reproduced signal is conducted. | 06-16-2011 |
20110216436 | INFORMATION RECORDING DEVICE - Excellent magnetization switching of a magnetic recording medium is promoted in microwave assisted magnetic recording to provide a highly-reliable high-density information recording device. A receded section from an air bearing surface is arranged at an end section in a write track width direction on an FGL laminate film for generating a high-frequency field. Alternatively, a cross section of the FGL laminate film (plane perpendicular to the direction of the flow of the electric current) has an inverted trapezoid shape or has a structure in which the area of the cross section increases with distance from the main pole. Since an excellent recording pattern is formed on the recording medium, areal recording density in the information recording device can be increased, and the reliability can be improved at the same time. As a result, the cost can be reduced. | 09-08-2011 |
20110299374 | MULTILAYER OPTICAL DISC - A multilayer optical disc which has three or more recording layers and enables easy positioning of a focused beam spot onto a particular recording layer in which a BCA is disposed. An inter-layer distance between a particular recording layer and a recording layer adjacent to the particular recording layer is larger than the other inter-layer distances in which, at the focused beam spot positioning, the focused beam spot traverses the said adjacent recording layer earlier than the other recording layer adjacent to the particular recording layer. | 12-08-2011 |
20110317532 | Power Adjustment Method, Information Write Method And Information Write Medium - An evaluation method and print wire method which includes (a) fitting a modulation characteristic formula M,m=Msat (1−(Pws−Pasy)/(Pw,m−Pasy)) having a saturated modulation Msat, write start power Pws, and asymptotic power Pasy as parameters to a relation between a plurality of kinds of write power Pw,m and a modulation M,m which is obtained from a signal amplitude of a trial-written signal, and finding an index value of an error; and (b) evaluating whether or not the relation between the write power and the modulation is valid for write power adjustment by using the index value of the error and a predetermined value the print write method further including (c) setting the write power based upon the result of evaluating and executing a write power process with the set write power. | 12-29-2011 |
20110317535 | Multilayered Optical Disk And Its Recording Method - A multilayered optical disk an information recording method and information reproducing method utilizing the disk includes three or more recordable or rewritable information recording layers, which has, among the plurality of information recording layers, at least a first recording layer and a second recording layer located on a side nearer to a light incident surface than the first recording layer, and which respectively has a first test area configured by a plurality of segments in the first recording layer, a second test area configured by a plurality of segments in the second recording layer, and comprising a specific area in which there is recorded information used to determine whether or not the respective segments in the first test area can be used. | 12-29-2011 |
20120182842 | THERMAL-ASSISTED-MAGNETIC-RECORDING HEAD AND MAGNETIC RECORDING SYSTEM EQUIPPED WITH THE SAME - Provided is a thermal-assisted-magnetic-recording head capable of irradiating a magnetic recording medium with light with a spot size reduced on the submicron order with high utilization efficiency. A spot size converter | 07-19-2012 |
20120250483 | WRITE POWER ADJUSTMENT METHOD AND INFORMATION RECORDING METHOD - In write power adjustment for an optical disc having a plurality of information storage layers, data of trial writing is varied by the influence of layers other than a target layer. It is difficult, therefore, to determine optimal write power. A modulation M[m] is obtained from a reproduction signal amplitude of a signal subjected to the trial writing performed with use of write powers Pw[m] (m being an integer) of a plurality of kinds. At least an optimum write power intercept Pint_opt is determined by fitting a relation between the Pw[m] and the M[m] by a modulation characteristic formula M=Masy×(1−(Pint−Pasy)/(Pw−Pasy)) having an asymptotic modulation Masy, a write power intercept Pint, and an asymptotic write power Pasy as parameters. Approximation accuracy by the fitting and/or quality of the trial writing signal are evaluated with use of at least the M[m], the modulation characteristic formula, and the Pint_opt. An optimum write power Pw_opt is calculated by performing a specified operation at least with use of the Pint_opt. | 10-04-2012 |
20120327751 | MAGNETIC RECORDING SYSTEM USED THERMAL-ASSISTED-MAGNETIC- RECORDING HEAD - A thermally assisted recording magnetic head is provided in which a magnetic recording medium can be irradiated with light having a spot size reduced in the submicron order with high total optical propagation efficiency. In a magnetic head, a spot size converter that propagates the light from an optical source in the magnetic head is provided adjacent to a main pole. The spot size converter includes a cover layer having a refractive index lower than that of a clad material and formed in contact with the optical waveguide core, and is formed in a shape composed of a substantially rectangular shape in a light traveling direction and a tapered shape where the width is increased toward the bottom surface of the magnetic head. The optical waveguide core having the cover layer formed is vertically interposed between multi-mode-thin-film-like cores that can excite a first or higher-order optical waveguide mode. | 12-27-2012 |
20130028058 | ENERGY-ASSISTED MAGNETIC RECORDING HEAD AND MAGNETIC RECORDING DEVICE - In a case in which a microwave-assisted magnetic recording system is applied to a shingled write system for recording with high density, the width of a high-frequency generation element is narrower than a track width of main pole, and both steep parts of magnetic field gradients | 01-31-2013 |
20130107678 | APPARATUS AND METHOD FOR INSPECTING THERMALLY ASSISTED MAGNETIC HEAD | 05-02-2013 |
20130229895 | MAGNETIC HEAD, MAGNETIC RECORDING METHOD AND APPARATUS FOR CONTROLLING MAGNETIC HEAD WITH SPIN TORQUE OSCILLATOR IN A DISK DRIVE - A microwave assisted magnetic recording head includes a recording magnetic pole unit that produces a recording field for writing to a perpendicular magnetic recording medium, and a high-frequency magnetic field oscillator that produces a high-frequency magnetic field. The recording magnetic pole unit includes a magnetic core with a write gap portion at which a main recording field component is concentrated, and the high-frequency magnetic field oscillator is disposed in the write gap. | 09-05-2013 |
20130235711 | WRITE POWER ADJUSTMENT METHOD AND INFORMATION RECORDING METHOD - In write power adjustment for an optical disc having a plurality of information storage layers, data of trial writing is varied by the influence of layers other than a target layer. It is difficult, therefore, to determine optimal write power. A modulation M[m] is obtained from a reproduction signal amplitude of a signal subjected to the trial writing performed with use of write powers Pw[m] (m being an integer) of a plurality of kinds. At least an optimum write power intercept Pint_opt is determined by fitting a relation between the Pw[m] and the M[m] by a modulation characteristic formula M=Masy×(1−(Pint−Pasy)/(Pw−Pasy)) having an asymptotic modulation Masy, a write power intercept Pint, and an asymptotic write power Pasy as parameters. Approximation accuracy by the fitting and/or quality of the trial writing signal are evaluated with use of at least the M[m], the modulation characteristic formula, and the Pint_opt. An optimum write power Pw_opt is calculated by performing a specified operation at least with use of the Pint_opt. | 09-12-2013 |