Abstract: A high performance polishing cloth having a densified surface state with ultrafine fiber bundles uniformly dispersed therein and having excellent smoothness is provided. The polishing cloth comprises a nonwoven fabric formed by entangling the ultrafine fiber bundles formed by bundling ultrafine fibers with an average single fiber diameter of 0.05 to 2.0 ?m and a polymeric elastic material, wherein the average size of the surface fiber-napped portions constituted by the aforementioned ultrafine fiber bundles of the aforementioned nonwoven fabric in the width direction of the ultrafine fiber bundles is 50 to 180 ?M.

Abstract: In an optical disc device, a way of canceling a lens shift due to an electric offset of an output of a tracking actuator driving circuit is desired. A tracking servo control circuit contains a first operation mode for setting an output current of the tracking actuator driving circuit to generally zero and a second operation mode for supplying a predetermined potential to the input. An average potential of a push-pull signal detected in the first operation mode is acquired. An object lens is moved by a predetermined amount in both radial directions by changing a potential supplied in the second mode to acquire correlative relationship between average potential of a push-pull signal relative to a lens movement amount and the supplied potential. An offset amount is acquired from the potential and the correlative relationship to cancel the offset.

Abstract: This invention provides an optical disc drive with more accurate and stable power control for a laser light source. An optical disc drive in an embodiment of this invention includes a monitor photodetector for receiving laser light emitted by a laser light source to monitor the laser light power. The monitor diode is a photodetector for generating an electric signal corresponding to the laser light power. A laser light controller controls drive current to the laser light source based on a result of measurement by the monitor diode. The optical disc drive measures output variations of the monitor diode and controls the gain of the monitor diode based on the result of the measurement. This gain control improves accuracy and stability in laser light control so that stability in recording/reading can be attained.

Abstract: Bandwidth is secured for a read signal transmission line by matching the characteristic impedance of the read signal transmission line with the output impedance of a photodetector of an optical pick up, while at the same time securing bandwidth for the photodetector. In an optical disc drive according to an embodiment of the present invention, each line forming a differential transmission line is divided into a plurality of lines of the same quantity, the quantity being two or more, at or near a connection point between a flexible line and the optical pick up.

Abstract: This invention provides accurate control of laser light power in a recording operation to achieve more stable recording operation. An optical disc drive in an embodiment of this invention monitors the power of laser light with a monitor diode and controls the laser light power based on the result of monitoring. The optical disc drive changes data transfer rate (recording frequency) depending on the disc radial position. The optical disc drive controls the gain of the monitor diode across the recording surface depending on the recording frequency. This control improves the accuracy in laser light power control to achieve stable recording operations by precise servo control.

Abstract: To identify the type of a loaded disc, there is provided an optical disc device, comprising: a light source driven by a drive signal with a high frequency signal superimposed; a detector for detecting return light emitted from the light source; and a controller for controlling the amplitude of the high frequency signal to be superimposed on the drive signal, the optical disc device being configured to read data from an optical disc loaded therein by a signal outputted from the detector, wherein: the controller causes the light source to irradiate the loaded optical disc with light in a condition in which a high frequency signal different from a high frequency signal for data reading is superimposed on the drive signal; and the controller identifies a type of the loaded optical disc based on the return light from the loaded optical disc.

Abstract: A composite memory device, a data processing method and a data processing program can efficiently and selectively use a nonvolatile solid-state memory and a recording medium. The composite medium device includes a nonvolatile solid-state memory and a recording medium and is adapted to combine the data area of the recording medium and the data area of the nonvolatile solid-state memory and manage them as totally or partly integrated data area by means of a predetermined file system. The composite memory device is connected to a host appliance by way of an interface section.

Abstract: To determine the optimum amplitude of high frequency signal for the loaded disc with a simple configuration to achieve stable playing performance, there is provided an optical disc device comprising: a light source driven by a drive signal with a high frequency signal superimposed; a detector for detecting return light emitted from the light source; and a controller for controlling amplitude of the high frequency signal to be superimposed on the drive signal for the light source; the optical disc device being configured to read data on an optical disc loaded therein by a signal outputted from the detector, wherein the controller determines the amplitude of the high frequency signal to be superimposed on the drive signal based on asymmetry of the signal outputted from the detector.

Abstract: There is provided a composite type recording apparatus restricting write operations depending on the type of a connected host apparatus, including a recording medium having a first data region, a non-volatile storage medium having a second data region and an identification information table for integrating and managing the first and second data region, an information selection section for selecting positional information having predetermined identification information from the identification information table according to the type of the host apparatus, a conversion section for converting positional information selected by the information selection section into positional information matching the first data region or positional information matching the second data region, a first write section for writing data supplied from the host apparatus in the first data region according to conversion process of the conversion section and a second write section for writing data supplied from the host apparatus in the se

Abstract: An optical disc drive for reading or writing information on a multilayer optical disc having three or more recording layers by irradiating the disc with a light beam includes an optical pickup for irradiating the disc with the light beam, a recording state detector for detecting data recording states at a start point of a focus jump, a transit point or transit points on a recording layer or recording layers to be passed through, and an expected landing point of a focal point of the light beam in a focus jump, and a controller for moving the optical pickup to a position where the recording states are the same at all of the start point, the transit point(s) on the recording layer(s) to be passed through, and the expected landing point if the recording states are different among those points, before starting the focus jump.

Abstract: Prevention of deletion of data in an unintended recording layer of an optical disc is ensured even when servo deviation occurs while controlling data reproduction. A light source outputs a light beam with light intensity according to a driving current on which a high frequency signal is superimposed. The light beam is collected on a recording layer of an optical disc. As triggered by detection of servo deviation during data reproduction, a light intensity controller adjusts a superimposed amount of the high frequency signal in the driving current to suit to a specific recording layer with the lowest reproduction tolerance in the optical disc and thereby controls the light intensity of the light beam output from the light source.

Abstract: Bandwidth is secured for a read signal transmission line by matching the characteristic impedance of the read signal transmission line with the output impedance of a photodetector of an optical pick up, while at the same time securing bandwidth for the photodetector. In an optical disc drive according to an embodiment of the present invention, each line forming a differential transmission line is divided into a plurality of lines of the same quantity, the quantity being two or more, at or near a connection point between a flexible line and the optical pick up.

Abstract: This invention provides an optical disc drive with more accurate and stable power control for a laser light source. An optical disc drive in an embodiment of this invention includes a monitor photodetector for receiving laser light emitted by a laser light source to monitor the laser light power. The monitor diode is a photodetector for generating an electric signal corresponding to the laser light power. A laser light controller controls drive current to the laser light source based on a result of measurement by the monitor diode. The optical disc drive measures output variations of the monitor diode and controls the gain of the monitor diode based on the result of the measurement. This gain control improves accuracy and stability in laser light control so that stability in recording/reading can be attained.

Abstract: This invention provides accurate control of laser light power in a recording operation to achieve more stable recording operation. An optical disc drive in an embodiment of this invention monitors the power of laser light with a monitor diode and controls the laser light power based on the result of monitoring. The optical disc drive changes data transfer rate (recording frequency) depending on the disc radial position. The optical disc drive controls the gain of the monitor diode across the recording surface depending on the recording frequency. This control improves the accuracy in laser light power control to achieve stable recording operations by precise servo control.

Abstract: In an optical disc device, a way of canceling a lens shift due to an electric offset of an output of a tracking actuator driving circuit is desired. A tracking servo control circuit contains a first operation mode for setting an output current of the tracking actuator driving circuit to generally zero and a second operation mode for supplying a predetermined potential to the input. An average potential of a push-pull signal detected in the first operation mode is acquired. An object lens is moved by a predetermined amount in both radial directions by changing a potential supplied in the second mode to acquire correlative relationship between average potential of a push-pull signal relative to a lens movement amount and the supplied potential. An offset amount is acquired from the potential and the correlative relationship to cancel the offset.

Abstract: An optical disc drive for reading or writing information on a multilayer optical disc having a plurality of recording layers by irradiating the disc with a light beam includes an optical pickup for irradiating the disc with the light beam, a focus error signal generator for generating a focus error signal that indicates a state of displacement of a focal point of the light beam from a recording layer based on reflection from the disc, a recording state detector for detecting a data recording state at a landing point of the focal point in a focus jump, a threshold setting unit for setting a threshold to be compared with the focus error signal based on the data recording state at the landing point, and a focus jump controller for controlling the focus jump based on a result of comparison of the focus error signal with the threshold.

Abstract: An optical disc drive for reading or writing information on a multilayer optical disc having three or more recording layers by irradiating the disc with a light beam includes an optical pickup for irradiating the disc with the light beam, a recording state detector for detecting data recording states at a start point of a focus jump, a transit point or transit points on a recording layer or recording layers to be passed through, and an expected landing point of a focal point of the light beam in a focus jump, and a controller for moving the optical pickup to a position where the recording states are the same at all of the start point, the transit point(s) on the recording layer(s) to be passed through, and the expected landing point if the recording states are different among those points, before starting the focus jump.

Abstract: To identify the type of a loaded disc, there is provided an optical disc device, comprising: a light source driven by a drive signal with a high frequency signal superimposed; a detector for detecting return light emitted from the light source; and a controller for controlling the amplitude of the high frequency signal to be superimposed on the drive signal, the optical disc device being configured to read data from an optical disc loaded therein by a signal outputted from the detector, wherein: the controller causes the light source to irradiate the loaded optical disc with light in a condition in which a high frequency signal different from a high frequency signal for data reading is superimposed on the drive signal; and the controller identifies a type of the loaded optical disc based on the return light from the loaded optical disc.

Abstract: An optical disc device comprising: a controller for reading data from an optical disc having a plurality of recording layers, wherein: the controller, in shifting a focus of the laser light from a first layer to a second layer, performs a first change that changes a setting on the high frequency signal to a predetermined value at which the high frequency signal is superimposed to suppress peak power of the drive signal if a light density of the second layer is higher than a light density of the first layer; the controller shifts the focus from the first layer to the second layer; and the controller, after the focus has been shifted, performs a second change that changes the setting on the high frequency signal to a predetermined value at which the high frequency signal is superimposed to increase the peak power of the drive signal.

Abstract: Prevention of deletion of data in an unintended recording layer of an optical disc is ensured even when servo deviation occurs while controlling data reproduction. A light source outputs a light beam with light intensity according to a driving current on which a high frequency signal is superimposed. The light beam is collected on a recording layer of an optical disc. As triggered by detection of servo deviation during data reproduction, a light intensity controller adjusts a superimposed amount of the high frequency signal in the driving current to suit to a specific recording layer with the lowest reproduction tolerance in the optical disc and thereby controls the light intensity of the light beam output from the light source.