Abstract: In an foreign body detection apparatus, an optical signal detection unit irradiates a light spot onto a surface of an object to be inspected while scanning the surface by employing the light spot in a predetermined direction, and receives a reflected beam from the surface of the inspected object to generate a photodetection signal corresponding to the light intensity of the reflected beam. A foreign body detection unit generates a foreign body detection signal appearing with respect to a leader and a trailer in the scanning direction of a foreign body adhering to the inspected object from the photodetection signal. The foreign body detection signal is obtained, for example, as a difference signal between the photodetection signal and a delayed photodetection signal with a predetermined delay time. A foreign body discrimination unit generates a foreign body discriminating signal indicating a region in which the foreign body is present from the foreign body detection signal.

Abstract: The invention is directed to self-referenced holographic recording techniques that make use of an element of a holographic medium to create a reference beam from a zero frequency Fourier component of a data encoded object beam. In other words, the self-referencing element may be formed on the holographic medium, rather then being a separate element of the holographic recording system. The element may comprise a diffusive element on the medium, designed to create a reference beam having controlled angles, phase and/or amplitude.

Abstract: A method of generating an efficient sequence of “nm+m?1” level random numbers, each sub-sequence of “m” successive random numbers thereof having a different pattern, including the steps of generating a sequence of n-level random numbers based on an initial value, a number being generated at a time, determining whether a pattern of a sub-sequence is “used”, if the pattern of the sub-sequence is “used”, setting a different value to the initial value, if the pattern of the sub-sequence is not “used”, accepting the newly generated number and marking the pattern as “used”. All of the steps are repeated until all of “nm” patterns are exhausted. Since the newly generated number is rejected if the pattern of the sub-sequence is “used”, the sequence becomes the shortest one of which all of “nm” patterns are exhausted.

Abstract: An optical pickup includes a light source which emits first and second lights having different wavelengths for a first recording medium and a second recording medium having a relatively large thickness, respectively, an optical path changer which alters a traveling path of incident light, and an objective lens which focuses the first and second lights on the recording medium. While the light source emits the first light, a photodetector is adjusted to be aligned with the optical axis for the first recording medium. The light source and/or a sensing lens are adjusted in the direction of the optical axis, and the tilt of the objective lens is adjusted. Next, while the light source is operated to emit the second light, the light source is adjusted in a rotating direction. As such, an optical axis alignment is completed for the first and second recording media.

Abstract: A method for determining the recording power of a laser beam so that jitter from a reproduced signal obtained by reproducing data recorded in a data rewritable type optical recording medium can be controlled within a tolerance even when cross erasing of data occurs, the reproduced signal having the highest obtainable level. The power of a laser beam is measured for each level of the recording power of the laser beam. Critical parameters are also calculated for each level of the recording power of the laser beam. The critical parameters are projected onto a data rewritable type optical recording medium for recording data therein. A data recording apparatus storing a critical parameter used for determining the power of a laser beam is associated with ID data for identifying the kind of optical recording medium. A data recording apparatus storing an optimum recording power used for determining the power of a laser beam is also associated with ID data for identifying the kind of optical recording medium.

Abstract: A method for determining the recording power of a laser beam so that jitter from a reproduced signal obtained by reproducing data recorded in a data rewritable type optical recording medium can be controlled within an acceptable tolerance even when cross erasing of data occurs. The power of a laser beam is measured for each level of the recording power of the laser beam. Critical parameters are calculated for each level of the recording power of the laser beam. The critical parameters are projected onto a data rewritable type optical recording medium for recording data therein. Direct overwriting required for saturating an influence of cross erasing of data is performed x times in one embodiment to determine a critical parameter. A data recording apparatus storing a critical parameter used for determining the power of a laser beam is associated with ID data for identifying the kind of optical recording medium.

Abstract: An optical recording/reproducing method and an optical recording medium capable of performing excellent optical recording with a simple structure in a recording layer made of environmentally friendly materials. The optical recording medium has a recording layer formed on a substrate and made of a mixture of a recording assist material and a dielectric material. A laser beam of which intensity is modulated in accordance with information to be recorded is irradiated onto this recording layer to cause a state change in the recording assist material and/or the dielectric material. The information can be recorded by changing optical characteristics thereof such as reflectivity. The recording assist material includes an element selected from Sn, Ti, Si, Bi, Ge, and C as a principle component, while the dielectric material as a base material for the dielectric layers is at least one of ZnS, SiO2, AlN, and Ta2O5.

Abstract: The present invention provides a control system of following a follow target position. A control system has a disturbance observer for obtaining a disturbance force estimation value and a speed estimation value as estimation values of a disturbance force and a speed as a speed to be controlled by using an actuator control signal cont and a zero follow position which can be observed. Since the disturbance force estimation value and speed estimation value are fed back.

Abstract: The present invention provides an information recording/reproducing device capable of ejecting an information recording medium during a process of formatting the medium or continuously writing data on the medium, characterized in that the device records a variable length of a lead-out in a lead-out area on the information recording medium; and the device allows the information recording medium to be ejected after the recording of the lead-out is completed.

Abstract: Method and apparatus for authenticating a data storage medium (such as an optical disc including a compact disc, CD or a digital versatile disc, DVD) in which data are nominally stored in a plurality of sectors have a defined sector size containing a first total number of bits. A number of altered sectors are formed on the medium each having a second total number of bits different from the first total number of bits. The altered sectors will provide readback data at a different rate than a nominal rate determined by the defined sector size. The altered sectors are used to verify the medium as being an authorized copy and prevent unauthorized copying efforts.

Abstract: The present invention provides a data-recordable optical disk device. Test data is recorded in a predetermined area of an optical disk while varying recording power level, and an optimum recording power level is selected based on reproduced signal quality of the test data. When the optimum recording power level does not exceed an allowable recording power level of the laser diode, data is recorded at that optimum recording power level. When the optimum recording power level exceeds the allowable recording power level of the laser diode, the recording strategy is changed to a low-power strategy. A low-power strategy is, for example, a strategy having an increased recording pulse width compared to that of a standard strategy. An optimum recording power level is selected for the low-power strategy, and data is subsequently recorded.

Abstract: A controller for recording data on a CD with a DVD recorder. The controller includes an LPP decoder, an ATIP decoder for decoding address information of a CD, and an address converter for converting an ATIP address into an LPP address. When recording DVD format data on a CD, a write timing generation circuit is driven in response to the LPP address, which is converted from the ATIP address. The write data is modulated for use in the CD, and the intensity of the write data is adjusted for use in the CD.

Abstract: In a recording stop processing method according to an aspect of this invention, when a recording stop instruction is input and the data size of stream data, which is stored in a storage destination, is smaller than the predetermined data size, dummy data is added to the stream data stored in the storage destination, and the stream data with the dummy data, whose data size becomes equal to the predetermined data size, is DMA-transferred to terminate DMA transfer, thus stopping recording of stream data.

Abstract: An apparatus and method detecting whether a signal read from an optical disc has a defect. The apparatus generates a defect signal of an optical disc and includes an average maximum value detecting unit, an average minimum value detecting unit, an instantaneous maximum value detecting unit, an instantaneous minimum value detecting unit, and a defect signal generating unit. The average maximum value detecting unit receives a predetermined RF signal for a predetermined period of time and calculates an average maximum value of maximum values of the RF signal. The average minimum value detecting unit receives the predetermined RF signal for a predetermined period of time and calculates an average minimum value of minimum values of the RF signal. The instantaneous maximum value detecting unit receives the RF signal and calculates an instantaneous maximum value that is a maximum value of the RF signal at an instant of time when the RF signal is input.

Abstract: An optical pickup unit for scanning an optical disk includes a first optical branch including a first radiation source for emitting a first radiation beam of a first wavelength, and a dichroic mirror (8) located in the path of the first radiation beam for reflecting the first beam towards the disk, and a second optical branch including a second radiation source for emitting a second radiation beam of a second wavelength, different to said first wavelength, and a folding mirror (28) located in the path of the second radiation beam for reflecting the second beam towards the disk. The first and second branches are stacked in the axial direction of the disk, and are arranged substantially perpendicularly when viewed along the axial direction.

Abstract: An apparatus detects the number of tracks traversed on an optical disk. The apparatus includes a differentiation part for differentiating an output signal of a bandpass filter provided on an adjacent stage which eliminates a low DC component, a high frequency component and noise of an inputted modulation signal. A sample trigger generating circuit generates top and bottom signals in response to a data signal outputted through the differentiation part and a signal outputted through a comparator. A top hold part and a bottom hold part holds the data signal at top and bottom. A subtraction part performs a subtraction to obtain a difference between the top and bottom signals outputted from the top and bottom hold parts, thereby resulting in counting the number of the tracks traversed, while increasing a jumping speed required for a detection of the number of the tracks traversed.

Abstract: An attempt is made to prevent an adequate recording power detection lag from being generated according to data from a defective area at trial writing, by detecting a defective area portion based on a fluctuation of return light when a trial write recording mark is formed, recording it in another portion under the same conditions as the detected portion, and using the information on the recorded area instead of the area in which the defective area was detected at reproduction of the trial writing.

Abstract: An offset measuring method is for measuring an offset based on an optical beam reflected by an information medium, in a recording and reproduction apparatus including an optical pickup placed on transportation means so as to be driven along a radial direction of the information medium. The method includes the steps of directing an optical beam toward a first measuring position, thereby measuring a first offset amount based on the optical beam reflected at the first measuring position; moving the transportation means by a first distance in a first direction along the radial direction; driving the optical pickup by a second distance, which is equal to the first distance, in a second direction; and directing an optical beam toward a second measuring position, thereby measuring a second offset amount based on the optical beam reflected at the second measuring position.

Abstract: A multi-value data recording and reproducing device is provided that can accurately eliminate interference among codes through waveform equalization when reproducing information from a reproduction signal having levels multi-valued through modulation of the areas of recording marks on an optical information recording medium. This multi-value data recording and reproducing device is embodied by a multi-value data detecting circuit that varies the sizes of the recording marks in accordance with multi-value data (0, 1, 2, . . . , (m?1): m being an integer of 3 or greater) on the optical information recording medium, and detects the multi-value data through predetermined signal processing on signals obtained by scanning the recording marks with an optical spot.

Abstract: A method and apparatus for generating an optimum recording power before recording user data in a recordable optical recording medium is disclosed. According to the method and apparatus, an optimum power calibration (OPC) is performed in the unit of a sector, and the start position of the respective physical sector can be synchronized. Thus, the optimum recording power can be determined even in a DVD-R/RW in which a PCA area exists but no OPC method is prescribed. Also, the degree of OPC can be heightened, and the limitation of the PCA area can be overcome. The method and apparatus also enables an easy and accurate search of the start position even in an odd sector where LPP data is recorded in odd positions.