Abstract: A tilt detecting apparatus of an information-recording medium having a photo diode for detecting a light reflected from an information-recording medium and outputting a light amount signal according to the detected light amount; and a calculating unit for calculating a radial tilt amount by using the light amount signal, wherein the photodiode is divided into a plurality of cells which are identified as regions according to a light amount of the reflected light, based on which a tilt signal is detected. A portion of the reflected light diffracted at the information-recording medium is detected by using the 8-divided photo diode, the region having a large difference in a light amount by the tilt and the region having a small difference in a light amount by the tilt in view of the characteristic of the reflected light are detected.

Abstract: A method of compensating for tilt and/or defocus and an apparatus therefor. The apparatus has a tilt and/or defocus detector detecting the tilt and/or defocus of an optical recording medium, and a recording compensator compensating a write pulse having a predetermined recording pattern using a predetermined system with respect to the detected tilt and/or defocus. The apparatus both adjusts write power with respect to the detected defocus, shifts the recording pattern with respect to the detected tilt, adjusts a power level and/or write time required for recording, and records a recording mark having a desired size (length and width). The apparatus is useful in compensating for tilt and/or defocus in a high-density optical system.

Abstract: The present invention is capable of selectively reproducing an information signal from an optical disk with any of a plurality of types having different track pitches of recording tracks, that is, capable of selectively reproducing an information signal from an optical disk having a low or high recording density by determining the type of the optical disk, that is, determining whether a mounted optical disk is a low-recording-density optical disk or a high-recording-density optical disk. The present invention deliberately generates aberration in an optical beam by controlling a voltage applied to a liquid-crystal device in order to vary the diameter of the optical beam in accordance with the determined type of the optical disk.

Abstract: A method is provided for determining whether a rotating disk in an optical disk reading device is unbalanced. According to the method, the disk is first rotated at a preset rotational speed, and a lens is then located to a first position. Then, as the lens is moved towards a second position at a predetermined speed, a time duration during which a preliminary signal is generated is determined. The disk is determined to be unbalanced if the time duration exceeds a preset value.

Abstract: A tilt servo control device of an apparatus for recording information on and reproducing information from an optical recording medium, the apparatus comprising an optical system for leading a laser beam emitted from a light source to a recording surface of the optical recording medium and a laser beam reflected by the recording surface of the recording medium to a split type photo detector and a read signal generator for generating a read signal in accordance with an output signal of the photo detector. The tilt servo control device generates a push-pull component signal including a differential component of output signals of respective split portions of the photo detector, generates a tilt error signal representing a tilt angle at a position of the laser beam irradiating the recording surface and an optical axis of the laser beam based on the push-pull component signal, and drives a tilt angle adjuster for adjusting the tilt angle so as to reduce the tilt error signal.

Abstract: An optical recording apparatus has a semiconductor laser for generating a light spot used for information recording, a detector for detecting the aberration amount of the light spot, and a controller for controlling the output of the semiconductor laser by use of the detected aberration amount.

Abstract: An optical pickup includes a light emitting unit, an object lens, and a correction unit. The object lens focuses a beam of light onto a recording surface of an optical disc. The correction unit has a light transmitting surface. A plurality of electrodes are arranged on a plurality of divided areas of the light transmitting surface. The correction unit corrects an aberration caused by a tilt of an optical axis of the beam of light relative to the recording surface of the recording disc by applying voltages to the electrodes. The applied voltages correspond to the tilt of the optical axis of the beam of light. The correction unit also changes phases of the beam of light passing through the divided areas of the light transmitting surface.

Abstract: An optical disc apparatus for recording test data on a predetermined area of an optical disc under varied recording powers to determine an optimum recording power based on the quality of a signal obtained by reproducing the recorded test data. The test data is recorded under adverse recording conditions so as to evaluate the amount of change in quality of the reproduction signal. In order to create adverse recording conditions, the optical disc is tilted or the laser is defocused. A recording power for which the change in signal quality due to the deteriorated recording conditions is sufficiently small is determined as an optimum recording power capable of providing adequate recording margin.

Abstract: An error signal detection method and apparatus for an optical recording/reproducing system.

Abstract: The present invention relates to a tilt control device and method for an optical disc player, wherein an output offset of a tilt detecting means (3) is calibrated by using an output of a focus controller (7). Since the offset is calibrated based on the focus controlling output, the calibration can be performed for all written and non-written discs. As an alternative, a tilt control with high accuracy can be performed by adjusting a tilt frame based on at least two measurements of the controlling output of said focus control means at different radial positions. Thereby, the disc can be positioned in a radial tilt zero position with the aid of the focus controlling output. Now, the tilt detecting means is no longer required for tilt adjustment.

Abstract: An optical pickup apparatus includes a photodetector for receiving a diffracted light reflected from the recording medium; and a tilt detector for detecting a tilt amount of the recording medium on the basis of a light intensity within an interference region of a 0th-order diffraction light and at least one diffraction light other than the 0th-order diffraction light of the reflected light received by the photodetector.

Abstract: The present invention discloses a method for adjusting a tilt angle of an optical disc driver. The method includes the following steps. First, to move the optical pick up to close the outer end of the first and second guiding shafts. Next, the turntable drives a disc to rotate. Then, the light source provides a light to penetrate through the disc and the lens. The image sensor receives the reflection light from the disc and the lens. The monitor displays the traces projected from the reflection lights. According to the traces, the driving device adjusts the positions of the first and second guiding shafts.

Abstract: An aberration correcting unit includes: a first element having a liquid crystal sandwiched between first electrode layers, the first element having a first predetermined orientation direction and providing a light with a phase change by applying a voltage; a second element having a liquid crystal sandwiched between the second electrode layers, the second element having a second predetermined orientation direction that is substantially perpendicular to the first orientation direction and providing a light with a phase change by applying a voltage; and a polarization-direction changing element which is arranged between a light source of the light beam and the first and second elements to change a polarization direction of the light beam.

Abstract: An apparatus and a method for compensating a tilt of an optical recording medium comprising a servo error generating unit for generating RF(Radio Frequency) signal and a servo error signal from an electric signal outputted from an optical pickup unit, a servo control unit for generating a focus operation signal and a tracking operation signal by signal-processing separately a focus error signal and a tracking error signal outputted from the servo error generating unit, performing a focus search at a certain position in order to detect tilt, and generating a tilt operation signal by detecting tilt, a focus servo operation unit for operating a focus actuator inside of the optical pickup unit by receiving the focus operation signal outputted from the servo control unit, and a tilt operation unit for compensating tilt by controlling the pickup unit in accordance with the tilt operation signal outputted from the servo control unit.

Abstract: Laser light is irradiated from a lateral side of an optical disk (2) set in place to a peripheral side face of the optical disk (2), return light from the peripheral side face irradiated with the laser light is detected, and a displacement of the optical disk (2) is measured based on the detected amount of return light. Also, the focus is adjusted in relation to the information recording surface correspondingly to the measured disk displacement. Thus, a displacement of an optical disk can be measured in an extremely simple manner and with an extremely high accuracy, and information can accurately be recorded or reproduced to or from the optical disk with the focus being controlled.

Abstract: There is employed a configuration to detect, by making use of an optical pick-up (104) when tracking servo is performed along wobble grooves of an optical disc (102), phase errors between main wobble signal outputted as the result of the fact that reflected light beams corresponding to main spot of the optical disc (102) are received at a main light receiving section (321) of light detecting means (32) and side wobble signals outputted every side spot as the result of the fact reflected light beams corresponding to respective side spots of the optical disc (102) are received at a first sub-light receiving section (322) and a second sub-light receiving section (323) to calculate difference between the both phase errors at a difference calculating circuit (59) to generate, from this difference, a skew signal including inclination direction and inclination quantity of the optical disc (102).

Abstract: In a tilt correction method, first information about a specific inclination of an object lens is acquired in response to an access request to an information recording medium. The specific inclination is obtained when the signal characteristic of a push-pull signal becomes a prescribed level in or near a target access area. Then, second information about the optimum inclination of the object lens is acquired for the target access area, based on the first information and tilt difference information representing a difference between a first inclination and a second inclination of the object lens defined in advance in a particular area on the information recording medium. The first inclination corresponds to an optimum reproduced signal from the particular area, and the second inclination is obtained when the signal characteristic of the push-pull signal from the particular area becomes the prescribed level. Finally, tilt correction information is estimated from the second information.

Abstract: A recording unit includes a laser diode emitting a recording light for information recording, a strategy signal generating unit generating a strategy signal, a correction signal generating unit generating the correction signal for offsetting a tilt of a waveform level of the recording light, and a driving signal generating unit generating a corrected driving signal for correcting the tilt of the waveform level of the recording light based on the strategy signal and the correction signal.

Abstract: An apparatus and a method for reducing a lead-in time of a disc, on which data is always recorded, and detecting exactly a tilt of the disc. The apparatus includes a pickup, and a system controller. Even if the disc is a blank disc which is devoid of user data, control data is recorded on the disc. The pickup can record data on the disc or reproduce data from the disc. If a seek command is received, the system controller detects the tilt of the disc once in each of a plurality of zones while the pickup is moving.

Abstract: The present invention relates to an optical pickup and an optical disc drive that records or reproduces data signals on or from optical discs different in specifications, such as recording density and thickness. One objective lens (17) is used for optical discs (22a, 22b) of two types that differ in specifications. The optical pickup and the optical disc drive comprise two light source sections (24a, 24b) and a lens-supporting mechanism (15). The light source sections emit two laser beams of different wavelengths, respectively. The lens-supporting mechanism (15) controls the position of the objective lens (17) in the radial direction of the discs and along the optical axis.

Abstract: A tilt detection apparatus capable of detecting the tilt of the optical disk, provided with a laser for outputting a laser beam, a diffraction grating for diffracting the laser beam from said laser to generate a 0th order diffraction beam and +-first order diffraction beams which have the phase distribution equal to the phase distribution due to the wave front aberration generated on an optical disk when the optical disk is tilted, an objective lens for collecting said diffraction beams and exposing the beams to the optical disk, a photodetector for generating signals corresponding to said +-first order diffraction beams reflected at said optical disk, a signal generation circuit for generating the push-pull signals based on the generated signals, and a tilt detection circuit for detecting the tilt of the optical disk based on the push-pull signals.

Abstract: An optical disc drive includes an objective lens for focusing light on an optical disc with five or more stacked data storage layers and a tilt control mechanism for controlling a tilt angle defined between the optical axis of the light and a normal to the storage layers. The drive reads and/or writes data from/on a selected one of the storage layers by focusing the light on the selected layer. The numerical aperture NA of the objective lens is defined so as to fall within the range of 1.3009×D3−2.9315×D2+2.3133×D−0.0502 to 1.3009×D3−2.9315×D2+2.3133×D+0.2028, where D is a distance (mm) from a light incident side of the disc to the deepest one of the storage layers, which is located most distant from the light incident side.

Abstract: The invention relates to a method and an arrangement for a replay or recording appliance for optical recording media having an inclination control system for vertical alignment of the scanning beam with respect to optical recording media. In order to exclude other factors which, in addition to the inclination of the scanning beam, influence the radio-frequency signal which is detected by the recording medium, without any additional inclination sensors from the disadvantageous influence of the inclination control, an inclination control system is provided which uses the lower envelope curve signal of a radio-frequency signal which is detected by the optical recording medium and represents the dark value of the detected radio-frequency signal.

Abstract: A screw axis and a guide axis are provided in parallel in a base plate, and both sides of an optical pickup are supported by the screw axis and the guide axis. The base plate is provided with a first supporting portion for supporting one end portion of the screw axis in a side of a driven gear, and a second supporting portion for supporting another end portion of the screw axis. The first supporting portion has a first elastic member which presses the screw axis in an axial direction of a turn table, and the second supporting portion is provided with a second elastic member and a tilt adjusting screw which are opposed to each other with holding a collar therebetween in the axial direction of the turn table. One end portion of the screw axis is rotatably fitted to the collar, and the collar is pressed toward the tilt adjusting screw by the second elastic member.

Abstract: A tilt sensor for detecting information related to a tilt of an object to a reference plane is disclosed. The tilt sensor includes a diffraction element disposed that diffracts an incident light at diffraction efficiency depending on the incident angle, and a photo detector that detects a diffraction light diffracted by said diffraction element and outputs an photoelectric signal. Since the diffraction efficiency of the diffraction element changes as the incident angle changes, the intensity of the diffraction light from the diffraction element changes. As a result, the photoelectric signal output from the photo detector contains the information related to the tilt of the object.

Abstract: An actuator of an optical disk system and an apparatus producing a signal for driving the actuator, the actuator including a light source, with which information is recorded on or reproduced from an optical disk surface. In the actuator, an inner focusing coil and an outer focusing coil are installed near an inner boundary and an outer boundary, respectively, of the optical disk surface. A first signal wire is connected to a first port of the inner focusing coil and transmits an inner coil signal. A second signal wire is connected to a first port of the outer focusing coil and transmits an outer coil signal. A common signal wire is connected to a second port of the inner focusing coil and a second port of the outer focusing coil and transmits a common reference signal. Thus, a simple, inexpensive 8-wire actuator can be obtained.

Abstract: A tilt detection system includes an optical disk having a series of data recorded therein, the series of data having a pulse width smaller than the minimum pulse width of data recorded in an ordinary optical disk; a reproducing part reproducing a signal from the optical disk by emitting a light beam onto the optical disk; and a tilt detecting part detecting a tilt of the light beam with respect to the optical disk based on a reproduced RF signal provided by the reproducing part when the series of data having the smaller pulse width is reproduced.

Abstract: Disclosed are a moving-magnet type actuator capable of controlling voltage sensitivity and phase, an optical pick-up actuator equipped with a current feedback circuit for improving voltage sensitivity, and an optical pick-up device equipped with the current feedback circuit implemented by one chip. As the voltage sensitivity of a moving-magnet type actuator is improved and its phase is compensated, the operation performance of the optical pick-up actuator can be improved.

Abstract: To improve a tilt detection sensitivity and to detect a tangential tilt of recordable and rewritable optical recording media where no signal is recorded previously, An optical head assembly includes a semiconductor laser 6, an objective lens 5 which focuses a laser beam onto a disk D, and a photodetector 9 adapted to receive reflected light from the disk D.

Abstract: An optical pickup apparatus for compensating for the deviation in the thickness of the optical disk and method therefor.

Abstract: An optical head has an initial setting for a tilt angle of an objective lens with respect to an optical disk. If a different optical disk having a different transparent layer is used for recording/reproducing data thereon, the lens actuator changes the tilt angle of the objective lens to an optimum tilt angle with respect to the different optical disk, or a optical correction device optically compensates the wave front aberration.

Abstract: Tilt correction means is operated so that the degree of modulation represented by the ratio of the amount of the detected reflected light from the groove areas G and the amount of the detected reflected light from the flat land areas L becomes maximal in a state wherein focus servo-control is made effective. Hence, the present invention can provide a system applicable to all optical disks including recording types and reproduction-only types, and capable of detecting a tilt correction signal without providing any special countermeasures on optical disks and devices, whereby it is possible to obtain an optical recording apparatus not adversely affecting the usage feeling of a user.

Abstract: An optical pickup capable of focusing a main light spot and an auxiliary light spot including optical aberration when an optical disk is not tilted, and analyzing the main light spot and the auxiliary light spot with a photodetector, thereby correcting aberration.

Abstract: A drive device has a feed mechanism that causes a control object to move in order to control the positioning of the control object, a motor that serves as the drive source of said feed mechanism, and a control means that controls this motor. The control means has an operation history memory unit that stores the operation history of whether the motor is doing an initial start or a restart, and a command selection unit that selects control commands and outputs them to said motor based on information stored in said operation history memory unit. Because intermittent operation that repeatedly drives and stops the motor occurs when there is a restart, the thermal shutdown associated with overheating of the driver IC is avoided, and any difference between the feed amount due to the control means and the actual feed amount can be prevented.

Abstract: An optical pickup includes a lens holder body having a first surface and a second surface opposing to each other, tracking coils, a focusing coil, and tilt coils which are formed on a pair of flat panels respectively disposed on the first and second surfaces, and first and second magnetic bodies respectively disposed to face the first and second surfaces of the lens holder body and each constituting a planar closed magnetic circuit.

Abstract: An optical pick-up generates a 0-th order diffraction light and ±1st order diffraction lights by a diffraction grating and irradiates the same to an optical disc. The ±1st order diffraction lights have phase distributions equivalent to a wavefront aberration of the optical disc when there is a tilt in the optical disc. Distances between the center of the main optical spot and centers of sub optical spots in a disc radial direction on a recording surface are whole multiples of a track pitch. The generation circuit generates a main push-pull signal corresponding to the 0-th order diffraction light and first and second sub push-pull signals corresponding to the ±1st order diffraction lights and generates tracking error signals TE as differential push-pull signals obtained by subtracting a sum signal of the first and second sub push-pull signals from the main push-pull signal.

Abstract: A method for determining an emitting angle of an optical pickup head of an optical drive. A jitter inspection device comprises a jig, simulating and adjusting a tilt angle of the optical pickup head, and a jitter meter installed on the jig, inspecting jitter values at different tilt angles. A quadratic surface equation decreases the data points required for measurement to five, and enables product efficiency to raise 17% , such that the minimum jitter value and optimum tilt angle can be obtained quickly.

Abstract: In the tilt correction method, information about inclination of an object lens relative to an information recording medium is acquired. A direct current signal Sdc for correcting the inclination is produced based on the information. An alternating current signal Sac having a prescribed signal characteristic is superposed onto the direct current signal Sdc to produce a driving signal Sout. The driving signal Sout is supplied to a driving mechanism to correct the inclination of the object lens against friction.

Abstract: An objective lens drive device (8) includes a supporting block (9), a movable block (10) for holding an objective lens (27), and supporting springs (22) for connecting the supporting block and the movable block. Elements of the supporting block of the objective lens drive device (8) are a stationary section (11), a supporting shaft (12), a tilt drive section (13), and tilt drive magnetic circuits (20 and 20). The stationary section (11) is secured to a movable base (7) that is movable in radial directions of a disc-shaped recording medium (100). An axial direction of the supporting shaft (12) is perpendicular to both focusing directions and tracking directions. The tilt drive section (13) is rotatably supported at the stationary section through the supporting shaft and is connected to the movable block through the supporting springs. The tilt drive magnetic circuits (20 and 20) are used to rotate the tilt drive section with respect to the stationary section.

Abstract: A light pickup device includes a light projection optical system comprising a light source which emits light, and an objective lens which condenses the light on an optical disk, a light detection optical system comprising a light detector, and a condenser lens which condenses light reflected from the optical disk on the light detector, and an adjustment optical element for coinciding a center axis of an intensity distribution of the light condensed on the optical disk by the light projection optical system with an optical axis of the objective lens.

Abstract: A method of recording data to an optical disk is disclosed that enables correction of recording power during an recording operation using multi-pulse recording. The method includes the steps of interrupting a recording operation when a predetermined amount of data is continuously recorded in the optical data recording medium, measuring the recording state of the optical data recording medium immediately before the interruption, correcting the recording power for the next recording operation based on the measured recording state, and starting the next recording operation by using the laser beam with the determined recording power in the optical data recording medium at a position immediately after the interruption.

Abstract: An optical disk read/write apparatus detects a shift in the tilt during a write operation and corrects it before resuming the write operation. Specifically, when the ROPC control signal detector of the optical disk read/write apparatus controlling the write power determines that the write power has exceeded a predetermined value after a control operation, the optical disk read/write apparatus suspends the write operation through control of the laser power and controls the shift in the tilt with the tilt controller before resuming the write operation.

Abstract: A tilt adjusting apparatus including a digital signal processor, a first drive integrated circuit, and a tilt adjuster. When an optical recording medium is loaded into a deck, the digital signal processor outputs a focus control signal to control a focus of an optical recording medium, measures a tilt with respect to the optical recording medium, and outputs a tilt adjustment signal and a switch control signal so as to adjust the tilt. The first drive integrated circuit either synthesizes the tilt adjustment signal and the focus control signal or receives only the focus control signal according to the switch control signal and then outputs the synthesized signal or the focus control signal to the optical pickup. The tilt adjuster synthesizes the tilt adjustment signal output from the first drive integrated circuit and the focus control signal and then outputs the synthesized signal to the optical pickup.

Abstract: A displacement detection method in which by reflecting a light beam on a surface of an object to be measured, a displacement of the surface of the object is detected from a change of the reflected light beam due to a change of the displacement of the surface of the object, includes the steps of: causing light beams to be incident upon a substantially identical position on the surface of the object from at least two light sources confronting each other substantially; detecting by position detectors directional changes of the light beams reflected on the surface of the object, respectively; normalizing output signals of the position detectors by luminous intensities received by the position detectors, respectively; and calculating a sum or a difference of the normalized output signals of the position detectors.

Abstract: A lens actuator includes a lens holder to support an objective lens and having a pair of first side surfaces in a tracking direction and a pair of second side surfaces in a tangential direction, a fixed magnet disposed to confront the second side surface and comprising four regions having approximately the same area and are magnetic, such that magnetic directions of the four regions are perpendicular to a plane including a focusing direction and the tracking direction but are in opposite directions between two mutually adjacent regions, a pair of tracking coils disposed between the second surface and the magnet and having centers located on an outer side of corresponding centers of the four regions in the tracking direction, a focusing coil disposed between the second surface and the magnet and having a center located on an outer side of corresponding centers of the four regions in the focusing direction, and a radial tilt coil disposed between the second surface and the magnet and having a center located on

Abstract: An optical head and a disk drive reduce the weight of a moving section of the optical head including an objective lens, and achieve more precise aberration correction by independently driving the objective lens and an aberration correcting device. An optical head (3) that constitutes a disk drive (1) is provided with an aberration correcting device (8) for an optical system including an objective lens (6). A first driving means (7) for driving the objective lens (6) and a second driving means (9) for driving the aberration correcting device (8) or a moving section including the device and components (10) of the optical system are provided. The misalignment between the objective lens (6) and the aberration correcting device (8) is corrected.

Abstract: A highly accurate and stable tilt servo system is provided. A liquid crystal device for phase correction is driven based on drive data stored in a lookup memory to thereby make a tilt correction. Upon pre-processing, a pickup is moved to a predetermined position on the inner circumference of a disc for a tilt correction to employ tilt error data delivered from a tilt sensor as reference tilt error data and drive data served for the tilt correction as a reference tilt correction quantity. After the pre-processing, when the pickup is moved, the difference between the tilt error data delivered from the tilt sensor at each position of movement and the reference tilt error data is employed as a relative correction quantity. The drive data equivalent to the relative correction quantity is acquired from the lookup memory. The drive data acquired is added to the reference correction quantity to thereby determine a tilt correction quantity.

Abstract: A tilt angle detection device and method which generates, as a first push-pull signal, a difference between light reception signals corresponding to two light receiving surfaces of one side of a photodetector, which are divided along the track tangent direction; generates, as a second push-pull signal, a difference between the light reception signals corresponding to two light receiving surfaces of the other side of the photodetector; and generates a tilt signal that indicates a tilt angle defined by a normal on the recording surface of the optical recording medium at a position of irradiation of the laser beam and the optical axis of the laser beam in accordance to a difference between amplitudes of the first and second push-pull signals.

Abstract: The method for reproducing records for the optical recording medium detects and compensates for detrack, tilt and defocus, having advantages in that: (1) the magnitude and the direction of detrack, tilt and defocus can be detected from a difference signal (for example, a read channel 2 signal or a tracking error signal obtained by processing the read channel 2 signal) between optical reflecting signals detected at the header fields staggered on the basis of the tract center, and compensates for detrack, tilt and defocus, thereby preventing deterioration of data quality caused by detrack, tilt and defocus during a recording/reproducing operation and enabling the stable operation of the system; and (2) the focus servo is rapidly stabilized to enable real-time recording as well as the stable operation of the system.

Abstract: An offset adjustment signal is recorded in a test recording area provided on the inner side of a disc while modifying the level of a driving signal for offset detection that is supplied to a tilt adjustment coil. Thereafter, an operation to play back the offset adjustment signal is performed, and a &bgr; value is detected from an RF signal that is played back. When a signal is recorded for which the detected &bgr; value reaches a maximum, the level of the driving signal supplied to the tilt adjustment coil is set as an offset value. Tilt control is then performed by adding the offset value to a tilt signal for performing tilt control.