Abstract: A semiconductor memory device includes a first data line electrically connected to selected one of a plurality of memory cells in response to activation of a word line, a second data line provided hierarchically with respect to the first data line, a read circuit provided between the first data line and the second data line to drive the second data line to a fixed voltage with a driving power according to a voltage on the first data line at the time of data reading, and a voltage supply control circuit for supplying a predetermined voltage to the second data line in response to a precharge/equalize instruction. The voltage supply control circuit includes a voltage supply stop circuit disconnecting the second data line from the predetermined voltage in a predetermined period except for the time of data reading.

Abstract: A method for programming one or more reference cells is described. The reference cell is programmed a predetermined amount, its program state is sensed relative to a prescribed cell on the same die (e.g., a memory cell or a golden bit cell), and the programming process continues until the reference cell fails a preselected read operation. In one preferred embodiment, the memory cell used during the reference cell programming process is the cell in the memory array having the highest native threshold value. In another preferred embodiment, the memory cell used during the reference cell programming process is a native cell that is on-board the die containing the memory array, but not a cell within the memory array.

Abstract: A synchronous semiconductor memory device includes a memory cell array and a command decoder. In the memory cell array, dynamic memory cells are arranged in a matrix form. The command decoder decodes a plurality of commands in synchronism with an external clock signal. The plurality of commands are set by combinations of logical levels of a plurality of control pins at input timing of a first command and at input timing of a second command one cycle after the input timing of the first command. The command decoder includes a first decode section which determines a read operation, a second decode section which determines a write operation, and a third decode section which determines an auto-refresh operation. Setting of an auto-refresh command is determined only by a combination of the logical levels of the plurality of control pins at the input timing of the first command.

Abstract: A control circuit in a semiconductor memory device accessing a memory cell for a plurality of cycles includes an internal command generating circuit and a mask signal generating circuit. Upon receiving a control command, the internal command generating circuit outputs an internal signal instructing an operation to access the memory cell at H level when a mask signal is at L level, while outputs an internal signal at L level when the mask signal is at H level, because a latch circuit is reset. The mask signal generating circuit outputs the mask signal at H level for a following cycle, when the internal signal is output at H level.

Abstract: The memory device includes a memory cell array, and an output buffer receiving data addressed from the memory cell array and outputting the data based on a latency signal. A latency circuit selectively associates at least one transfer signal with at least one sampling signal based on CAS latency information to create a desired timing relationship between the associated sampling and transfer signals. The latency circuit stores read information in accordance with at least one of the sampling signals, and generates a latency signal based on the transfer signal associated with the sampling signal used in storing the read information.

Abstract: A vehicle with one or more accessory systems that are capable of drawing power from a flow of pressurized hydraulic fluid and utilizing that power toward their intended functionality. The vehicle has a powertrain including a primary internal combustion engine and driveline components that are operable to couple the driveline end of a crankshaft of the primary internal combustion engine to one or more driven ground-engaging components of the vehicle to move the vehicle along the ground. The vehicle includes a hydraulic pump that is coupled to the non-driveline end of the crankshaft and that provides a flow of pressurized hydraulic fluid for powering the accessory systems of the vehicle.

Abstract: A hydration apparatus for use with a hydration tank. The hydration apparatus disperses incoming gel into existing gel in the hydration tank to increase the hydration time of the incoming gel. The hydration apparatus includes flow conduits communicated with gel inlets in the hydration tank. The flow conduits redirect the flow of the incoming gel. The flow conduits preferably redirect the flow from a generally horizontal direction to generally vertically upwardly direction. The hydration apparatus has a plurality of deflectors positioned in the hydration tank. Flow exiting an end of the flow conduits is deflected by the deflectors and dispersed into existing gel in the hydration tank. The flow conduits are preferably perforated flow conduits so that a portion of incoming gel passes through openings in the sides of the flow conduits while a portion of the incoming gel passes through an exit of the flow conduits.

Abstract: A rail segment for use in a track assembly for supporting a stirring machine and mounted to a cylindrical grain bin having a longitudinal flange with a slot in a forward end portion of the flange and a connecting hole in a second end portion of the flange.

Abstract: Tempering apparatus having disc-free stirring tool (8) with plate-shaped arms (12, 13). The upper side (14) of each arm (12) has a different geometrical configuration than the lower side (19) thereof. Each neighbouring arm (13) has the opposite configuration of the upper and lower sides (23 and 24). The mass is thereby given an intermittent up- and downwards movement in the mass treatment chamber (2) and the tempering capacity of the apparatus is improved.

Abstract: A method for wrapping continuous strands of steel wire about a seismic cable including interconnected sensor sections and conductor sections where a cross sectional diameter of the sensor section is at least four times that of the conductor section. Two layers of armoring are provided with a first layer wrapped in a first angular direction opposite that of the second layer. A stranding assembly is provided which has two selective positions, one for providing a die hole for stranding the conductor section, another for providing a passage hole for allowing the sensor section to pass after wrapping with armor wire.

Abstract: A pressure pulse generator to generate pressure signals in drilling fluid for transmission to surface comprising: an outer housing (100) having an inlet (9) and an outlet for supply to the drilling assembly (59); a control element (10) slidably mounted in the housing (100) for opening and closing said inlet (9), said element being operative to generate a pressure pulses when it closes; a control passage (26, 27, 28) extending through the element (10) and closable by a valve element (36) arranged to be exposed to the pressure in the passage; and an actuator assembly (13, 14, 15, 17, 19, 21, 35, 36, 37) connected to the control element (10). The control element moves upon activation (10) relative to the inlet to generate a pulse. When deactivated, it blocks the flow through the passage (26, 27, 28) so that all of the fluid bypasses via the inlet.

Abstract: A neural net sonic identification system includes an ultra-sonic emitter and receiver configured to detect characteristics of a subject by detecting reflections of the ultrasonic waves. The sonic reflections are processed by a neural network pattern recognition system that learns to recognize a particular subject and distinguish it from other subjects. The emitter/receiver is continuously optimized for phase, wavelength, spectral, and power frequencies, and the received sound “picture” is written-over the previously stored encrypted image data file for a particular individual, so as to continuously update the processor's retained identification information. In one embodiment, the emitter/receiver comprises a solid-state multi-layer tunable array of piezoelectric emitters and receivers that can be selectively “aimed” in different directions without physically moving by independently varying the wavelength and power of the various emitters/receivers.

Abstract: An acoustic method for measuring of a distance between an emitter of acoustic energy and a target object provides for an accurate measurement by having the measurement's outcome invariant to the speed of sound variations along the acoustical path between the emitter and the target. A plurality of emitters and a plurality of receivers are used in the invention. One acoustic emitter and one receiver are located in a spatial region such that the sent and the reflected acoustical energy passes along substantially same vertical line between the emitter and the target. Another acoustic emitter sends the acoustical energy at an angled direction to the same area on the target's reflecting surface as the first emitter does. The corresponding echo travels to another receiver. During the measurement, two specific variables are being monitored. The first variable is associated with the distance between the first emitter and the target.

Abstract: An apparatus for ultrasonically detecting an edge of a web, includes a ultrasonic-wave transmitter transmitting ultrasonic-wave pulse train, a ultrasonic-wave receiver receiving the ultrasonic-wave pulse train and converting the received ultrasonic-wave pulse train into electric signals, the web being fed between the ultrasonic-wave transmitter and receiver, a rectifying circuit for rectifying the electric signals, a low-pass filter circuit for smoothing output signals transmitted from the rectifying circuit, a first sample-holding circuit for sampling an output signal transmitted from the low-pass filter circuit, at first timing, a second sample-holding circuit for sampling an output signal transmitted from the low-pass filter circuit, at second timing later than the first timing, a third sample-holding circuit for sampling an output signal transmitted from the first sample-holding circuit, at the second timing, and a differentially amplifying circuit for calculating a difference between output signals trans

Abstract: A pill container having a body for containing pills, a time/alarm control circuit, and a keypad and a time display connected to the alarm circuit. The keypad includes keys for entering a first pill time and further keys for entering a number of daily medications. The control circuit includes an IC chip for calculating alarm times at regular intervals from the first pill time based on the number of daily medications. The control circuit also provides an audio alarm signal at each of the alarm times.

Abstract: The present invention relates to a wristwatch with functions of basal body temperature (BBT) charting and ovulation phase informing, comprising: a case, for demarcating an space with a control circuit unit accommodated therein; a display unit; a memory cell; a timer unit; a battery; and a sensor unit containing a temperature sensor and a computing device for taking the basal body temperature of a female so as to inform her with predicted ovulation phase.

Abstract: This invention discloses a wristwatch capable of storing and transmitting data of computers. The wristwatch of this invention comprises a timing indicating component, a watch case, and a watch band for fixing the wristwatch to people's wrist, wherein, said wristwatch further comprises a circuit board assembly and a USB connector assembly. The internal structure of the watch case of the wristwatch of the present invention is well sealed, so that the electricity property of the internal elements can be ensured, and the elements for storing and transmitting data of computers can be secured and protected, while the appearance of the wristwatch remains concise and natural.

Abstract: Watch comprising a case with the following components arranged inside it:

Abstract: Timepiece including an analogue display (12, 36) arranged such that the hour hand completes one revolution in twelve hours. This analogue display is associated with a coaxial disc (10) driven so as to complete one revolution in twenty-four hours in the same direction as the hour hand. The visible surface (14) of the disc visually defines two half-discs arranged to indicate AM-PM or day-night information relating to the displayed time.

Abstract: A timepiece includes a light emitting device for generating a light, and one or more rotary wheels having one or more light receiving orifices, and one or more reflective members attached onto the sides of the rotary wheels for reflecting the light generated by the light emitting device and emitted through the orifices of the rotary wheels. The orifices may be easily and precisely formed in the rotary wheels while forming the rotary wheels, and the reflective members may be easily attached onto the rotary wheels without precisely positioning relative to the rotary wheels.

Abstract: A cam-operated timer for a household appliance including a housing and a switch wafer mounting in the housing used to receive and locate the wafers to prevent inaccuracies in wafer thickness from accumulating through the stack of wafers. The switch wafer mounting includes first and second locating features for receiving first and second switch arm wafers. The first switch arm wafer rests against the first locating feature, and the second switch arm wafer is stacked atop the first switch arm wafer and rests against the second locating feature.

Abstract: A hybrid head to record and reproduce high density data. The hybrid head to record and reproduce data includes an element to record and reproduce data which is formed at the back side of a slider. The element to record and reproduce data includes an energy source to supply energy required to heat a predetermined region of a recording medium to be data-recorded, a magnetic field applier to apply a magnetic field to the predetermined region of the recording medium heated by the energy supplied from the energy source, a data reproducer to reproduce data from the recording medium, a channel to allow the magnetic field supplier to transmit the energy supplied from the energy source to the predetermined region of the recording medium, a heat shield element to prevent heat from being transmitted from the channel to other elements around the channel, a write pole covering the heat shield element, and a magnetic field generator to generate a magnetic field to the write pole.

Abstract: To generate a satisfactory recording magnetic domain on a recording medium and to improve the durability of a recording head, an information recording apparatus for generating an optical near field and thermo-magnetically recording information on the recording medium is provided with a light source, a magnetic pole for applying a magnetic field to the recording medium and a diffuser that generates an optical near field in the vicinity of the recording medium when light from the light source is radiated. The diffuser is formed with it in contact with the magnetic pole so that the face which light from the light source irradiates is substantially perpendicular to the recording medium. Thereby, recording density in the information recording apparatus can be increased, simultaneously the reliability can be also enhanced and as a result, the cost can be reduced.

Abstract: Two-dimensionally annular or spiral lands and grooves are formed in a magneto-optical disk having a magnetic layer composed of a magnetic domain wall displacement layer, a switching layer, and a record retaining layer. The lands and the grooves are each used as a recording and reproducing area. A side wall present between the land and the groove and its vicinity are annealed so as to change the physical properties of these areas. The width of the land is larger than the width of the groove by 0.5 to 4 times the width of the side wall. Further, the ratio of the width of the land to the width of the groove is 1.05 to 1.20. Furthermore, the grooves have a period of 1.0 to 1.2 microns.

Abstract: A multi-layer optical information storage system comprising several layers of generally flat waveguide, arranged one on top of the other in a stack. The reading energy is projected through the layers perpendicularly, and is focussed onto the layer to be read. A detector disposed at the side of the layers detects the energy scattered or reflected from information or data points within the layer. The points within the layers may be in the form of defects of a type that can carry the information assigned to each point, generally by means of the presence or absence of the defect. The energy scattered or reflected from the defects in any specific layer is preferably contained within that layer because of waveguiding properties imparted to the layers by means of a graded or stepped index structure.

Abstract: A method for performing a track skip and a playback device (10) for optical storage disks (15) are proposed that enable an accelerated track skip in the case of a non-moving storage disk (15). A time is determined for the track skip of a read device (2) between a current track and a selected track (3) of a storage disk (15) inserted in the playback device (10), as a function of the tracks to be skipped in this instance, and the read device (2) is moved in the direction of the selected track (30) for the determined time. In response to a track skip request, the read device (2) is moved in the direction of a lead-in area (20) of the optical storage disk (15) until a starting position (25) is detected. The time necessary for the track skip from starting position (25) to the selected track (30) is determined from this track (30).

Abstract: A rotary tray apparatus includes a counter for counting L levels and H levels of a pulse signal in one cycle at a predetermined time interval, a detecting unit for detecting whether or not a signal of an opposite level is input during counting of respective levels executed by the counter, a memory for storing previously-input counted numbers of respective pulse signals as reference values, and a controlling unit for comparing a counted value at this input time point with the reference values in the memory when an opposite level detecting signal is sent out from the detecting unit 10a during counting, then deciding that a noise signal is input when the counted value is out of tolerances of the reference values, and then initializing the counted values and continuing determination of the identification numbers based on the input pulse signal.

Abstract: The present invention provides a method for calibrating focus positions of a pickup head. The pickup head is in a focus position of a predetermined distance from an optical recording medium for producing a recording light beam of a predetermined power for recording corresponding data onto the optical recording medium. A predetermined position adjustment procedure is performed to adjust the focus position of the pickup head during data recording. The procedure comprises the steps of sensing a reflected light beam from the optical recording medium by means of a sensor to generate a corresponding write RF signal; searching an extreme value of the write RF signal and obtain a target focus position corresponding to the searched extreme value; and adjusting the pickup head to the target focus position, so as to enable further data recording onto the optical recording medium by the pickup head in the target focus position.

Abstract: A method and device are provided for controlling a beginning point of an optical pick-up unit. The optical pick-up unit moves to a beginning point of an optical disc such as a DVD (Digital Versatile Disc) to execute a servo-tuning function at the beginning point. The method includes a) performing a focus search operation on an optical disc and at the same time determining whether there is a reflection signal from the optical disc; b) after performing the focus search operation, moving the optical pick-up unit toward a predetermined beginning point of the optical disc based on the result of the determining step; and c) based on the reflection signal from the optical disc, determining whether or not the optical pick-up unit has moved to the beginning point of the optical disc while the optical pick-up unit is in motion.

Abstract: The present invention provides a control loop bandwidth adjusting system for adjusting a control loop bandwidth of an optical reproducing device. The optical reproducing device comprises a data signal processing circuit, which uses the control loop bandwidth to process the data signal. The control loop bandwidth adjusting system comprises a control loop bandwidth generator for generating the control loop bandwidth and a control loop bandwidth adjusting module for adjusting the control loop bandwidth according to whether a defect signal corresponding to the defective data is received or not. If the control loop bandwidth adjusting module receives the defective data entry signal, the defective data duration signal, and the defective data exit signal, the control loop bandwidth is adjusted to a first bandwidth value, a second bandwidth value, and a third bandwidth value respectively.

Abstract: An objective lens drive having an optical axis adjustment function. An objective lens is supported by a lens holder, and the lens holder is supported on a suspension holder by way of a suspension. The suspension holder is supported so as to be rotatable about an axis extending in a direction in which the suspension extends, whereby the suspension holder is supported laterally by means of multilayer piezoelectric elements. When a drive voltage is applied to the multilayer piezoelectric elements, the piezoelectric elements are displaced vertically, whereupon the suspension holder is rotated about the axis, to thus adjust the optical axis of the objective lens.

Abstract: An optical disc controller of the present invention servo-controls an optical disc device which comprises a disc motor rotating an optical disc and an optical head emitting a light beam for recording data on the optical disc and/or reproducing data from the optical disc. The optical disc controller comprises: a variable clock output section for outputting a plurality of clock signals of different frequencies, and a control section which receives from the optical head a signal indicating a deviation from a predetermined target value to servo-control the light beam of the optical disc device and performs an operation according to the signal indicating the deviation so as to obtain and output a signal indicating a control amount.

Abstract: An apparatus for controlling a monitor photo diode (PD) of an optical pickup system monitors an optical power signal output for writing data on or reading data from a disk. The apparatus includes a comparator which compares a voltage signal corresponding to the optical power signal output from the LD with a predetermined reference voltage signal, and a gain selector which selectively issues a gain output from the comparator depending on the type of the optical power signal output from the LD.

Abstract: An optical disc drive includes an optical system, a photodetector, a filter, a phase difference detecting section, a signal generating section, and a control section. The optical system focuses a light beam on an optical disc loaded. The photodetector includes areas to receive the light beam reflected from the disc and generates read signals representing quantities of light received. The filter receives the read signals and outputs processed signals with a frequency component of the read signals attenuated according to mark lengths. The phase difference detecting section detects a phase difference between the processed signals. The signal generating section generates a tracking error signal, representing a positional relationship between the focal point and a target track, based on the phase difference. The control section generates a control signal based on the tracking error signal such that the focal point is controlled across the tracks on the disc.

Abstract: The present invention provides an optical disk device and an optical splitter in each of which even if an objective lens and a polarization hologram substrate deviate in a disk radial direction, off-track does not occur under tracking control, and two radiation light sources can simultaneously be handled in the case of employing a configuration with two radiation light sources. Light emitted from a radiation light source is reflected by a signal plane of an optical disk, and passes through an objective lens to enter an optical splitter. The optical splitter is divided into four quadrants Ak (wherein k=1, 2, . . . ) by two straight lines that intersect with an optical axis. The photodetector is divided into at least four regions Bk. First-order diffracted lights ak are derived from light that has entered the quadrants Ak by the optical splitter and are projected on the regions Bk of the photodetector, respectively.

Abstract: The invention provides an information recording medium, a storage medium, an information reproduction apparatus and method, and an information recording and reproduction apparatus and method as well as a providing medium by which information recorded on an information recording medium can be utilized only by a predetermined apparatus which corresponds to the information recording medium. A ROM has data for identification of a DVD player/recorder stored therein. A recording and reproduction section records data stored in the ROM onto a DVD and reproduces data for identification of the DVD player/recorder recorded on the DVD. A CPU controls the recording and reproduction section in accordance with the data stored in the ROM and the data reproduced by the recording and reproduction section.

Abstract: A method and device for retrieving data in low-power is provided. More specifically, it relates to a method and device for minimizing power consumption while retrieving the continuous media data from a disk drive for the purpose of real-time playback. The data reproducing device reproduces multimedia data by a determined playback strategy after it computes power consumption values according to various playback strategies and retrieves data from a storage medium by a playback strategy having the least power consumption by means of comparing respective power consumption values.

Abstract: An optical recording method and recording apparatus using this method is described in which an optimum write power of a radiation beam in the apparatus is set by writing a series of test patterns on an optical recordable medium, forming a read signal from the patterns, reading a preset value of the derivative of the modulation of the read signal with respect to the write power from the medium, and processing the read signal together with the preset value to derive an optimum value of the write power.

Abstract: Password management methods of an optical disc apparatus are provided for recording/reproducing data on an optical disc such as a CD or DVD disc. The password management method for managing a password in an optical disc apparatus, includes the steps of: a) determining if a current optical disc has been reproduced previously by the optical disc apparatus; and b) requesting a user to enter a first password prescribed by a user if the determining step (a) determines that the current optical disc has been reproduced previously.

Abstract: A local track pitch measuring apparatus is disclosed for an optical disk of the type that stores optically readable information in the form of a spiral or annular pattern defining a plurality of essentially concentric tracks. The apparatus has a laser light source and a drive mechanism which projects a laser beam spot from the laser light source onto a surface of the optical disk and moves the projected laser beam spot radially over a portion of the disk surface across at least some of the tracks. A light detector detects a diffraction or reflection from the projected laser beam spot during its movement. The light detector produces a time variant measurement signal having a periodicity associated with the passages of the moving laser beam spot across respective tracks. A processing device determines a local deviation in the periodicity of the measurement signal and provides an output indicative of a local track pitch for the spiral or annular pattern.

Abstract: A method for discriminating an optical storage medium is disclosed. A predetermined range of the optical storage medium is read after the light source is focused on; and thereby a plurality of data transition points and transition regions defined by an interval of two neighboring points are obtained. Thereafter, the time-consumption for reading the longest transition region is used to determine the type of the currently accessed optical storage medium. Another physical characteristics according to data storage formats, such as the PLL clock frequency or the distance between the reflection layer and the surface layer of the optical storage medium, may be used as references to discriminate the currently accessed optical storage medium.

Abstract: A photodetector and optical pickup device which comprises: a monitoring photodetection element (photodiode) 23 for receiving laser beams having different wavelengths from laser light sources; a light source-discriminating photoreceiver 24 represented by a photodiode (240) and a wavelength selection filter (241) for discriminating the wavelength spectra of the laser light sources; and a sensitivity regulation circuit (25) for regulating the sensitivity of the monitoring photodetection element 23 in response to the light source-discriminating photoreceiver 24.

Abstract: A jitter detection apparatus includes an A/D conversion section for converting an input analog signal into a plurality of discrete multiple value digital signals; a binarization section for performing binarization of the plurality of multiple value digital signals to generate a binary signal; a jitter calculation section for calculating a jitter amount based on an error between a value of a prescribed multiple value digital signal sampled at a time which is substantially the same as a time when the value of the binary signal is changed and a prescribed threshold value; a pattern detection section for detecting patterns of the binary signal before and after the time when the prescribed multiple value digital signal is sampled; and a correction section for correcting the jitter amount based on the detected pattern.

Abstract: A method for recording information is disclosed in which an information recording medium is irradiated with a recording energy beam power-modulated into at least a record power level and a record-ready power level lower than the record power level. When forming a mark portion of a predetermined length, the radiation energy of the energy beam is increased as compared with when forming a mark portion of a different length before or after the first pulse of an energy beam pulse train including at least a pulse for forming the mark portion. Also, only in the case where the energy beam is modulated by the power lower in power level than the record-ready power level after the last pulse of the energy beam pulse train including at least one pulse for forming a mark portion and the mark portion is followed by a space portion of a predetermined length, the particular radiation energy of low power level is reduced as compared with when the mark portion is followed by a space potion of a different length.

Abstract: An event timing adjustment device that can realize timing adjustment of any event in a simpler and more correct way. The event timing adjustment circuit has multiphase clock generating portion 5 that generates multiphase clocks, and multiphase clock use portion 3. The multiphase clock generating portion 5 generates plural phase clocks having different phases applied for an event input received by input terminal 1. The plural pulse clocks represent plural different adjustment quantities, respectively. Multiphase clock use portion 3 uses any one phase clock among the multiphase clocks, and it generates an event change timing signal representing the changed timing of said event.

Abstract: One embodiment of the present invention is a small form factor disk drive for use in an appliance, which disk drive includes: a connector side, a removal side, and gripping sides; wherein the gripping sides include gripping mechanisms that are disposed along the gripping sides so that the gripping mechanisms are exposed whenever the appliance ejects the disk drive.

Abstract: An inventive recording medium loader includes a connector provided on a chassis for engagement with a front edge of a generally rectangular planar recording medium, and a tray provided on the chassis for transporting the recording medium toward and away from the connector. An engagement piece having a claw to be brought into and out of engagement with a notch formed in the recording medium is provided on the tray, and a cam is provided in an engagement piece movement path on the chassis. Before the forward edge of the recording medium is engaged with the connector, the claw is brought into engagement with the notch of the recording medium by the cam to lock the recording medium on the tray. In this state, the recording medium is brought into engagement with the connector.

Abstract: The present invention relates to a disc data storage apparatus with a structure for preventing cracked discs from jetting out. The disc data storage apparatus has a tray for receiving a disc, a cover and a housing. The cover has a first portion and a second portion. The first portion is connected to a front flange of the housing, and the second portion is extended into the housing to form a barrier portion. When a disc cracks, the barrier portion is configured to stop and prevent the cracked disc from jetting out.

Abstract: There is provided an optical pickup device comprising a laser light source for emitting a laser beam, an object lens for focusing the laser beam onto the recording surfaces of layers 0 and 1 of an optical disk and condensing the laser beam onto the recording surfaces, photodetectors for receiving the laser beam reflected by the optical disk, and a diffraction grating for diffracting a part of the reflected laser beam toward the photodetectors, wherein data can be simultaneously written to layers 0 and 1. The photodetector detects the reflected light from layer 0 after being refracted by the diffraction grating, and detects the reflected light from layer 1 without being refracted, so that the data of layers 0 and 1 can be simultaneously read. Thus, data can be simultaneously read from and written to the recording surfaces of a plurality of layers of an optical disk.

Abstract: Provided are an optical pickup device, which is capable of detecting and correcting spherical aberration while suppressing an increase in the number of construction elements and without increasing outer dimensions of a pickup device main body, and a recording and/or reproducing device having the optical pickup device built therein. A lens is designed such that when the thickness of a disk protective layer is greater than an optimum value, returning light (reflection light) from a disk is condensed on a sensor. The sensor is arranged at a condensing point and has a shape with which around 50% of the returning light is received when the thickness of the protective layer assumes the optimum value. With this construction, the quantity of light received by the sensor is increased when the thickness of the protective layer is greater than the optimum value, and is conversely reduced when the thickness of the protective layer is smaller than the optimum value.