Abstract: In an optical disk device, an output terminal is connected to an optical pickup, and a preceding sub-beam returning light signal which is electrical signal obtained by converting returning light of a sub-beam preceding an main beam is output through the output terminal. A defect period detection circuit detects a defect period during which a beam is passing through a defective portion on an optical disk based on the preceding sub-beam returning light signal from the output terminal. A servo hold circuit holds tracking servo during the detected defect period. Therefore, even when an amplitude of an RF signal is quickly attenuated during the defect period, the defect period is detected at an early stage of the attenuation, thereby suppressing a change in an amplitude of a tracking error signal to a small level.

Abstract: To increase the vibration resistance of an optical disk device with respect to vibrations in the focus direction. More specifically, an optical disk device is provided with a multiplication means for generating a focus vibration component FC from the focus error signal FE, a multiplication means for generating a tracking vibration component TC from the tracking error signal TE, an adder for adding the focus vibration components FC and TC, and a low-pass filter for extracting the vibration component VC from the added results. Thus, the vibration component VC is extracted considering not only vibrations in the tracking direction but also vibrations in the focus direction, so that vibrations acting on the device can be more accurately detected, and vibration resistance is increased.

Abstract: A light branching element which branches a light beam emitted from a light source and reflected on a magneto-optical recording medium is provided with four light branching portions, and three phase compensating means which give a fixed phase &dgr;M to a light beam branched by an M-th (M=2 to 4) light branching portion is disposed on paths of light beams branched by the three light branching portions except the first light branching portion of the four light branching portions. In this optical pickup, servo signals of four kinds of optical recording mediums are respectively detected using light beams detected by three or less groups of light receiving portions selected from among four groups of light receiving portions.

Abstract: A pickup for a magneto-optical recording medium is provided, which improves quality of reproduced signals by eliminating a phase difference between the polarizations and is capable of coping with magneto-optical recording media of different recording/reproducing systems. A return light beam of light reflected by a magneto-optical recording medium is polarized and separated into ± first-order diffracted lights through a light-branching diffraction element provided between a light source and an objective lens. The ± first-order diffracted lights are compensated for their phases through first and second phase compensation elements so that there is no phase difference between the polarizations, and are, further, polarized and separated through the first and second polarization/separation elements, and are received by first and second light detectors.

Abstract: An off-track duty measurement unit measures off-track detection sensitivity on the basis of an off-track signal, and track cross cycle information that is obtained from a tracking error signal measured by a track cross cycle measurement unit, whereby off-track detection sensitivity can be measured more accurately. Further, an off-track detection sensitivity controller changes the detection sensitivity of an off-track signal detector according to the obtained off-track detection sensitivity, whereby the off-track sensitivity can be kept constant for various kinds of discs, and accordingly, stabilities of off-track detection, track pull-in judgement, and track jumping can be secured.

Abstract: In a mail delivery system 10, a mail-incoming rejection system is configured so that: transmission destination mail address information 130 of electronic mail 120 includes transmission destination mail addresses 131a to 13na, and destination names 131b to 13nb including a keyword 125 specific to the transmission destination mail address; and with regard to the electronic mail 120 received in a mail delivery center 300, which corresponds to the transmission destination mail address, via a network 500, its receiving section 320 collates the keyword from the destination name to be included in the transmission destination mail address information, and delivers only the electronic mail, for which the collation of the keyword was able to be made, to the above transmission destination mail address.

Abstract: A swivel type working vehicle having a turntable (3) with a rear hood (28) covering an engine (11) and a side hood (42) covering hydraulic equipment. The rear hood (28) includes a pivot device (30) disposed in an upper front end region thereof and having a pivot axis extending transversely of a vehicle body. The rear hood is pivotable by the pivot device between a closed position covering the engine and an open position exposing the engine. The side hood (42) includes a pivot mechanism (50) disposed in a lower front end region thereof and having a pivot axis extending transversely of the vehicle body. The side hood being pivotable by the pivot mechanism between a closed position covering the hydraulic equipment and an open position exposing the hydraulic equipment.

Abstract: Beam shaping means may have a shaping ratio set to allow a light beam emitted from a semiconductor laser and having an elliptic intensity distribution to have an ellipticity of no more than two to obtain a spot achieving high light availability and reduced in size. Furthermore, the shaping ratio can be set to no more than 2.5 to allow a polalized-beam splitter (light separation means) and other components to be arranged in a converged flux passing between the semiconductor laser and a collimator lens.

Abstract: A swivel type working vehicle having a turntable (3) with a rear hood (28) covering an engine (11) and a side hood (42) covering hydraulic equipment. The rear hood (28) includes a pivot device (30) disposed in an upper front end region thereof and having a pivot axis extending transversely of a vehicle body. The rear hood is pivotable by the pivot device between a dosed position covering the engine and an open position exposing the engine. The side hood (42) includes a pivot mechanism (50) disposed in a lower front end region thereof and having a pivot axis extending transversely of the vehicle body. The side hood being pivotable by the pivot mechanism between a dosed position covering the hydraulic equipment and an open position exposing the hydraulic equipment.

Abstract: To increase the vibration resistance of an optical disk device with respect to vibrations in the focus direction. More specifically, an optical disk device is provided with a multiplication means for generating a focus vibration component FC from the focus error signal FE, a multiplication means for generating a tracking vibration component TC from the tracking error signal TE, an adder for adding the focus vibration components FC and TC, and a low-pass filter for extracting the vibration component VC from the added results. Thus, the vibration component VC is extracted considering not only vibrations in the tracking direction but also vibrations in the focus direction, so that vibrations acting on the device can be more accurately detected, and vibration resistance is increased.

Abstract: A relative traveling speed detector receives a focus error signal and detects a traveling speed of a pickup relative to a disk. A drive mode determining unit determines a drive mode of the pickup according to the detected relative traveling speed. A drive output generating means generates a focus drive signal for driving the pickup according to the drive mode. The disk drive device is thus capable of reducing the time required to restore a focus servo operation.

Abstract: A backhoe (1) includes an upper structure (3) supported by a traveling device (2) to be rotatable about a vertical swivel axis (X). The upper structure (3) carries an excavator (4) and a cab (12) and has a rear edge (3A) formed arcuate about the swivel axis (X) in plan view. The cab (12) defines an opening (31) with a door (32) attached through hinges (34). The door (32) is pivotable about a vertical open/close axis (Y) of hinges (34). The hinges (34) are arranged on a rear edge opening (31). Each hinge (34) includes a pair of hinges (34A and 34B) which are bent to place the axis (Y) forwardly of the rear end of door (32). Consequently, when the door (32) is set to a fully open position, the free end of door (32) is displaced to a position forwardly of the rear edge (3A) of upper structure (3).

Abstract: A light spot detects a focus offset amount based on an amount of variation of a focus error signal when a light spot passes a boundary between a land section and a groove section adjacent to the land section on an optical disk. Specifically, an amount of variations in the focus error signal at a center of a land section at a time the light spot passes the boundary between the land and the groove adjacent to the land is detected as a focus offset amount, and an amount of variation in the focus error signal at a center of the groove section is detected as a focus offset amount for the groove sections, thereby providing an optical information recording/reproducing device which permits recording/reproducing information on and from a tracking area of an optical disk under just-in-focus conditions without increasing a cost of the device nor being affected by an error due to changes over time or variations in optical disks.

Abstract: A reproducing light quantity control method for an optical memory device includes the steps of (1) recording test data on an optical recording medium; (2) reproducing the test data recorded on the optical recording medium by changing a reproducing light quantity in a plurality of light quantity values; (3) measuring a quality value and a signal quantity of each of a plurality of reproducing signals from the test data; (4) selecting an optimum reproducing signal quantity from a plurality of reproducing signal quantities in accordance with quality values of the plurality of reproducing signals so as to decide a target value of reproducing signal quantity; and (5) recording the target value on a target value recording region of the optical recording medium. This method reduces the time required to obtain a target value of a reproducing signal quantity and speeds up an operation from installing of the optical recording medium to finishing of preparation for recording and reproducing.

Abstract: A hologram laser unit to be used for performing recording and reproducing operations of information for an optical disk, includes a light source, a photodetector, and a hologram element which are formed integrally with each other. The hologram element includes: a first hologram for detecting information signals from the optical disk, the first hologram being provided in an area having an effective diameter corresponding to a numerical aperture suitable for the optical disk; and a second hologram for compensating for only a transmitted light amount of light traveling toward the optical disk from the light source, the second hologram being provided contiguously outside the first hologram.

Abstract: A method of manufacturing a pressure roll including a cylindrical core member having a center shaft, an intermediate layer surrounding the core member and formed from a flexible material, and an outermost layer surrounding the intermediate layer and formed from a high-thermal conductivity material. The method includes forming a plurality of axially extending notches in a cylindrical member to form tongues, radially bending the tongues of the cylindrical member so as to enlarge one end of the cylindrical member, and inserting a core member into the enlarged end of the cylindrical member.

Abstract: In an optical information recording-reproduction apparatus, a focus servo control circuit generates a focus error signal and a light beam is accurately converged on a surface of an optical disk according to a focus servo control signal based upon the focus error signal. In accordance with the present invention, the focus error signal is compensated by selecting a land section focus offset amount by a switch when land sections are tracked, and it is compensated by selecting a groove section focus offset amount when groove sections are tracked. As a result, since the land sections and the groove sections are controlled by different focus servo control signals, recording and reproducing operations are carried out at the most optimal focusing positions respectively obtainable, thereby making it possible to significantly improve the quality of a reproduced signal.

Abstract: The present invention is directed to a pressure roll including a cylindrical core member having a center shaft, an intermediate layer surrounding the core member and formed from a flexible material, and an outermost layer surrounding the intermediate layer and formed from a high-thermal conductivity material having a thermal conductivity of not less than 0.03 cal/cm.multidot.sec.multidot..degree.C. Also disclosed is a molding apparatus for a plastic sheet using the pressure roll. According to the pressure roll and the molding apparatus using the pressure roll, when a resin extruded sheet interposed between the pressure roll and a main cooling roll is pressed onto the main cooling roll, the outermost layer of the pressure roll is elastically deformed slightly to apply a surface pressure onto the resin extruded sheet, while cooling the plastic sheet.