Hitachi, Ltd.

Hitachi Maxell, Limited

Hitachi Media Electronics Co., Ltd.

Other

Nidec Copal Corporation

Seiji Ono

Nobuyuki Kaku

Yoshimi Maehara

Mikihisa Inoue

Naomitsu Kuroda

Kenmei Masuda

Yasushi Kinoshita

Eiji Okubo

Nobuo Masuoka

Atsushi Inoue

Hiroaki Ono

Katsuhiko Kimura

Tomomi Okamoto

Seiichi Katou

Hidekazu Takeda

Hidenao Saito

Makoto Ibe

Shinji Ozaki

Noboru Katohno

Katsuo Konishi

Kuniaki Hirayama

Yasushi Horie

Noriaki Masuda

Kiyokazu Watanabe

Hiroyuki Nagatomo

An aspect of the invention provides an optical pickup in which an optical axis is not displaced even if ambient temperature is changed. The optical pickup of the invention has an optical unit and an optical pickup case. The optical unit has a lens member having an optical axis, and the optical axis of the lens member is offset to one side from the center of the optical unit. The optical pickup case holds the optical unit from both sides. A thermal expansion amount of the optical unit is absorbed by compression amounts of a first adhesive and a second adhesive such that the optical axis of the lens member is not displaced when the optical unit is thermal expanded.

Optical pickup having thermal expansion compensation

In an optical element feeding device and an optical pickup unit using the same, in order to make the device compact and light and achieve a stable operation, the device has a main shaft and a sub shaft supporting a movable frame in which an optical element is arranged in such a manner as to be movable in a direction of an optical axis, a stepping motor, a lead screw rotating on the basis of a rotation of the stepping motor, a resin nut engaging with the lead screw and being movable in the direction of the optical axis on the basis of the rotation of the lead screw, and a spring pressing the movable frame in the direction of the optical axis so as to bring the movable frame into contact with the nut, and a cushioning material is provided between the nut and the movable frame so as to connect the nut and the movable frame.

Optical element feeding device and optical pickup unit using the same

An optical element feeding device driving method and an optical disk apparatus capable of detecting biting in a stepping motor and conducting restoration. The optical disk apparatus includes an optical element feeding device including a movable frame for supporting a spherical aberration correcting lens to move the lens in optical axis direction, a spring for applying force to the frame in the direction, a sensor for detecting a lens reference position, a stepping motor, and a lead screw and a nut for converting motor rotation into the direction, a motor driving circuit, a decision circuit for judging abnormality when an output of the sensor does not change even if the driving circuit outputs a driving signal to the motor after reference position detection, and a changeover circuit for lowering a driving frequency than in ordinary operation, based on an abnormality signal.

Optical element feeding device driving method and optical disk apparatus

A first tape cassette adapted to be interchangeably used with a second tape cassette of a different thick case thickness is provided. A first tape cassette includes a first case having a first total thickness. The first case having a bottom face which is formed with an indentation and a first depression formed within the indentation. The indentation is used for positioning the cassette in a plane parallel to its bottom face. The second tape cassette includes a second case having a second total thickness that is smaller than the first total thickness of the first case. The second case has a bottom face which is formed with a second reference depression opened towards the bottom face. The second reference depression is for positioning the second tape cassette in a plane parallel to its bottom face.

Tape cassette

A tape cassette which can maintain stably the accuracy of the reference planes for determining the height of the tape cassette and which allows enhancement in accuracy of positioning, height positioning reference planes being provided inwardly a specified distance apart from an outside casing surface of the tape cassette such that the reference plane for determining the height of the tape cassette relative to the apparatus is not provided on the outside casing surface of the tape cassette, thus the reference planes remain free from contact with any mechanism for loading the tape cassette or with any foreign matter in transport, thus the reference planes can be kept free from damage.

Tape cassette having a surface recess for positioning accuracy in

In a rotary head drum of a recording/reproduction apparatus, for smoothly holding a magnetic tape over a guide step provided on a lower drum to guide the magnetic tape, part of a chamfer formed in the guide step is formed as a large chamfer in which a chamfered amount is larger than that of the remaining part of the chamfer. With the provision of the large chamfer, even if the lower edge of the magnetic tape deviates from the guide step when the tape is wound over or unwound from the drum, damages of the magnetic tape can be prevented. Therefore, the position and attitude control of tape withdrawing members can be greatly simplified and the magnetic tape can always run stably while being restricted in its position by the guide step. In the process of machining a tape running surface on the drum, by increasing the feed distance of a blade in the part of the chamfer where the large chamfer is to be formed by chamfering the guide step with a large chamfered amount, in comparison with the feed distance set in the remaining part of the chamfer, the large chamfer and the small chamfer can be both machined at the same time, resulting in simplified machining steps.

Tape guide structure of rotary head drum in recording/reproduction

A cassette transport configuration provides a cassette insertion slot for introducing a cassette cartridge, guide rails for guiding and positioning each cassette cartridge and a plurality of cassette detecting elements for detecting the correct positioning of each cassette. The detecting elements are spaced apart on an upper inner portion of the insertion slot.

Cassette detecting and discriminating arrangement in a cassette

A tape cassette which can maintain stably the accuracy of the reference planes for determining the height of the tape cassette and which allows enhancement in accuracy of positioning, height positioning reference planes being provided inwardly a specified distance apart from an outside casing surface of the tape cassette such that the reference plane for determining the height of the tape cassette relative to the apparatus is not provided on the outside casing surface of the tape cassette, thus the reference planes remain free from contact with any mechanism for loading the tape cassette or with any foreign matter in transport. Thus, the reference planes can be kept free from damage.

An optical recording and reproducing system has an optical recording and reproducing head driving arrangement including an optical pick-up and has an optical recording medium provided between the recording heads. The optical recording and reproducing head is mounted on a rotating arrangement. The head scans tracks while a relative position of the recording medium and rotating arrangement is changed. Each track has an address recorded at the beginning of scanning and a hold signal at the end of scanning. The recording and reproducing heads are separated one track. The recording head makes recording while the reproducing head makes reproduction. In the recording or reproducing mode of operation, the track address is looked. If wrong, it is corrected. The hold signal is detected to operate a tracking device and focusing device. Scanning the next track is determined by the address before tracking is made for recording or reproduction.

Optical recording and reproducing system

This invention relates to a rotary drum device used in magnetic recording and playback apparatus such as VTRs, and particularly to the structure of a magnetic head and flying erasure head mounted on the rotary drum. The flying erasure head and recording head are of virtually same design, with the erasing frequency being set lower than the recording frequency with the intention of obliterating the old record instead of erasing it completely, and the flying erasure head has an azimuth angle of 0.degree. and operates for erasing the old record at a frequency close to the maximum recording frequency of the apparatus, allowing the erasure of record of any particular channel. The flying erasure head and recording head of the virtually same shape reduce their manufacturing cost. The erasing frequency lower than the recording frequency effects the head isolation, and the flying erasure head can be mounted without special shielding measures against such defective performance as crosstalk. The old record can be erased or obliterated easily, and the signal imprinted by the flying erasure head is not picked up because of the azimuth loss. The erasing signal frequency within the recording frequency band causes little crosstalk.

Growing community of inventors

Yokosuka, Japan

Seiji Ono