Hitachi, Ltd.

Fumio Hara

Seiichi Mita

Morishi Izumita

Hiroyuki Tsuchinaga

Takeshi Maeda

Shigeru Nakamura

Hisataka Sugiyama

Atsushi Saito

Yoshito Tsunoda

Yoshizumi Eto

Masuo Kasai

A tape recorder of the present invention comprises a pair of feed and take-up spools for winding a tape as recording media, a rotatable drum rotated to wind and run the tape between the pair of spools over the drum surface helically, a head for recording, reproducing or erasing signals on the tape wound over said drum surface, and control means for controlling the relative positional relationship between the head and the tape wound over the drum surface based on an error signal such that said signals are stably recorded, reproduced or erased along a desired track, the control means having means for holding the error signal during the period in which the tape is discontinued over a drum surface. The value of the error signal at the time immediately before the tape disappears from the drum surface, or the value of the error signal at the time immediately after the tape reappears over the drum surface during the preceding rotation of the drum is used as the error signal to be held, thereby allowing to stably restart the positioning control when the tape reappears over the drum surface.

Tape recorder with means for sampling and holding focusing and tracking

An optical tape apparatus having improved focus and tracking control. An optical head records, reproduces, or rewrites data on an optical tape by helically scanning the tape with a laser beam. A guide plate is disposed between the optical head and the tape to prevent the beam from becoming unfocused due to fluctuation of the tape cuased by an air film between the optical head and the tape. The optical head contains a semiconductor laser and an optical system exhibiting chromatic aberration for directing the laser beam onto the tape. The optical system includes a condenser lens for focusing the beam onto the tape. Fine focus control is achieved by changing the wavelength of the laser beam by directing part of the beam reflected from the tape back to the laser, thereby changing the focal point of the beam by virtue of the chromatic aberration of the optical system. Coarse focus control is achieved by mounting the condenser lens on a piezoelectric actuator which moves the consenser lens to focus the beam onto the tape. A recording head for recording timing marks and tracking signals on the tape is disposed in advance of the optical head. A reading head reads the timing marks and the optical head reads the tracking signals. The timing marks and tracking signals are used to control the operation of the apparatus such that the tape is transported with a constant speed and data on diagonal signal tracks on the tape is accurately recorded, reproduced, or rewritten.

Optical tape apparatus with a tracking control mechanism and/or a

In optically coupling a plurality of light sources to an optical system for focusing light beams from the light sources into spots on a record plane, a center axis of a light beam from a first one of the light sources is aligned to an optical axis of the focusing optical system, and the spots other than a first spot formed by the light beam from the first light source are rotated around the first spot on the record plane to position the spots to the respective target tracks, and a tracking error signal for at least one of the first spot and another spot is detected and the positions of the plurality of spots are integrally controlled based on the detected tracking error signal so that the plurality of spots can follow the respective target tracks. The target tracks to which the spots are to be positioned may be either one track or different tracks. The positioning of the spots to the target tracks may be done either manually or automatically. In the automatic method, a tracking error signal is detected for the first spot, and a deflection mechanism for radially swinging beams from the laser light sources is controlled to control the positions of the spots on the record plane and to cause the first spot to follow the target track.

Optical recording and reproducing apparatus having a multi-spot

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Kodaira, Japan

Fumio Hara