Hitachi, Ltd.

Masayoshi Sunada

Shigeyoshi Kawano

Shigemitsu Higuchi

Isamu Terashima

Shigeru Matsuoka

Hiroshi Kanai

Seiichi Hayashi

Kazuo Kikuchi

Kenji Nakamura

Yousuke Nagano

Toshio Tsubaki

Hisao Hanmura

Takeo Sonobe

Hitoshi Ishida

Giichi Ishida

Junichi Enomoto

Kuniaki Kubokura

Tetsuro Hatakeyama

Shinji Mizunuma

Kazuei Saito

Hiroshi Jumonji

Sinji Mizunuma

Yasumasa Saito

Toshiaki Suematsu

An alignment disk having an adjust signal recorded thereon to maintain data interchangeability of a magnetic disk drive apparatus and loadable and unloadable to and from the magnetic disk drive apparatus, and method and apparatus for verifying a tracking errors of the magnetic disk drive apparatus are disclosed; the magnetic disk drive apparatus including magnetic head means for recording and reproducing data on and from a magnetic recording medium, a head carriage for carrying the magnetic head means, and drive means for driving the head carriage radially of a track of the magnetic recording medium; the alignment disk having a set of track diameter adjust signal pairs recorded on tracks equal to or larger in number than the number of phases of a stepping motor for driving the head carriage and corresponding to at least the excitation phases of the stepping motor; the set of track diameter adjust signal pairs each having an inner track signal and an outer track signal extending inward and outward from a center of the track; and the set of track diameter adjust signal pairs being arranged symmetrically about a rotation axis of the disk.

Alignment disk for magnetic disk driving apparatus and method and

A magnetic storage disk tracking system employing a stepping motor is operable to compensate the tracking error within a certain expected range caused by the hysteretic movement of the motor. The system incorporates means for recognizing the track to which the magnetic head is positioned and memory means in which is stored data for compensating the positioning error depending on each track. The stepping motor is controlled through the excitation voltage of each winding under modulation in terms of the magnitude or duty cycle in compliance with the stored data.

Head positioning system for magnetic recording/playback apparatus

A remote-controlled automatic door control apparatus includes a door, a driving unit connected to the door for driving the door to open and closed positions, and a control arrangement for controlling the door operation through the driving unit and including a radio communication system having a transmitter and a receiver. A signal containing a specific code transmitted from the transmitter is received by the receiver and collated with a code set previously in the receiver, and if they have a predetermined relationship with each other, an operation command is issued to the driving unit. The transmitter is capable of being set to a specific code, and the receiver includes a memory device for storing the specific code transmitted from the transmitter. A signal switching device is further provided for actuating the collating operation for collating the stored code with the signal from the transmitter under normal conditions and for storing a signal from the transmitter in the memory device if required.

Remote-controlled automatic control apparatus

A developer quality monitoring device for monitoring the mixed state of toners and carriers in the developer used for developing a latent image formed on a recording medium, wherein a developer circulating mechanism and a toner density detector are used in common, an electrical signal representative of a decrement of toner density and a magnitude of pulsations is produced, and by using this electrical signal, decay condition of the developer is monitored and decay condition limit is discriminated.

Developer quality monitoring device

In a control circuit for controlling the rotating speed of a clutch and brake motor of a sewing machine capable of performing non-ravel seaming, an improved non-ravel seaming controller for enabling non-ravel seaming during a certain number of seams at the start of sewing and for generating a medium speed signal at a predetermined level during a certain number of seams at the end of sewing to enable non-ravel seaming at such time.

Sewing machine with improved non-ravel seaming controller

A control circuit for controlling the shaft speed of a motor having clutch and brake devices comprises a speed detector for detecting the actual rotating speed of the motor and generating a first pulse signal having a period in inverse proportion to the actual rotating speed, a speed selector for setting the desired-speed of the shaft, a signal generator for generating a second pulse signal having a period in inverse proportion to the desired-speed from the speed selector, a first means for detecting the ratio of the period of the first signal to the period of the second signal, and a second means for controlling the operation of the clutch and brake devices in response to the detected ratio.

Control circuit for controlling the shaft speed of a motor having clutch

An electromagnetic guidance system used, for example, for guiding a driverless mobile vehicle. For example, a two-core wire or cable is in the surface of a travelling course. The core conductors of the two-core wire are connected at its end so that current may circulates through the conductor. By detecting the magnetic flux induced by the circulating current by means of detecting coils mounted on the driverless mobile vehicle, the vehicle can be automatically run along the two-core wire without any change-over operation.

Electromagnetic guidance system

In a system for optically detecting with a plurality of light detecting elements a reflecting object in the form of long stripe disposed on the surface of a traveling path, the average value of the respective electric quantities derived from the light detecting elements is obtained through arithmetic operation and the reference value is automatically changed according to the degree of the surface being soiled, by multiplying the average value by a certain safety factor, so that accurate detection can be performed independent of the degree of the soil on the traveling path surface.

System for detecting reflecting objects

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Hitachi, Japan

Masayoshi Sunada