Sharp Kabushiki Kaisha Corporation

Hiroaki Takeuchi

Tohru Okuda

Hideo Okada

Takamitsu Tadera

Shigemi Asai

Yoshiyuki Yokomachi

Kazuki Murata

In a plasma processing method making use of a plasma processing gas of a reactant gas and an inert gas, it is aimed at enhancing an efficiency of use of high-frequency power and a reactant gas to increase a processing rate. The plasma processing method comprises supplying high frequency power to an electrodeopposed to a substrateto thereby generate plasma between the electrodeand the substrateon the basis of a plasma processing gas comprising a reactant gas and an inert gas to perform film formation, etching, surface treatment or the like on the substrate, pressure P(Torr) of the plasma processing gas being set to satisfy the following relationship 2&#xd7;10(Torr/Hz)&#xd7;f(Hz)&#x2266;P(Torr)&#x2266;500(Torr) where f(Hz) is a frequency of high frequency power.

Plasma processing method

A driving circuit for generating a motor driving voltage has a positive feedback loop for feeding back the motor driving voltage through a filter. The filter is arranged so as to have a transfer function given as G.sub.F (s) which (1) satisfies G.sub.F (s).apprxeq.1 in a frequency band in which disturbances should be suppressed while (2) satisfies .vertline.G.sub.F (s).vertline.&lt;.vertline.G.sub.open .vertline. in a full range of frequencies, where G.sub.open represents an open loop transfer function of a motor control device in which a positive feedback loop is not provided. With this arrangement, it is possible to suppress disturbances, irrelevant to motor characteristics which may vary. Besides, it is possible to provide a motor control device in which computations for disturbance compensation are considerably decreased.

Motor control device

An actuator moves a signal reproducing element based on an applied control input. An error detector detects a difference in relative position between a desired track and the signal reproducing element. A drive circuit computes the input valuable applied to the actuator based on an output from the error detector and applies it to an adder. On the other hand, the actuator simulation circuit for electrically simulating the characteristics of the actuator estimates the position of the actuator from the control input. Furthermore, a target follow-up estimator estimates a track bend based on outputs from the actuator simulation circuit and the error detector and are fed forward to the adder via a feedforward gain. The Adder applies the computed control input to the actuator. As a result, a control system which offers an improved precision over a wide band can be achieved while maintaining the stability.

Control system and information recording and reproducing apparatus

The relative height between two sets of magnetic head groups shared for recording and reproduction and mounted on actuators is adjusted at high accuracy, so that a track of a predetermined track width and track pitch can be formed. In a rotary head type magnetic recording/reproduction apparatus including two sets of magnetic head groups AT and BT of one or a plurality of magnetic heads displaceable in the track width direction by actuators 100A and 100B, a signal which becomes the reference for relative height adjustment of the heads is recorded by one of the magnetic head groups. Then, the magnetic tape is rewound, and the run of the magnetic tape is controlled by one of the magnetic head groups. Under this state, the relative height between the two sets of magnetic head groups is detected by the other magnetic head group, whereby the relative height of the two sets of magnetic head groups is adjusted according to that information.

Magnetic recording/reproduction apparatus and method for adjusting head

A closed magnetic circuit is formed in a rotary drum by first and second yokes of a soft magnetic material and a permanent magnet. In addition, a drive coil is provided in a gap provided between the first and second yokes so as to cross a magnetic flux running in the closed magnetic circuit. The first yoke is supported by a parallel leaf spring so as to be movable along the axis of the rotary drum. An electromagnetic force is applied to the first yoke in the direction of the axis of the rotary drum by applying a control current to the drive coil. The first yoke can be shifted in this manner to a position where the electromagnetic force balances the reaction force of the parallel leaf spring. In this manner, the closed magnetic circuit generates a sufficient drive force and eliminate a leak magnetic flux that affects a head or a transformer. Moreover, the movable portion is light-weighted, and the following frequency of a dynamic tracking operation is improved, compared to a case where all the closed circuit section is disposed with a movable portion of the parallel leaf spring.

Rotary head cylinder device

A shaft is fixed on a fixed drum, and a rotary drum is supported rotatably on the shaft. Parallel plate springs are supported by the rotary drum, and at movable portions of the plate springs, a permanent magnet is gripped and a magnetic head is supported. A yoke having a wall surface opposing to both side surfaces of the permanent magnet with a prescribed distance therebetween is fixed on the fixed drum. A first coil is mounted and fixed to oppose to one side surface of the permanent magnet with a prescribed space, and a second coil is attached and fixed to oppose to the other side surface with a prescribed space therebetween, on the yoke. Accordingly, responsiveness in dynamic tracking operation at the time of signal reproduction can be improved, and vibration of the magnetic head during signal recording can be prevented.

Rotary head type magnetic recording reproducing apparatus

A shaft is fixed on a fixed drum, and a rotary drum is supported rotatably on the shaft. Parallel plate springs are supported by the rotary drum, and at movable portions of the plate springs, a permanent magnet is gripped and a magnetic head is supported. A yoke having a wall surface located opposite to both side surfaces of the permanent magnet with a prescribed distance therebetween is fixed on the fixed drum. A first coil is mounted and fixed to be opposite to one side surface of the permanent magnet with a prescribed space, and a second coil is attached and fixed to be opposite to the other side surface with a prescribed space therebetween, on the yoke. Accordingly, responsiveness in dynamic tracking operation at the time of signal reproduction can be achieved, and vibration of the magnetic head during signal recording can be prevented.

The present invention has been achieved to provide a novel tape cassette capable of stable and excellent magnetic recording and reproducing operations realizes highly accurate head touch necessary for tendency to Hi-Fi and digitization with a simple structure that does not require relatively high shape accuracy. In order to achieve the above object, a novel tape cassette for use in magnetic recording/reproducing apparatus of fixed head type, comprises: magnetic tape 2, a pressure pad 3 and a pad base 13 having the pressure pad 3 fixed thereon, incorporated in a tape cassette 10, being characterized in that when a magnetic head 8 is inserted in the tape cassette 10, the pad base 3 is positioned relative to the magnetic head 8 by positioning pins 17a and 17b disposed in the magnetic recording/reproducing apparatus.

Tape cassette and magnetic recording/reproducing apparatus used therefor

In order to obtain a desired output characteristic in magnetic recording/reproducing apparatus, a proper range of magnetic tape wrap angles on a magnetic head are determined according to the following expressions, taking account of tension:

Magnetic recording/reproducing apparatus capable of high-density

A magnetic head device includes a magnetic head having a sliding surface on which a magnetic tape slides. The sliding surface has a magnetic gap formed on the vertex portion thereof in a manner to allow the magnetic gap itself to record or reproduce information signal on or from the magnetic tape. Defining that .alpha. is an angle formed between a tangent drawn at the vertex portion of the sliding surface and a tangent drawn at the end portion of the sliding surface, .beta. is an angle formed between the inflow direction of the magnetic tape to the sliding surface and the tangent drawn at the vertex portion of the sliding surface and T is tension applied on the magnetic tape per unit width, the form of the magnetic head and the location and tension of the magnetic tape are arranged so that a parameter value obtained by an equation of T.times.sin (.beta.-.alpha.) is in the range of 0.02 gf/mm to 0.15 gf/mm.

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Tenri, Japan

Hiroaki Takeuchi