Dynamic magnetic information storage or retrieval – Record transport with head stationary during transducing – Drum record
Patent
1996-09-10
1998-03-24
Renner, Craig A.
Dynamic magnetic information storage or retrieval
Record transport with head stationary during transducing
Drum record
360106, G11B 5584, G11B 555
Patent
active
057319359
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The object of the present invention is to provide an actuator solution for adjusting reading/writing heads of tape streamers. Such an actuator will position the active elements of the reading/writing head, so that they take the correct position when reading and writing. With an increasing track density there is a need for bringing forth an accurate servo track tailing since the distance between the tracks becomes smaller and smaller with increasing number of tracks. Due to economic reasons it is at the same time desired to have a few active elements as possible in the reading/writing head. An actuator for head positioning must therefore be able to fine position the reading/writing head controlled by servo signals from for example the tape, said actuator at the same time being able to displace the reading/writing head over the total width of the tape, so that all tracks can be read and written. Up till today these two requirements for displacing the reading/writing head of a tape drive have appropriately been attended to by using a plurality of actuators in combination, or a plurality of channels on the reading/writing head.
The present invention succeeds in both fine adjustment of the head (track tailing) and displacement of the reading/writing head across the complete width of the tape with the same motor. An additional objective has been to reduce the radiation of magnetic field from the electromagnetic motor, so that the tape or the reading/writing head should not be damaged or disturbed by the motor.
PRIOR ART
A linear motor or a "voice coil motor" constitutes a known principle and is used in connection with both actuators and loudspeakers. There are also known various variants including a displaceable magnet. In the present application the motor proper of the actuator is described in the drawings as a "voice coil motor". However, other types of electromagnetic motors can also be used, reference being made to Norwegian Patent Application No. 95.3646, which is regarded as a part of the known technology.
Tape drives represent prior art technology. Reading/writing heads are known, and parallel guiding is a known principle for controlling movement. Servo control of linear motors is regarded as prior art technology--and has been disclosed in a series of text books for tape drives and loudspeakers. There exist a plurality of various manners for making such servo systems. When a specific embodiment has not been included in this patent application, this is due to the fact that it is not important for the invention as regards which one is chosen. Materials which are used in connection with the invention are per se prior art materials, i.e. iron, copper, neodym magnets, ceramics, Liquid Crystaline polymer-plastics and ruby bearings. The publications which were presented in a pre-examination in the Norwegian Patent Office in connection with NO 94.4103 are well known and regarded as not barring the present invention. This relates to EP 0 477 030 A1 to Iwamatsu/Okuda from Sharp. It clearly appears from the drawing and schedule of the publication that the second order dynamic system is based on suspension of leaf springs. Even if these have been made very long, they will not be able to carry out the long and at the same time precise movement as in accordance with the present invention.
Neither is GB 2034956 to Billy Richard Baker to be regarded as barring the present invention, since it therefrom clearly appears that this is a drum head adjustment for a video tape recorder. U.S. Pat. No. 5,182,683 to Yasuo Misuhashi from Mitsubishi Denki also relates to a drum adjustment actuator based on a leaf spring for suspending a voice coil. This actuator has not the necessary flexibility to carry out the movement which is necessary, and is neither regarded as a bar. U.S. Pat. No. 5,247,404 to Munehisa Takeda from Mitsubishi Denki is, due to the same reasons as above, regarded as not representing a bar even if the arrangement of the magnets of the motor is of the same type as in the present invention
REFERENCES:
patent: 4212043 (1980-07-01), Baker
patent: 4882635 (1989-11-01), Sanai
patent: 5247404 (1993-09-01), Takeda
patent: 5280402 (1994-01-01), Anderson et al.
patent: 5590007 (1996-12-01), Yanagawa et al.
Patent Abstracts of Japan, vol. 15, No. 376, p-1255, abstract of JP,A, 3-147514 (Sharp Corp), 24 Jun. 1991.
Lian Ragnar
Rudi Guttorm
Simonsen Lars
Renner Craig A.
Tandberg Data ASA
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