IEEE Computer Volume 11 Number 1 -- NEW APPLICATIONS
Original Publication Date: 1978-Jan-01
Included in the Prior Art Database: 2005-Nov-10
Software Patent Institute
D. A Michalopoulos: AUTHOR [+3]
NEW APPLICATIONS * Applications of the magnetoresistance effect * Taipei gets first major telephone directory assistance computer system * Software factory backs up pulp and paper mill * TV monitors speed detection of tumors
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Prof. D. A Michalopoulos
California State University. Fullerton edited by
Prof. D. A Michalopoulos California State University. Fullerton
Applications of the magnetoresistance effect
Although it was discovered more than 100 years ago that the electrical resistance of certain metals can be influenced by an applied magnetic field, it is only in recent years that proposals have been put forward for practical applications of this "magnetoresistance effect," as it is called. There are two important reasons for the revival of research in this field. The first is the development of magnetic recording in the direction of increasingly high information densities, which calls for magnetic sensors of a compactness that cannot be achieved with conventional inductive sensors. The second is the development of methods, related to integrated circuit technology, by which micropatterns can be made in thin metal layers, making it possible to fabricate tiny magnetoresistive elements capable of detecting magnetic fields varying on a micron scale.
The new possibilities for the detection and measurement of magnetic fields have also been investigated at Philips Research Laboratories in Eindhoven, The Netherlands, with a particular view to the readout of information recorded on magnetic tapes and in bubble memories. This work has resulted in entirely new constructions for magnetoresistive heads /MRH). They prove to be much more sensitive than the conventional inductive type of reading heads, so that amplifier noise is less of a problem.
The special feature of the new MRH constructions is the following: The magnetoresistance effect is essentially nonlinear, and hitherto this has been an obstacle to applications requiring the reproduction of recorded information without distortion. A simple means of avoiding this distortion has been devised by K.E. Kuijk of Philips Research Laboratories. It consists of depositing on the MRH strip a series of oblique bands of a highly conductive material, such as gold See Figure 1 ).This measure leaves the sensitivitv virtually unaffected. The new MRH construction is referred to as a "barber pore," a name suggested by the appearance of these strips with their oblique bands of alternating color.
In the field of magnetic data recording the development of magnetic tapes and disks, with the associated electronics for the read and write heads, has been greatly stimulated by the need for increasingly high information densities. This had led to the continuous refinement and miniaturizatio...