Magnetic head based on magnetic resistance technology

Abstract

The invention discloses a magnetic head based on a magnetic resistance technology. The magnetic head comprises at least one or more sensing units and an output pin, wherein the sensing units are the same in magnetic field inducing direction. The sensing units are used for detecting a leakage magnetic field of a magnetic medium; the input end and the output end of the output pin are electrically connected with corresponding ports of the sensor respectively and used for connecting a sensor with a system; sensitive elements of the sensing units are giant magnetic resistance elements or magnetic tunnel junction elements, wherein the giant magnetic resistance elements and the magnetic tunnel junction elements are of a multi-layer film structure with nanoscale thickness, and the each nanoscale multi-layer film structure at least comprises a free layer nanoscale film, a non-magnetic layer nanoscale film and a pinning layer nanoscale film. The sensor has the advantages of being high in sensitivity and precision, small in size, high in signal-to-noise ratio and anti-interference capacity and the like, non-contact measuring is achieved, the magnetic head can be built in a mobile terminal and is suitable for mobile payment, the JitterShift phenomenon is effectively solved, and the magnetic head is suitable for large-scale industrial production.

Description

technical field [0001] The invention relates to the technical field of magnetic sensors, in particular to a sensor for identifying the magnetic properties of media such as magnetic cards, confidential paper, bills and checks. Background technique [0002] In daily life, magnetic media are widely used in magnetic cards, security paper, checks and other fields. Taking a magnetic card as an example, its recording medium has the following characteristics: (1) The magnetic signal attenuates very sharply with distance; (2) It has multiple magnetic recording strips and requires information encryption; Such sensors put forward new requirements, that is, mobile payment, which requires sensors to be built into mobile terminals such as mobile phones. In view of the above characteristics, the sensor used to identify the magnetic medium of the medium needs to have the following characteristics: (1) high sensitivity, high precision, high signal-to-noise ratio, small size and strong anti-...

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Problems solved by technology

[0004] (1) Using a single inductive coil or multiple inductive coil arrays as a sensitive element has very low sensitivity and precision, no anti-interference ability, high power consumption, and a large volume that cannot be built into mobile devices;

[0005] (2) When measuring, it must be used close to the magnetic card and cannot be used without contact

The sensitivity of the Hall element is very low and the volume is large, but it is difficult to achieve thinning and its measurement accuracy is also very low due to its poor physical properties

In the application of magnetic cards, the leakage magnetic field of the magnetic medium is relatively strong on the surface of the medium, while the saturation field (i.e., the working field) of the anisotropic magnetoresistance is very low, so the leakage field of the magnetic medium can easily make the anisotropic magnetoresistance The element is saturated, so it cannot be used as a sensitive element for media recognition sensors

[0008] In recent years, magnetoresistive sensing elements represented by giant magnetoresistance elements (Giant Magneto-resistance, GMR) and magnetic tunnel junction elements (Magnetic Tunnel Junction, MTJ) have smaller volumes than existing sensing elements , higher precision and sensitivity, better temperature characteristics and high signal-to-noise ratio, because this technology is concentrated in the field of information storage technology, the application in other fields is still in the stage of exploration and small-scale production, and has not been industrialized Mass production, at the same time in the actual research and development, due to the increase of the distance between the sensor and the magnetic medium, the phenomenon of Jitter Shift will appear, which will seriously distort the output signal

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