JPH0672915B2 - Magnetic pattern detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to an apparatus for detecting a magnetic pattern by disposing a plurality of superconductor magnetoresistive elements.

<Prior Art> The conventional magnetic measuring device has a large shape, and it is difficult to measure a fine magnetic pattern due to accuracy and operability.
In particular, the SQUI is highly sensitive to weak magnetic fields and makes high-speed measurements.
Although there is D (superconducting quantum interference device), the structure of SQUID is delicate, and the magnetic measurement by SQUID is complicated by the related electronics technology. It is difficult to form a large number of SQUIDs in an array to detect and measure the magnetic patterns of the most expected magnetocardiograms and brain magnetoencephalograms, and a single person can limit simultaneous measurement of magnetic waves at several locations. Met.

Moreover, the electronic devices connected to it, including the SQUID, are extremely expensive, and require tens of millions of yen for simultaneous measurement at several locations, which is not realistic.

<Problems to be Solved by the Invention> In order to accurately measure a magnetic pattern, small magnetic sensors are arranged at high density on the surface of the magnetic pattern to be measured. The sensor is preferably a superconducting magnetoresistive element that detects a weak magnetic field due to the grain boundary that has been produced previously. An object of the present invention is to provide an apparatus for efficiently detecting a magnetic pattern by using this superconductor magnetic sensor.

<Means for Solving Problems> The present invention uses a superconducting magnetoresistive element having an extremely high-speed magnetic detection characteristic peculiar to superconductivity without deteriorating the magnetic detection sensitivity even if it is downsized. The magnetic power supply is arranged in a matrix, and the power supply terminals are alternately connected to the magnetic detection unit, and elements are connected so that they are commonly used by the elements adjacent to the power supply line. This is a magnetic pattern detection device that increases element density by minimizing wiring for wiring.

In the above superconducting magnetoresistive element, the directivity of the sensitivity with respect to the direction of the magnetic field to be measured is very small, and therefore there are almost no restrictions when disposing the element.

It should be noted that the superconducting magnetoresistive element used in the present invention has a non-inductive structure formed by precise processing so that a current flowing through the element does not generate a magnetic field affecting an adjacent element.

<Operation> The sensitivity does not decrease due to the small size, the detection speed is extremely fast due to the superconducting characteristics, and the superconducting magnetoresistive element that operates by the effect of grain boundaries can be arranged at high density on the surface that detects the magnetic pattern. A magnetic pattern detection device capable of measuring even a high-speed change of a pattern can be provided.

<Example> An example of the present invention will be described in detail with reference to the drawings.

FIG. 4 is a diagram showing an example of the characteristics of the ceramic high temperature superconducting magnetoresistive element having grain boundaries used in the examples of the present invention. The horizontal axis of this figure shows the strength of the magnetic field applied to the element and the vertical axis. The axis is the resistance value generated by the device, and the current I = 0.1 mA was passed through the device.

The ceramic high temperature superconducting magnetoresistive element is Y-Ba-Cu.
Since the critical temperature (Tc) of the -O type oxide film is about 90K, the measurement is performed at the liquid nitrogen temperature of 77K. The superconductor to be used can be cut out from a bulk superconductor prepared by firing powder raw materials, but the element can be made smaller by using a thin film or thick film of the μm order by sputtering or CVD. Since the generated resistance value can be increased, the measurement becomes easy.

As can be seen from the figure, the characteristic of Fig. 4 is that when a very weak magnetic field (1 Gauss or less) is applied, the superconducting state is broken from the vicinity of the grain boundary and resistance is generated. The increase in the resistance of the device with respect to is rapid.

FIG. 3 shows an example of the configuration of one magnetic sensor unit 6, which is composed of a superconductor magnetoresistive element 1 and a resistor 2 connected in series, and both ends 3 and 4 of which are connected to a power source for supplying a current to the element 1. Power line 3,4
The signal terminal 5 is connected to the element 1 and the resistor 2 and is connected to the signal terminal 5. The voltage applied from the signal terminal 5 to the power supply voltage terminals 3 and 4 outputs a voltage divided by the element 1 and the resistor 2. Therefore, the change in the strength of the magnetic field can be measured from the change in the output of the signal terminal 5. Here, the element 1 of FIG.
Is a superconducting film, in which a dividing line is inserted to increase the length as a resistance and a non-inductive structure is used to minimize the magnetic field generated from the current flowing through the element 1 to prevent interference with surrounding elements. It is a small one.

The example of FIG. 3 has a configuration in which one resistor 2 is connected in series to the element 1, but whether a resistor is connected in parallel to the configuration of FIG.
It is also possible to adjust the characteristics of the element with respect to the magnetic field by connecting a resistor and a variable resistor.

FIG. 1 shows an array in which n magnetic sensor units 6 described in FIG. 3 are connected in parallel between power supply lines 3 and 4 in the first embodiment of the present invention. The output terminal of this embodiment is 51
From 1 to 5n, a one-dimensional magnetic pattern can be detected.

FIG. 2 shows a second embodiment in which the one-dimensional array of the first embodiment is connected to the two-dimensional array. In the second embodiment, in order to simplify the power supply line, the power supply lines 3 and 4 are alternately arranged so that the magnetic sensor portions 6 on both sides of the power supply line can be commonly used.

However, also in the second example, the power supply lines 3 and 4 may not be arranged alternately, but the one-dimensional array of the first embodiment may be arranged two-dimensionally. In the configuration of the second embodiment, the signal terminal ^{5 (51~5n, ... 51n 1 ~5n} 1 n) by measuring the, it is possible to detect the two-dimensional magnetic pattern.

<Effects of the Invention> The magnetic pattern detection device of the present invention has a high sensitivity to a magnetic field, has no sensitivity decrease due to miniaturization, and has a non-induction structure that operates at high speed. A magnetic sensor composed of a superconducting magnetoresistive element having a crystal grain boundary in which the superconducting state is broken and resistance is generated.
Since the two-dimensional or two-dimensional arrangement can be performed with high density, it is possible to detect even a high-speed change of a weak magnetic pattern with high density.

[Brief description of drawings]

FIG. 1 is a block diagram of the first embodiment of the present invention, FIG. 2 is a block diagram of the second embodiment of the present invention, FIG. 3 is a block diagram of a magnetic detection sensor section, and FIG. 4 is a superconducting magnet. It is a figure which shows an example of the characteristic of a resistance element. 1 and 11, 12, ..., 11 ', 12', ... are superconducting magnetoresistive elements,
Reference numeral 2 is a resistor, 3 and 4 are power supply lines, 5 is a signal terminal, and 6 is a magnetic sensor unit.

Claims (1)

[Claims] 1. A superconductor in which a superconducting film has a non-inductive structure in which a superconducting film is formed on a magnetic pattern detecting surface so as to have a non-inductive structure, and the superconducting state is broken from the vicinity of the grain boundary to generate resistance. A magnetic pattern detecting apparatus comprising: a plurality of magnetic sensor units, each of which is connected to a magnetoresistive element and its resistance change detecting unit; and a power supply line commonly connected to each of the magnetic sensor units.