JPH03283604A - Differentiation type coil - Google Patents

Abstract

PURPOSE:To make analysis of magnetic field source easy and to eliminate limitation of a base line by winding a bendable material of low temperature resistance whereon a thin superconductor film is formed to a specified pattern to form a space differentiation type coil shape. CONSTITUTION:A thin superconductor film is formed on a surface of a bendable substrate 1 of low temperature resistance, a thin superconductor film pattern 2 of approximately square loop is formed, the bendable substrate 1 is rolled to a tube shape with the thin superconductor film pattern 2 outside, and both ends thereof are laminated and bonded. Thereby the thin superconductor film pattern 2 is shaped into a space primary differentiation type coil. Therefore, it is possible to eliminate distortion of detected magnetic field like a plane differentiation type coil, to realize easy analysis of magnetic field source, and to relax limitation of a base line greatly as a coil pattern is not formed on a wafer.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a differential coil used to pick up a magnetic field to be measured and transmit it to a magnetic sensor in order to measure extremely small magnetic fields.

<Prior Art> Magnetic sensors such as 5QUID do not directly pick up the magnetic field to be measured, but instead use an input circuit in which a differential coil called a magnetic flux transformer or the like is used as a detection coil. That is,
The magnetic field to be measured is picked up by a differential coil, and the input coil connected to this differential coil is connected to a 5QUI.
By magnetically coupling to a magnetic sensor such as D, the magnetic field to be measured is transmitted to the magnetic sensor.

Differential type coils used for such purposes are broadly divided into three-dimensional types (spatial differential type) and planar types (plane differential type).

The three-dimensional type is made by winding a superconducting wire 82 around the surface of a bobbin 81, as illustrated in FIG.

In the planar type, as illustrated in FIG. 9, a superconductor thin film 9
It is made by buttering 2.

<Problems to be Solved by the Invention> Among the conventional differential type coils described above, the three-dimensional type requires skill to manufacture because the coil is made by hand-winding wire, etc. and the compensation coil If! There is a problem in that it is difficult to adjust the baseline, which is II (coil spacing), and it is easy to shift.

On the other hand, although the flat type does not have the above problems, the distribution of the detected magnetic field is distorted, making it difficult to analyze the source of the magnetic field. Additionally, information about deep magnetic field sources cannot generally be obtained unless the baseline of the differential coil is increased.
When creating on a wafer, there is a problem that the baseline is limited depending on the wafer size.

The present invention has been made in view of these points, and provides a differential coil that does not distort the distribution of the detected magnetic field, has almost no baseline restrictions, and does not cause baseline deviation. intended to provide.

<Means for Solving the Problems> In order to achieve the above object, the differential coil of the present invention has the following features:
A superconductor thin film 2 is formed in a predetermined pattern on the surface of a low temperature resistant flexible material (substrate) 1, and the flexible material 1 is wound to form a spatially differentiated coil shape. It is characterized by having the following characteristics:

<Operation> Since it is basically a spatial differential type coil, there is no distortion of the detected magnetic field unlike a planar differential type coil, and the coil pattern is not formed on the wafer, so the baseline limit is limited when using a wafer. This will be greatly eased compared to the previous year. Further, pattern formation of the superconductor thin film 2 on the flexible material 1 can be performed using, for example, a photolithography method, and good reproducibility can be obtained, thereby achieving the intended purpose.

<Example> FIG. 1 is a perspective view of an embodiment of the present invention.

A flexible substrate 1 having low temperature resistance, such as a polyimide substrate, is wound into a cylindrical shape, and both ends thereof are overlapped.

On the surface of this flexible substrate 1, a superconductor thin film pattern 2 having a substantially rectangular loop is formed.

As this superconductor, Nb, Pb, etc. can be used. When the flexible substrate 1 is wound, the superconductor thin film pattern 2 has a spatially differentiated coil shape as shown in FIG. Note that 3 is a pad for connecting to the input coil.

In this embodiment of the present invention, when the pattern 2 is cooled to a temperature at which it becomes superconducting, as illustrated in FIG. They flow in opposite directions and operate as a differential coil.

Next, the manufacturing method of the above embodiment will be explained with reference to FIGS. 3 and 4.

First, a superconductor thin film is formed on the surface of a flexible substrate 1, and a substantially square loop superconductor thin film pattern 2 as shown in FIG. 3 is created using photolithography.

Next, this flexible substrate 1 is rolled into a cylindrical shape, as shown in FIG. 4, with the superconductor thin film pattern 2 on the outside, and both ends thereof are overlapped and bonded.

As a result, a space-order differential type coil having the structure shown in FIG. 1 is obtained.

According to the manufacturing method described above, the precision and reproducibility of the superconductor thin film pattern 2 are extremely good, and problems such as baseline adjustment and deviation are solved.

Here, the precision of the coil will be improved if the inside of the flexible substrate 1 is not made hollow and is wound around a cylinder that is close to a perfect circle. However, it is desirable to select a material for the cylinder that is resistant to low temperatures and has a coefficient of thermal expansion approximately equal to that of the flexible substrate 1.

Furthermore, when rolling the flexible substrate 1 into a cylindrical shape, if the lines A and B of the superconductor thin film pattern 2 shown in FIG. In addition to forming a magnetically closed circle, the probability of sensing magnetism between the lines connecting the upper and lower coils is also significantly reduced, resulting in a highly sensitive detection coil.

FIG. 5 and FIG. 6 are diagrams showing an example of use of the embodiment of the present invention as described above.

The example shown in FIG. 5 is an example in which a chip 11 on which a magnetic sensor, an input coil, etc. are formed is placed separately, and is connected to the chip 11 from a pad 3 via a superconducting wire 12.

The example shown in FIG. 6 is an example in which a magnetic sensor chip 11 is firmly bonded onto the flexible substrate 1, and the chip 11 is connected to the pad 3 by wire bonding.

5 and 6, 13 is the flexible substrate 1
It is a holding cylinder.

Note that the present invention is not limited to the spatially differentiated coil as described above, but can also be applied to higher order spatially differentiated coils.

FIG. 7 shows an example of a superconductor thin film pattern 2' on a flexible substrate 1' when the present invention is applied to a second-order differential type coil.

In this case, a notch is provided in the flexible substrate 1', and the superconductor thin film pattern 2' is placed with the end shown as a in the figure inside.
It is preferable to wrap the flexible substrate 1' twice so that the outer side is on the outside.

This allows the pad 3' portion to be located below the notch, making it easier to connect to an external circuit.

However, in this case, since the lines of the superconductor thin film pattern 2' cross, it is necessary to form multiple layers on the flexible substrate 1'.

<Effects of the Invention> As explained above, according to the present invention, since it is basically a spatial differential coil, the distribution of the detected magnetic field is not distorted, making it easy to analyze the magnetic field source. In addition, the size of the flexible substrate can be sufficiently formed up to the size for making a normal FPC, and the baseline restrictions are significantly relaxed compared to the conventional planar differential coil that is patterned on a wafer.

Moreover, since it is only necessary to form a coil pattern on the surface of a flexible material using, for example, photolithography, and to roll the flexible material, it is extremely easy to manufacture with good reproducibility and does not require any manufacturing skill. , and there will be no deviation of the baseline. at the same time,
Since the baseline is determined by the accuracy of photolithography, high accuracy can be easily achieved.

Furthermore, as mentioned above, the coil circles can be almost magnetically closed circles with a deviation equal to the thickness of the flexible material, in which case magnetism can be sensed between the lines connecting the upper and lower coils. Since the probability of this occurring is also significantly reduced, a highly sensitive detection coil can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of the present invention, FIG. 2 is an explanatory diagram of a space-order differential coil equivalent to the embodiment of the present invention, and FIGS. 3 and 4 are explanations of the manufacturing method of the embodiment of the present invention. Figures 5 and 6 are explanatory diagrams of usage examples of the embodiments of the present invention. Figure 7 is an explanatory diagram of superconductor thin film patterns when the present invention is applied to a spatial second-order differential coil. is an explanatory diagram of a conventional three-dimensional differential coil (spatial differential coil), and Figure 9 is a conventional planar differential coil (planar differential coil).
FIG. 1... Flexible substrate 2... Superconductor thin film pattern 3... Pad 11... Magnetic sensor chip 2... Superconducting wire 3... Holding cylinder

Claims (1)

[Claims] A coil for picking up a minute magnetic field to be measured and transmitting it to a magnetic sensor, the coil having a superconductor thin film formed in a predetermined pattern on the surface of a low temperature resistant flexible material, and
A differential coil characterized in that the flexible material is wound so that the superconductor thin film forms a spatially differential coil shape.