JP2004538467A6 - Magnetic field detector - Google Patents

Abstract

A sensing inductor (1), specifically a saturated core type, for a magnetic field has at least one inductor coil (10) wound as a planar helix around the core (20), more preferably A plurality of planar spirals (10a-d) are stacked along the axis (50) of the core, and a pair of adjacent coils (10a, 10b) are connected to each other by an inner end (32a) connected by a bridge (44). , 32b). Two or three such pairs can be used. The multiple coils (10a-d) and the central core (20) can be manufactured using planar selective deposition techniques from the semiconductor industry. The magnetic core (50) may be another entity that is inserted into the axial hole formed through the stacked coils. A preferred core material is permalloy. The winding width (w), spacing (s), and thickness (t) of the helical coil are discussed along with the axial spacing (d) and core diameter (φ) between the coils.

Description

【Technical field】
[0001]
The present invention relates to a magnetic field sensing device, and more particularly, but not exclusively, to a sensing device for use with a magnetized transducer element that generates a magnetic field that is a function of applied torque or force. . The invention further relates to a detection circuit incorporating such a detection device. Such a circuit is also called a signal processing circuit.
[Background]
[0002]
In recent years, magnetic transducers have been increasingly applied to measure shaft torque. The magnetized transducer element is provided on the shaft and becomes its magnetized region. A non-contact sensing device comprising one or more sensing devices is arranged adjacent to the area. Non-contact sensing devices are particularly advantageous when the torqued shaft is rotating. Permanently magnetized transducer elements that generate a torque-dependent magnetic field can be considered passive in that they do not require active excitation to magnetize the transducer element. It is advantageous for operation.
[0003]
Various types of sensing devices are known, including Hall effect devices and magnetoresistive devices, and what are known as saturated or saturable core inductors. Each of these types of devices currently available has various practical problems.
[0004]
Hall effect devices are basically produced in the form of a plane, whose maximum sensitivity is perpendicular to the device surface. If the surface of the device is radial, for example with respect to the axis of rotation of the shaft, the Hall effect device is sensitive to components directed in the axial direction of the magnetic field (in-line) and allows high lateral resolution in the axial direction. . The lateral resolution is not so high when the device is oriented at 90 ° to the radial plane in order to detect radial magnetic field components. The main drawbacks of the Hall effect device are its low sensitivity and resolution, and it is not a suitable detector for small magnetic fields often found in magnetic transducers.
[0005]
Magnetoresistive (MR) devices are classified into two types: anisotropic magnetoresistors (AMR) and giant magnetoresistors (GMR). Recently, the latter is more preferred. Both types of devices are originally in the form of a plane, and a change in resistance according to the area of the region of the device is seen, so the sensitivity must be balanced against the resolution. Even the thinness of these devices limits the area of the magnetic field that can be detected. Although higher lateral resolution is possible than known saturable inductor devices, it does not have as good a range as the Hall effect device, so a compromise between resolution and sensitivity must be found as described above.
[0006]
The saturable core sensing device includes an inductor in the form of a coil spirally wound around the core. For example, the core may be of a material available from Allied Signal under the name 2705M. This is a saturable high permeability cobalt-based amorphous glassy alloy foil. One or more such inductors can be connected to a signal processing circuit as disclosed in WO 98/52063 (WO 98/52063). Saturable core detectors can be made with high sensitivity and two or more inductors are offset by a common external field such as the geomagnetic field, but act additively on the measured magnetic field Thus, it can be connected in series in the signal processing circuit. The saturable core detector has maximum sensitivity in the axial direction of the coil. The response pattern is circularly symmetric about the axis.
[0007]
A drawback of current saturable inductor sensing devices is their lack of lateral resolution. Typically, these devices are 4-8 mm long and 2 mm in diameter. The length dimension determines the lateral resolution for the axial magnetic field component. The response of the sensor is essentially the integration of the detected field along the length of the device, and the field can vary in both magnitude and direction over that length.
[Patent Document 1]
International Publication No. 98/52063 (WO98 / 52063)
DISCLOSURE OF THE INVENTION
[Problems to be solved by the invention]
[0008]
Therefore, there is still a need for a magnetic field detection device with high resolution and high sensitivity.
[Means for Solving the Problems]
[0009]
According to the present invention, it is proposed to provide such a detection device by means of a helical coil formed around a core. The helix is essentially a plane, and preferably the plane is perpendicular to the axis through the core. Such techniques can be realized in essentially planar form using fabrication techniques known in semiconductor manufacturing. The sensing device can have a plurality of spatially parallel helical coils, preferably even, all acting on a single core element with a small overall length dimension.
[0010]
As discussed below, the coil and the insulating (separating) material supporting the coil can be formed using semiconductor manufacturing techniques, and the core can be provided as a separate object inserted into the axial hole. The holes are formed by a drill during the manufacturing process for the electrical structure or after manufacturing. The core may be part of a wire of a suitable magnetic material such as permalloy. The required magnetic properties are discussed further below.
[0011]
A sensing device embodying the invention comprises means for driving the sensing device to or from saturation, and a signal that depends on the parameters of such drive as a measure of the detected magnetic field in response to driving the sensing device. Can be connected as a magnetic field sensing element in the sensor circuit.
[0012]
A sensing device embodying the present invention can find particular application as a saturable inductor in the signal processing circuit disclosed in the aforementioned WO 98/52063.
The aspects and features of the invention are set forth in the appended claims.
Preferred circuit configurations for measuring the magnetic field in order to use a saturable inductor according to the invention are described in claims 8, 9 and 10. The circuit configuration itself is described in WO 98/52063, which is incorporated herein by reference.
[0013]
Coils used in the practice of the present invention can be manufactured with small dimensions called microcoils. Proposals for manufacturing microcoils have already been made. They are applied as part of thin film write heads for data storage applications, but are not used as read heads to detect magnetic fields because of their extremely low sensitivity. Another proposal is to provide an actuator that uses a pair of opposed helical coils to generate forces during coil turns by local interaction of the magnetic field created by the current flowing through the coils. is there. The Institute for Microtechnology (IMT) at Braunschweig University, Germany, has successfully produced a pair of microcoils for this purpose. This coil system has no magnetic core. Of interest with respect to actuators is the force that can be generated between the current in one coil turn and the current in the other coil turn. The work done so far is a verification of the feasibility of producing a planar helical coil structure, but it is not known if a practical actuator has already been created.
[0014]
It will be appreciated that the helical coil investigated in the proposal outlined above has not been applied to the detection of magnetic fields. In contrast, the present invention is directed to structures relating to magnetic field sensing applications. The detection device uses a saturable core. A detection device embodying the present invention is directed to combining high sensitivity and high resolution as previously discussed. The invention and its implementation will be discussed in more detail with reference to the accompanying drawings.
BEST MODE FOR CARRYING OUT THE INVENTION
[0015]
FIG. 1A shows a saturable inductor 1 in the form of a single-layer spiral coil formed by a single spiral plane winding 10 extending clockwise (cw) from an outer end 31 to an inner end 32. FIG. The winding includes a plurality of windings, and one winding can be regarded as a winding rotated 360 ° around the central axis 50 with respect to the radial wire 12 or the like. In the example shown, the windings are of uniform winding with a uniform width w and spacing s shown more clearly in FIG. 1 (b) and a uniform thickness perpendicular to the plane shown in FIG. and formed of a layer of conductive material having t. As can be seen from FIG. 3 and FIG. 4, the saturable core 20 that is assumed to have a round cross section is disposed in alignment with the central axis 50. The coil windings are preferably wound relatively tightly so that every turn is substantially circular so that the magnetization across the cross section of the core 20 is uniform (uniform), so that the radius It changes relatively slowly as a function of the central angle. This is discussed in more detail below.
[0016]
Accordingly, the winding pitch is (w + s), and as a result, the radius is increased by one (w + s) to one winding (angle 2 mm). Other relevant dimensional parameters are shown in FIG. 4 and the following describes the design and manufacture of a saturable inductor embodying the present invention and discusses the effects of relative changes in certain parameters. The parameters s and w are shown in FIG. 1 (b), which shows a part of two adjacent turns of the spiral 10, and the turns are shown shaded.
[0017]
When a positive current flows from end 31 to end 32, the coil generates a magnetic field perpendicular to the coil along axis 50 to act on core 20. In the case of the winding direction of cw shown in the figure, the magnetic field direction of the axis is from the plane of FIG.
[0018]
Preferably, the core material is saturated magnetization B _S 1 Tesla (10 ⁴ Less than Gauss). Furthermore, the crystal material has a small crystal anisotropy constant (K) and magnetostriction constant (λ) to minimize noise sources due to internal stresses induced in the core material during the described deposition process. There must be. Suitable materials that meet these requirements are permalloy (Ni / Fe alloys with other less important components (Ni ₇₈ Fe ₂₂ )), And its K and λ values are close to zero. Permalloy can be deposited by electroplating, sputtering, and other deposition techniques, and then etched.
[0019]
In the described planar manufacturing technique, it is more convenient to make an external connection to the outer end 31 than to the inner end 32 of the helical coil 1. The convenience of having an external connection outside the inductor also applies to a pair of three-dimensional parallel spiral coils wound around the axis 50 in opposite directions (one cw, one ccw). . The inner ends are connected to each other, and excitation power is applied to the outer ends to excite the series coils. By having spirals in opposite directions, magnetic flux in the same direction is generated in the core. The use of multiple helical coils is also advantageous to achieve the desired saturation of the core. Also, using a plurality of parallel coils is consistent with using an axially long core that is advantageous in reducing core demagnetization. These elements are discussed in detail below.
[0020]
FIG. 2 is a front view showing a pair of helical coils 10a and 10b wound in opposite directions, shown one over the other (hence the interference pattern), with each inner end 32a. And 32b and can be excited at the respective outer end portions 31a and 31b. The coils act to generate magnetic flux in the same direction in the common core 20. In practice, as can be seen in FIGS. 3 and 4, the coils 10a and 10b are in a spaced parallel plane perpendicular to the axis 50.
[0021]
FIG. 3 is a diagram illustrating the diametrical axes of a pair of coils 10a and 10b with windings such as 41a, 41b and 42a, 42b shaded. The turns 41a, 42a are in the same spiral coil (10a), but are shown separately because the current direction in them is opposite with respect to the plane of the figure, the turns 41b of the coil 10b, The same applies to 42b. In the diametrical cross section shown, the coil turns 10a, 10b are axially aligned and overlapped as can be seen from the front view of FIG. It will be appreciated that the turns are staggered or alternated at 90 ° relative to the diametrical cross section of FIG. FIG. 4 is an enlarged view showing a central portion of the structure of FIG. FIG. 4 also shows the coil layer thickness parameter t, which is the axial thickness.
[0022]
3 and 4, it can be seen that the core extends through both coils. Inner end portions 32a and 32b preferably overlap as seen in the front view and are connected by an axial through bridge 44 to connect the coils in series. By connecting the outer ends 31a and 31b to an excitation power source (not shown), the current in the winding on one side of the shaft 50 is shown in a current direction perpendicular to the plane of the drawing at 40a and 40b. Thus, in the two coils 10a and 10b are opposite and on the other side of the shaft 50 are opposite as shown by 40a 'and 40b', it still remains in the opposite direction in the two coils is there. The current acts additively to generate a magnetic field H in the core 20 in a direction along the axis 50. As a result, the magnetic flux and magnetization generated in the core 20 are also originally axial.
[0023]
FIG. 4 also shows other dimensional parameters discussed below. It is the distance d between adjacent layers, the diameter φ of the core 20 and its axial length l.
The above concept can be extended to other pairs of helical coils as shown in FIGS. In addition to the coil pairs 10a, 10b, there are other similar coil pairs 10c, 10d. The core 20 extends through all four coils spaced in parallel.
[0024]
As in FIGS. 3 and 4, the winding turns, for example 41a, 41d, and 42a, 42d, are shown shaded. The coils 10a and 10b are connected by a bridge 44a at their inner ends, and the coils 10c and 10d are similarly connected by a bridge 44b. The coils arranged in order along the axis have alternating winding directions, for example, cw-ccw-cw-ccw. The outer end of the coil 10b is connected to the outer end of an adjacent coil 10c by an axially oriented bridge 46, so that the coil is a power source (not shown) connected to the ends 31a and 31d. Electrically connected in series with respect to excitation by.
[0025]
The same current flows in each coil. The resulting alternating current direction is indicated by 40a-d on the upper side of the axis and 40a'-d 'on the lower side of the axis, and the directions are reversed. It will be appreciated that other winding directions and interconnections (eg, parallel and series / parallel combinations) are possible provided that each coil produces a magnetic field in the same direction in the core. It will also be appreciated that although an odd number of coils can be used, by making it even, all external connections can be made at the outer periphery of the coil assembly.
[0026]
The helical coil may be any conductive material having a low resistivity, and is preferably a non-magnetic material. Among these conductors are aluminum, copper, and gold. By selecting a non-magnetic material, a parasitic magnetic field is prevented from being generated in the conductor itself.
[0027]
As already indicated above, the helical coil structure described above can be implemented using techniques known in the semiconductor and related fields, and this structure is relative to the orientation shown in FIGS. Each layer is manufactured using a 90 ° coil. The manufacturing steps are illustrated in FIGS. 7 (a) and (b).
[0028]
FIG. 7 (a) shows a first layer of a conductive material such as Al, Cu, Au, for example, deposited using masking, such as photolithography and, where applicable, etching techniques well known in the art. FIG. 2 is a diagram showing an insulating layer or substrate 100 forming a helical coil 110a. A central boss 120 of core material such as permalloy is also deposited on the first layer. Next, for example, AlO2 or SiO ₂ Followed by another layer 102 of oxide insulating material, such as 122 and 124, as shown in FIG. 7 (b). The opening 122 overlaps the inner end of the coil 110 a, and the opening 122 overlaps the core 124.
[0029]
When the second helix 110b is deposited on the layer 102, a conductive material is deposited through the opening 122 to form a bridge connection 144 at the inner ends of the coils 110a and 110b. The core material will be deposited through the openings 124 to form the extension 120 ′ of the core 120. This manufacturing step is repeated to form other planar helical coils that are stacked on adjacent coils and spaced axially. However, it should be noted that according to the scheme of FIGS. 5 and 6, the next coil layer above 110b is separated from layer 110b at the inner end and bridged at the outer end.
[0030]
The formation of the electrical components of the structure of FIGS. 7 (a) and (b) may be separate from providing a magnetic core. The structure includes a core opening 124, but can be manufactured without vapor deposition of the core material. The core can be inserted into the hole as part of another entity, eg, a wire of core material. In the case of manufacturing one layer at a time, the opening 124 may be omitted initially, and as a result, the shaft portion is made of an insulating material. The structure can then be drilled to accept the core as another entity as described above. In these situations, the inner end of the coil is spaced further away from the coil and spaced radially, increasing the coil thickness t to compensate for any subsequent loss of the magnetic field in the core. Can prove desirable. The various parameters of the sensing device made in accordance with the above teaching will now be discussed.
[0031]
The helical coil of the described embodiment is “circular”, ie in the form of r = pθ, where r is the radius, θ is the angle about the axis, and p is a constant. It should be noted that other helical shapes can be adapted, but it is desirable that the magnetization in the core be homogeneous. Of course, the cross section of the core can be other than circular, and the shape of the winding can be selected based on the shape of the cross section.
[0032]
For the reasons already described, the preferred minimum configuration for a coil system consists of two spirals (FIGS. 2 and 3) with a common core. In principle, in a coil system, there are no restrictions on the direction and connection of the spiral. As already mentioned, the preferred design of the coil system is to produce a continuous spiral conductor layer with alternating winding directions, connecting the pair of spirals by a connection made at the inner end of the pair. As well as connecting successive pairs (assuming there are multiple pairs) at the outer ends of adjacent spirals. This is the design method adopted in FIG. The outer ends of the outermost two spirals of the complete group are then used for sequential excitation of the group. By combining this winding direction and interconnection, the current applied to all the spirals produces a magnetic flux in the same direction that is induced in a common core. By using an even number of spirals in the coil system, the connection leads of the circuit that will connect the saturable inductor can always be connected outside the spiral.
[0033]
This eliminates the need to add another layer for leads from the excitation power source to connect the central ends of the helix. Using separate leads to contact each helix individually allows the same winding direction to be used for each coil, but creates additional layers, resulting in a layer that is always later deposited as a result. It becomes less flat. Layer flatness is important in achieving a uniform field distribution. On the one hand, the benefits of using more coil layer pairs to saturate the core more appropriately and increase sensitivity, and on the other hand, increase the dimensional error in the manufacturing process, and the longer the core, the more loss of resolution. There must be a balance between them.
[0034]
The number of turns of the helix must be optimized according to the resulting bundle density and lead resistance (given by resistivity and lead length) induced in the core. Increasing the number of turns does not necessarily increase the resulting bundle density at the same rate, but increases the overall resistance and hence the power consumption of the coil system. For a given cross section of leads, eg 16 μm (thickness) × 20 μm (width) and copper, it is preferable to select 20 turns for each helix in the region in terms of resistance and achievable bundle density . Depending on any other cross section of the lead, different turns may result as a result.
[0035]
By using four spiral sets, a coil system with more turns and longer cores can be achieved. Assuming all coils are connected in series, doubling the number of spirals will surely increase the resistance (and power consumption) of the saturable inductor, but the bundle density induced in the core will be the same Increases by a factor. What is actually more important than increasing the number of spirals is the core geometry. When both have the same core diameter, a short core in the axial direction has a lower demagnetization coefficient N than a long core (0 <N <1). A large demagnetization factor N results in a demagnetizing field at the open end of the core, which cannot be fully saturated by the coil system. The longer the core, the less impact it has on the percentage of core volume that cannot be saturated and thus the efficiency of the system. In view of these factors, six or more spirals (three pairs) would be preferred to achieve an acceptable core demagnetization factor N.
[0036]
It is contemplated that the magnetic field sensing device according to the present invention can be manufactured to have an axial length in the range of 0.1 to 0.2 mm and a diameter in the range of 1 to 2 mm.
One or more saturable core inductors of the present invention can be used as the inductor L in the signal processing circuit described in the aforementioned WO 98/52063, whereby the inductor senses An output representing the magnetic field is provided.
[0037]
The foregoing has described coefficients and dimensional parameters that can affect the performance of a saturable inductor as a saturated core detector for magnetic fields. The core must operate in a manner that is sensitive to an external magnetic field that acts in conjunction with the magnetic field generated by the coil structure associated with the core. The operation of the saturated core in the presence of a detected external magnetic field is to produce an output signal that is a function of the detected field. One way of operating a saturated core for this purpose is disclosed in the aforementioned WO 98/52063.
[0038]
Studies have been conducted to investigate the design of saturated inductors and the manner of distribution of magnetic fields in and around them. This research has been done by computer simulation. In general, it is important to adopt a design where the entire core is saturated as much as possible. A fully saturated core can be described as being homogeneously saturated, and the quantitative degree of saturation can be expressed as saturation homogeneity.
[0039]
In the computer simulation, the aforementioned Ni / Fe alloy, Ni ₇₈ Fe ₂₂ Selected. This material has no crystal anisotropy K and no magnetostriction λ. In the manufacturing process described earlier, the magnetic properties cannot be known in detail, but a suitable operating estimate for the selected dimension, ie the saturation magnetization B _S = 0.8T, coercivity Hc = 2.4 A / m, and permeability μr = 1000 could be achieved.
[0040]
As the coil conductor material, copper having a cross section (t × w) of 8 μm × 20 μm was selected. A preferred thickness obtained from the simulation discussed below is 16 mm. When the pitch (w + s) per turn of the helical coil was 30 μm, the interval s between adjacent turns was selected as 10 μm.
[0041]
In the simulation procedure, the current density was considered to be present in the winding, the width being taken to be the total winding pitch (w + s) where there was a uniform (homogeneous) DC density Jh. The value of Jh is the current density relationship Jh = J. The ratio of the actual conductor width w to the total pitch (w + s) to obtain w / (w + s) = J / 1.5 is related to the current density J in the winding width w. The excitation current I is the current density J = 0.9375 kA / mm in the simulation model. ² Is selected to be 150 mA, and a uniform current density Jh = 0.625 kA / mm ² Calculated based on
[0042]
The simulations performed were limited to magnetic properties only, heat due to current density, quality of electrical separation between turns, or inhomogeneous or incomplete material properties (eg B _S , Μr, Hc) etc. were not considered. The following design aspects were considered.
[0043]
Core material
In order to measure the external magnetic field by saturating the core of the conductor under the influence of the external magnetic field, the saturation magnetization B of the core _S Must be low. In order to reduce noise, it is desirable that the influence of magnetostriction in the core is also low. This can be achieved by using an amorphous material such as a glassy alloy that does not have a crystallization axis. Unfortunately, glassy alloys cannot be deposited on the substrate. The candidates for the material to be deposited on the substrate include the Ni described above. ₇₈ Fe ₂₂ Alloy (permalloy), nickel itself, and other Ne ₆₅ Fe ₃₅ Ni / Fe alloys such as The Ni core is not fully saturated. Ne ₆₅ Fe ₃₅ The alloy saturates as well as permalloy, but only permalloy has no crystal anisotropy or magnetostriction.
[0044]
Core diameter (φ)
In order to achieve core saturation, the length of the core must be approximately the same as the axial length of the stacked planar helical coils. As the diameter increases, the demagnetization factor decreases, so the aspect ratio (diameter / length) of the core is important. This can be counteracted by the core material having a high coercivity Hc. However, for this purpose, a material having high crystal anisotropy that leads to magnetostriction is used. Therefore, the problem discussed in the above “core material” arises.
[0045]
Core length (l)
The helical coil is relatively flat, i.e. thin in the axial direction and spreads radially. As a result, the magnetic field is strongly concentrated in the coil and in the coil stacked at a close interval. Therefore, it is preferable to use a core having the same axial length as that occupied by the stacked helical coils. Keeping the core length short is also advantageous in achieving adequate resolution in the axial or longitudinal direction of the sensing device.
[0046]
Number of spiral coils (C)
The use of multiple or stacked axially separated helical coils has already been illustrated in the example embodiments of the present invention. The effect on each of the latest spirals is quite large. Since each helix field line is close to the next helix field line, it increases the axial field in the core. As already mentioned, it is preferred that there be an even number of spirals in the pair wound clockwise, and a value of C = 4 is advantageous, but it is even better if C = 6 or more. As described with reference to FIGS. 7 (a) and (b), as the number of spirals formed by the deposition process increases, the probability that the dimensions of each spiral coil formed will be inaccurate increases, and As a result, exceeding C = 6 may not always provide the expected benefits. Furthermore, the core length will also increase.
[0047]
Number of turns per coil (n)
As the number of turns of the helical coil increases, the influence of the outer turns on the magnetic flux in the core decreases. For the dimensions contemplated in the practice of the present invention, it is currently preferred to use 20 to 30 turns. When the number of windings exceeds 30, the degree to which the core magnetic flux is strengthened decreases.
[0048]
Conductor layer thickness (t)
As the layer thickness increases, the overall length of the stacked coils increases without compromising the uniformity of the core magnetization (homogeneous magnetization), even if the volume of the core material increases. Furthermore, as the conductor layer becomes thicker (but with the same width w), the current during winding for the same allowable current density increases. This increases the amount of saturated material in the core. At present, the conductor layer thickness is preferably t = 16 μm.
[0049]
Spiral coil spacing (d)
As the spacing or separation between adjacent conductor layers increases due to the effect of increasing conductor layer thickness, the core length increases as well, but the homogeneity of the core magnetization decreases. In the above-described embodiment, the distance is preferably d = 10 μm.
[Brief description of the drawings]
[0050]
FIG. 1 (a) shows the structure of a planar helical coil with a core to form a saturable inductor according to the present invention, and (b) is annotated with dimensional parameters. It is the enlarged view which shows some helical coils.
FIG. 2 is a front view of a pair of spiral coils that are stacked on each other and have opposite winding directions.
FIG. 3 is an axial cross-section of a pair of parallel planar helical coils structured and interconnected to produce an axial field in the same direction within a central core providing a saturable inductor according to the present invention. FIG.
4 is an enlarged view showing a central portion of the structure of FIG. 3;
FIG. 5 is an axial cross-sectional view showing another embodiment of a saturable inductor according to the present invention using two pairs of four parallel planar helical coils.
6 is an enlarged view showing a central portion of the structure of FIG. 5;
FIGS. 7A and 7B are diagrams showing each stage in the manufacturing process of the helical coil and the core. FIGS.

Claims (10)

A magnetic field sensing device for saturable inductors, comprising a saturable core and a conductive winding extending about an axis passing through the core, the winding comprising:
A magnetic field sensing device comprising at least one coil essentially spirally wound in each plane. The magnetic field detection apparatus according to claim 1, wherein the plane is perpendicular to the axis. The windings were wound in respective spirals with opposite winding directions, with the inner ends of the two helical coils connected to each other to provide a series current path between the respective outer ends. The magnetic field detection device according to claim 1, comprising two adjacent coils. The magnetic field detection device according to any one of claims 1 to 3, wherein at least the spiral coil is manufactured one layer at a time and is arranged at an interval by an insulating material. The magnetic field detection apparatus according to claim 1, wherein the number of the helical coils is at least four. 6. The magnetic field detection device according to claim 1, wherein the core is made of a permalloy material. A detection circuit for detecting a magnetic field,
A magnetic field detector that reacts to a magnetic field;
Means for driving the sensing device to or from saturation and means for generating a signal in response to the driving of the sensing device that is dependent on parameters of such driving as a measure of the sensed magnetic field. A detection circuit characterized by that. A circuit configuration for measuring a magnetic field,
A saturable inductor for detecting the magnetic field to be measured;
An oscillator circuit connected to the inductor to drive the inductor, having a voltage waveform that saturates the inductor in the opposite direction in half consecutive cycles;
Means including a current-voltage converter connected to the inductor to generate an output signal representative of a saturation imbalance in a continuous half cycle by the magnetic field;
The oscillator circuit is operable to drive the inductor to generate an average current in the inductor per oscillator cycle that is a measure of the imbalance;
The current to voltage converter is responsive to the average current to generate a voltage representative of the average current;
A circuit configuration, wherein the saturable inductor includes at least one magnetic field detection device according to any one of claims 1 to 6. A circuit configuration for measuring a magnetic field,
A saturable inductor for detecting the magnetic field to be measured;
An oscillator circuit connected to the inductor to drive the inductor having a voltage waveform that saturates the inductor in the opposite direction in half consecutive cycles;
Means for generating an output signal representative of a saturation imbalance in a continuous half cycle by the magnetic field,
The oscillator circuit is connected to the switchable means for generating two voltage states to generate the voltage waveform, and the switchable means is connected to the switchable means, and the current of approximately equal magnitude in half successive cycles. Current sensing means responsive to the current through the inductor to be switched at
A circuit configuration, wherein the saturable inductor includes at least one magnetic field detection device according to any one of claims 1 to 6. A circuit configuration for measuring a magnetic field,
A saturable inductor for detecting the magnetic field to be measured;
An oscillator circuit connected to the inductor to drive the inductor, wherein the current flow in the inductor has a voltage waveform that saturates the inductor in the opposite direction in half consecutive cycles;
Means including a current-voltage converter connected to the inductor to generate an output signal representative of a saturation imbalance in a continuous half cycle by the magnetic field;
The oscillator circuit is operable to drive the inductor to generate an average current in the inductor per oscillator cycle that is a measure of the imbalance;
The current-voltage converter is connected in a circuit path through which an inductor current flows and is responsive to the average current in the inductor to generate a voltage representative of the average current;
A circuit configuration, wherein the saturable inductor includes at least one magnetic field detection device according to any one of claims 1 to 6.

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