CN100343674C - Rotation detecting apparatus - Google Patents

Abstract

Rotation detecting apparatus for detecting rotation of a magnetic rotor includes: a sensor chip having a magnetoresistive device; and a bias magnet. The magnetoresistive device is capable of detecting change of a magnetic vector near the sensor chip so that the rotation detecting apparatus detects the rotation of the magnetic rotor. The change of the magnetic vector is generated by the bias magnetic field and the rotation of the magnetic rotor. The bias magnet is disposed around the sensor chip so that a deflection angle of the magnetic vector is controllable.

Description

Rotation detecting

Technical field

The present invention relates to rotation detecting.

Background technology

The rotation detecting test example is as the rotation that is contained in the engine on the vehicle and the rotation of universal machine rotor.More specifically, rotation detecting utilizes the rotary mode of the variation energy detection rotor of magnetoresistive element resistance.

Traditionally, the rotation detecting that for example discloses among Japan's special permission publication application H07-333236 as the rotation detecting of the above-mentioned change-detection rotation that can utilize the magnetoresistive element resistance is known.

This rotation detecting comprises magnetoresistive element and magnetic bias magnet.Magnetoresistive element and magnetic bias magnet are contained in the casing component.In this rotation detecting, the end portion of magnetic bias magnet leans against on the casing component inner bottom plane, and the moulded parts end portion that contains magnetic sensor chip leans against on the outshot that forms on this inner bottom plane, thereby determines this " M-M distance ".This " M-M distance " is corresponding to the distance between magnetoresistive element and the magnetic bias magnet.In other words, in this rotation angle detection apparatus, optimized above-mentioned magnetic vector deflection angle, wherein comprise the relation of the outstanding length of the outshot that forms on rotor and the casing component inner bottom plane, that is, optimize the detection sensitivity relevant with rotation angle detection apparatus.

On the other hand, though the deflection angle of the magnetic vector corresponding with the detection sensitivity of rotation detecting, can be according to above-mentioned M-M distance adjustment, but, must regulate the outstanding length of the outshot that forms on the casing component in order to regulate the detection sensitivity of this rotation detecting.As a result, consider inevitable reason must change above-mentioned M-M distance and this variable in distance for the rotation detecting pattern be by, for example, under the situation that rotor shapes causes, consider that inevitable reason also must change casing component itself.That is, for example, the number of spare parts relevant with the casing component of these variations increases, and increases the sum of the required metal die of the casing component of these variations that are used to be shaped inevitably.Under actual conditions, only can cause some problems by this adjusting itself that changes above-mentioned M-M distance adjustment magnetic vector deflection angle.That is, the design freedom relevant with rotation detecting is low, and the scope of regulating the magnetic vector deflection angle is restricted in actual environment.

Summary of the invention

Consider the problems referred to above, an object of the present invention is to provide a kind of rotation sensor with high detection sensitivity and high design freedom.

The rotation detecting that detects the magnetic vector rotation comprises: the sensor chip with magnetoresistive devices; And the magnetic bias magnet that magnetoresistive devices is applied bias field.Magnetic bias magnet and sensor chip are integrated.Magnetoresistive devices can change according near the magnetic vector the change in resistance detecting sensor chip of magnetoresistive devices, thereby rotation detecting detects the rotation of magnetic vector.The variation of magnetic vector is produced by bias field and magnet rotor rotation.The magnetic bias magnet arrangement around sensor chip, thereby can control the magnetic vector deflection angle.

Said apparatus can be controlled the magnetic vector deflection angle, thereby improves the detection sensitivity of rotation.And, can control the magnetic vector deflection angle by the shape of magnetic bias magnet, big thereby design freedom becomes.

Preferably, the magnetic bias magnet includes the hollow space of groove, and groove has reservation shape, so that the control of magnetic vector deflection angle to be provided.More preferably, the hollow space of magnetic bias magnet holds sensor chip, and is the rectangle with a pair of wide side.The wide side of hollow space is towards sensor chip, and is parallel to the surface of sensor chip, and magnetoresistive devices is arranged on this surface, and the groove of hollow space is along magnetic bias magnet longitudinal extension.

And the rotation detecting that detects the magnet rotor rotation comprises: the sensor chip with magnetoresistive devices; And the magnetic bias magnet that magnetoresistive devices is applied bias field.Magnetic bias magnet and sensor chip are integrated, and integrated mode is that the magnetic bias magnet arrangement is around sensor chip.Magnetoresistive devices can change according near the magnetic vector the change in resistance detecting sensor chip of magnetoresistive devices.Magnetic vector changes by bias field and magnet rotor rotation generation.The magnetic bias magnet comprises the hollow space with groove.Sensor chip is contained in the hollow space of magnetic bias magnet.Groove is arranged on the hollow space inwall.

Said apparatus can be controlled the magnetic vector deflection angle, thereby improves the detection sensitivity of rotation.And the magnetic vector deflection angle can be controlled by the shape of magnetic bias magnet, and is big thereby design freedom becomes.

And the rotation detecting that detects the magnetic vector rotation comprises: the sensor chip with magnetoresistive devices; And the magnetic bias magnet that magnetoresistive devices is applied bias field.Magnetic bias magnet and sensor chip are integrated, and integrated mode is that the magnetic bias magnet arrangement is around sensor chip.Magnetoresistive devices can change according near the magnetic vector the change in resistance detecting sensor chip of magnetoresistive devices.Magnetic vector changes by bias field and magnet rotor rotation generation.The magnetic bias magnet comprises hollow space, and sensor chip is contained in the hollow space of magnetic bias magnet.Hollow space comprises the inwall towards magnetoresistive devices.The magnetic bias magnet has low magnetic field intensity near the inwall of magnetoresistive devices, low magnetic field intensity is lower than the magnetic field intensity of other position of magnetic bias magnet.

Said apparatus can be controlled the magnetic vector deflection angle, thereby improves the detection sensitivity of rotation.And, can control the magnetic vector deflection angle by the shape of magnetic bias magnet, thereby design freedom increases.

And the rotation detecting that detects the magnetic vector rotation comprises: the sensor chip with magnetoresistive devices; And the magnetic bias magnet that magnetoresistive devices is applied bias field.Magnetic bias magnet and sensor chip are integrated, and integrated mode is that the magnetic bias magnet arrangement is around sensor chip.Magnetoresistive devices can change according near the magnetic vector the change in resistance detecting sensor chip of magnetoresistive devices.Magnetic vector changes by bias field and magnet rotor rotation generation.The magnetic bias magnet comprises hollow space, and sensor chip is contained in the hollow space of magnetic bias magnet.Hollow space comprises the inwall towards magnetoresistive devices.The magnetic bias magnet does not have high magnetic field intensity near the inwall of magnetoresistive devices, the high magnetic field intensity of high magnetic field intensity part is greater than the magnetic field intensity of other position of magnetic bias magnet.

Said apparatus can be controlled the magnetic vector deflection angle, thereby improves the detection sensitivity of rotation.And, can control the magnetic vector deflection angle by the shape of magnetic bias magnet, thereby design freedom increases.

Description of drawings

In conjunction with the accompanying drawings, from following detailed description, above and other objects of the present invention, feature and advantage will become clearer.In the accompanying drawings:

Fig. 1 is the cut-open view according to the rotation detecting of first embodiment of the invention;

Fig. 2 is the vertical view according to the magnetic bias magnet of first embodiment of the invention device;

Fig. 3 is the schematic cross sectional views along the magnetic bias magnet of Fig. 2 center line III-III intercepting;

Fig. 4 A and 4C are vertical view and the side views according to the magnetic bias magnet of first simulation of first embodiment, and Fig. 4 B is the synoptic diagram of the vee gutter of the first magnetic bias magnet of simulating;

Fig. 5 is the synoptic diagram of explaining according to first simulation of first embodiment;

Fig. 6 A is the skeleton view of demonstration according to the magnetic flux of the slotless magnetic bias magnet of first embodiment, and Fig. 6 B is the skeleton view that shows the magnetic flux of groove magnetic bias magnet;

Fig. 7 A is the first Simulation result table of explaining according to first embodiment to 7C;

Fig. 8 is the M-M distance that obtained by first simulation according to first embodiment and the relation curve between the magnetic vector deflection angle;

Fig. 9 A is the vertical view of magnetic bias magnet vee gutter according to second simulation of first embodiment to 9E;

Figure 10 is the second Simulation result figure that explains according to first embodiment;

Figure 11 is the skeleton view according to the magnetic bias magnet of the 3rd simulation of first embodiment;

Figure 12 is the 3rd Simulation result table of explaining according to first embodiment;

Figure 13 is the skeleton view according to the magnetic bias magnet of first embodiment, first modification;

Figure 14 is the skeleton view according to the magnetic bias magnet of first embodiment, second modification;

Figure 15 be explain according to first embodiment, magnetic bias magnet analog result table shown in Figure 13 and 14;

Figure 16 is the vertical view according to the magnetic bias magnet of first embodiment the 3rd modification;

Figure 17 explains to utilize the synoptic diagram that is rotated detection according to the rotation detecting of the first embodiment Comparative Examples;

Figure 18 is the cut-open view according to the rotation detecting of the first embodiment Comparative Examples;

Figure 19 is the skeleton view according to magnetic bias magnet and sensor chip in the rotation detecting of second embodiment;

Figure 20 is the skeleton view according to the magnetic bias magnet magnetic flux of the second embodiment Comparative Examples;

Figure 21 is the vertical view according to the magnetic bias magnet magnetic flux of the second embodiment Comparative Examples;

Figure 22 is the skeleton view according to the magnetic bias magnet magnetic flux of second embodiment;

Figure 23 is the vertical view according to the magnetic bias magnet magnetic flux of second embodiment;

Figure 24 is the air gap that obtains of second embodiment and the second embodiment Comparative Examples and the relation curve between the magnetic vector deflection angle;

Figure 25 is the vertical view according to the magnetic bias magnet manufacturing equipment of second embodiment;

Figure 26 is the cut-open view along the equipment of Figure 25 center line XXVI-XXVI intercepting;

Figure 27 is the cut-open view of explaining according to second embodiment magnetic orientation before the control orientation;

Figure 28 is the cut-open view of explaining according to second embodiment magnetic orientation after the control orientation;

Figure 29 is the skeleton view according to the magnetic flux of the magnetic bias magnet of third embodiment of the invention;

Figure 30 is the vertical view according to the magnetic bias magnet manufacturing equipment of the 3rd embodiment;

Figure 31 is the cut-open view of explaining according to the 3rd embodiment magnetic orientation after the control orientation;

Figure 32 is the skeleton view according to the magnetic flux of the magnetic bias magnet of the 3rd embodiment modification; And

Figure 33 is the vertical view according to the magnetic flux of the magnetic bias magnet of the 3rd embodiment modification.

Embodiment

(first embodiment)

The present inventor has studied a kind of rotation detecting in advance, as the Comparative Examples of first embodiment of the invention.This device is the change-detection rotation that utilizes the magnetoresistive element resistance.Figure 17 represents the planar structure of this rotation detecting such as the engine crank angular transducer.

As shown in figure 17, in this rotation detecting, the arrangement of sensor chip 11 is, this sensor chip 11 relatively is provided with rotor " RT " corresponding to detected target.Sensor chip 11 is equipped with the magnetoresistive element be made up of two magnetoresistive element MRE1 and MRE2 to 1, and another magnetoresistive element of being made up of two magnetoresistive element MRE3 and MRE4 is to 2.Then, sensor chip 11 therewith the treatment circuit of sensor chip 11 make the form of integrated circuit together, and utilize moulded parts 12 that integrated sensor chip is molded as an integrated entity.Particularly, this rotation detecting has following structure.That is, sensor chip 11 is contained in moulded parts 12 lead frame inside (not shown) end, and various terminal, and for example power supply terminal T1, lead-out terminal T2 and GND (ground connection) terminal T3 draw from the other end of lead frame.In addition,, around the mode of moulded parts 12 magnetic bias magnet 13 is arranged near the sensor chip 11 by magnetic bias magnet 13.13 pairs of above-mentioned two magnetoresistive elements of magnetic bias magnet apply bias field to 1 and 2.Then, this magnetic bias magnet 13 is made hollow cylindrical, vertically has a hollow space 14 along this magnetic bias magnet 13.When moulded parts 12 is contained in this hollow space 14, use cementing agent or analog that magnetic bias magnet 13 is fixed on the precalculated position.

In the rotation detecting that constitutes by said structure, when rotor R T rotates, the magnetic vector that produces with above-mentioned bias field changes that to can be used as each magnetoresistive element MRE1 detected to the change in resistance of MRE4, and then, the change in resistance that response detects is exported electric signal from sensor chip 11.Promptly, in this rotation detecting, the magnetoresistive element that constitutes a half-bridge circuit is applied to above-mentioned treatment circuit to the potential change of 1 magnetoresistive element MRE1 and the central point between the MRE2 and the magnetoresistive element that constitutes a half-bridge circuit equally to 2 the magnetoresistive element MRE3 and the potential change of the central point between the MRE4.In treatment circuit, carry out various processing operations according to potential change, for example differential amplifieroperation and scale-of-two are handled operation.After this, derive the electric signal of handling from lead-out terminal T2.

And when using the rotary mode of this rotation detecting detection rotor under physical condition, the moulded parts 12 and the magnetic bias magnet 13 that have been molded with sensor chip 11 and analog are contained in the suitable casing component.In addition, pack into one can protect each terminal T1 in the resin enclosure of T3 and this casing component the time at whole rotation detecting, the resin enclosure that obtains is contained on the engine and similar position.Figure 18 represents to be contained in an example of rotation detecting engine and similar position, that have said structure.

As shown in figure 18, in this rotation detecting, moulded parts 12 and magnetic bias magnet 13 are contained in the columniform casing component 30 in the bottom that has, and these members 12,13,30 and resin enclosure 40 are molded as a whole.The resin enclosure 40 of this shaping is contained on the engine or similar position.This resin enclosure 40 also can play the function of jointing, by the mode of connection resin enclosure 40 self is connected to electronic-controlled installation.And above-mentioned each terminal T1 has been connected electrically to terminal conducting piece 50a to 50c to T3, and they also have the terminal that plays above-mentioned joint function.These terminal conducting pieces 50a is arranged in the resin enclosure 40 by the one mode to 50c.Then, in this rotation detecting, the end portion of magnetic bias magnet 13 leans against on the inner bottom plane of casing component 30, and, end portion with moulded parts 12 of sensor chip 11 leans against on the outshot 31 that forms on this inner bottom plane, thereby determined this " M (being MRE)-M (being magnet) distance ", this " M-M distance " corresponding to magnetoresistive element to 1 and 2 and magnetic bias magnet 13 between distance.In other words, in this rotation angle detection apparatus, optimized the deflection angle of above-mentioned magnetic vector, wherein also contain the outstanding length of the jut 31 that forms on the inner bottom plane by casing component 30 and the relation of rotor R T, that is, optimized the detection sensitivity relevant with rotation angle detection apparatus.

On the other hand, though the magnetic vector deflection angle corresponding with the detection sensitivity of rotation detecting can be according to above-mentioned M-M distance adjustment, but as mentioned above,, must change the outstanding length of the outshot 31 that forms on the casing component 30 in order to regulate the detection sensitivity of this rotation detecting.As a result, consider inevitable reason must change above-mentioned M-M distance and this variable in distance for the rotation detecting pattern be by the situation that for example rotor R T shape causes under, consider that inevitable reason also must change casing component 30 itself.That is, for example, the number of spare parts relevant with the casing component 30 of these variations increases, and increases the sum of the required metal die of the casing component 30 that is used to touch these variations of system inevitably.Under actual conditions, only can cause some problems by this adjusting itself that changes above-mentioned M-M distance adjustment magnetic vector deflection angle.That is, the design freedom relevant with rotation detecting is low, and the scope of regulating the magnetic vector deflection angle is restricted in actual environment.

As the experimental result that inventor of the present invention obtains, can confirm the following fact: promptly, the cross sectional shape of the deflection angle of above-mentioned magnetic vector and the magnetic bias magnet hollow space that sensor chip is housed is accordingly with the variation of rotor rotation.And, according to the cross sectional shape of hollow space, the deflection angle of magnetic vector, promptly the detection sensitivity of this rotation detecting improves greatly.The result, said structure according to rotation detecting, relative position relation in magnetoresistive element and magnetic bias magnet (for example, above-mentioned M-M distance) can be regulated by the cross sectional shape of hollow space the magnetic vector deflection angle that magnetoresistive element exerts an influence when always not changing.Not only can amplify the deflection angle of magnetic vector in the above described manner, and can realize easily that the detection sensitivity of rotation detecting improves.And,, can regulate the deflection angle of magnetic vector substantially, thereby can improve the design freedom of this rotation detecting greatly by the cross sectional shape of design hollow space.

In addition, in this case, as the cross sectional shape of magnetic bias magnet hollow space, for example, according to the viewpoint of an innovation, forming groove on the hollow space internal side wall of above-mentioned magnetic bias magnet will be favourable a kind of shape.This shape has also been confirmed by experiment by inventor of the present invention.

In addition, as this groove, for example, viewpoint according to an innovation, when the hollow space of magnetic bias magnet has formed general rectangular shape corresponding to the sensor chip cross sectional shape, it will be effective forming groove under following forming mode: this groove with respect to the internal side wall of each long edge side of hollow space along magnetic bias magnet extend longitudinally, with the parallel and setting relatively of plane of arrangement of magnetoresistive element in the hollow space sensor chip.And, in this case, according to the viewpoint of an innovation, because this groove forms at the core of the internal side wall of each side, long edge of hollow space, in the symmetrical feature that can keep the magnetic vector deflection angle, regulates the deflection angle of magnetic vector easily, that is, be exaggerated easily.

For example it should be understood that,,, can use following shape for the shape of above-mentioned groove according to the viewpoint of an innovation:

(A) use groove, the cross sectional shape of groove is a triangle, and trench bottom is the summit.

In addition, according to the viewpoint of an innovation,, can use following shape for the shape of above-mentioned groove:

(B) use groove, the cross sectional shape of groove is semicircle, and the bottom of groove is a circular arc.Because what use is the groove of triangle or semicircular sectional shape, when using metal die to touch system magnetic bias magnet, the flowability of magnetic material in this metal die hindered by groove hardly.As a result, compare, can be molded as the magnetic bias magnet having better inhomogeneity magnetic material with situation with other difform groove.And, owing to use the shape of these grooves, therefore can be easily and stably realize the above-mentioned adjusting operation of magnetic vector deflection angle, this also can be confirmed by experiment by inventor of the present invention.

To Figure 12, first by way of example of implementing the rotation detecting according to the present invention will be described below referring to Fig. 1.

Fig. 1 represents the total according to the rotation detecting of first by way of example.As shown in Figure 1, this rotation detecting is provided with by being similar to mode for example shown in Figure 17.That is, comprise two pairs of magnetoresistive elements to 1 with 2 by similar mode be arranged in sensor chip 11 wherein moulded parts 12 and to two pairs of magnetoresistive elements to the 1 and 2 magnetic bias magnets 13 that apply bias field be contained in have the bottom cylinder blanket member 30 in.This casing component 30 has outshot 31.And this casing component 30 has been assemblied in and has become as a whole in the resin enclosure 40.Resin enclosure 40 is molded as follows, and this mode is the function that resin enclosure 40 also can play jointing, is used for by the mode of connection resin enclosure 40 itself being connected to electronic-controlled installation and analog.On the other hand, electrical terminal guiding piece 50a is to 50c to T3 for above-mentioned each terminal T1, and they have also had the terminal of above-mentioned joint function.These terminal guiding pieces 50a is contained in the resin enclosure 40 to 50c and becomes one.But according to this by way of example, above-mentioned magnetic bias magnet 13 manufactures has following feature, and this is illustrated in separately in the front elevation of Fig. 2.That is, in magnetic bias magnet 13, vee gutter 17 be formed on sensor chip 11 in magnetoresistive element to the core of the madial wall of 1 each the long edge side parallel and relative with 2 plane of arrangement.Each vee gutter 17 is from its cross section formation triangle.In this triangle, trench bottom is the summit.From Fig. 1, know and see that this vee gutter 17 is along the whole extend longitudinally of above-mentioned magnetic bias magnet 13.

Fig. 3 is the skeleton view that is illustrated in along the cross section structure of magnetic bias magnet 13 under the situation of line III-III intercepting magnetic bias magnet 13 shown in Figure 2.The interior shape of the above-mentioned vee gutter 17 in this magnetic bias magnet 13 and the interior shape of hollow space 14 have been represented to be formed among the figure.

The analog result that above-mentioned magnetic vector deflection angle that inventor of the present invention carries out, relevant changes is described below, because in the hollow space 14 of magnetic bias magnet 13, formed vee gutter 17.

Theing contents are as follows of corresponding simulation: promptly, as first simulation, in forming the magnetic bias magnet 13 of above-mentioned vee gutter 17, under the situation that " the M-M distance " formerly explained changes relatively the deflection angle of magnetic vector carry out analysis operation.And as second simulation, the deflection angle of magnetic vector carries out analysis operation relatively under the situation of the change of shape of vee gutter 17.And as the 3rd simulation, the deflection angle of magnetic vector carries out analysis operation relatively under the situation of the length variations of vee gutter 17.Describe simulated conditions, analog result or the like in detail according to first to the 3rd simulation below.

[first simulation]

The analysis condition of above-mentioned first simulation at first is described.To shown in the 4C,, use following magnetic bias magnet as Fig. 4 A as the magnetic bias magnet 13 that in this analysis operation, uses.That is, this magnetic bias magnet 13 is of a size of: the length 13.5mm of magnetic bias magnet 13, transverse width 10.0mm, vertically width 9.0mm.In this magnetic bias magnet 13, form such hollow space 14, its size is as follows: the transverse width 6.5mm of hollow space 14, vertically width 2.6mm.And,, use the vee gutter shown in Fig. 4 B as the vee gutter 17 that forms in this hollow space 14.That is, vee gutter 17 is of a size of: the width x of vee gutter 17 (being the base width) is 2.0mm, and depth z is 0.8mm.Then, use above-mentioned magnetic bias magnet 13, carry out analysis operation according to following conditions: promptly, as the analysis site that the opening degree that calculates the required magnetic vector of above-mentioned magnetic vector deflection angle is analyzed, operational analysis point IVA and another analysis site IVB two group analysis point, this corresponding to above-mentioned magnetoresistive element to 1 and 2 actual arrangement position.And, during as this 2 group analysis point IVA, IVB and as the variable in distance between the rotor opposite face 13a of magnetic bias magnet 13 end faces, promptly during the M-M variable in distance, the relation of magnetic vector deflection angle and each M-M distance is carried out analysis operation.

On the other hand, as the rotor R T that this first analysis operation uses, use the rotor R T of shape shown in Figure 5.Then, in rotor R T rotary course shown in Figure 5, when the position of the some VC of the some VM of projection and recessed part is relative with above-mentioned rotation detecting, analyze the magnetic vector opening degree of above-mentioned analysis site IVA and IVB.The point VC of the some VM of projection and recessed part is formed on the neighboring part of rotor R T.Then, according to rotation detecting and some VC when relative the magnetic vector open angle of analysis site IVA and IVB and rotation detecting with put VM differential seat angle between another open angle of magnetic vector at analysis site IVA and IVB when relative, calculating magnetic vector deflection angle.Should also be understood that as shown in Figure 5 the distance setting between the rotor opposite face of rotation detecting and the rotor R T projection is 0.5mm, promptly air gap AG is set at 0.5mm.

Fig. 7 A represents first Simulation result to 7C.Fig. 7 A represents the analog result that obtained by the magnetic bias magnet 13 that does not form above-mentioned vee gutter 17.Fig. 7 B represents the analog result that obtained by the magnetic bias magnet 13 that forms above-mentioned vee gutter 17.

These analog results shown in Fig. 7 A and Fig. 7 B can be known and find out, for each M-M distance, though the magnetic sensitivity that forms the magnetic bias magnet 13 of vee gutter 17 is lower than the magnetic sensitivity of the magnetic bias magnet 13 that does not form vee gutter 17, there is the magnetic vector deflection angle of the magnetic bias magnet 13 of groove 17 to surpass the magnetic vector deflection angle of the above-mentioned magnetic bias magnet 13 of slotless.And as a factor that causes magnetic induction density to descend, following reason can be taken into account.That is, for the magnetic bias magnet 13 that forms vee gutter 17, this magnetic bias magnet 13 is compared with the magnetic bias magnet 13 that does not form vee gutter 17 as the volume of magnet, has reduced the volume of vee gutter 17.On the other hand, as the factor that the deflection angle that causes magnetic vector amplifies, following reason can be taken into account.That is, because magnetic induction density reduces the deflection raising of magnetic vector.Should also be understood that the following fact also may be thought of as in these factors.That is, owing in magnetic bias magnet 13, form vee gutter 17, so the producing method that magnetic bias magnet 13 itself produces magnetic flux (magnetic field) changes.In other words, as shown in Figure 6A, in the above-mentioned magnetic bias magnet 13 that does not form vee gutter 17, it is contained in example in rotation detecting shown in Figure 180, becomes lower along the magnetic flux density (solid arrow shown in Fig. 6 A) of rotor R T sense of rotation with comparing along the magnetic flux density (the blank arrow shown in Fig. 6 A) of vertical rotor RT sense of rotation.On the contrary, in the magnetic bias magnet 13 that forms vee gutter 17, shown in Fig. 6 B, become higher with comparing along the magnetic flux density (solid arrow shown in Fig. 6 B) of vertical rotor RT sense of rotation along the magnetic flux density (the blank arrow shown in Fig. 6 B) of rotor R T sense of rotation.As the result of high magnetic flux density, can estimate that the deflection angle of magnetic vector can increase.

And, from Fig. 7 A and Fig. 7 B dotted line around the contrast between the numerical value in district as can be seen, for the magnetic field intensity of above-mentioned some VM, no vee gutter 17, M-M distance is that the magnetic field intensity of the magnetic bias magnet 13 of 1.3mm becomes-14.0mT; And having vee gutter 17, M-M distance to become-13.9mT for the magnetic field intensity of the magnetic bias magnet 13 of 1.4mm, these magnetic field intensitys of promptly putting VM are equal to each other substantially.But, still in this case, the magnetic vector deflection angle of the magnetic bias magnet 13 of no vee gutter 17 equals 24.3 degree, and the magnetic vector deflection angle that the magnetic bias magnet 13 of vee gutter 17 is arranged equals 28.0 degree, cause the magnetic vector deflection angle to increase, M-M can reduce apart from the negative effect that causes simultaneously.

On the other hand, Fig. 7 C represents to have considered the analog result of magnetoresistive element to 1 and 2 sensitivity with respect to the magnetic field intensity that Fig. 7 A and Fig. 7 B obtain.The analog result of Fig. 7 C is expressed as the curve of Fig. 8.As shown in Figure 8, compare, have the magnetic vector deflection angle of the magnetic bias magnet 13 of vee gutter 17 on all M-M distances, all to increase with the magnetic vector deflection angle of the magnetic bias magnet 13 of no vee gutter 17.For example, with the dotted line of Fig. 7 C around the district corresponding, when the M-M distance is 1.3mm, the magnetic vector deflection angle that has the magnetic vector deflection angle of the magnetic bias magnet 13 of vee gutter 17 to compare the magnetic bias magnet 13 of no vee gutter 17 increases about 1.35 times.

As mentioned above, can make this affirmation.That is, owing to form vee gutter 17 in the hollow space 14 of magnetic bias magnet 13, therefore the formation of this groove can produce very big advantage, to increase the magnetic vector deflection angle.

[second simulation]

Explained later second simulation.In this second simulation, under the width X of the vee gutter 17 that in hollow space 14, forms and the situation that degree of depth Z changes respectively, above-mentioned magnetic vector deflection angle is carried out analysis operation.It should be understood that this magnetic bias magnet 13 other shape and above-mentioned first the simulation identical.

Fig. 9 A represents to form the shape of the vee gutter 17 of this second sunykatuib analysis target to 9E.To shown in the 9E, in this second simulation, 5 sample S1 have been analyzed respectively as Fig. 9 A to S5.That is, to S3, use following vee gutter 17 for sample S1: width X is 0.5mm, 1.0mm and 1.5mm, and degree of depth Z is 0.5mm.And, as sample S4 and S5, use following vee gutter 17: degree of depth Z to be 1.0mm and 1.5mm, width X is 1.0mm.It should be understood that analysis operation is to carry out under the situation that above-mentioned air gap AG is three kinds of air gaps in this second simulation, promptly air gap is respectively 0.5mm, 1.0mm and 1.5mm.Should also be noted that shape, be to use and the identical shape of first simulation for rotor R T.And analysis operation is to carry out under the situation that above-mentioned M-M fixed distance is 1.3mm.

Figure 10 is the figure of this second analog result of expression.The figure of Figure 10 clearly illustrates that the magnetic vector deflection angle of above-mentioned sample S1 to S5, in addition in order to compare, gives the magnetic vector deflection angle of the magnetic bias magnet that does not form vee gutter 17.Analog result from sample S1 to S3 is clear finds out that as the diagrammatic representation among Figure 10, the width X of vee gutter 17 is wide more, and the increase of magnetic vector deflection angle is big more.And, find out that from the analog result of sample S2, S4 and S5 is clear as the diagrammatic representation among Figure 10, the degree of depth Z of vee gutter 17 is dark more, the increase of magnetic vector deflection angle is big more.Note also that, in expression these samples S1 appended angle in each figure of S5 analog result, compare the numerical value that each sample S1 had increased to the magnetic vector deflection angle of S5 when air gap was 1.5mm corresponding to being chosen as magnetic bias magnet magnetic vector deflection angle 1.5mm, that do not form vee gutter 17 equally with air gap AG.It can also be seen that from these data, only for above-mentioned sample S1 to S5, increase (broadening) with the width X of vee gutter 17 and compare, if the degree of depth Z of vee gutter 17 increases (deepening), then the magnetic vector deflection angle can further increase.

[the 3rd simulation]

Explained later the 3rd simulation.In this 3rd simulation, as the length L of the vee gutter 17 of Figure 11 example situation about changing under, rather than vee gutter 17 carries out analysis operation along vertical situation about forming of magnetic bias magnet 13 to above-mentioned magnetic vector deflection angle on its entire portion.Should be noted that when other shape of magnetic bias magnet 13 is identical with previous first simulation, carry out analysis operation under the situation that above-mentioned air gap AG is three kinds of air gaps, promptly air gap is respectively 0.5mm, 1.0mm and 1.5mm.Should also be noted that shape, be to use and the identical shape of first simulation for rotor R T.And analysis operation is to carry out under the situation that above-mentioned M-M fixed distance is 1.3mm.

Figure 12 represents this 3rd Simulation result.From Figure 12, know and find out, at air gap AG in any case corresponding to 0.5mm, 1.0mm and 1.5mm, because the vee gutter 17 of length L is formed in the magnetic bias magnet 13, therefore with this magnetic bias magnet that does not form vee gutter 17 (promptly, sample U1) compare, the magnetic vector deflection angle increases (seeing that sample U2 is to U5).But for the length L of the vee gutter 17 magnetic bias magnet greater than certain length, specifically, length L can not be found out big variation from the magnetic vector deflection angle of this magnetic bias magnet greater than the 6.7mm of sample U3.Can disclose the following fact from above-mentioned condition: promptly, in order to form vee gutter 17 at hollow space 14, thereby increase the magnetic vector deflection angle, if form the vee gutter 17 of certain length that this rotor opposite face 13a that has with magnetic bias magnet 13 separates in the empty hereinto part 14, then can obtain enough big magnetic vector deflection angle.

And, in this 3rd simulation, only under the situation of formation vee gutter 17 on any madial wall of the long edge side of hollow space 14, carry out analysis operation.In other words, shown in sample U6 among Figure 12, ought be only forming under the situation of a vee gutter 17 on any madial wall at the long edge side of hollow space 14, the enlarged degree of magnetic vector deflection angle is lower than the situation that forms vee gutter 17 on the internal side wall of the side, a plurality of long edge of hollow space 14.But, compare with the traditional magnetic bias magnet 13 (sample U1) that does not form vee gutter 17, at first the magnetic vector deflection angle of the magnetic bias magnet 13 of Ti Chuing increases.Find out from above-mentioned analog result is clear, in order to form vee gutters 17, thereby increase the deflection angle of magnetic vector, even the structure that only forms a vee gutter 17 on of these madial walls of hollow space 14 also has superiority at hollow space 14.

Below the result who obtains in first to the 3rd simulation is summarized as follows:

(a) owing in the hollow space 14 of magnetic bias magnet 13, form vee gutter 17, therefore increase the magnetic vector deflection angle.

(b) the width X of vee gutter 17 is wide more, and the increase of magnetic vector deflection angle is big more.

(c) degree of depth Z of vee gutter 17 is dark more, and the increase of magnetic vector deflection angle is big more.

(d) for the degree of depth Z and the width X of vee gutter 17, if degree of depth Z deepens, then the magnetic vector deflection angle can further increase, and this will be favourable.

(e) if vee gutter 17 has certain length that the rotor opposite face 13a with magnetic bias magnet 13 separates, then can obtain enough big magnetic vector deflection angle.Therefore, vee gutter 17 always is not formed on the whole length of magnetic bias magnet 13.

(f) even when vee gutter 17 only be formed on the madial wall of hollow space 14, can increase the magnetic vector deflection angle.

As a result, according to the foregoing description pattern, wherein using at least, said structure (a) can reach following effect to (d):

(1) when magnetoresistive element to 1, magnetoresistive element to 2 and magnetic bias magnet 13 between relative position relation (for example, above-mentioned M-M distance) when always not changing, the 1 and 2 magnetic vector deflection angles that influence can be regulated by the vee gutter 17 that forms in the hollow space 14 by magnetoresistive element.Not only can under aforesaid way, increase the magnetic vector deflection angle, and can realize easily that the detection sensitivity of rotation detecting improves.In addition, can regulate the magnetic vector deflection angle substantially by the vee gutter 17 that hollow space 14 is set, thereby can improve the design freedom of this rotation detecting greatly.

(2) because vee gutter 17 is formed on the core of madial wall of the long edge side of hollow space 14, in the symmetrical feature that can keep the magnetic vector deflection angle, can regulate the magnetic vector deflection angle easily, promptly increase the magnetic vector deflection angle easily.

(3) owing to use cross sectional shape to become leg-of-mutton vee gutter 17 as the groove that forms in the hollow space 14, when using the molded magnetic bias of metal die magnet 13, the flowability of magnetic material is hardly by vee gutter 17 overslaughs in this metal die.Therefore, compare, the better magnetic material of homogeneity can be molded as the magnetic bias magnet with the situation of using other difform groove.

The rotation detecting that should also be understood that the foregoing description mode can be amended as follows:

That is, under the foregoing description mode, vee gutter 17 longitudinally is formed on the entire portion of magnetic bias magnet 13.In addition, when the content of total concluding a research item (e) of considering analog result, vee gutter 17 can form as follows: vee gutter 17 has isolated certain length of rotor opposite face 13a (being 6.7mm) with magnetic bias magnet 13 in above-mentioned example.

Similarly, when the content of total concluding a research item (f) of considering analog result, vee gutter 17 can form alternatively: vee gutter 17 only is formed on 14 1 madial walls of hollow space that constitute magnetic bias magnet 13.

Under the foregoing description mode, the magnetic bias magnet 13 that forms vee gutter 17 at hollow space 14 is for example understood.In addition, do not use above-mentioned vee gutter 17, for example, shown in Figure 13 as corresponding to prior figures 3 can be used other magnetic bias magnet 13, wherein forms semi-circular groove 18, and the trench bottom of this semi-circular groove 18 forms circular arc.And similar with above-mentioned modification, shown in Figure 14 as corresponding to prior figures 3 also can be used the magnetic bias magnet 13 that forms rectangular channel 20, and the trench bottom of this rectangular channel 20 forms rectangle.Explain the analysis result of the magnetic vector deflection angle of magnetic bias magnet 13 that uses semi-circular groove 18 or the magnetic bias magnet 13 that uses rectangular channel 20 below referring to Figure 15.Shown in the analysis result of Figure 15, to compare with the magnetic vector deflection angle of the magnetic bias magnet that does not form vee gutter 17 (sample U1 among Figure 12), the magnetic vector deflection angle that forms the magnetic bias magnet 13 (sample V1) of semi-circular groove 18 also increases.And the number of degrees of the deflection angle of increase are greater than the magnetic bias magnet (sample V4) that forms vee gutter 17, and vee gutter 17 has same widths X, same depth Z and length L.As a result, owing to formed semi-circular groove 18, the magnetic vector deflection angle can increase the identical number of degrees, and perhaps the number of degrees are higher than above-mentioned vee gutter 17.In addition, detection sensitivity can further improve.And, use under the situation of semi-circular groove 18 at magnetic bias magnet 13, similar with the situation of the above-mentioned vee gutter 17 of use in magnetic bias magnet 13, the flowability of the magnetic material that uses when this magnetic bias magnet 13 is molded is hindered hardly, and this has superiority.On the other hand, compare, also increase the magnetic vector deflection angle of the magnetic bias magnet (sample V2 and V3) that forms rectangular channel 20 with the magnetic vector deflection angle of the magnetic bias magnet that does not form vee gutter 17 (sample U1 among Figure 12).Then, in the case, more specifically, the degree of depth Z of this rectangular channel 20 and the deep equality of other groove, perhaps dark than the degree of depth of other groove, therefore the analysis result from Figure 15 can disclose the following fact.That is, the increase number of degrees of magnetic vector deflection angle can be bigger than the magnetic vector deflection angle increase number of degrees of the magnetic bias magnet that forms vee gutter 17 or semi-circular groove 18.As a result, for the shape of groove, not only can suitably use above-mentioned vee gutter 17, and can suitably use semi-circular groove 18 and rectangular channel 20.Inventor of the present invention can confirm that the content of above-mentioned total concluding a research item (a) to (f) of first to the 3rd analog result can be applied to semi-circular groove 18 and rectangular channel 20 equally.

Under the foregoing description mode, for example understood such magnetic bias magnet 13, i.e. vee gutter 17 of formation on each madial wall of the hollow space 14 of the long edge side of magnetic bias magnet.For example, as shown in figure 16, such magnetic bias magnet 13 also can be used, and wherein forms a plurality of vee gutters 23 (for example, three vee gutters 22) on each madial wall of long edge side.And under this other situation, inventor of the present invention can confirm: can reach the operating effect similar to the foregoing description mode.

And, under the foregoing description mode, form vee gutter 17 at the madial wall core of the hollow space 14 of long edge side.But the position that forms this vee gutter 17 can be chosen to any position in addition, as long as these positions are positioned at hollow space 14.Under this other situation, though can not keep the symmetrical feature of magnetic vector deflection angle, can easily regulate the deflection angle of magnetic vector, promptly can easily increase according to the mode similar to the foregoing description mode.

(second embodiment)

Before second by way of example of explanation, explain basic thought of the present invention to Figure 21 with reference to Figure 19 according to rotation detecting of the present invention.It should be understood that for the ease of understanding as an example, and a part of magnetic bias magnet is expressed as magnifying state with traditional rotation detecting of using the magnetic bias magnet.In this magnetic bias magnet, set magnetic field intensity substantially equably at all peripheral parts of magnetic bias magnet.For easy, superincumbent Figure 17 or same reference numbers shown in Figure 180 will be used for representing the identical or similar structural element of Figure 19 to Figure 21.

Figure 19 represents the skeleton view structure of sensor chip 11 and magnetic bias magnet 13 in the amplification mode, and this constitutes rotation detecting.As shown in figure 19, magnetic bias magnet 13 forms hollow cylindrical, and has hollow space 14, and vertical this magnetic bias magnet 13 in while hollow space 14 edges direction cross sectional shape longitudinally is a rectangular shape.Have magnetoresistive element MRE1 and put into hollow space 14 and moulded parts 12, thereby can apply bias field with respect to the magnetoresistive element MRE1 of storage sensor chip 11 to MRE4 from magnetic bias magnet 13 to the sensor chip 11 of MRE4.Note also that, in this magnetic bias magnet 13, be magnetized into the N utmost point with above-mentioned rotor opposing end faces 13a, and another end face relative with end face 13a is magnetized to the S utmost point.

In the enlarged perspective that uses magnetic bias magnet 13, the magnetic field status list that magnetic bias magnet 13 produces is shown in Figure 20.For convenience, note also that, in Figure 20, the arrow representative that the magnetic field of the long edge side of hollow space 14 is represented by 8 solid lines, and the arrow representative that the magnetic field of the short edge side of hollow space 14 is represented by 2 solid lines.In the following description, the high/low of magnetic field intensity will be according to the width means of solid line.But as mentioned above, because the magnetic field intensity of magnetic bias magnet 13 shown in Figure 20 is equal to each other substantially at its all peripheral parts, therefore above-mentioned magnetic field can be expressed as all solid lines with same widths.As shown in figure 20, in the single main body of magnetic bias magnet 13, the magnetic field that single thus magnetic bias magnet 13 produces converts annular to, and its mode is that the S utmost point is pointed to from the N utmost point in magnetic field.But,, under the condition that forms magnetic field, can generate magnetic vector at this toothed portion when the toothed portion of above-mentioned rotor is relative to out-of-date with the end face 13a of magnetic bias magnet 13.Then, the variation that comprises of the angle of the magnetic vector of generation can be used as change in resistance and is detected to MRE4 by magnetoresistive element MRE1.

On the other hand, in above-mentioned rotation detecting, it is detected to the change in resistance of MRE4 that the magnetic vector angle variation that produces when above-mentioned rotor rotates can be used as above-mentioned magnetoresistive element MRE1.Under the situation of magnetic bias magnet 13 shown in Figure 20, all magnetic fields of magnetic bias magnet 13 generations can be used to produce above-mentioned magnetic vector thus.As a result, particularly, the magnetic confinement that the deflection angle of the magnetic vector of generation also can be produced by the long edge side of hollow space 14.Referring to Figure 21 in detail, the above-mentioned restriction of magnetic vector deflection angle will be described.

Figure 21 schematically shows the magnetic field state that magnetic bias magnet 13 produces, this from see with above-mentioned rotor opposing end faces 13a one side, the vertical view of magnetic bias magnet 13.As shown in figure 21, being subjected to the rotor rotation easily from the magnetic field that the XXIA1 part and the XXIA2 of the short edge side of hollow space 14 partly produces influences, if notice is only noticed from the magnetic field of these parts XXIA1 and XXIA2 generation, then magnetic vector deflection easily, this is to be produced by the magnetic field of these generations and rotor rotation.In other words, its deflection angle is to a great extent by himself deflection angle maintenance.On the contrary, from the magnetic field that the XXIB1 of hollow space 14 long edge sides part and XXIB2 partly produce, intersect vertically with the sense of rotation of rotor.As a result, the magnetic vector component that forms in conjunction with the rotor rotation from the magnetic field that these parts XXIB1 and XXIB2 the produce easy deflection that can produce the above-mentioned magnetic vector that magnetic field that following effect: part XXIA1 and XXIA2 produce forms in conjunction with the rotor rotation may be obstructed.In other words, if the magnetic field intensity in magnetic field can reduce, this is partly to be produced by the XXIB1 of the long edge side of hollow space 14 and XXIB2, can expect that then above-mentioned magnetic vector deflection angle increases.

Figure 22 represents rotation detecting according to the second embodiment of the invention mode to Figure 24, and this rotation detecting designs according to above-mentioned basic thought.To Figure 24, will describe design referring to Figure 22 below in detail according to the rotation detecting of second by way of example.Should be noted that, because the structure of this rotation detecting and the said structure of traditional rotation detecting are basic identical, therefore therefore the constitutional detail that will be used to represent to have same or similar function in the same reference numbers shown in traditional rotation detecting omits its detailed description.

Figure 22 schematically shows the magnetic field situation that the magnetic bias magnet 13 that uses in the rotation detecting according to first embodiment produces, and this figure is corresponding to Figure 20.As shown in figure 22, magnetic bias magnet 13 forms hollow cylindrical, and has hollow space 14.This hollow cylindrical of magnetic bias magnet 13 is not different fully with the shape of traditional magnetic bias magnet.The cross sectional shape of hollow space 14 along perpendicular to magnetic bias magnet 13 longitudinally direction be rectangle substantially.And the material that constitutes magnetic bias magnet 13 is and traditional magnetic bias magnet identical materials.But this magnetic bias magnet 13 has and the basic different following difference of evenly setting of traditional magnetic bias magnet of magnetic field intensity.Promptly, in this magnetic bias magnet 13, the magnetic field intensity of the magnetic bias magnet part that is oppositely arranged to the front/rear placement-face of MRE4 with the magnetoresistive element MRE1 of the sensor chip 11 (seeing Figure 19) that is contained in hollow space 14 optionally is set in low magnetic field intensity from the end face 13a of magnetic bias magnet 13 to its opposite planar.This end face 13a is relative with rotor.As a result, in the magnetic field that magnetic bias magnet 13 produces, the magnetic field that the magnetic bias magnet part that is oppositely arranged to the front/rear placement-face of MRE4 with magnetoresistive element MRE1 produces represents that with narrow solid arrow the magnetic field of the other parts of magnetic bias magnet 13 generation contrasts therewith.

Figure 23 schematically shows the magnetic field state that magnetic bias magnet 13 produces, and this has used the vertical view of magnetic bias magnet 13, from seeing with above-mentioned rotor opposing end faces 13a one side, corresponding to the figure of Figure 21.As shown in figure 23, if notice the XXIA1 part of magnetic bias magnet 13 inherent hollow space 14 minor faces one sides and the magnetic field that another part XXIA2 produces, with above-mentioned magnetic bias magnet 13 similar (seeing Figure 21), deflection magnetic vector easily then, this is to produce by the magnetic field of these generations and in conjunction with the rotor rotation, so its deflection angle is fixing greatly.On the contrary, in magnetic bias magnet 13, the magnetic field intensity in these magnetic fields that the magnetic bias magnet part that is oppositely arranged to the front/rear placement-face of MRE4 with magnetoresistive element MRE1 produces, promptly, the magnetic field intensity in the magnetic field that the part XXIB1 of hollow space 14 long edge sides and another part XXIB2 produce, selectivity is set at low magnetic field intensity, and these are different with above-mentioned magnetic bias magnet 13.As a result, compare with the magnetic vector that above-mentioned magnetic bias magnet 13 produces, these rotate the magnetic vector deflection easily that forms by magnetic field and the rotor that these parts XXIB1 and XXIB2 produce.Therefore, these magnetic vectors can be suppressed, and this can hinder the magnetic field of part XXIA1 and XXIA2 generation and the easy deflection of the above-mentioned magnetic vector that the rotor rotation forms.As a result, the magnetic vector component of the magnetic field of magnetic bias magnet 13 generations and rotor rotation generation strengthens greatly.

Figure 24 represents the analog result of the deflection angle of the magnetic field of magnetic bias magnet 13 generations and the magnetic vector that the rotor rotation produces, and has wherein considered the sensitivity of magnetoresistive element MRE1 to MRE4 simultaneously.It should be understood that the rotor of air gap representative rotation detecting under the situation of arranging the rotation detecting that designs as shown in figure 18 that Figure 24 represents and the distance between the rotor opposite face.From figure, can know and find out, under nearly all air gap, the analog result of the magnetic vector deflection angle that under the magnetic vector deflection angle that produces under the situation of using magnetic bias magnet 13 can be greater than the situation of using traditional magnetic bias magnet 13, obtains.Therefore, owing to used magnetic bias magnet 13, wherein the magnetic field intensity selectivity of the part that is oppositely arranged to the front/rear placement-face of MRE4 with magnetoresistive element MRE1 is set at low magnetic field intensity, and is therefore very effective for increase magnetic vector deflection angle.

Explain the manufacture method of above-mentioned magnetic bias magnet 13 to Figure 28 below with reference to Figure 25.

Usually, when making the magnetic bias magnet, form the molded of resin material body that contains magnetic, then, with the molding magnetization of resin material.But the feature of above-mentioned magnetic bias magnet 13 is that the magnetic field intensity selectivity of the part that is oppositely arranged to the front/rear placement-face of MRE4 with magnetoresistive element MRE1 is set at low magnetic field intensity.As a result, in the described below device for molding, when aligned the differing from one another of magnetic contained in the above-mentioned molding, set above-mentioned magnetic field intensity according to these aligned differences.Then will describe the device for molding of carrying out these forming step in detail.

Figure 25 is the vertical view of the device for molding 70 of the above-mentioned molding of shaping.As shown in figure 25, this device for molding 70 has used molding die 72, and mould has the cavity 71 corresponding to the shape of magnetic bias magnet 13.Also be appreciated that this molding die 72 is to use no magnetic made.And this device for molding 70 is by the upper and lower at cavity 71 two groups of field coils 73 to be set to constitute.These two groups of field coils 73 can cover except corresponding to the cavity 71 the cavity of above-mentioned magnet part XXIB1 and the XXIB2 part.

Figure 26 is the cut-open view of expression along the device for molding 70 of Figure 25 center line XXVI-XXVI intercepting.As shown in figure 26, molding die 72 is made of patrix 72a and counterdie 72b, cavity 71 internal shapings of molding 74 between patrix 72a and counterdie 72b.Two groups of field coils 73 with aforesaid way are arranged in each patrix 72a and the counterdie 72b.

The following describes device for molding 70 that use makes in a manner described and make the method for above-mentioned magnetic bias magnet 13.

In other words, state device for molding 70 in the use and make under the situation of magnetic bias magnet 13, will carry out following steps:

(a) resin material that will contain magnetic is expelled to the cavity 71 of molding die 72.The injection that it should be understood that resin material is carried out by reel (spool) (not shown).

(b) thus when the magnetic that each field coil 73 is contained in the resin material in the cavity 71 relatively by excitation applies suitable magnetic field, the orientation of control magnetic before resin material solidifies.

(c) after above-mentioned resin material is cured as molding, to all part demagnetizations of this molding.

(d) after this, utilize magnetizing assembly (not shown), the molding relative with rotor partly is magnetized into the N utmost point, and another part molding relative with above-mentioned part is magnetized into the S utmost point.

Be further explained in detail above-mentioned manufacturing step (b) below.It is aligned that Figure 27 utilizes above-mentioned device for molding 70 to represent to control magnetic orientation magnetic before along the cut-open view of Figure 25 center line XXVII-XXVII intercepting.And Figure 28 is corresponding to Figure 27, and the magnetic after the expression control magnetic orientation is aligned.Should also be noted that in Figure 27 and Figure 28,, show magnetic in the amplification mode for the ease of understanding the aligned of magnetic.As shown in figure 27, under the condition that obtains before field coil 73 excitations, the orientation of the magnetic MP that exists in the resin material is in not matching status.Matching status is not opposite therewith, when each field coil 73 by excitation, when producing magnetic field around each field coil 73, as shown in figure 28, according to the orientation of the magnetic field control magnetic MP of these generations.In other words, the orientation of magnetic MP can realize by following mode: the particle of magnetic MP points to each field coil 73.As a result, lower corresponding to the magnetic MP degree of orientation of these parts of above-mentioned magnet part XXIB1 and XXIB2 in the molding of making by device for molding 70, thus aligned there are differences of magnetic MP in this molding.Because having the molding of above-mentioned aligned difference is by above-mentioned manufacturing step (c) and (d) magnetized, thereby produces the magnetic bias magnet 13 in the magnetic field that can produce above-mentioned Figure 22 and Figure 23.

Then, the sensor chip 11 is stored into the hollow space 14 (seeing Figure 19) of the magnetic bias magnet of making by above-mentioned manufacturing step (a) to (d) 13 with moulded parts 12.After this, press integration mode with this memory structure spare and casing component assembling, or the like.As a result, can produce rotation detecting shown in Figure 180.

In above-mentioned first by way of example, can obtain following effect:

(1) generation type of magnetic bias magnet 13 is, and the magnetic field intensity of the magnetic bias magnet part (above-mentioned XXIB1 and XXIB2 part) that is oppositely arranged to the front/rear placement-face of MRE4 of magnetoresistive element MRE1 is set at low magnetic field intensity at the end face 13a of magnetic bias magnet 13 from then on to selectivity between its opposite face.As a result, strengthen greatly by the bias field of magnetic bias magnet 13 generations and the magnetic vector component of rotor rotation generation.In other words, when magnetoresistive element MRE1 to the relative position relation between MRE4 and the magnetic bias magnet 13 (for example, above-mentioned M-M distance) when always not changing, can regulate the magnetic vector deflection angle that magnetoresistive element MRE1 is exerted an influence to MRE4, and realize improving the detection sensitivity of rotation detecting easily.

(2) when magnetic bias magnet 13 can form the molding of the resin material that comprises magnetic, the magnetic field intensity of the part that is oppositely arranged to the front/rear placement-face of MRE4 with magnetoresistive element MRE1 is according to the aligned difference of magnetic in the molding and selectivity is set at low magnetic field intensity.As a result, above-mentioned magnetic field intensity can be by suitably utilizing the setting simple in structure of above-mentioned molding.And,, can suppress the increase of manufacturing cost owing to can directly use the conventional magnet material.

(the 3rd embodiment)

Figure 29 represents the rotation detecting according to the third embodiment of the invention mode, and wherein rotation detecting designs according to above-mentioned basic concept.Referring to Figure 29, describe rotation detecting below in detail according to the third embodiment of the invention mode.It should be noted, because the structure of rotation detecting and the structure of above-mentioned traditional rotation detecting are basic identical, therefore therefore the structural member that will be used to represent to have same or similar function of the same reference numbers in traditional rotation detecting omits its detailed description.

Figure 29 schematically shows the magnetic field state that the magnetic bias magnet 13 that uses in the rotation detecting according to first by way of example produces, and this figure is corresponding to Figure 20.As shown in figure 29, magnetic bias magnet 13 is configured as hollow cylindrical, and has hollow space 14.This hollow cylindrical magnetic bias magnet 13 is not the shape that is different from traditional magnetic bias magnet fully.The vertical magnetic bias magnet 13 in cross sectional shape edge of hollow space 14 direction longitudinally is rectangle substantially.And the material that constitutes magnetic bias magnet 13 is and traditional magnetic bias magnet identical materials.But this magnetic bias magnet 13 has the following difference different with traditional magnetic bias magnet.Promptly, in magnetic bias magnet 13, the magnetic field intensity of the magnetic bias magnet part that is oppositely arranged to the front/rear placement-face of MRE4 with magnetoresistive element MRE1, the magnetic field intensity (seeing Figure 21) in the magnetic field of promptly above-mentioned XXIB1 and XXIB2 part is from being set at low magnetic field intensity up to the magnetoresistive element MRE1 of covering sensor chip 11 to the regioselectivity of MRE4 with rotor opposing end faces 13a.As a result, compare with the magnetic field of the other parts generation of magnetic bias magnet 13 from then on, the magnetic field intensity selectivity is set at the magnetic field of the magnetic bias magnet part generation of low magnetic field intensity and is represented by the arrow of narrow solid line.

Then, if notice the XXIA1 part of minor face one side of hollow space 14 in the magnetic bias magnet 13 and the magnetic field that another part XXIA2 (seeing Figure 21) produces, similar to above-mentioned explanation magnetic bias magnet 13 (seeing Figure 21), then magnetic vector deflection easily, this is to be produced by the magnetic field of these generations and rotor rotation, so its deflection angle is fixing greatly.On the contrary, in magnetic bias magnet 13, can selectivity be set at low magnetic field intensity from the magnetic field intensity in the magnetic field that XXIB1 and the XXIB2 of above-mentioned end face 13a partly produces to the position of MRE4 covering magnetoresistive element MRE1, these are different with above-mentioned magnetic bias magnet 13.As a result, the magnetic vector contrast that produces with above-mentioned magnetic bias magnet 13 is from magnetic field that XXIB1 and XXIB2 partly produce and the magnetic vector deflection easily that produces of the rotation of rotor.Therefore, this magnetic vector can suppress, and this can hinder the easy deflection of the above-mentioned magnetic vector that magnetic field that XXIA1 and XXIA2 partly produce and rotor rotation form.As a result, the magnetic vector component can strengthen greatly, and this is that the magnetic field and the rotor rotation that produce of magnetic bias magnet 13 produces thus.

Explain the manufacture method of above-mentioned magnetic bias magnet 13 below with reference to Figure 30 and Figure 31.It should be understood that because magnetic bias magnet 13 is to make according to the manufacturing step identical with above-mentioned first by way of example substantially therefore following main explanation difference.

Figure 30 represent to be shaped device for molding 70 of above-mentioned magnetic bias magnet 13, this is corresponding with Figure 25.As shown in figure 30, this device for molding 70 has used molding die 72, and it has the cavity 71 corresponding to magnetic bias magnet 13.Also be appreciated that this molding die 72 is to use no magnetic made.Then, at the patrix 72a (seeing Figure 21) that constitutes this molding die 72 two groups of field coils 73 are set, these two groups of field coils 73 can cover except corresponding to the cavity 71 the cavity part of above-mentioned XXIB1 and XXIB2 part.On the contrary, the field coil 94 of covering cavity 71 is contained in the counterdie 72b (seeing Figure 31) that constitutes mould 72.Therefore, above-mentioned magnetic orientation is by operating these field coils 73 and field coil 94 controls.

Figure 31 represents that the magnetic after the control of magnetic orientation is aligned, and this is corresponding to Figure 28.When each field coil 73 and 94 energisings, when producing magnetic field around each field coil 73 and 94, as shown in figure 31, control the orientation of magnetic MP according to the magnetic field of these generations.In other words, the orientation of magnetic MP can realize in the following manner: the particle of magnetic MP points to each field coil 73 and 94.The result, in the molding of making by device for molding 70, cover magnetoresistive element MRE1 to the position of MRE4 corresponding to these parts of above-mentioned magnet part XXIB1 and XXIB2, lower from the magnetic MP degree of orientation of the above-mentioned end face 13a of magnetic bias magnet 13, therefore in this molding, have the aligned difference of magnetic MP.Then, by above-mentioned manufacturing step (c) and (d) molding of magnetization, thereby make to produce the magnetic bias magnet 13 in above-mentioned magnetic field shown in Figure 29 with this different orientation mode.

According to above-mentioned second by way of example, except the effect of equal value of the effect (1) of above-mentioned second by way of example and (2), obtain following effect:

(3) mode of the formation of magnetic bias magnet 13 is, the magnetic field intensity of the magnetic bias magnet part (above-mentioned part XXIB1 and XXIB2) that is oppositely arranged to the front/rear placement-face of MRE4 with magnetoresistive element MRE1 is set at low magnetic field intensity from the magnetic bias magnet relative with rotor 13 end face 13a selectivity covering magnetoresistive element MRE1 to the position of MRE4.The result, except from and rotor opposing end faces 13a up to covering the part of magnetoresistive element MRE1 to the part the position of MRE4, according to can realizing the orientation control of magnetic, thereby use the conventional molded mould can suppress the increase of manufacturing cost with the similar mode of prior art.

It is also noted that above-mentioned each by way of example can be carried out other and be revised back enforcement.

That is, in second by way of example, the generation type of magnetic bias magnet is, is set at low magnetic field intensity with magnetoresistive element MRE1 to the magnetic field intensity selectivity of the relative magnetic bias magnet part of the front/rear placement-face of MRE4.In addition, only have with magnetoresistive element MRE1 and can selectivity be set at low magnetic field intensity to the magnetic field intensity of a relative part of MRE4 placement-face.As a result, shown in figure 32, the corresponding Figure 20 of Figure 32, the realization of this magnetic bias magnet 13 can be, from being represented schematically that to the magnetic field that this relative part of MRE4 placement-face produces its width is narrower than other parts with magnetoresistive element MRE1 by solid line.Then compare with the magnetic vector (seeing Figure 21) that above-mentioned magnetic bias magnet 13 produces, deflection magnetic vector easily, and these magnetic vectors are by from obtaining to magnetic field and the rotor rotation that this relative part of MRE4 placement-face produces with the magnetoresistive element MRE1 of magnetic bias magnet 13.As a result, only being set under the situation of low magnetic field intensity to this relative part magnetic field intensity selectivity of the placement-face of MRE4, also can reach the effect similar to first by way of example with magnetoresistive element MRE1.It should be understood that when making this magnetic bias magnet 13, use the shown in Figure 33 device for molding 70 corresponding with Figure 25.That is, this device for molding 70 uses the molding die 72 with cavity 71 corresponding with magnetic bias magnet 13.It is also noted that this molding die 72 is to use no magnetic made.And this device for molding 70 is to provide two groups of field coils 113 to constitute by the upper and lower part at cavity 71.These two groups of field coils 113 can cover except with the cavity 71 of magnetoresistive element MRE1 to the relative part of the placement-face of MRE4.The method of using this molding die 70 to make magnetic bias magnet 13 is to carry out under the situation identical with first by way of example.And above-mentioned magnetic bias magnet is being set at low magnetic field intensity with magnetoresistive element MRE1 to the magnetic field intensity selectivity of the relative part of MRE4 placement-face, and this also can be as the modification of second by way of example.

In above-mentioned second by way of example, the magnetic orientation that comprises in the molding is utilized this field coil 73 controls.In addition, can use permanent magnet.Under above-mentioned situation about can select, similar to the foregoing description mode, the magnetic field control magnetic orientation that also can use permanent magnet to produce.It is also noted that this permanent magnet also can be used as a modification relevant with second by way of example.

In each the foregoing description mode, be set at low magnetic field intensity to the magnetic field intensity selectivity of the relative part of the front/rear placement-face of MRE4 with magnetoresistive element MRE1.In addition, when setting this magnetic field intensity, for example, these magnetic field setting operations can be implemented by demagnetization.In other words, the basic magnetic bias magnet of evenly setting of magnetic field intensity can use the device for molding similar to the conventional molded device to be shaped.After this, utilize demagnetizer (not shown), will be set at low magnetic field intensity to the magnetic field intensity selectivity of the relative part of the front/rear placement-face of MRE4 with magnetoresistive element MRE1.And, under this alternative situation, can realize producing magnetic bias magnet as Figure 22 and magnetic field shown in Figure 29.

Above-mentioned each by way of example has illustrated the situation of the magnetic bias magnet 13 with hollow space 14, and its cross sectional shape is made rectangle.In addition, even use the magnetic bias magnet with hollow space of making other shape, this magnetic bias magnet also can be covered by invention viewpoint of the present invention equally.And, for magnetic bias magnet itself, not only can use the magnetic bias magnet that forms hollow cylindrical, and can use other difform magnetic bias magnet of formation.

These variations and modification should be thought in the scope of the invention that claim limits.

Claims (4)

1. one kind is detected the rotation detecting that magnet rotor (RT) rotates, and described device comprises:

Have magnetoresistive devices (1,2, sensor chip MRE1-MRE4) (11); And

To magnetoresistive devices (1,2, MRE1-MRE4) apply the magnetic bias magnet (13) of bias field, wherein:

Magnetic bias magnet (13) and sensor chip (11) are integrated;

Magnetoresistive devices (1,2, MRE1-MRE4) can (1,2, near the magnetic vector the change in resistance detecting sensor chip (11) MRE1-MRE4) changes, and makes rotation detecting detect the rotation of magnet rotor (RT) according to magnetoresistive devices;

Magnetic vector changes by bias field and magnet rotor (RT) rotation generation;

Magnetic bias magnet (13) is arranged in sensor chip (11) on every side, makes that the magnetic vector deflection angle is controlled;

Wherein, magnetic bias magnet (13) comprises the have groove hollow space (14) of (17,18,20,22);

Groove (17,18,20,22) has reservation shape, so that the control of magnetic vector deflection angle to be provided;

The hollow space (14) of magnetic bias magnet (13) holds sensor chip (11), and is the rectangle with a pair of wide side;

The wide side of hollow space (14) is towards sensor chip (11), and is parallel to the surface of sensor chip (11), and magnetoresistive devices (1,2, MRE1-MRE4) be arranged on this surface;

The groove of hollow space (14) (17,18,20,22) is along the longitudinal extension of magnetic bias magnet (13); And

Groove (17,18,20,22) is arranged on the center of the wide side of hollow space (14).

2. device as claimed in claim 1 is characterized in that:

Groove (17,22) has the triangular cross-sectional shape on band summit; And

Described summit is arranged on the bottom of groove (17,22).

3. device as claimed in claim 1 is characterized in that:

Groove (18) has the semi-circular section shape of band semi arch; And

Described semi arch is arranged on the bottom of groove (18).

4. device as claimed in claim 1 is characterized in that:

Groove (17,18,20,22) is arranged on the inwall of hollow space (14).

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