CN100501835C - Magnetic encoder - Google Patents
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- CN100501835C CN100501835C CNB2006101396980A CN200610139698A CN100501835C CN 100501835 C CN100501835 C CN 100501835C CN B2006101396980 A CNB2006101396980 A CN B2006101396980A CN 200610139698 A CN200610139698 A CN 200610139698A CN 100501835 C CN100501835 C CN 100501835C
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Abstract
A magnetic encoder having a magnetic sensor composed of SVGMR elements, in which a signal output with a half of a cycle of magnetic regions on a magnetic medium. The magnetic encoder comprises the magnetic medium, on which first magnetic regions and second magnetic regions are oppositely magnetized along the medium extending and disposed successively and alternately with each other, and the magnetic sensor that has an even number of SVGMR elements and is movable relatively to the medium along the medium extending. Magnetizations of pinned magnetization layers of all the SVGMR elements are directed in a same direction along the medium extending. Each of the even number of SVGMR elements in the magnetic sensor is apart by a half of the sum of a first magnetic region length plus a second magnetic region length from each other along the medium extending, and the even number of SVGMR elements are connected in series so that a cycle of resistance change of the magnetic sensor is a half of a cycle length of the first and the second magnetic regions on the medium and the signal output with high resolution can be obtained.
Description
Technical field
The present invention relates to use the magnetic encoder of magnetic sensor, described magnetic sensor has rotary valve (spin valve) type giant magnetoresistive effect film.
Background technology
In recent years, be applied to be required not only cheap and miniaturization, and have high resolving power and excellent gap output characteristics such as the magnetic encoder of the civil equipment of small scale robot, digital camera and ink-jet printer.In other words, require the magnetic encoder miniaturization but do not need to be used to double the treatment circuit of signal frequency, and can resist the gap and change and keep stable output at its run duration.In addition, require low electric power consumption.
In traditional magnetic encoder, used the magnetic resistor that forms by anisotropic magnetoresistance effect film (hereinafter referred to as " AMR element ").The AMR element is widely used, even because in less relatively field region, resistance also can be to a certain extent changes according to wherein changes of magnetic field, and because its film is manufactured easily.Yet, need this film is thickeied 20nm to 40nm, obtain stable magnetoresistance effect so that have the AMR element of NiFe alloy firm or NiCo alloy firm.But they are difficult to use, because the resistance of element is owing to thicker film reduces.If the width dimensions of AMR element is reduced to increase resolution, shape anisotropy (Hk) increases with the influence of thicker film, and can not obtain the electricity output that enough resistance variations produce expectation in the low-intensity magnetic field zone.Owing to this reason, be difficult to improve the resolution in the magnetic encoder that uses the AMR element.Increase this resolution and mean the spacing of dwindling element and/or the magnetization on the medium, and increase the electrical output signal number of unit length.
Replace being difficult to improve the AMR element of resolution, use the element of the giant magnetoresistive effect film (hereinafter referred to as " coupling GMR element ") of coupling in Jap.P. 2812042, to be disclosed.This coupling GMR element has two to four times resistance change rate (variation ratio) of AMR element. in Jap.P. 2812042, in the coupling GMR element of explanation, used artificial grid metal film with ten layers of alternately laminated NiCoFe film and nonmagnetic metal film.Multilayer ferromagnetic thin film and nonmagnetic metal film cause big magnetoresistance rate of change.Yet, be difficult to realize low electric power consumption because the nonmagnetic metal film is the resistance of good electrical conduction material and film be low to moderate the AMR element half to 1/3rd.Coupling GMR element has 20% to 30% resistance change rate, but resistance change rate can only obtain by use them in big magnetic field.Because this reason is difficult in the less relatively magnetic field as magnetic encoder and uses them.
Rotary valve type giant magnetoresistive effect film in a kind of magnetic head that is used in hard disk storage devices (HDD) is arranged, and is the film that presents the resistance change rate the same with coupling GMR element in relatively little field region.As explanation in Jap.P. 3040750, rotary valve type giant magnetoresistive effect film is made up of fixed magnetization layer (pinned magnetic layer), unmagnetized conductive layer and free magnetization layer, in described fixed magnetization layer, direction of magnetization does not change with the variation of external magnetic field (or magnetic flux) direction, in described free magnetization layer, direction of magnetization is followed the variation of external magnetic field and is changed.Have the resistance of five times to six times of coupling GMR elements from the element (hereinafter referred to as " SVGMR element ") of rotary valve type giant magnetoresistive effect film machining, and when it is used to magnetic sensor, realize the minimizing of electric power consumption easily.Equally, it can be operated in as 1A/m to 160A/m, in the less relatively field region of promptly about 0.006 Oe to 20 Oe.
Yet magnetic encoder has and can only reduce the shortcoming of resolution by replace AMR element and coupling GMR element with the SVGMR element.When the SVGMR element when using with the N utmost point and S utmost point alternating magnetization, magnetic medium with magnetization spacing λ, signal has the 2 λ output cycle for the twice of magnetization spacing.In other words, resolution becomes half.This is caused by the magnetoresistance variation characteristic, and can't avoid reducing of resolution in the conventional codec structure.
This is because the SVGMR element has following characteristic: when applying the external magnetic field on the direction identical with the direction of magnetization of fixed magnetization layer in the element, the resistance of element changes, and when applying the external magnetic field on the contrary, the resistance of element does not change.Perhaps because the SVGMR element has following characteristic: when applying the external magnetic field on the direction identical with the direction of magnetization of fixed magnetization layer in the element, the resistance of element does not change, and when applying the external magnetic field on the contrary, the resistance of element changes.When magnetic medium is magnetized when having magnetization spacing λ, magnetic direction changes for each λ.Because this, the resistance of SVGMR element is with the cyclomorphosis of twice magnetization spacing 2 λ.On the contrary, use coupling GMR element or AMR element that the electric signal of cycle as λ is provided.Coupling GMR element and AMR element are not having to demonstrate maximum resistance under the state in magnetic field, and resistance reduces when the external magnetic field increases.That is, no matter magnetic direction, by the increase of magnetic field intensity with reduce to produce signal.Owing to this reason, can obtain and magnetize the electric signal of spacing λ same period.It is because they almost can not satisfy the high resolving power of market demands that the SVGMR element is not applied to magnetic encoder.Yet, because the SVGMR element presents the resistance of five times to six times of the magnetoresistance rate of change the same with coupling GMR element and coupling GMR elements in relatively little field region, be difficult to abandon easily to realize by the SVGMR element advantage of low electric power consumption.
Summary of the invention
An object of the present invention is to provide a kind of magnetic encoder, comprise the magnetic sensor of forming by the SVGMR element and have the continuous magnetized magnetic medium of alternating magnetization in the opposite direction, half the electric signal in cycle in magnetized area cycle with magnetic medium is provided, low electric power consumption in the magnetic encoder is provided, and the stable output attribute that changes with respect to the gap is provided.
Magnetic encoder according to the present invention comprises: extend and have the magnetic medium of first magnetized area and second magnetized area in one direction, described first magnetized area and second magnetized area alternately are arranged on the described medium and along described medium continuously and each other and reciprocally magnetize; And magnetic sensor, having even number SVGMR element, described SVGMR element has with the rectangle plane of predetermined gap towards described medium, and can move with respect to described medium along the bearing of trend of described medium.First magnetized area and second magnetized area have the length that differs from one another, and have length lambda l than one that grows in them, and one that lacks in them has length lambda s.The rectangle plane of SVGMR element and medium bearing of trend vertically extend.In the even number SVGMR element each is along the bearing of trend each interval of the medium length lambda by (λ l+ λ s)/2 definition.What each SVGMR element was fixed magnetization layer, non-magnetic conductive layer and free magnetization layer by their order is stacked, and the fixed magnetization layer in all SVGMR elements has along the magnetization of medium bearing of trend equidirectional.When the external magnetic field is applied to the SVGMR element with the direction identical with the magnetization of the fixed magnetization layer of SVGMR element, the SVGMR element presents minimum resistance, and when the external magnetic field is applied to the SVGMR element with the direction opposite with the magnetization of the fixed magnetization layer of SVGMR element, present maximum resistance.This even number SVGMR element in series is electrically connected, and takes out signal output from the electric terminal of the SVGMR element that is electrically connected.
When the magnetization antiparallel of the magnetization of free magnetization layer in the SVGMR element and fixed magnetization layer, the SVGMR element presents maximum resistance for the electric current of the SVGMR element of flowing through, and when the magnetization of free magnetization layer in the SVGMR element was parallel with the magnetization of fixed magnetization layer, the SVGMR element presented minimum resistance.In can be applicable to SVGMR element of the present invention, externally magnetic field is not applied to the SVGMR element or applies under the situation of external magnetic field with the direction opposite with the magnetization of fixed magnetization layer, the magnetization antiparallel of the magnetization of free magnetization layer and fixed magnetization layer, and when applying the external magnetic field with the direction identical with the magnetization of fixed magnetization layer, it is identical with the direction of external magnetic field that the magnetization of free magnetization layer becomes, promptly, the same with the magnetization of fixed magnetization layer, and when the external magnetic field is increased to sufficient intensity, it is parallel with the magnetization of fixed magnetization layer that the magnetization of free magnetization layer becomes, and the SVGMR element presents minimum resistance.Perhaps, when the external magnetic field is not applied to the SVGMR element or applies the external magnetic field with the direction identical with the magnetization of fixed magnetization layer, it is parallel with the magnetization of fixed magnetization layer that the magnetization of free magnetization layer becomes, and the SVGMR element presents minimum resistance, and when applying the external magnetic field with the direction opposite with the magnetization of fixed magnetization layer, it is identical with the direction of external magnetic field that the magnetization of free magnetization layer becomes, promptly, opposite with the magnetization of fixed magnetization layer, then, when the external magnetic field becomes sufficient intensity, the magnetization of the free magnetization layer magnetization antiparallel with fixed magnetization layer that becomes, and the SVGMR element presents maximum resistance.
In the SVGMR element, decided by the thickness of the non-magnetic conductive layer that inserts between the material of fixed magnetization layer and/or free magnetization layer and fixed magnetization layer and the free magnetization layer not apply under the situation of external magnetic field, the magnetization of free magnetization layer is parallel or antiparallel with the magnetization of fixed magnetization layer.
Magnetic encoder of the present invention can use the magnetic medium that forms or form with linear magnetic yardstick at the circumference of disk or end face.Because the shape of the magnetic medium of magnetic encoder is well-known, omits its detailed description here.
In the magnetic medium of magnetic encoder of the present invention, require first magnetized area on length, to be different from second magnetized area. when the higher part (mountain peak) that forms by the long zone in first and second magnetized areas in the resistance, the higher part that resistance occurs is overlapping with the adjacent higher part of resistance, and overlapping higher part and the non-overlapped higher part resistance difference between dividing manifests.When the higher part (mountain peak) that forms by the short zone in first and second magnetized areas in the resistance, the skirt section of the higher part of the skirt section of the higher part of resistance (skirt) and adjacent resistor is not overlapping, makes higher part and manifest than the resistance difference between the lower part.But, when first magnetized area has the length identical with second magnetized area, the skirt section of the higher part of the skirt section of the higher part of resistance and adjacent resistance is overlapping, make not the occurring than lower part of resistance, and resistance difference reduces to make and is difficult to obtain output.
In magnetic encoder of the present invention, described magnetic sensor is made up of even number SVGMR element, and each SVGMR element is along the bearing of trend each interval λ of medium.When the SVGMR element was placed in towards first magnetized area or second magnetized area, the resistance of SVGMR element changed to maximal value R1 to present the mountain peak of resistance from minimum value R2.Because magnetic sensor is made up of the SVGMR element of even number series connection and space λ, cause the resistance mountain peak by the interval λ of SVGMR element, and signal to export the cycle that has be half of magnetic chart cycle (λ l+ λ s).
In addition, in magnetic encoder of the present invention, preferably each SVGMR element is equal to or less than λ s along the width w of medium bearing of trend.
In the resistance mountain peak of the SVGMR element that repeats with interval λ, the part of resistance variations has length w.Suppose when the SVGMR element is positioned at towards first magnetized area, to present maximum resistance R1, and when being positioned at towards second magnetized area, it presents minimum resistance R2, since the SVGMR element when it before the first magnetized area forward position during w towards second magnetized area, the SVGMR element has resistance R 2.When the position of w is further near first magnetized area before it is from the first magnetized area forward position, the part of SVGMR element begins towards first magnetized area, and the magnetization of the free magnetization layer of SVGMR element is subjected to the influence of first magnetized area, begins to be parallel to from the magnetization of free magnetization layer the magnetized position transition of fixed magnetization layer.Thereby the resistance of SVGMR element rises from minimum value R2.When the SVGMR component side when the degree of first magnetized area further increases, resistance increases, and when the SVGMR element arrives complete face to the position of first magnetized area, the magnetization of the free magnetization layer of SVGMR element becomes the magnetization antiparallel with fixed magnetization layer, so that resistance is almost maximal value R1.The SVGMR element is from advancing towards the position of first magnetized area to reach the position of w before the second magnetized area forward position.In addition, the SVGMR element advances and the part of SVGMR element begins towards second magnetized area, here, field weakening from first magnetized area, make the magnetization of free magnetization layer of SVGMR element begin magnetization antiparallel position rotation, and the resistance of SVGMR element reduce from maximal value R1 from it and fixed magnetization layer.When SVGMR element when the position towards first magnetized area is advanced further and arrives complete face to the position of second magnetized area from it, the magnetization of the free magnetization layer of SVGMR element becomes parallel with the magnetization of fixed magnetization layer, and resistance becomes minimum value R2, because begin not the free magnetization layer of SVGMR element is worked from the magnetic field of first magnetized area.The resistance of SVGMR element from minimum value R2 change to maximal value R1 or change to the length in zone of minimum value R2 from maximal value R1 and the width w of SVGMR element much at one.The resistance of SVGMR element changes in an identical manner, even it is minimum value R2 when the SVGMR element is positioned at the SVGMR component side to the position of first magnetized area, and when the SVGMR element is positioned at the SVGMR component side to the position of second magnetized area, be maximum resistance R1.
Thereby, the resistance of SVGMR element is minimum value R2 at the SVGMR component side during to the position of the second/the first magnetized area, and from its position apart from the edge w of the first/the second magnetized area, resistance rises gradually, although the SVGMR component side is to the second/the first magnetized area, and to the position of the first/the second magnetized area, the resistance of SVGMR element becomes and is almost maximal value R1 at SVGMR element complete face.And when the time from the position of its w before the edge of the second/the first magnetized area, the resistance of SVGMR element reduces gradually, although the SVGMR component side is to the first/the second magnetized area, and to the position of the second/the first magnetized area, the resistance of SVGMR element becomes minimum value R2 at SVGMR element complete face.Suppose that first magnetized area has long magnetized area length lambda l, and second magnetized area has short magnetized area length lambda s, then the length in the skirt section on the resistance mountain peak of SVGMR element is w, and the peak value length on resistance mountain peak is almost λ l-w or λ s-w.
The peak value length on the resistance mountain peak of SVGMR element is that λ l-w or λ s-w are by the magnetization decision of the fixed magnetization layer of the SVGMR element identical with the direction of magnetization of second magnetized area or first magnetized area.Yet,, should be appreciated that the peak value length on resistance mountain peak can be λ l-w and λ s-w because first magnetized area or second magnetized area can replace mutually.Here, because hypothesis λ l〉λ s, if the magnetized area length lambda s of weak point is less than w, then the SVGMR element can not can not be maximum/minimum value to this short magnetized area and resistance by complete face.Thereby the width w of SVGMR element must equal or be shorter than this short magnetized area length lambda s.
In magnetized encoder according to the present invention, the expectation magnetic sensor has the first sensor and second sensor along medium bearing of trend each interval λ (1/2+n), and wherein n is 0 or positive integer.Each of first and second sensors is made up of same even number SVGMR element, and described SVGMR element is electrically connected in series, and along medium bearing of trend and another SVGMR element spacing λ.The electric terminal of first sensor promptly forms an electric terminal that is electrically connected to second sensor in the open electric terminal of even number SVGMR element of first sensor, promptly forms in the open electric terminal of even number SVGMR element of second sensor.Another terminal at first sensor, promptly form another terminal of another and second sensor in the open electric terminal of even number SVGMR element of first sensor, promptly form between in the open electric terminal of even number SVGMR element of second sensor another and apply measuring voltage.Take out signal output from the electric terminal that connects between the first sensor and second sensor.
In magnetic encoder of the present invention, because the first sensor and second sensor are along medium bearing of trend each interval distance lambda (1/2+n), by the length lambda that is defined as (λ l+ λ s)/2 with comprise that 0 positive integer n expresses, the resistance view of the resistance view of first sensor and second sensor differs 1/2 λ on phase place.The mid point electromotive force that takes out between the first sensor and second sensor is exported as signal, can obtain bridge-type output.
In magnetic encoder of the present invention, the long magnetized area length lambda l of expectation is equal to or greater than λ+w, and short magnetized area length lambda s is equal to or less than λ-w.
When magnetized area length lambda l long in magnetic encoder was equal to or greater than λ+w, it caused λ l-λ-w 〉=0.By way of parenthesis, if the resistance mountain peak of SVGMR element appears at the position towards longer magnetized area, then advance or the SVGMR element that retreats λ has the resistance mountain peak in the position of advancing from above-mentioned resistance mountain peak or retreat λ from above-mentioned SVGMR element.Because the peak value length on the resistance mountain peak of SVGMR element is almost λ l-w, then two of the resistance mountain peak adjacent peak values are overlapped on the length of λ l-λ-w almost.This value is 0 or on the occasion of meaning that two adjacent peak values are overlapped.And when a plurality of SVGMR elements were connected in series in each sensor, the maximal value of resistance summation and the difference between the minimum value can become bigger.
On the contrary, when the resistance mountain peak of SVGMR element appears at position towards shorter magnetic regions, advance or the SVGMR element that retreats λ has the resistance mountain peak in the position of advancing from the resistance mountain peak of above-mentioned SVGMR element or retreat λ from above-mentioned SVGMR element.Length from the skirt section on the resistance mountain peak of each SVGMR element to another skirt section is λ s+w.Because shorter magnetized area length lambda s is equal to or less than λ-w, the length lambda s+w from the skirt section on the resistance mountain peak of SVGMR element to another skirt section is included in the length lambda.This means that the skirt section of two adjacent peak values is not overlapped.Thereby when a plurality of SVGMR element connected in series in each sensor connected, the maximal value of resistance summation and the difference between the minimum value can become bigger.
By way of parenthesis, λ+w and the λ s≤λ-w of two condition λ l are shown in the above, but these mean identical thing.Because 2 λ=λ l+ λ s is from the definition of λ, it by first formula of substitution with cancellation λ l and form second formula.
In magnetic encoder of the present invention, the SVGMR element of best second sensor is between two adjacent S VGMR elements of first sensor.Because first and second sensors are made up of identical even number SVGMR element, the apart λ of described SVGMR element, the dispersion of distribution of the SVGMR element in each sensor is λ (number of SVGMR element-1).Can the dispersion of distribution of all SVGMR elements that are included in first and second sensors be narrowed down by between two adjacent S VGMR elements of first sensor, placing the SVGMR element of one second sensor.
In addition, in magnetic encoder of the present invention, each of best first and second sensors is by forming more than four SVGMR elements.When each of first and second sensors was made up of four SVGMR elements, each of first and second sensors can detect the magnetic field that produces from two the first/the second continuous magnetized areas simultaneously.And (n: positive integer), each of first and second sensors can detect the magnetic field that produces from n the first/the second continuous magnetized area simultaneously when each of first and second sensors is made up of 2n SVGMR element.Because each of first and second sensors can detect the magnetic field from n the first/the second continuous magnetized area simultaneously, produce from the output of first and second sensors average magnetic field, make that can compensate n length or the magnetic intensity in the first/the second continuous magnetized area changes by n the first/the second magnetized area.As a result, the shake in the signal output can be reduced.
Although each of first and second sensors preferably comprises more SVGMR element to reduce shake, each of best first and second sensors has maximum six SVGMR elements, because if sensor comprises too much SVGMR element, the width of sensor will be wide.
According to the present invention, coming performance period by the magnetic encoder with SVGMR element is the electric signal of λ, and λ is the average length of each magnetized area.And, owing to used the SVGMR element of big resistance, realized the still less magnetic sensor of electric power consumption.In addition, in less relatively field region, obtain big magnetoresistance rate of change, and realized to obtain to resist the magnetic encoder of the stable output attribute (gap attribute) that the gap between magnetic sensor and the magnetic medium changes.
Description of drawings
Fig. 1 is according to the present invention, uses the perspective diagram of the magnetic encoder of SVGMR element;
Fig. 2 is for explaining the synoptic diagram of the SVGMR element that is used for the present invention;
Fig. 3 A and 3B are for explaining resistance R and being applied to the figure that concerns between the external magnetic field H of SVGMR element, Fig. 3 C is for the explanation resistance R and be applied to the figure that concerns between the external magnetic field H of coupling GMR element, and Fig. 3 D is for explaining resistance R and being applied to the figure that concerns between the external magnetic field H of AMR element;
Fig. 4 A is the explanation view of 26S Proteasome Structure and Function of magnetic encoder with example of the present invention 2 of magnetic medium, wherein, the first magnetized area length is longer than the second magnetized area length, Fig. 4 B has shown the resistance of the SVGMR element in the explanation first sensor and the figure of the relation between the position on the magnetic medium, Fig. 4 C has shown the resistance of another SVGMR element in the explanation first sensor and the figure of the relation between the position on the magnetic medium, Fig. 4 D has shown the resistance of explanation first sensor and the figure of the relation between the position on the magnetic medium, Fig. 4 E has shown the resistance of explaining second sensor and the figure of the relation between the position on the magnetic medium, Fig. 4 F is the figure of mid point electromotive force output between explanation first and second sensors and the relation between the position on the magnetic medium, and Fig. 4 G has shown the figure in the overlapping skirt section of the resistance of explaining two SVGMR elements;
Fig. 5 is for showing the figure of the connection of SVGMR element in the example 2 by equivalent electrical circuit;
Fig. 6 A is the explanation view of 26S Proteasome Structure and Function of magnetic encoder with example of the present invention 3 of magnetic medium, wherein first magnetized area is shorter in length than the second magnetized area length, Fig. 6 B has shown the resistance of the SVGMR element in the explanation first sensor and the figure of the relation between the position on the magnetic medium, Fig. 6 C has shown the resistance of another SVGMR element in the explanation first sensor and the figure of the relation between the position on the magnetic medium, Fig. 6 D has shown the resistance of explanation first sensor and the figure of the relation between the position on the magnetic medium, Fig. 6 E has shown the resistance of explaining second sensor and the figure of the relation between the position on the magnetic medium, and Fig. 6 F is for explaining the mid point electromotive force output between first and second sensors and the figure of the relation between the position on the magnetic medium;
Fig. 7 A is the explanation view according to the 26S Proteasome Structure and Function of the magnetic encoder of the example of the present invention 4 with magnetic sensor, wherein, the one SVGMR element of second sensor is arranged between the SVGMR element and the 2nd SVGMR element of first sensor, Fig. 7 B has shown the resistance of the SVGMR element in the explanation first sensor and the figure of the relation between the position on the magnetic medium, Fig. 7 C has shown the resistance of another SVGMR element in the explanation first sensor and the figure of the relation between the position on the magnetic medium, Fig. 7 D has shown the resistance of explanation first sensor and the figure of the relation between the position on the magnetic medium, Fig. 7 E has shown the resistance of explaining second sensor and the figure of the relation between the position on the magnetic medium, and Fig. 7 F is for explaining the mid point electromotive force output between first and second sensors and the figure of the relation between the position on the magnetic medium;
Fig. 8 is presented in the magnetic encoder that has the SVGMR element according to the present invention and in the compared magnetic encoder with coupling GMR element, the figure of the relation (gap attribute) between magnetic sensor output and the gap length;
Fig. 9 is the explanation view of the structure of the magnetic encoder that shows the example 6 that has magnetic sensor according to the present invention, and for first and second sensors each, magnetic sensor is made up of four SVGMR elements;
Figure 10 is for showing the figure of the connection of the SVGMR element in the example 6 by equivalent electrical circuit;
Figure 11 A is the explanation view according to the 26S Proteasome Structure and Function of the magnetic encoder of the example of the present invention 7 with magnetic sensor, wherein, each of first and second sensors of magnetic sensor is made up of four SVGMR elements, and wherein, the one SVGMR element of second sensor is arranged between the SVGMR element and the 2nd SVGMR element of first sensor, Figure 11 B has shown the resistance of the SVGMR element in the explanation first sensor and the figure of the relation between the position on the magnetic medium, Figure 11 C has shown the resistance of another SVGMR element in the explanation first sensor and the figure of the relation between the position on the magnetic medium, Figure 11 D has shown the resistance of explanation first sensor and the figure of the relation between the position on the magnetic medium, Figure 11 E has shown the resistance of explaining second sensor and the figure of the relation between the position on the magnetic medium, and Figure 11 F is for explaining the mid point electromotive force output between first and second sensors and the figure of the relation between the position on the magnetic medium.
Embodiment
With reference to accompanying drawing, will be described in detail below according to the magnetic encoder of example of the present invention.In order to understand conveniently, identical number designation will be used to identical part and identical position.Example will be illustrated, use rotary valve type magnetoresistance effect film to be used for the SVGMR element, wherein when the external magnetic field is not applied to, the magnetization of free magnetization layer is opposite with the magnetization of fixed magnetization layer and resistance is very high, and when the external magnetic field is applied to the SVGMR element with the direction identical with the magnetization of the fixed magnetization layer of SVGMR element, the resistance of SVGMR element reduces, and when opposite external magnetic field was applied to the SVGMR element, the resistance of SVGMR element did not change.When the direction of magnetization of the magnetization of free magnetization layer and fixed magnetization layer is identical, the resistance minimum of SVGMR element, yet, when the magnetization of free magnetization layer is opposite, magnetoresistance does not occur and change, and the resistance minimum of SVGMR element.
Example 1
Fig. 1 has shown the perspective diagram of explaining the magnetic encoder with SVGMR element.Magnetic encoder 1 is made up of magnetic medium 2 and magnetic sensor 6.On magnetic medium 2, magnetized two magnetized areas opposite each other, promptly first magnetized area 21 and second magnetized area 22 are arranged continuously and alternately along the bearing of trend of medium.In the following explanation, suppose that the length lambda l of first magnetized area 21 is longer than the length lambda s of second magnetized area 22.In magnetic sensor 6, on base material 4 with in the vertically extending rectangle plane of the bearing of trend of magnetic medium 2, form a plurality of SVGMR elements 5, and the end of SVGMR element 5 is connected to flexible print circuit 3 by the lead (not shown).Magnetic medium 2 by predetermined gap towards SVGMR element 5 with rectangle plane.When magnetic sensor when magnetic medium moves, the magnetic field that is applied to the SVGMR element changes, and the resistance variations of SVGMR element.In the following description, suppose magnetic medium be fix and magnetic sensor move.
In Fig. 2, SVGMR element 5 is shown in the diagram.In the manufacturing of SVGMR element 5, after fixed magnetization layer 10, non-magnetic conductive layer 11 and free magnetization layer 12 are layered on the base material 4 in order, make Etching mask, and form rectangular element by ion beam milling by photoetching.As for base material 4, having used thermal expansivity a is 38 * 10
-7Deg.
-1Aluminosilicate (aluminosilicate) glass.Fixed magnetization layer 10 has at 12nm thickness Mn
50Pt
505nm thickness C o on (atom %) inverse ferric magnetosphere
90Fe
10(atom %) forms.Non-magnetic conductive layer 11 for copper and thickness be 3nm.Free magnetization layer 12 is a two membranes, Ni
85Fe
15Layer and Co
90Fe
10Layer and gross thickness are 5nm.Ni
85Fe
15Layer and Co
90Fe
10The thickness of layer is than being 3:1 to 5:1.Fixed magnetization layer 10 in the magnetic field that is about 240A/m (about 30 Oe) by sputter (sputter) with fixed magnetization.NiFe layer in the free magnetization layer in magnetic field by sputter, so that its magnetic anisotropy and strengthen the magnetic attribute.
Form Etching mask on the rotary valve type giant magnetoresistive effect rete of making by photoetching technique on base material 4 after, SVGMR element 5 forms target shape by the ion beam milling of argon ion.The SVGMR element has the shape that is almost rectangle.In Fig. 2, the width of rectangle SVGMR element is shown as w and length is shown as L.Length L is treated to the width of being longer than magnetic medium, and the SVGMR element is electrically connected in series outside the magnetic medium width.By making this rotary valve type giant magnetoresistive effect film zig zag, element is connected.Do not connect because the external magnetic field is applied to element, they do not demonstrate magnetoresistance and change.
The direction of magnetization of fixed magnetization layer 10 uses solid arrow 13 to show, and is applied to the external magnetic-field direction dash-dot arrows 14 and dotted arrow 15 demonstrations of free magnetization layer 12.Because identical with the direction of magnetization of fixed magnetization layer in the external magnetic field that dash-dot arrows 14 applies, the resistance of SVGMR element 5 reduces according to the increase of external magnetic field.When applying the external magnetic field by dotted arrow 15, magnetic field is opposite with the direction of magnetization of fixed magnetization layer, and the resistance of SVGMR element 5 is constant.Fig. 3 has shown the relation between resistance R and the external magnetic field H.Fig. 3 A is the resistance variations when the external magnetic field is applied to the SVGMR element.The resistance of SVGMR element is not R1 when applying magnetic field, and works as in positive dirction, and when promptly identical with the direction of magnetization of fixed magnetization layer direction applied magnetic field, resistance reduced and is saturated at the R2 place.Even, when promptly opposite with the direction of magnetization of fixed magnetization layer direction applies magnetic field, magnetoresistance does not take place change, and resistance is maintained R1 when in negative direction.Be called as the magnetoresistance rate of change by the value that formula (R1-R2)/R1 * 100 (%) obtains.Fig. 3 B has shown the relation between magnetoresistance variation and the external magnetic field, used the SVGMR element, wherein when applying magnetic field on the direction identical with the magnetization of fixed magnetization layer, the resistance of element does not change, and changes when applying magnetic field on the direction opposite with the magnetization of fixed magnetization layer.When the direction of magnetization of the magnetization of free magnetization layer and fixed magnetization layer is identical, the resistance minimum of SVGMR element, and when it is opposite, magnetoresistance does not take place change, and the resistance maximum of SVGMR element.In order to compare, the resistance and the relation between the external magnetic field of coupling GMR (giant magnetoresistive effect) element and AMR (anisotropic magnetoresistance effect) element are presented at respectively among Fig. 3 C and Fig. 3 D.In coupling GMR element and AMR element, different with the SVGMR element, magnetoresistance changes externally magnetic field increase and reduces all to take place on two kinds of directions.Magnetic field increases and reduces to take place on two kinds of directions because magnetoresistance changes in such a way externally, and the electric signal that obtains has and unit magnetized area length lambda, i.e. the identical cycle of magnetization length of magnetic medium.The initial resistance R3 (not applying magnetic field) of coupling GMR element is about 322 Ω, and the initial resistance R1 of SVGMR element is about 1560 Ω, is about five times of initial resistance of coupling GMR element.Resistance R 3 and R1 are that element width w is that 5 μ m and leement duration L are the example of the element of 1000 μ m.The difference of initial resistance becomes the difference of electric power consumption in the magnetic sensor.Initial resistance is big more, and the electric power consumption in the magnetic sensor is more little.
Example 2
With reference to Fig. 4, wherein the first magnetized area length lambda l is longer than the second magnetized area length lambda s on magnetic medium 2, and the work of magnetic encoder will be illustrated.Fig. 4 A has illustrated the SVGMR element 51a to 52b of magnetic sensor 6 and the relation of the position between the magnetic medium 2, and Fig. 4 B to 4F has shown resistance and the electric signal figure with respect to SVGMR element 51a to 52b position on the magnetic medium 2.The resistance view of another SVGMR element 51b of the SVGMR element 51a of first sensor 51, first sensor 51, the first sensor of being made up of SVGMR element 51a and 51b 51, second sensor 52 be made up of SVGMR element 52a and 52b is presented at respectively among Fig. 4 B, 4C, 4D and the 4E.In magnetic sensor 6, four SVGMR element 51a to 52b are arranged on the base material.Each SVGMR element has cell width w, and the SVGMR element mutual distance λ in each sensor.Second sensor 52 is shifted by lambda/2 after first sensor 51.Be added in the magnetization of the fixed magnetization layer among the arrow presentation graphs 4A on each SVGMR element.In magnetic medium 2, first magnetized area 21 and second magnetized area 22 be reversal magnetization mutually, and the length of first magnetized area 21 is longer than the length of second magnetized area 22.The length of first magnetized area shows with λ l, and the length of second magnetized area shows with λ s.The total length of λ l and λ s equals the twice of the distance lambda between the SVGMR element in each magnetic sensor.The leakage field direction with dashed lines arrow that is caused by each magnetized area shows, the two ends of each of first and second magnetic regions 21,22 of connection magnetic medium.
Fig. 5 has shown the connection of SVGMR element 51a to 52b in equivalent electrical circuit.SVGMR element 51a and 51b in first magnetic sensor 51 are connected in series, and same, SVGMR element 52a and 52b in second magnetic sensor 52 are connected in series.The end of the SVGMR element 51b of first magnetic sensor is connected to the end of the SVGMR element 52a of second magnetic sensor, and the terminals that should link to each other are connected to output terminal to take out mid point electromotive force Vout.The other end of the SVGMR element 51a of first magnetic sensor 51 is connected to power Vcc, and the other end ground connection of the SVGMR element 52b of second sensor 52.
When moving magnetic sensor 6 with the direction of arrow among Fig. 4 A, SVGMR element 51a and 51b receive leakage field from magnetic medium, and the resistance of SVGMR element 51a changes shown in Fig. 4 B, and the resistance of SVGMR element 51b changes shown in Fig. 4 C.The maximal value of resistance is set to R1, and the minimum value of resistance is set to R2.Fig. 4 D has shown the resistance that mixes, and it equals the SVGMR element 51a of first sensor 51 and the resistance of 51b.Though the resistance cycle of each of SVGMR element 51a among Fig. 4 B and the SVGMR element 51b among Fig. 4 C is 2 λ, the hybrid resistor of SVGMR element 51a and 51b (seeing Fig. 4 D) has maximum resistance change R1-R2 and cycle λ, because element mutual distance λ places.The hybrid resistor of second sensor 52 is displayed among Fig. 4 E equally.In Fig. 4 E, phase place shifts to an earlier date λ/2 than Fig. 4 D, mid point electromotive force Vout, i.e. and the output of magnetic sensor 6 is the electric signal with center voltage amplitude Vcc/2 and cycle λ.Owing to output amplitude along with the bigger difference between R1 and the R2 becomes bigger, when use as the SVGMR element have the element of bigger resistance variations the time, output can be bigger.Use configuration as the SVGMR element among the present invention, wherein the SVGMR element distances in each of first and second sensors is λ, promptly the first magnetized area length lambda l and the second magnetized area length lambda s's is average, and wherein the distance between first and second sensors is λ/2, be half of SVGMR element distances, then realized high-resolution magnetic encoder, this can not only obtain by replacing traditional element with the SVGMR element.
Very clear from Fig. 4 B, the resistance variations zone is almost identical with SVGMR element width w.In the figure, the SVGMR component resistance has length lambda s+w greater than the scope of R2, promptly the second magnetized area length lambda s add SVGMR element width w and.When SVGMR element width w increased, resistance mountain peak width was broadened, and the skirt section on the resistance mountain peak of the skirt section on the resistance mountain peak of SVGMR element 51a and SVGMR element 51b is overlapping, as shown in Fig. 4 G.When the skirt section on resistance mountain peak was overlapped, the minimum value of resistance became the R2 ' greater than R2.Because this, the resistance variations of each the SVGMR element never R1-R2 under the overlapping situation in skirt section becomes R1-R2 ', with the amplitude of the output Vout that reduces to show among Fig. 4 F.
When first and second magnetized areas had equal length, the overlapping of skirt section, mountain peak will inevitably have a resistance.Therefore, the length of first magnetized area must be different with the length of second magnetized area.In this example, the resistance mountain peak width of lambda s+w of the resistance mountain peak width of lambda s+w of SVGMR element 51a and SVGMR element 51b is comprised among total length 2 λ of the first magnetized area length lambda l and the second magnetized area length lambda s.When the first magnetized area length is longer than the second magnetized area length, overlapping the reducing in the skirt section, resistance mountain peak of the skirt section, resistance mountain peak of SVGMR element 51a and SVGMR element 51b, and further when λ l+ λ s (=2 λ) 〉=2 (λ s+w), the skirt section, resistance mountain peak of the skirt section, resistance mountain peak of SVGMR element 51a and SVGMR element 51b is not overlapping.
Example 3
With reference to Fig. 6 A to 6F, the magnetic encoder of example 3 will be illustrated, and will be similar to the magnetic encoder of example 2 in being presented at Fig. 4 A, have the first area length that is shorter than the second magnetized area length except magnetic medium 2.Fig. 6 A has illustrated the SVGMR element 51a to 52b of magnetic sensor 6 and the relation of the position between the magnetic medium 2, and Fig. 6 B to 6F has shown resistance and the electric signal figure with respect to SVGMR element 51a to 52b position on the magnetic medium 2.The resistance view of another SVGMR element 51b of the SVGMR element 51a of first sensor 51, first sensor 51, the first sensor of being made up of SVGMR element 51a and 51b 51, second sensor 52 be made up of SVGMR element 52a and 52b is presented at respectively among Fig. 6 B, 6C, 6D and the 6E.In magnetic sensor 6, four SVGMR element 51a to 52b are arranged on the base material.Each SVGMR element in each sensor has cell width w, and each the SVGMR element mutual distance λ in each first and second magnetization sensor.Second sensor 52 is shifted by lambda/2 after first sensor 51.Be added in the magnetization of the fixed magnetization layer among the arrow presentation graphs 6A on each SVGMR element.In magnetic medium 2, first magnetized area 21 and second magnetized area 22 are by reversal magnetization mutually, and the length that is shorter in length than second magnetized area 22 of first magnetized area 21.The length of first magnetized area shows with λ s, and the length of second magnetized area shows with λ l.The total length of λ s and λ l equals the twice of the distance lambda between the SVGMR element in each magnetic sensor.The direction with dashed lines arrow of the leakage field that is caused by each magnetized area shows, it connects each two ends of first and second magnetic regions 21,22 of magnetic medium 2.
When magnetic sensor 6 moved with the direction of arrow among Fig. 6 A, SVGMR element 51a and 51b received leakage field from magnetic medium, and SVGMR element 51a changes resistance as shown in Fig. 6 B, and SVGMR element 51b changes resistance as shown in Fig. 6 C.The maximal value of resistance is set to R1, and the minimum value of resistance is set to R2.Fig. 6 D has shown the resistance that mixes, and it equals the SVGMR element 51a of first sensor 51 and the resistance of 51b.Although the resistance cycle of each of the SVGMR element 51b among the SVGMR element 51a among Fig. 6 B and Fig. 6 C is 2 λ, the hybrid resistor of SVGMR element 51a and 51b (seeing Fig. 6 D) has maximum resistance change R1-R2 and cycle λ, because element mutual distance λ places.The hybrid resistor of second sensor 52 is displayed among Fig. 6 E equally.In Fig. 6 E, phase place shifts to an earlier date λ/2 than Fig. 6 D, mid point electromotive force Vout, i.e. and the output of magnetic sensor 6 is the electric signal with center voltage amplitude Vcc/2 and cycle λ, as shown in Fig. 6 F.Use the configuration of SVGMR element described above, realized high-resolution magnetic encoder, this can not obtain by only replacing traditional element with the SVGMR element.
Example 4
The magnetic encoder that comprises magnetic medium 2 and magnetic sensor 6 will be illustrated with reference to Fig. 7 as example 4, in magnetic medium 2, the length of first magnetized area 21 is longer than the length of second magnetized area 22, and described magnetic sensor 6 has a SVGMR element 52a of second sensor in a SVGMR element 51a of first sensor and the structure between the 2nd SVGMR element 51b.The length of first magnetized area shows with λ l, and the length of second magnetized area shows with λ s.As shown in Figure 7A, the SVGMR element distances of each in first and second sensors is λ, promptly the first magnetized area length lambda l and the second magnetized area length lambda s's is average, and a SVGMR element 52a of second sensor is apart from SVGMR element 51a shifted by lambda/2 of first sensor.The one SVGMR element 52a shifted by lambda/2 of the 2nd SVGMR element 51b distance second sensor of first sensor.And the width of each SVGMR element is w.When magnetic sensor 6 moved with the direction of arrow, SVGMR element 51a and 51b received leakage field from magnetic medium, and the resistance among SVGMR element 51a and the 51b changes as shown in Fig. 7 B and 7C respectively.The maximal value of resistance is set to R1, and the minimum value of resistance is set to R2.Shown the resistance that SVGMR element 51a and 51b mix among Fig. 7 D, it equals the resistance of first sensor.Though the SVGMR element 51a that shows among Fig. 7 B and Fig. 7 C and each resistance of 51b have cycles 2 λ, the hybrid resistor of SVGMR element 51a and 51b has maximum resistance change R1-R2 and cycle λ (seeing Fig. 7 D), because element mutual distance λ places.The hybrid resistor of second sensor is presented among Fig. 7 E equally.In Fig. 7 E, phase place shifts to an earlier date λ/2 than Fig. 7 D, and mid point electromotive force Vout is that the output of magnetic sensor 6 is the electric signal with center voltage amplitude Vcc/2 and cycle λ.
Since in this example 4 with example 2 in the same first magnetized area length be longer than the second magnetized area length, the same variation in the resistance of SVGMR element 51a to 52b and mid point electromotive force and the example 2, and obtained high-resolution magnetic encoder.In Fig. 7 A, the element distribution length from the SVGMR element 51a of front to the SVGMR element 52b of end is { λ+(λ/2)+w}.As a comparison, in the magnetic sensor after second sensor is arranged on first sensor as shown in example 2, SVGMR element distribution length is { λ+(λ/2)+λ+w}.The magnetic sensor width can become littler and more cheap by the configuration of example 4, because can produce more magnetic sensor from wafer.Equally, realized miniaturization.
Example 5
Figure 8 illustrates gap attribute according to magnetic encoder of the present invention.By change the gap magnetic medium and the magnetic sensor at interval from 0 μ m to 25 μ m with 5 μ m, measure the relation of magnetic sensor output, i.e. the gap attribute with respect to gap length.To use in the example 2 and 3 similar, here in the magnetic sensor of Shi Yonging, second sensor is in first sensor shifted by lambda/2 afterwards.Distance lambda between the SVGMR element in each sensor is 20 μ m, and the width w of SVGMR element is 5 μ m.In magnetic medium, the first magnetized area length and the second magnetized area length sum, 2 λ are 40 μ m.The magnetic of the magnetic material that uses in the magnetic medium is coercivity H: 217kA/m, residual inductance Br:1.4T and verticality R:0.8.Be longer than the second magnetized area length in 1: the first magnetized area length of condition, 2: the first magnetized area length of condition equals the second magnetized area length, and 3: the first magnetized areas of condition are shorter in length than under the second magnetized area length and finish measurement.As a comparison, measure the gap attribute of relevant coupling GMR sensor.In coupling GMR sensor, the first magnetized area length equals the second magnetized area length.
Assess the gap attribute by providing greater than the gap length scope of 80% output of maximum output.The Z-axis of Fig. 8 has shown exports the ratio of exporting with the maximum that is set to 1 under each condition.From Fig. 8 obviously, use the gap length scope of the sensor of SVGMR element to compare wideer with coupling GMR sensor under all conditions.In coupling GMR sensor, when the gap became big, magnetic sensor output sharply reduced, and provided little of 0 μ m to 1.8 μ m more than the gap length scope of 80% output.In the sensor of SVGMR element, the gap length scope of condition 1 is 0 μ m to 10.1 μ m, and the gap length scope of condition 2 is 7.9 μ m to 13.8 μ m, and the gap length scope of condition 3 is 0 μ m to 13.8 μ m.Under all conditions, obtained than the big five times gap length scope of coupling GMR sensor.By changing the length of first and second magnetized areas, obtain bigger magnetization sensor output, and obtained than the big five times gap length scope of coupling GMR sensor.The fact of the bigger gap length scope of such acquisition has supported the SVGMR element to work in little magnetic field.
Example 6
The magnetic encoder that comprises magnetic medium 2 and magnetic sensor 6 will be illustrated with reference to Fig. 9 as example 6, in magnetic medium 2, the length of being longer than second magnetized area with the length of the same first magnetized area in the example 2, and in magnetic sensor 6, each of the first sensor 51 and second sensor 52 has four SVGMR elements.First sensor 51 is made up of SVGMR element 51a to 51d, and second sensor 52 is made up of SVGMR element 52a to 52d.The distance of the SVGMR element of each in first and second sensors is set to λ, promptly the first magnetized area length and the second magnetized area length is average, and a SVGMR element 52a of second sensor is arranged on the 4th SVGMR element 51d distance lambda/2 with first sensor.Identical with example 2 among Fig. 4 towards a part of magnetic medium of SVGMR element 51c to 52b among Fig. 9, its job description is omitted.Can reduce shake by the number that increases SVGMR element in first and second sensors 51,52, i.e. phase shift.First magnetized area 211 to 214 of magnetic medium 2 and each length lambda l, the λ s of second magnetized area 221 to 224 are numbered as λ l1 to λ l4 and λ s1 to λ s4 in Fig. 9.If λ l1 to λ l4 is equal fully, and if λ s1 to λ s4 equal fully, then can not shake.But, when length not simultaneously, shake takes place in the electric signal that produces and cause reducing accuracy of detection.Can compensate the length variations of the magnetized area in the magnetic medium by the number that increases the SVGMR element, and shake can be reduced.Shake in the example 6 is compared with example 2 and has been improved 1% to 1.5%.
Figure 10 has shown the connection of SVGMR element 51a to 52d in the equivalent electrical circuit.SVGMR element 51a to 51d in first magnetic sensor 51 is connected in series, and similarly, the SVGMR element 52a to 52d in second magnetic sensor 52 is connected in series.The end of the SVGMR element 51d of first magnetic sensor 51 is connected to the end of the SVGMR element 52a of second magnetic sensor 52, and the end that should link to each other is connected to output terminal to take out the mid point electromotive force.The other end of the SVGMR element 51a of first magnetic sensor 51 is connected to power Vcc, and the other end ground connection of the SVGMR element 52b of second sensor 52.
Example 7
Example 7 is a kind of magnetic encoder, has magnetic sensor, described magnetic sensor have with example 6 in the SVGMR element 51a to 52d of similar number, and a SVGMR element 52a of second sensor is arranged between the SVGMR element 51a and the 2nd SVGMR element 51b of first sensor.The 26S Proteasome Structure and Function of this magnetic sensor illustrates with reference to Figure 11.Because a SVGMR element 52a of second sensor is arranged between the SVGMR element 51a and the 2nd SVGMR element 51b of first sensor, and SVGMR element 51a distance lambda/2 with first sensor, the distribution length of SVGMR element 51a to 52d becomes and is about in the example 6 half, and has realized the miniaturization of magnetic sensor.In this example, the length of the length of first magnetized area 21 of magnetic medium and second magnetized area 22 on average also is set as λ.Because the first magnetized area length is longer than the second magnetized area length, the first magnetized area length shows with λ l, and the second magnetized area length shows with λ s.The connection of SVGMR element 51a to 52d is with the same shown in Figure 10.When magnetic sensor 6 moves with the direction of the arrow among Figure 11 A, the SVGMR element 51a to 51d of first sensor receives leakage field from magnetic medium 2, SVGMR element 51a and 51c change resistance as shown in Figure 11 B, and SVGMR element 51b and 51d change resistance as shown in Figure 11 C.SVGMR element 52a and 52c shift to an earlier date λ/2 than Figure 11 B, and SVGMR element 52b and 52d shift to an earlier date λ/2 than Figure 11 C.The maximal value of resistance is set to R1, and the minimum value of resistance is set to R2.Figure 11 D has shown the hybrid resistor of SVGMR element 51a to 51d, and it equals the resistance of first sensor.Although each resistance cycle of 51b among SVGMR element 51a among Figure 11 B and 51c and Figure 11 C and 51d is 2 λ, the hybrid resistor of SVGMR element 51a to 51d has maximum resistance variations R1-R2 and cycle λ, because they are placed with element distances λ.Similarly, the hybrid resistor of second sensor has the cycle λ as shown in Figure 11 E, and the phase differential of λ/2 is arranged than the hybrid resistor shown in Figure 11 D.Mid point electromotive force Vout, i.e. the output of magnetic sensor 6 is the electric signal with cycle λ, as shown in Figure 11 F.In the magnetic encoder of this example, have four SVGMR elements in each first and second sensor, shake is compared with the magnetic encoder of example 4 and has been improved 1% to 1.5%, in example 4, the one SVGMR element of second sensor is arranged between the first and second SVGMR elements of first sensor, and has two SVGMR elements in each first and second sensor.
Claims (10)
1. magnetic encoder comprises:
Magnetic medium, extend in one direction and have first magnetized area and second magnetized area, described first magnetized area and second magnetized area also alternately are arranged on the described medium each other continuously, and reciprocally magnetized and had the length that differs from one another along described medium bearing of trend, wherein long magnetized area has length lambda l, and short magnetized area has length lambda s; And
Magnetic sensor, has even number SVGMR element and removable with respect to described medium along described medium bearing of trend, described SVGMR element have with the vertically extending square surface of described medium bearing of trend and with predetermined gap towards described medium, wherein, in the described even number SVGMR element each is along the length lambda of described medium bearing of trend each interval by (λ l+ λ s)/2 definition
Wherein, each of described SVGMR element is a fixed magnetization layer, non-magnetic conductive layer and free magnetization layer are stacked by this order, fixed magnetization layer in all described SVGMR elements has along the magnetization on the equidirectional of described medium bearing of trend, and when on the direction identical, applying the external magnetic field to the SVGMR element with the magnetization of the fixed magnetization layer of described SVGMR element, described SVGMR element presents minimum resistance, and when on the direction opposite, applying the external magnetic field to described SVGMR element with the magnetization of the fixed magnetization layer of described SVGMR element, described SVGMR element presents maximum resistance, and
Wherein, described even number SVGMR element is electrically connected in series, and takes out signal output from the electric terminal of the SVGMR element of described electrical connection.
2. magnetic encoder as claimed in claim 1, wherein, each of described SVGMR element is equal to or less than λ s along the width w of described medium bearing of trend.
3. magnetic encoder as claimed in claim 1, wherein, described magnetic sensor has along the first sensor of described medium bearing of trend each interval λ (1/2+n) and second sensor,
Wherein, n is 0 or positive integer,
Wherein, each of described first and second sensors is made up of same even number SVGMR element, and described SVGMR element connected in series is electrically connected and along described medium bearing of trend each interval λ, and
Wherein, an electric terminal of described first sensor is electrically connected to an electric terminal of described second sensor, and be applied in measuring voltage between another terminal of another terminal of described first sensor and described second sensor during, take out signal output from the described continuous electric terminal between described first sensor and described second sensor.
4. magnetic encoder as claimed in claim 2, wherein, described magnetic encoder has along the first sensor of described medium bearing of trend each interval λ (1/2+n) and second sensor,
Wherein, n is 0 or positive integer,
Wherein, described first and described second sensor in each form by same even number SVGMR element, described SVGMR element is electrically connected in series and along described medium bearing of trend each interval λ, and
Wherein, an electric terminal of described first sensor is electrically connected to an electric terminal of described second sensor, and be applied in measuring voltage between another terminal of another terminal of described first sensor and described second sensor during, take out signal output from the described continuous electric terminal between described first sensor and described second sensor.
5. magnetic encoder as claimed in claim 3, wherein, λ l is equal to or greater than λ+w, and λ s is equal to or less than λ-w.
6. magnetic encoder as claimed in claim 4, wherein, λ l is equal to or greater than λ+w, and λ s is equal to or less than λ-w.
7. magnetic encoder as claimed in claim 3, wherein, the SVGMR element of described second sensor is between two adjacent S VGMR elements of described first sensor.
8. magnetic encoder as claimed in claim 4, wherein, the SVGMR element of described second sensor is between two adjacent S VGMR elements of described first sensor.
9. magnetic encoder as claimed in claim 3, wherein, each of described first and second sensors has four or more SVGMR elements.
10. magnetic encoder as claimed in claim 4, wherein, each of described first and second sensors has four or more SVGMR elements.
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| US20110101964A1 (en) * | 2009-11-05 | 2011-05-05 | Udo Ausserlechner | Magnetic Encoder Element for Position Measurement |
| CN102192699A (en) * | 2010-03-12 | 2011-09-21 | 许耿祯 | Non-contact-type sensing device |
| TWI401423B (en) * | 2010-09-07 | 2013-07-11 | Geeng Jen Sheu | Contactless vibration meter |
| CN102410872B (en) * | 2010-09-25 | 2012-12-19 | 许耿祯 | Non-contact vibration sensor device |
| JP2015114138A (en) * | 2013-12-10 | 2015-06-22 | 日本電産サンキョー株式会社 | Magnetic sensor device, magnetic encoder device, and magnetic sensor |
| US9958294B2 (en) * | 2016-06-30 | 2018-05-01 | Mitutoyo Corporation | Absolute position encoder including scale with varying spatial characteristic and utilizing Fourier transform or other signal processing |
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| US5680042A (en) * | 1994-12-30 | 1997-10-21 | Lake Shore Cryotronics, Inc. | Magnetoresistive sensor with reduced output signal jitter |
| US6300758B1 (en) * | 1994-12-30 | 2001-10-09 | Northstar Technologies Inc. | Magnetoresistive sensor with reduced output signal jitter |
| US6629371B1 (en) * | 1999-10-22 | 2003-10-07 | Pentax Corporation | Surveying instrument incorporating a magnetic incremental rotary encoder |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5680042A (en) * | 1994-12-30 | 1997-10-21 | Lake Shore Cryotronics, Inc. | Magnetoresistive sensor with reduced output signal jitter |
| US6300758B1 (en) * | 1994-12-30 | 2001-10-09 | Northstar Technologies Inc. | Magnetoresistive sensor with reduced output signal jitter |
| US6629371B1 (en) * | 1999-10-22 | 2003-10-07 | Pentax Corporation | Surveying instrument incorporating a magnetic incremental rotary encoder |
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