Magnetoresistive sensor for measuring magnetic field

The technical field of

[0001] the invention claims a magnetic electric resistance sensor especially claims a method for measuring magnetic field of magnetic electric resistance sensor.

Background technology

[0002] magnetic sensor it can be widely used in modern system so as to measure or induction magnetic field intensity of the current position of the moving direction of the physical parameter such as. In existing technology has many different types of sensors for measuring magnetic field and the other parameters. But they can be in the present technique all kinds of public known the limitation of size such as the high sensitivity low dynamic range is narrow and the cost is high the reliability is low and the other factors. So that it is continuously improved magnetic sensor especially it is easy to be improved the semiconductor device and integrated circuit integrated with the sensor and its manufacturing method is that it is necessary to the.

[0003] tunnel junction magnetic electric resistance sensor with high sensitivity small size low cost and low power consumption etc. Although the mtj sensor is connected with the standard semiconductor manufacturing process and it is compatible but with high sensitivity mtj sensor and it does not achieve the low cost large scale production. Especially the sensor the rate of finished products is determined by the mtj element magnetic resistance output from the offset value to form electric bridge mtj of the magnetic resistance it is difficult to get the effect of high matching degree of the same time the alternating magnetic field sensor in the same semiconductor substrate is integrated on the manufacturing technique of it is very complex.

[0004] can be used for of the sensor is connected with the magnetic resistance element the response is comprised of sensing material which is composed of multilayer film the magnetization direction of the function of. In order to obtain magnetic induction is often needs to an external magnetic field to the torque to bias the working at a stable sensitivity of the working point is. The offset method is usually adopts the heating coil or the permanent magnet these designs the power consumption the cost and great scale production of the angle can not be seen from the.

The content of invention

[0005] aiming to problem mentioned above this invention claims a method for measuring magnetic field of magnetic electric resistance sensor which can realize mass production measuring magnetic field of the sensitivity higher and at the same time it has low power consumption small size.

[0006] this invention claims a method for measuring magnetic field of magnetic electric resistance sensor it comprises:

[0007] substrate said substrate has a x y the surface of said magnetic electric resistance sensor the sensitive axle is parallel to x y axis vertical to shaft on the y axis;

[0008] at least one inductive arm and said inductive arm is composed of the magnetic resistance element said magnetic resistance element is set on the substrate the x y on the surface of said magnetic resistance element along y-axis direction is larger than length of it along the x shaft direction the length of;

[0009] several are set on the magnetic electric resistance sensor the substrate on the strip permanent magnet of which the two adjacent to the strip permanent magnet is formed between the gap magnetic field the gap magnetic field having along the x axis and the y axis component;

[0010] bonding pad the bonding pad is set on the sensing arm the tail end of the can through the induction arm is electrically connected.

[0011] is preferably at least one of the magnetic resistance element is the gap magnetic field on the x axle direction saturated.

[0012] preferably said magnetic electric resistance sensor resistance value of the magnetic field along with the change of the response curve in said magnetic electric resistance sensor the work area is connected with high linearity high slope lambdamin and low magnetic hysteresis.

[0013] preferably the strip permanent magnet charged with magnetism can be adjusted the strip permanent magnet magnetization strength and direction can be adjusted said magnetic electric resistance sensor output performance of.

[0014] preferably said magnetic resistance element is the mtj elements or gmr element.

[0015] preferably the magnetic electric resistance sensor is bridge type magnetic field sensor.

[0016] preferably said bridge type magnetic field sensor is push-pull full bridge the magnetic field sensor.

[0017] preferably said push-pull full bridge magnetic field sensor comprises four induction arm on the magnetic electric resistance sensor the work area is set in the two arms of the magnetic sensing resistance value with outer field the change of the response curve corresponding to the other two arms of the magnetic sensing resistance value with outer field the change of the response curve at the same the outside of the field effect is opposite to the change trend of.

[0018] preferably said push-pull full bridge magnetic field sensor comprises two sensor chip each sensor chip comprises x y on the surface of the substrate and is set on the substrate on the surface of two induction arm wherein at least one sensor chip are correspondingly to the other sensor chip is rotated 180 degree and the two sensor chip by the same wafer is cut into.

[0019] preferably induction between the arm can be connected through arch i wire connection welding disks to realize electrical connection.

[0020] preferably said bridge type magnetic field sensor is taken as the reference full bridge the magnetic field sensor the reference full bridge the magnetic field sensor comprises sensing arm and reference arm of each reference arm is composed of the magnetic resistance element.

[0021] preferably said reference full bridge magnetic field sensor comprises two induction arms and two reference arm on the magnetic electric resistance sensor the working area of the arm in the induction of magnetic electric resistance value with the change of outer field responding curve slope of the absolute value is also far greater than the reference arm of the magnetic resistance value with the change of outer field responding curve slope of the absolute value.

[0022] preferably said reference full bridge the magnetic field sensor comprises a sensor chip the sensor on the chip comprises x y on the surface of the substrate and is set on the substrate is set on the surface of the structure of induction arm of the magnetic resistance element and forming reference arm of the magnetic resistance element.

[0023] is preferably composed of the reference arm of the magnetic resistance element along the x shaft direction is more than the length along the x axis direction of the length of the x shaft direction is more than the length of the said induction arm of the magnetic resistance element on the x axle direction the length of.

[0024] is preferably of the forming reference arm of the magnetic resistance element is covered on the surface of the a layer of high magnetic conductivity of the iron shielding layer magnetic.

[0025] is preferably set on the reference arm in the vicinity of the strip permanent magnet on the x axial direction of the components of the bigger than set on the sensor arm in the vicinity of the strip permanent magnet on the x axial direction of the components of the.

[0026] is preferably of the reference arm or induction arm of the magnetic resistance element is set with a layer or several layers of permanent magnet offset layer.

[0027] is preferably of the reference arm of the magnetic resistance element is set with a layer or several layers of exchange off-center layer.

[0028] preferably said bridge type magnetic field sensor is push-pull half bridge the magnetic field sensor the push-pull half bridge magnetic field sensor is composed of two induction shaft is a.

[0029] preferably said push and pull half bridge magnetic field sensor comprises two induction arm on the magnetic electric resistance sensor the working area of the inside of the one arm of the induction of magnetic electric resistance value with outer field the change of the response curve corresponding to the other arm of the induction of magnetic electric resistance value with the field of the change of the response curve at the same the outside of the field effect is opposite to the change trend of.

[0030] preferably said push-pull half bridge magnetic field sensor comprises two sensor chip each sensor chip comprises x y on the surface of the substrate and is set on the substrate is set on the surface of the induction arm wherein at least one sensor chip are correspondingly to the other sensor chip is rotated 180 degree and the two sensor chip by the same wafer is cut into.

[0031] preferably said push-pull half bridge the magnetic field sensor the sensing arm is connected through the wire lead bonding pad electrically connected to realize.

[0032] preferably the magnetic electric resistance sensor is taken as the reference half bridge the magnetic field sensor the reference half bridge the magnetic field sensor comprises sensing arm and reference arm of each reference arm is composed of the magnetic resistance element.

[0033] preferably said reference half bridge the magnetic field sensor comprises an induction arm and a reference arm on the magnetic electric resistance sensor the working area of the arm in the induction of magnetic electric resistance value with the change of outer field responding curve slope of the absolute value is also far greater than the reference arm of the magnetic resistance value with the change of outer field responding curve slope of the absolute value.

[0034] preferably said reference half bridge the magnetic field sensor comprises a sensor chip the sensor chip is comprised of x y on the surface of the substrate and is set on the substrate is set on the surface of the structure of induction arm of the magnetic resistance element and forming reference arm of the magnetic resistance element.

[0035] is preferably composed of the reference arm of the magnetic resistance element along the x shaft direction is more than the length along the x axis direction of the length of the x shaft direction is more than the length of the said induction arm of the magnetic resistance element on the x axle direction the length of.

[0036] is preferably of the forming reference arm of the magnetic resistance element is covered on the surface of the a layer of high magnetic conductivity of the iron shielding layer magnetic.

[0037] is preferably set on the reference arm in the vicinity of the strip permanent magnet on the x axial direction of the components of the bigger than set on the sensor arm in the vicinity of the strip permanent magnet on the x axial direction of the components of the.

[0038] is preferably of the reference arm or induction arm of the magnetic resistance element is set with a layer or several layers of permanent magnet offset layer.

[0039] is preferably of the reference arm of the magnetic resistance element is set with a layer or several layers of exchange off-center layer.

[0040] preferably the magnetic electric resistance sensor is composed of two independent current drive power source and two sensor arm full bridge is connected to form half bridge push-pull magnetic field sensor.

[0041] preferably said half bridge push-pull magnetic field sensor in a sensing arm of the magnetic field the resistance value with the change of the response curve corresponding to the other arm of the induction of magnetic electric resistance value with outer field the change of the response curve at the same the outside of the field having opposite to the change trend of.

[0042] preferably said half bridge push-pull magnetic field sensor comprises two sensor chip each sensor chip comprises x y on the surface of the substrate and is set on the substrate is set on the surface of the induction arm wherein at least one sensor chip are correspondingly to the other sensor chip is rotated 180 degree and the two sensor chip by the same wafer is cut into.

[0043] preferably said half bridge push-pull magnetic field sensor the sensing arm is connected through the wire lead bonding pad electrically connected to realize.

[0044] preferably the magnetic electric resistance sensor is composed of two independent the electric current of the driving source a sensing arm and a reference arm of full bridge is connected to form half bridge reference magnetic field sensor.

[0045] preferably said induction arm of the magnetic resistance value with the change of outer field responding curve slope of the absolute value is also far greater than the reference arm of the magnetic resistance value with the change of outer field responding curve slope of the absolute value.

[0046] preferably said half bridge reference magnetic field sensor comprises a sensor chip the sensor chip comprises x y on the surface of the substrate and is set on the substrate is set on the surface of the structure of induction arm of the magnetic resistance element and forming reference arm of the magnetic resistance element.

[0047] is preferably composed of the reference arm of the magnetic resistance element along the x shaft direction is more than the length along the x axis direction of the length of the x shaft direction is more than the length of the said induction arm of the magnetic resistance element on the x axle direction the length of.

[0048] is preferably of the forming reference arm of the magnetic resistance element is covered on the surface of the a layer of high magnetic conductivity of the iron shielding layer magnetic.

[0049] is preferably set on the reference arm in the vicinity of the strip permanent magnet on the x axial direction of the components of the bigger than set on the sensor arm in the vicinity of the strip permanent magnet on the x axial direction of the components of the.

[0050] is preferably of the reference arm or induction arm of the magnetic resistance element is set with a layer or several layers of the magnetic bias layer.

[0051] is preferably of the reference arm of the magnetic resistance element is set with a layer or several layers of exchange off-center layer.

[0052] this invention claims a standard semiconductor manufacturing technology is used for scale production of linear bridge type magnetic electric resistance sensor. This sensor adopts high sensitivity of magnetic electric resistance sensor element such as the tunnel junction mtj magnetic resistance or giant magneto-resistance gmr multilayer film. Is equipped with a single piece of permanent magnet body is used for generating dispersion field to the invention claims bias field so as to counteract of the sensing element is a ideal magnet. The permanent magnet generated by the bias field can balance the inner part of the edge of the sensitive direction of the shape and material of the anisotropy energy at the same time cross shaft magnetic bias field can be optimized the sensitivity of sensor. So the high sensitivity of the magnetic field sensing element can be connected to form electric bridge type further strengthening its low offset high linearity good temperature stability so as to widen it is suitable for the field of.

Specification attached drawing

[0053] image i is a tunnel junction mtj magnetic electric resistance the cross section of the sketch map on the mtj elements with the top electrode layer and the bottom electrode layer is connected between the ohm gauge display the resistance value change.

[0054] picture 2 is a rotary valve element reference layer is along the axial direction of magnetization of magnetic electric resistance in response to sketch map.

[0055] picture 3 is mtj elements of the response curve image

[0056] picture 4 is the rotating of 180 degrees the mtj elements on a same outer flipped field under the action of die the response curve image.

0057 image ] [ 5 is a plurality of mtj elements are connected as a magnetic resistance element of the sketch map.

[0058] picture 6 is push-pull full bridge of the sensor is connected with the circuit picture.

[0059] reference picture 7 is full bridge of the sensor is connected with the circuit picture.

[0060] image push-pull 8 is half bridge of the sensor is connected with the circuit picture.

[0061] reference image 9 is half bridge of the sensor is connected with the circuit picture.

[0062] image 10 is a push-pull full bridge the magnetic field sensor the circuit of the sketch map.

[0063] 11 image reference is a half bridge of the sensor is connected with the circuit picture.

[0064] image 12 which is bridge type circuit external field is changed along with the output voltage of the module sketch map the bridge type circuit is composed of four high sensitivity of the mtj elements of bridge arm is composed of overturning arraying.

[0065] pattern 13 marking the integration of the permanent magnet and the putting position of. Permanent magnet corresponding to the mtj sensing element shaft and the length of the sensing axle is parallel.

[0066] 16 14 is an image of the permanent magnet and mtj wu part of the cross sectional view and a pair of the permanent magnet magnetic induction line distribution.

[0067] pattern 15 is through setting the mtj elements around the field strength and the direction of the angle to control the response curve excursion and saturated field.

[0068] image sensor is 16 wu part of said a pair of plate type permanent magnet is set in the middle part of the magnetic field distribution of the magnetic field intensity is magnet and magnet and the width of the distance between the function of.

[0069] image image 16 17 is in the magnetic resistance element around the magnetic field component picture. Image 18 are sensitivity related to hcmss and hk function of image.

[0070] picture 19 the two chips turning arranged in sensor design layout of every one chip are set with two sensor arm two pieces of chip so as to form a whole bridge. Is the same with the two pieces of chip base plate along the standard shaft to rotate 180 degree are arranged.

[0071] image 20 is a specification of the reference bridge type sensors chip layout of this design uses the incline of the permanent magnet body is equipped with sensing arm of the bias field are arranged vertically the permanent magnet set reference arm of the bias field to optimize electric bridge the output of the same time can be selectively set the shielding layer.

Specific implementing manner

[0072] image i is a magnetic tunnel junction mtj junctions tunnel magnetic resistance element and structure of electronic measuring principle picture. Mtj elements i is composed of pinned layer 2 a tunnel barrier layer 5 ferromagnetic layer of sensitive layer 6 is composed of. Pinned layer 2 is pinned magnetic layer iron layer 4 and the ferromagnetic layer 3 is composed of ferromagnetic layer 4 and the ferromagnetic layer 3 between the exchange of the coupling effect that the ferromagnetic layer the magnetization direction of the 4; A tunnel barrier layer 5 is normal it is composed of mgo or al 2o3 is composed of the ferromagnetic layer 4 the upper part of the. Ferromagnetic layer 6 is set in the tunnel barrier layer 5 the upper part of the. Arrow arrow head 7 and 8 respectively represent pinned layer 4 and sensitive layer 6 the magnetization direction of the. Pinned layer the magnetic moment 8 in a certain size of the magnetic field under the action is corresponding to the fixing of the sensitive layer 6 7 magnetic moment of relative to the pinned layer the magnetic moment 8 is corresponded to the free rotatable. 3 4 5 6 the typical thickness is i nm 0 to 100 nm between.

[0073] bottom electrode layer 16 and top electrode layer 17 is connected with the relative to the anti-ferromagnetic layer 3 and sensitive layer 6 electrical contact. Electrode layer is generally using a magnetic conductive material can be carried with electric current output of the ohm gauge 18. Ohm gauge 18 it is suitable for the known through the whole of the tunnel junction current and the electric current or voltage measuring. Normally under the condition of tunnel barrier layer 5 the invention claims device most of resistance is about 100 ohm to the conductor resistance value of about 10 ohm. Bottom electrode layer 16 is located on the insulating base sheet 9 on the upper part of the insulating base plate 9 than the bottom electrode layer 16 which is wider than other material which is composed of the substrate 10 the upper part of the. Substrate material is usually silicon quartz heat resisting glass gaas altic or the wafer can be integrated in any other materials. Silicon because it is easy to process the integrated circuit although the magnetic sensor is not always need to the circuit as the best choice of.

[0074] it is suitable for linear measurement of gmr magnetic field or mtj elements the output of the picture as picture 2 1 the. Response curve in the low resistance state 20 21 22 and high resistance state to the saturated and rh respectively represent low resistance state and high resistance state of the resistance value. Response curve 20 in the saturated place between the regions are at outside field hsmse linear change of. Hsmse parallel to the field of the sensing element sensitive shafts. Pinned layer the magnetic moment 8 and the sensitive shafts reverse parallel to any kinds of the pointing direction of h. The free layer 6 7 and the magnetic moment of pinned layer 4 8 the magnetic moment of parallel when magnetic resistance element of the response curve of 20 to the largest value when the two parallel to the minimum value. Magnetic electric resistance response curve 20 in the middle of the value with free layer 6 and pinned layer 4 the angle between the change of the. Response curve it is not h = 20 along the o point on the symmetrical. Saturated field 25 26 along the point htj 23 typical field so as to offset value to the saturation of the field is more close to the point = h o. H. Value is called as orange peel orange peel effect or haga gregory neel coupling coupled with the typical value of i to 40 oe0 the magnetic resistance element in iron magnetic property the structure of film and level switch is set depending on the material and manufacturing technique.

[0075] as picture 2 1 and the response curve in the saturated field 25*26 the area between the working state of the can is similar to process:

Or v r only one rr or rt v rzi and rr

[0076] richard h ^ ~ ~ + h ha

[0077] of the hs is saturated field. Hs by the amount is defined as linear area of the cutting line and the positive and negative saturation curve of the tangent point of intersection the value corresponding to the value is in the response curve corresponding to the point htj the asymmetry of the eliminating under the condition of the extracted.

[0078] is shown as picture 2 is the ideal condition of the response curve 20. In a perfect state and the upper and lower magnetic resistance r at outside field hsense is perfect the change of the linear relation at the same time it has no magnetic hysteresis in the practical situation of magnetic electric resistance of the response curve along with the outer field changing with lag phenomenon that they are called as magnetic hysteresis. Magnetic electric resistance of the response curve as a return circuit is used as the application of magnetic electric resistance of the material is very low magnetic hysteresis in the actual use can be regarded as a perfect performance curve line. The real application of the sensor field the magnetic sensor design of the restriction of material and the defect of the curved line 20 will be bent. The invention claims the design of the sensor structure and can produce the implementation procedure of the sensor has excellent work induction in the working region at the same time with high linearity low magnetic hysteresis high sensitivity the invention has the characteristic of the magnetic electric resistance responding curve slope of.

[0079] r hsense curved line 30 it has the advantages of low resistance state 21 of the resistance value and high resistance state and 22 of the resistance value rh. The high sensitivity the area near the zero field of the sensor is connected with the working area is located near zero field about is saturated field 25*26 between the area of 1/3. Curved line 30 the = h o at the point of cutting line is 33. The curve slope and the sensitivity of sensor is directly proportional. Zero field the yarn 33 are respectively and the field of wire cutting 34 and high magnetic field 35 cutting lines are crossed on hs h0 is 25 + 0 and the 26. The display picture when the magnetic moment 7 and 8 the magnetic moment is parallel to the curved line 30 corresponding to high resistance state; When the magnetic moment 7 and 8 the magnetic moment parallel curved line 30 corresponding to low resistance state. When 7*8 vertical to the resistance value r and rh is located between middle value it is a ideal magnetic line of the sensor is connected with the working point. Such as drawing 4 the other magnetic electric resistance r and the outer field hsmse changing curve of the magnetic electric resistance sensor along the method of the rotation of 180 degrees. On a same outer field hsmse under the action of the magnetic of the resistance r pinned layer 4 and vector magnetic moment 8 is parallel to the field of hsmse. In this situation of the rotating of the chip of the r hsmse slope is negative value. Ordinary place of the magnetic resistance and to rotate 180 degree is set on the magnetic resistance can be structure of bridge it is proved that can be compared with other method of output value is more than.

[0080] because of small size mtj elements which is connected in series to increase the sensitivity of the noise is reduced to 1/ f and at the same time it can improve the esd performance the implementation mode picture 5. The magnetic resistance element in series is used as more complicated circuit structure of magnetic electric resistance arm. Mtj elements 40 41 and the bottom electrode top electrode 42 the middle of the sandwich structure the inner part of the current 43 to pass through vertically mtj elements 40 horizontal direction alternatively flow through the top electrode layer and the bottom electrode layer. Bottom electrode 41 on the insulating layer 9 and the upper part of the insulating layer 9 is located on the substrate 10 and the. On each element in the tail end of the invention claims a bonding pad and it is the resistance arm and the other component and ohm gauge 18 is connected with the method or can be controlled by the chip on the other circuit of the connecting part and there is no any other connecting way of. In common situation the flow of electric current direction and not according to the bridge arm resistance of the effective resistance influence. The hold reference arm and induction of the arm mtj elements with equal size which is advantageous since this cause device etching the bias is not sensitive at the same time reference arm and induction arm mtj elements in series the resistance value can be mtj elements according to number is set and change of.

[0081] electric bridge is used to change magnetic electric resistance sensor signal it makes the output voltage is amplified it is convenient for. It can be changed signal the noise cancelling common mode signal it can reduce the temperature drift parameters or other is not enough. On the mtj elements can be connected in series to form the wheatstone bridge or other electric bridge.

[0082] picture 6 is push-pull full bridge of sensor circuit schematic diagram. Push-pull full bridge magnetic field sensor comprises four induction arm on the magnetic electric resistance sensor the work area is set in the two arms of the magnetic sensing resistance value with outer field the change of the response curve corresponding to the other two arms of the magnetic sensing resistance value with outer field the change of the response curve at the same the outside of the field effect is opposite to the change trend of.

[0083] push-pull full bridge magnetic field sensor comprises two sensor chip each sensor chip comprises x y on the surface of the substrate and is set on the substrate on the surface of two induction arm wherein at least one sensor chip are correspondingly to the other sensor chip is rotated 180 degree and the two sensor chip by the same wafer is cut into.

[0084] induction arm is connected through the wire lead bonding pad electrically connected to realize.

[0085] reference picture 7 is full bridge of sensor circuit schematic diagram.

[0086] bridge type magnetic field sensor is taken as the reference full bridge the magnetic field sensor the reference full bridge the magnetic field sensor comprises sensing arm and reference arm of each reference arm is composed of the magnetic resistance element.

[0087] reference full bridge magnetic field sensor comprises two induction arms and two reference arm on the magnetic electric resistance sensor the working area of the arm in the induction of magnetic electric resistance value with the change of outer field responding curve slope of the absolute value is also far greater than the reference arm of the magnetic resistance value with the change of outer field responding curve slope of the absolute value.

[0088] reference full bridge the magnetic field sensor comprises a sensor chip the sensor on the chip comprises x y on the surface of the substrate and is set on the substrate is set on the surface of the structure of induction arm of the magnetic resistance element and forming reference arm of the magnetic resistance element.

[0089] image push-pull 8 is half bridge of sensor circuit schematic diagram.

[0090] bridge type magnetic field sensor is push-pull half bridge the magnetic field sensor the push-pull half bridge magnetic field sensor is composed of two induction shaft is a.

[0091] push-pull half bridge magnetic field sensor comprises two induction arm on the magnetic electric resistance sensor the working area of the inside of the one arm of the induction of magnetic electric resistance value with outer field the change of the response curve corresponding to the other arm of the induction of magnetic electric resistance value with the field of the change of the response curve at the same the outside of the field effect is opposite to the change trend of.

[0092] push-pull half bridge magnetic field sensor comprises two sensor chip each sensor chip comprises x y on the surface of the substrate and is set on the substrate is set on the surface of the induction arm wherein at least one sensor chip are correspondingly to the other sensor chip is rotated 180 degree and the two sensor chip by the same wafer is cut into.

[0093] push-pull half bridge the magnetic field sensor the sensing arm is connected through the wire lead bonding pad electrically connected to realize.

[0094] reference image 9 is half bridge of sensor circuit schematic diagram.

[0095] the magnetic electric resistance sensor is taken as the reference half bridge the magnetic field sensor the reference half bridge the magnetic field sensor comprises sensing arm and reference arm reference arm is composed of the magnetic resistance element.

[0096] reference half bridge the magnetic field sensor comprises an induction arm and a reference arm on the magnetic electric resistance sensor the working area of the arm in the induction of magnetic electric resistance value with the change of outer field responding curve slope of the absolute value is also far greater than the reference arm of the magnetic resistance value with the change of outer field responding curve slope of the absolute value.

[0097] reference half bridge the magnetic field sensor comprises a sensor chip the sensor chip is comprised of x y on the surface of the substrate and is set on the substrate is set on the surface of the structure of induction arm of the magnetic resistance element and forming reference arm of the magnetic resistance element.

[0098] image 10 is a push-pull full bridge the magnetic field sensor of the circuit picture.

[0099] the magnetic electric resistance sensor is composed of two independent current drive power source and two sensor arm full bridge is connected to form half bridge push-pull magnetic field sensor.

[0100] half push-pull full bridge magnetic field sensor in a sensing arm of the magnetic field the resistance value with the change of the response curve corresponding to the other arm of the induction of magnetic electric resistance value with outer field the change of the response curve at the same the outside of the field having opposite to the change trend of.

- 0101 is a push-pull full bridge magnetic field sensor comprises two sensor chip each sensor chip comprises x y on the surface of the substrate and is set on the substrate is set on the surface of the induction arm wherein at least one sensor chip are correspondingly to the other sensor chip is rotated 180 degree and the two sensor chip by the same wafer is cut into.

[0102] half push-pull full bridge the magnetic field sensor the sensing arm is connected through the wire lead bonding pad electrically connected to realize.

[0103] 11 image reference is a half bridge of sensor circuit schematic diagram.

V- 0104 ] [ is composed of two independent the electric current of the driving source a sensing arm and a reference arm full bridge is connected with reference to the half bridge the magnetic field sensor.

[0105] induction arm of the magnetic resistance value with the change of outer field responding curve slope of the absolute value is also far greater than the reference arm of the magnetic resistance value with the change of outer field responding curve slope of the absolute value.

[0106] half reference full bridge the magnetic field sensor comprises a sensor chip the sensor chip comprises x y on the surface of the substrate and is set on the substrate is set on the surface of the structure of induction arm of the magnetic resistance element and forming reference arm of the magnetic resistance element.

0107 ] and [ electric bridge to form push-pull full bridge magnetic field sensor 50 as the example of the electric bridge with four at outside field hsmse the change of the bridge arm of the bridge arm is defined as induction arm; Positive and negative bridge arm of the soldering pad 27 at any one of sensor the bottom of the arm 52. Clear to see the bonding pad on the picture and not mark. Induction arm 52*52 ' of the responding curve slope of the r hsense is positive value at the same an external field under the action induction arm 54*54 ' of the responding curve slope of the r hsense is negative value. 52*54 located on the direction of arrow head can be showed each of r hsmse curve of slope of the symbols.

[0108] from the top terminal to start along the circumference is in the shape of rhombus arranged in the push-pull full bridge magnetic field sensor 50 welding plate is: Bias voltage vbias 45; The right arm of the centre of pad 2 48 v; Ground wire gnd welding plate 46 and the left arm in the centre of pad vi 47. Sensor bridge arm 9 10 on the substrate is prepared and it has the advantages of the substrate of the electric contact of the layout formula is as figure above said. There are several ways is connected with the electric bridge arm and electric bridge are connected with the bonding pad. Typical the connecting structure comprises: Integrated from chip is connected with the binding wire bonding and welding ball connecting.

[0109] push-pull full bridge the magnetic field sensor 50 v hsense output curve 60 picture 12 which can not. Is composed of the attached drawing 3 and attached drawing 4 rh and to obtain the curved line firstly calculating the output voltage is v1 v2 as the change of outer field hsmse. In this situation sensing arm 52 52 54 54 ' ' and the value rh are respectively and the bridge circuit of the resistance value is:

[0110] rm = r - + rh ^ paralmlrl and rh r1 = - + - 2 rh

[0111] the left and right bridge arm with the same resistance value of current passing through the right and left sides of the electric bridge after being divided:

01121 and 7 1 = t = ***

Rl rmli2 [ [ 2 and r + £ rs1 ' ***

[0113] left bridge arm of the central point of the voltage is vl:

Ir

[0114] f1 = rw9iuft = - rw * ^

V 1 + ] [ lxli ^ ¾

[0115] and right bridge arm of the central point of the voltage v2 is:

[0116] f2 = rh ' * insm = ri *

[0117] bridge type sensors the output is defined as:

[ j

[0118] mr f = f = h = ] v2

[0119] so that the output voltage v the positive magnetic field direction of the maximum value is shown as fig 12 the display is in + vpeak 61. Can be seen through the wire cutting 63 original point and the positive vpeak61 are crossed on the point hsmse = hsat. The bridge circuit the output of the sensitivity is defined as bridge circuit the output of the = h o of the node a derivative:

F r inside of v

[0120] ***

/ ks and r1j zfgaj

0121 ] and [

[0122] ^ sst = hqvss hk

[0123] the hcmss are distributed along the sensor is vertical to plane surface of the sensitive direction is the invention claims bias magnetic field to bias magnetic free layer 7 the invention claims a field torque. Hk 7 of the magnetic moment is effectively purified aeolotropism. Hk can be achieved by independent mode such as vibration sample magnetometer vibrating sample magnetomete vsm and super-conduct quanta interferometer superconducting quantuminterference squid device used for measuring. It is easy to replace the process to process 7 8 the invention can obtain the sensitivity of the v hsmse curved line as following the display image 12:

~ moed roy ~ rf i pgim

01241 invention claims a s - - q = -

L j r + h r h

Lksxht £ r j 11 *** * 5 uk

[0125] on the front surface of we detail description the push-pull full bridge sensor 50 the sensitivity of the computer.

[0126] the following to the needle to the relative of six electric bridge in the form of sensitivity to a table to compare the invention omits completely deducing the process of. Electric bridge the structure of 6-11 shown as picture. The corresponding sensitivity and peak value voltage of the gage i.

0127 ] [

Electric bridge type i peak value voltage i sensitivity to

<img id="idf0001" file="CN202494772UD00131.tif" img-content="drawing" img-format="tif" />

[0128] gage i

[0129] is showed in attached picture 7 the reference full bridge sensor 51 of an arm is the induction 52 52 53 reference arm as ' ' 53. Reference arm is no 53 is set with arrow representing the r hsmse curve slope of the very small.

[0130] as attached figure 6 the push-pull full bridge sensor 50 which has two kinds of induction arm 52 52 54 54 ' ' and the two induction arm of the r hsense curve of slope is opposite to the. Induction 52*54 arm is located at the upper part of the arrow head is that each of r hsense curve of slope of the symbols.

[0131] i is composed of surface the first and second to process comparison can be seen push-pull full bridge sensor 50 compared with reference full bridge sensor 51 and it has high sensitivity because all the four arms are set with the signal contribution.

[0132] as attached figure 8 which can not push pull half bridge sensor 55 with two asymmetrical of the induction arm 52 54

[0133] as attached figure 9 the reference half bridge sensor 56 only has a sensing 52 arm at the same time there is a reference arm 53.

[0134] as attached figure 10 the push-pull half bridge 57# sensor is set with two asymmetrical of the induction 52 54 arm and two driving source 59 half push-pull full bridge magnetic field sensor is composed of the driving source drive and there is no 59 bias voltage.

[0135] as attached figure 11 the half bridge reference sensor 58 with a sensing 52 arm and a reference arm 53. And two driving source 59 half reference magnetic field sensor is composed of the driving source drive and there is no 59 bias voltage.

[0136] as attached figure 6*7 the push-pull full bridge sensor 50 full bridge and reference sensor 51 of the soldering pad along the clockwise direction from the top part in turns into: Bias voltage vbias and right bridge arm the centre point of v2 is connected with the ground gnd point and the left bridge arm the central point of the vi. The four bridge type circuit is connected with the bonding pad can be connected with two different resistance arm. Normal through the pressure gauge is connected with the point vl and v2 measuring the difference value v1 v2 for measuring bridge circuit output voltage.

[0137] as attached figure 8 and 9 shown in attached drawing of push-pull half bridge circuit sensor 55 half bridge and reference sensor having 3 at the welding plate along the clockwise direction from the top part in turns into: Bias voltage central point vbias vl and the ground gnd point of bridge type circuit can be carried out through the electric connection.

[0138] push-pull half bridge sensor 55 and reference sensor 56 electric bridge the output voltage can be formed by many known method to measure. This utility model claims a method is as follows: Vl and gnd in the bonding pad is connected between vl and gnd voltage meter a potential difference between vl gnd is output voltage. The other method is as follows: The vl and vref it is comprised of external circuit and device the invention claims a constant voltage welding disk is connected between vl and the voltage vref a potential difference between vl vref is output signal. Vref can be composed of one of reversed offset diode a voltage division circuit or other known method for providing.

[0139] as attached figure 10 and 11 the attached drawing of the push-pull full bridge 57# magnetic field sensor and a reference full bridge sensor having 3 58# at the welding plate along the clockwise direction from the top part in turns into: Left half axle and right half bridge. Left half bridge is composed of constant current source i1

Central point vl and the ground gnd point is composed of. Left and right half bridge is composed of constant current source i2 59 ' the central point of v2 and the ground gnd point is composed of.

[0140] half push-pull full bridge 57# sensor and a reference full bridge sensor 58 the output voltage can be formed by many known method to measure. This utility model claims a method is as follows: Through the pressure gauge is connected with the point vl and v2 measuring the difference value v1 v2 for measuring bridge circuit output voltage.

[0141] half push-pull full bridge 57# sensor and a reference full bridge sensor 58 in the constant current source i1 and i2 can be composed of many known method to realize. Is composed of the invention claims a method for controlling voltage feedback loop carrying out monitoring and adjusting a group of magnetic resistance element single wu magnetic resistance element voltage generated by. The other method uses a group of magnetic resistance element wu a plurality of magnetic electric resistance wu part of the output. This method need to satisfy a group of magnetic resistance element of the resistance value is more than one magnetic resistance element of the resistance value. The circuit is bridge-type circuit resistance value of changing bridge circuit the voltage is corresponding to change because of the circuit is composed of the energy of constant current source supplying it is not the voltage source.

[0142] the reference full bridge sensor 52 reference half bridge sensor 56 and a reference full bridge sensor 58 to the reference arm 53. Said reference arm 53 is corresponded to the sensing to said arm has lower sensitivity in the response curve as upper surface of the sensor the working scope of the induction of arm of the responding curve slope of the absolute value is larger than reference arm 53. Changing reference element and sensor element and ar r is not actually so it can be controlled by changing by hs of changing sensitivity. The method can be formed by several different technology the combination of to realize:

[0143] magnetic shielding a high magnetic conductivity ferromagnetic layer deposited on the reference arm so as to weaken the effect of magnetic field.

[0144] shape of the anisotropy energy a because the reference component and inductive element with different sizes so it is not at the same shape of the anisotropy energy. The common method of the reference element the long shaft of the length is larger than the length of the sensing element shaft length being short axis length is less than the sensing element of the short shaft the length of the reference element is parallel to the sensitive direction of the demagnetization effect is also far greater than the sensing element.

[0145] switching bias the technology is that through the mtj magnetic resistance element free layer and adjacent reaction of ferromagnetic layer or permanent magnetic layer of the exchange coupling creating an effective which is vertical to sensitivity direction of the outer field. Can be used in the free layer and switching bias layer is set between the cu or ta the isolation layer to reduce the cost of exchange off-center intensity. Multi-layered film structure is said as follows:

[0146] seed layer anti-ferromagnetic layer i and iron magnetic lining layer and iron magnetic layer and insulating layer and iron magnetic layer separated layer 2 the ferromagnetic layer and protective layer ***

[0147] seed layer anti-ferromagnetic layer i and iron magnetic layer and iron magnetic lining layer insulating layer and iron magnetic layer separated layer permanent magnetic layer the protective layer ***

[0148] seed layer anti-ferromagnetic layer i and iron magnetic lining layer and iron magnetic layer and insulating layer and iron magnetic layer 2 the ferromagnetic layer and protection

M ***

[0149] seed layer anti-ferromagnetic layer i and iron magnetic lining layer and iron magnetic layer and insulating layer and iron magnetic layer permanent magnetic layer the protective layer

[0150] the anti-ferromagnetic layer i afl and the ferromagnetic layer 2 is af2 anti-ferromagnetic material such as ptmn irmrufemn. Ferromagnetic layer fm adopting some has representative of the iron magnetic alloy is composed of ferromagnetic film or multi-layer film comprises but not limited to nife cofeb cofe and nifeco. Insulating layer can be any it can spin polarization of the insulating material such as aluminium oxide or magnesium oxide. Isolation layer is usually ta ru or cu the non-magnetic material the thin film. Anti-ferromagnetic layer afl reaction of ferromagnetic barrier temperature of the blocking temperature is lower than af2 of the iron magnetic lining layer and iron magnetic layer structure of pinned layer of the bias field and the free layer of the bias field orthogonal vertical.

[0151] the bias magnetic field permanent magnet offset in the technology of fe cr and pt and so on permanent magnetic alloy material is deposited in the sensing element surface or magnetic tunnel junction is used for providing dispersed magnetic field so as to offset mtj elements response curve. Permanent magnet offset one of the advantage is that it can be used in the electric bridge is formed after using one of the magnetic field of the initialization of the permanent magnet. Another a very important advantage is that it bias field can be removed by using the mtj elements of magnetic domain in order to stabilize and linear mtj elements the output of the. The design of the large the advantages of the design of adjusting has great flexibility of. The lower side is can be achieved by multi-layered film structure:

[0152] seed layer anti-ferromagnetic layer i and iron magnetic lining layer and iron magnetic layer and insulating layer the magnetic layer separated layer thickness of permanent magnetic layer the protective layer ***

[0153] the other technology relates to the mtj wu piece is set at two sides of biasing magnet.

0154 ] and [ the upper adjusting sensitivity of the technology can be solely used or several technologies are combined to use. When these can be used several technology are combined together it can make the simple zf = very high so as to reduce the bridge type sensors reference arm of smtj provides a very stable the reference arm.

[0155] is to provide heross the field of the preferred manner as a certain description. As attached figure 13 the magnetic electric resistance sensor 70 is fixed on the two pieces upper permanent magnet 71 middle. Semiconductor substrate on the bottom of the structure of top layer of the display and it is not clear.

[0156] strip permanent magnet there is a gap between the gap width w 72 73 thickness t 74 and length ly 75. Strip permanent magnet are designed to provide one is vertical to sense shaft y axis crossing 76 bias field it is mainly on the substrate inner surface of. The shaft is called as cross shaft or directly is called as the x axis 78. Magnetic resistance element 70 are designed to have width wmk82 lmk83 length of the elliptical shape. Through the magnetic resistance element 70 part of the i picture.

[0157] strip permanent magnet the initial stage by using one of the magnetic field charging magnetism by the same remanence mpm77 it is mainly vertical to the sensitive shafts 76 of the great extent is parallel to x axis 78 field and is located on the inner face of x y. The x axis and y axis is standard orthogonal with cartesian coordinate axis z axis is a base plate method of the line direction. The magnetic induction line 14 is on the x z of the plane projection. The field of the size and the direction of the it can calculate.

[0158] strip permanent magnet of magnetic field is considered as the picture 15 and the magnetic body the edge of the 90*91 formed by the fictitious load and magnetic the boundary condition the result acted. Residual magnetic mpm77 the direction of the relative to the sensitive y is an angle 0pm92 76. Magnetic charge size with the residual magnetic mpm77 the size and direction of 0 *** 92 to the change of the strip permanent magnet the inclined angle of 9 ref '' or esns relative:

[0159] ps = mr costpmf + or4

0160 ] and [

[0161] pi = mr cos

[0162] virtual magnetic charge generated magnetic field is:

0163 = 4 ] [ ^ } jz ^ ds '

[0164] 15 picture displayed on the two pieces of strip permanent magnet 71 is set between the magnetic resistance element 70 on the surface of the final of the magnetic field is vector hgap94. The field of the component direction of it is mainly vertical to the strip permanent magnet 71 the edge of the. Field 94 ' is copied to move horizontally the right side of the image and comparing the. Vector hgap and x axis the angle between the egap satisfy:

0165 ] [

<img id="idf0002" file="CN202494772UD00161.tif" img-content="drawing" img-format="tif" />

0166 ] and [

[0167] bgsf br4 = n / 2

[0168] in the condition that the 9 *** = 0 or 2 m = 0 ji is set in the magnetic resistance element in the centre of the magnetic field is the function of magnetic qiu:

<img id="idf0003" file="CN202494772UD00162.tif" img-content="drawing" img-format="tif" />

[0170] 16 19 of the formula is represented by w73 gap72 and the function of the function expressing the reference element and inductive element the saturated field can be controlled by changing the shape of the magnet 71 dimension changes. Using the same mtj elements mtj three-dimension size the invention claims a strip permanent magnet thin film on the reference element and sensor element is set on the herossioo hsmseiol 6 5 times under the action of the reference element the saturated field is of the sensing element 6 5 times. The ratio with respect to the reference arm 53 electric bridge by it is enough to pass through appropriate design it can make the ratio is increased to 10. To the picture 6 in the push-pull full bridge sensor 50 is only set with the invention claims a strip permanent magnet the size of thin film because such a structure and there is no reference arm because it does not need to.

[0171] image image 16 17 is in the magnetic resistance element around the magnetic field component picture. Comprises a hra ss95 hoff96 and its combined with vector hgap94 '. The image surface is set with strip permanent magnet 71 edge and sensitivity direction the included angle of the same time can generate h ss95 and eliminate the offset field * *** 96 this invention claims: Is set with magnetic resistance element 70 saturation of the field value eliminate the offset field h 023; Optimizing electrical bridge outputting the symmetry of the offset and sensitivity. Is set outside of the residual magnetic mpm77 and sensitive direction the included angle of 0 *** 92 p is the sensor chip prepared can the invention claims a fine adjustment device capable of minimizing the deviation value or the symmetrical the method can improve product rate good.

[0172] to complete the sheet strip permanent magnet generated by the cross shaft of the magnetic field after generally described in the equation of the pushing process the equation indicates that the magnetic electric resistance sensitivity and the geometrical shape of the item and iron magnetic material the performance of the relation of. The theory of the development of the mtj elements a free layer 6 the magnetic substance has the thickness of the i picture tmeii. Magnetic resistance element 70 free layer on x-y plane the shape of the picture and pattern 11 the magnetic resistance element 70 it has the advantages of long shaft lmk83 wmk82 ratio and short axis length of the elliptic profile long shaft and short shaft are respectively and y axis 76 and x axis parallel 78.

[0173] when the magnetic resistance element work it by the picture clean 15 shown by vector field hmekm the effect of field and x axis there is an included angle emk 105 it can be generated magnetic resistance element 70 free layer 6 purifying magnetic energy mmk 106. Mmk 106 opposite to x axis there is an included angle 0mk 107.

[0174] sensitivity is defined as r hse *** curve in the field strength is zero when the slope of a derivative can pass through the lower surface of the method carries out calculation:

] and [ 0175 wu to the magnetic resistance element magnetic free energy about hmiomme function of hmk mmk about qme ome and the function of;

[0176] minimizing the energy level;

[0177] solves the problem of the angle emk and the field of the function relation;

[0178] mmk hme function obtaining the coefficient of the hme = o when the value of zero field which has been determined time the sensitivity of.

[0179] in order to release magnetic resistance element the size of the magnetic performance the influence of given typical lkowme and tme value is nm and 3000 nm 12000 6 nm the x y z direction of the proportion is as follows 500: 2000: I. So when the size of the lower part of the demagnetization factor is:

0180 ] [

<img id="idf0004" file="CN202494772UD00171.tif" img-content="drawing" img-format="tif" />

[0181] total energy = externally applied to the energy of itself and the energy of

0182 ] [

<img id="idf0005" file="CN202494772UD00172.tif" img-content="drawing" img-format="tif" />

[0183] the second item from the magnetic field it comprises two on the x y z has a normal amount of single shaft field: One is the magnetic field d the other one is material aeolotropism k.

0184 ] [

<img id="idf0006" file="CN202494772UD00173.tif" img-content="drawing" img-format="tif" />

[0187] and then do some simple similar:

[0188] hme completely along the y axis;

[0189] hcrtjss completely along x axis;

0190 ] o [4] mz = because the dz » dx dy.

[0191] bei ij process is simplified to be:

0192 ] [

<img id="idf0007" file="CN202494772UD00174.tif" img-content="drawing" img-format="tif" />

0193 ] and [ inserted into the total energy is changed into:

0194 ] [

<img id="idf0008" file="CN202494772UD00175.tif" img-content="drawing" img-format="tif" />

[0197] the minimum to find out process to the dependence of the 0:

0198 ] [

<img id="idf0009" file="CN202494772UD00176.tif" img-content="drawing" img-format="tif" />

[0199] hypothesis h ss the magnetic resistance element mmr saturated so that they can resolve the problem that the small angle 9 the limit:

0200 ] [

<img id="idf0010" file="CN202494772UD00177.tif" img-content="drawing" img-format="tif" />

[0202] the attention of the total aeolotropism is:

0203 ] [

<img id="idf0011" file="CN202494772UD00178.tif" img-content="drawing" img-format="tif" />

[0204] using extremely small angle of approximate:

0205 ] [

<img id="idf0012" file="CN202494772UD00181.tif" img-content="drawing" img-format="tif" />

[0206] zero field of the derivative as:

0207 ] [

<img id="idf0013" file="CN202494772UD00182.tif" img-content="drawing" img-format="tif" />

[0208] hypothesis electric bridge sensor in the saturated state the lower part of the voltage vp is the sensitivity is:

0209 ] [

<img id="idf0014" file="CN202494772UD00183.tif" img-content="drawing" img-format="tif" />

0210 ] and [ the cross field hcmss and anisotropic field hk the difference of relative. Image 18 are sensitivity v/v or oe hcmss with or without gang hk quantity curve of variation of. Can be seen from the h ss or hk with reduced to 1 sensitivity of the calculation value added value infinite. Actually hcross is set in slightly higher than hk so it can make the sensor the sensing area is wider and it reduces magnetic hysteresis avoid the affect the other magnetic free layer mmk to be saturated.

[0211] in large scale in industrial production magnetic resistance element is preparing the round base plate is named wafer in the specific application in the wafer through the cutting is single or two magnetic resistance element the chip is electrically connected to form electric bridge and then performing encapsulation.

[0212] picture 19 is used as picture 16 and an 13 the magnetic resistance element 70 of the push-pull full bridge of the sensor chip layout. Two same chip 122*123 is composed of the wafer is cut made by the package is a sensor. Two pieces of chip corresponding to the z axis with each other to rotate 180 degree the sensitive surface of the x-y plane. Each chip are set with two electrical isolation magnetic electric resistance sensor arm.

[0213] push-pull full bridge sensor 50 through the leading wire is electrically connected with 125. Rectangular of the welding disc is set on each chip the edge of the invention claims a welding line is circular so it is convenient to visually confirm each of the core chip bonding pad number and direction of. Each circuit of the nodes are set with two welding disk assembly there are eight one is used for the inner part of the bridge is connected with the other one is used to the outer part of the device is connected with the. It makes the position of the chip 122 the top part of the bonding pad can be connected through the wire lead the lead frame packaging pin and the pcb.

[0214] the to the chip of the element of the long shaft along the sense shafts direction. On the chip of the strip permanent magnet is inclined is set with the width of the two magnets w73 body and the distance between the inclined angle is 0 gap72 sns93. The magnetic body the invention claims a bias magnetic field to saturation induction element when the additional providing of htjff satisfy htjff htj &gt; hsat time. This invention claims a push-pull bridge display its linear working state of necessary. And the right upper part of the negative magnetic electric resistance 54 ' is connected with gnd and v2 between. The left upper part negative magnetic electric resistance is connected with the 54 vbias between vl and. Magnetic electric resistance of r ' 54*54 hsmse response curve inserted in the map 120 hsmse in the field of the negative direction has wen resistance state.

[0215] reference image 20 is full bridge sensor 51 of an image layout of the reference bridge is set with the induction arm and the reference arm having different width angle and interval of the inclined strip permanent magnet as the picture of the reference arm of the magnetic resistance element the long axis vertical to the sensitive shafts on the x axis y axis direction of the length is more than that of the induction arm of the magnetic resistance element the reference arm is parallel to the sensitive direction of the demagnetization effect is also far greater than the induction arm. In the design reference arm and induction arm on the substrate a one-off preparation can be finished through the deposition on the lead or lead bonding is electrically connected to form electric bridge structure from the wafer on the cutting which is made of the reference full bridge sensor is located on a substrate on which the structure they are called as single chip type sensor single chip type sensor corresponding to the multi-chip packaging a sensor to said simplify the preparation technique the same time it reduces the volume of sensor. Mtj elements are located on the same inclining angle of the strip permanent magnet 117*118 115 116 in the middle of the electric bridge of bridge arm. In the design of 0ref = 2 esns the ji or 4 and 2 between. The zero deviation of the optimization can be used at the same time adjust the reference arm and induction arm mtj elements quantity or only to the reference arm or induction arm offset optimizing. Picture dotted line and the rectangular 119 shielding layer is also can be selected the invention claims a method for. Of the shielding layer is used to further reduce the reference arm 115*116 with high sensitivity.

[0216] the other bridge type magnetic field sensor of the layout pattern and the similar the invention can not be tired and then the.

[0217] is used for measuring magnetic field of magnetic electric resistance sensor which can realize mass production measuring magnetic field of the sensitivity higher and at the same time it has low power consumption small size.

[0218] the embodiment of invention is only to the utility model claims a technique concept and feature of its aim is to make the familiar the item technology people can know the utility model claims a content and to implement and it can not so as to limit the utility model claims a protection range. Fan according to this utility model mental is the equivalent change or modifying both the covers on this utility model of the protection range.