CN103971444A - Magnetic sensor for magnetic detection - Google Patents
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- CN103971444A CN103971444A CN201310034302.6A CN201310034302A CN103971444A CN 103971444 A CN103971444 A CN 103971444A CN 201310034302 A CN201310034302 A CN 201310034302A CN 103971444 A CN103971444 A CN 103971444A
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Abstract
The invention provides a magnetic sensor for magnetic detection. The magnetic sensor comprises a chip and a flux-weakening reinforcement unit. The chip is used for inducting a magnetic anti-fake mark in a medium to be detected. The flux-weakening reinforcement unit is used for carrying out pre-magnetization on the magnetic anti-fake mark so that the chip can induct the magnetic anti-fake mark sensitively. The magnetic sensor for magnetic detection is particularly suitable for detection and identification of the flux-weakening mark, capable of identifying the flux-weakening anti-fake mark, high in capacity of resisting disturbance, small in size, easy to integrate and high in sensitivity.
Description
Technical Field
The invention belongs to the technical field of microelectronics, and particularly relates to a magnetic sensor capable of sensing and detecting a magnetic anti-counterfeiting mark, in particular to a weak magnetic anti-counterfeiting mark.
Background
Changes in current, stress strain, temperature, light, and the like can generate a magnetic field that can cause a change in the magnetic properties of the magneto-sensitive element. The change of the magnetic property of the magnetic sensing element is converted into an electric signal, and the electric signal is measured to obtain whether the current, stress strain, temperature or light and the like capable of generating a magnetic field exist in the detected region. The magnetic sensor is a measuring device developed by utilizing the characteristics of the magnetic sensitive element, and is widely applied to the fields of finance, aviation, aerospace, microelectronics, geological prospecting, medical imaging, information acquisition, military and the like.
In the industrial field, the most widely used magnetic sensor is a coil type magnetic sensor, i.e., a coil is used as a magnetic sensing element. Fig. 1 is a structural diagram of a magnetic sensor currently used in the financial field. As shown in fig. 1, the magnetic sensor includes a housing 101, a coil 109, and a printed circuit board 113, and an opening 103 is provided at the top end of the housing 101. A narrow magnetic gap 107 is provided at the center of the top ends of the magnetic cores 105a, 105b, and the magnetic cores 105a, 105b are fixed in the housing 101 by a bracket 111, and the top ends thereof protrude from the opening 103 of the housing 101. A plurality of turns of a coil are wound around the lower ends of the magnetic cores 105a, 105b, the coil 109 is connected to a printed circuit board 113, and the printed circuit board 113 is connected to other components provided outside the shield case 101 through bonding pins 114a, 114 b. The magnetic cores 105a, 105b and the coil 109 constitute an antenna device which easily receives electric signals and magnetic signals in the external environment. During currency detection, the magnetic ink strip or the magnetic metal strip of the banknote is scratched through the top ends of the magnetic cores 105a and 105b, and the magnetic gap 107 generates induced electromotive force corresponding to the magnetic field intensity ratio of the magnetic ink strip or the magnetic metal strip of the banknote in the coil 109, so that the authenticity of the banknote can be identified according to the induced electromotive force.
With the change of market demand, the magnetic sensor gradually develops towards miniaturization and integration. The coil type magnetic sensor has the advantages of large volume, heavy weight, slow response, low resolution, low sensitivity, poor reliability and poor anti-jamming capability. More importantly, as the financial anti-counterfeiting capacity is improved, the anti-counterfeiting mark is more weakly magnetic, so that the difficulty of counterfeiting is greatly increased, the difficulty of identifying the counterfeit is also increased, high sensitivity and reliability are required, multi-point detection, seamless detection and expansion of a detected range are required, and the existing magnetic sensor cannot meet the requirements of the market on the magnetic sensor. Therefore, there is an urgent need to develop a magnetic sensor that is compact, easy to integrate, highly sensitive, and capable of recognizing weak magnetic markers.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a magnetic detection magnetic sensor which has small volume, easy integration and high sensitivity and can be used for detecting weak magnetic marks aiming at the defects in the magnetic sensor.
To this end, the invention provides a magnetic detection magnetic sensor comprising:
the chip is used for sensing and detecting the magnetic anti-counterfeiting mark in the medium to be detected;
and the weak magnetic strengthening unit is used for pre-magnetizing the magnetic anti-counterfeiting mark so as to enable the chip to sense and detect the magnetic anti-counterfeiting mark.
The weak magnetic strengthening unit is provided with an accommodating space, the opening end of the accommodating space faces towards the medium to be detected, the chip is arranged in the accommodating space, and the induction surface of the chip faces towards the medium to be detected.
Wherein the weak magnetic strengthening unit comprises:
a permanent magnet for generating a magnetic field for pre-magnetizing the magnetic marker;
the magnetizer is overlapped on the permanent magnet and comprises at least one magnetic conduction arm extending towards the medium to be detected, and the accommodating space is arranged close to the magnetic conduction arm.
The magnetizer comprises two magnetic conduction arms extending towards the medium to be detected, and the accommodating space is arranged between the two magnetic conduction arms.
The magnetic guide arm is perpendicular to the detection surface of the medium to be detected, so that the direction of the magnetic field generated by the permanent magnet is perpendicular to the detection surface of the medium to be detected.
The permanent magnet is made of neodymium iron boron, samarium cobalt, aluminum nickel cobalt, ferrite, permalloy or silicon steel sheet.
The accommodating space is a blind hole or a through hole arranged on the magnetizer.
Wherein the weak magnetic strengthening unit comprises:
the winding is used for generating a magnetic field for pre-magnetizing the magnetic anti-counterfeiting mark;
a power supply for supplying electrical energy to the winding;
and the magnetizer enables the magnetic field generated by the winding to be vertical to the induction surface of the chip.
The magnetizer comprises a magnetizer body and at least two magnetizer arms, wherein the magnetizer arms are symmetrically arranged along the periphery of the magnetizer body;
the chip is arranged between the magnetic guide arms, and the induction surface of the chip faces to the medium to be detected;
each magnetic conduction arm corresponds to one winding, and each winding is correspondingly sleeved on the outer side of one magnetic conduction arm.
The magnetizer comprises a magnetizer body and two magnetizer arms, wherein the magnetizer is arranged on two sides of the magnetizer body in an opposite mode.
The magnetizer comprises a magnetizer body and a supporting part arranged at the end part of the magnetizer body, and the winding is sleeved outside the magnetizer body;
the chip is arranged on the supporting part.
The chip comprises at least one pair of magnetic sensitive films and bonding pads electrically connected with the magnetic sensitive films, and the magnetic sensitive films are connected into a Wheatstone bridge circuit by means of the bonding pads and wires.
Wherein each magnetic sensitive film is a continuous magnetic sensitive film; or,
each magnetic sensitive film comprises a plurality of magnetic sensitive film sections and a conductor connected with the magnetic sensitive film sections.
The magnetic sensitive film comprises a magnetic sensitive film, wherein n inhibition units for inhibiting the demagnetization field of the magnetic sensitive film in a segmented manner are arranged in the length direction of the magnetic sensitive film, the inhibition units are arranged on the surface and/or inside the magnetic sensitive film at intervals, and n is an integer larger than or equal to 2.
Wherein the inhibiting unit is a notch, an electric conductor, a heating body, a heat insulator or a hard magnet.
And the direction of the magnetic force line of the weak magnetic strengthening unit is vertical to the pinning direction of the magnetic sensitive film.
The magnetic sensitive film is a Hall effect film, an anisotropic magnetoresistance film, a giant magnetoresistance film, a tunnel magnetoresistance film, a giant magnetoresistance film or a giant Hall effect film.
Wherein, the device comprises a shell, a circuit board, a processing unit and welding pins, wherein,
the circuit board is electrically connected with the chip and is used for transmitting the differential signal obtained by the chip;
the processing unit is used for distinguishing the anti-counterfeiting mark according to the differential voltage signal;
the chip and the circuit board are arranged in the shell; the processing unit is arranged in the shell or outside the shell;
the welding pins are electrically connected with the circuit board and used for transmitting signals and supporting the shell.
The shell is provided with a magnetic conduction hole, and the chip is opposite to the magnetic conduction hole.
Wherein, the shell is made of copper, aluminum or oxide or plastic thereof.
Wherein the shell is made of permalloy, ferrite or selenium steel sheet; or, the metal material or the nonmetal material is adopted for manufacturing, and the chromium, the nickel iron or the permalloy plating layer is plated on the outer surface of the metal material or the nonmetal material.
The invention has the following beneficial effects:
the magnetic detection magnetic sensor provided by the invention comprises a weak magnetic strengthening unit, wherein when a medium to be detected is detected, the magnetic strengthening unit generates a magnetic field perpendicular to a detection surface of the medium to be detected, so that a weak magnetic anti-counterfeiting mark is pre-magnetized, the pre-magnetized weak magnetic anti-counterfeiting mark can generate the magnetic field, a chip induces the magnetic field generated by the weak magnetic anti-counterfeiting mark and obtains a differential output signal, the amplitude and waveform of the differential output signal correspond to the weak magnetic anti-counterfeiting mark, and the authenticity of the medium to be detected can be identified according to the amplitude and waveform of the differential output signal. In addition, the weak magnetic strengthening unit has good anti-interference capability, so that the reliability of the weak magnetic detection magnetic sensor can be improved.
Drawings
Fig. 1 is a structural view of a magnetic sensor currently used in the financial field;
FIG. 2a is a block diagram of a magnetic sensor for magnetic detection in accordance with an embodiment of the present invention;
FIG. 2b is an exploded view of a magnetic sensor for magnetic detection according to an embodiment of the present invention;
FIG. 2c is a partial schematic view of a magnetic sensor for magnetic detection according to an embodiment of the present invention;
FIG. 2d is a partial schematic view of another magnetic sensor of the present invention;
FIG. 3 is a diagram illustrating a state of use of a magnetic sensor for magnetic detection according to an embodiment of the present invention;
FIG. 4a is a diagram of a chip according to an embodiment of the present invention;
FIG. 4b is a partial block diagram of another chip according to an embodiment of the present invention;
FIG. 4c is a partial block diagram of another chip according to an embodiment of the present invention;
FIG. 5a is an exploded view of a magnetic sensor for magnetic detection according to another embodiment of the present invention;
FIG. 5b is a partial block diagram of another magnetic sensing magnetic sensor in accordance with an embodiment of the present invention;
FIG. 6 is a schematic diagram of a portion of a magnetic sensor of the present invention;
FIG. 7a is a cross-sectional view of a magnetic sensor for magnetic detection according to yet another embodiment of the present invention;
FIG. 7b is a cross-sectional view of another magnetic sensing magnetic sensor in accordance with an embodiment of the present invention;
FIG. 8a is an exploded view of a magnetic sensor for magnetic detection according to yet another embodiment of the present invention
FIG. 8b is a cross-sectional view of another magnetic sensing magnetic sensor in accordance with an embodiment of the present invention;
FIG. 8c is a cross-sectional view of yet another magnetic sensing magnetic sensor in accordance with an embodiment of the present invention.
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the following describes the magnetic detection magnetic sensor provided in the present invention in detail with reference to the accompanying drawings.
Fig. 2a is a structural diagram of a magnetic sensor according to an embodiment of the present invention, and fig. 2b is an exploded view of the magnetic sensor according to the embodiment of the present invention. As shown in fig. 2a and 2b, the magnetic detection magnetic sensor includes a housing 11, a chip 12, a circuit board 13, a field weakening unit 14, a processing unit (not shown in the figure), and a bonding pin 15. The chip 12 is used for sensing the anti-counterfeit mark in the medium to be detected and obtaining a differential signal, wherein the anti-counterfeit mark comprises a weak magnetic anti-counterfeit mark and/or a strong magnetic anti-counterfeit mark. The strong magnetic anti-counterfeiting mark can generate a magnetic field, and the weak magnetic anti-counterfeiting mark does not generate the magnetic field or generates a weak magnetic field. Therefore, if the weak magnetic anti-counterfeit mark is to be detected by the chip 12, the weak magnetic anti-counterfeit mark needs to be pre-magnetized to generate a magnetic field that can be induced by the chip 12. The weak magnetic strengthening unit 14 can pre-magnetize the weak magnetic anti-counterfeiting mark, and enable the weak magnetic anti-counterfeiting mark to generate a magnetic field in a short time, and the chip 12 senses and detects the magnetic field of the pre-magnetized weak magnetic anti-counterfeiting mark.
The chip 12, the circuit board 13 and the weak magnetic reinforcing unit 14 are arranged in the shell 11. The chip 12 is electrically connected to the bonding pins 15 via the wiring board 13. The processing unit is used for distinguishing the anti-counterfeiting mark according to the differential voltage signal, can be arranged in the shell 11, also can be arranged outside the shell 11, and is used for distinguishing the authenticity, the size or the strength of the anti-counterfeiting mark according to the differential signal output by the chip 12, so that the authenticity of the medium to be detected is distinguished.
In this embodiment, the circuit board 13 is a hard circuit board, the chip 12 is fixed on the hard circuit board, and the signal output end of the chip 12 is electrically connected to a conductive circuit disposed on the hard circuit board and electrically connected to the soldering pin 15 through the conductive circuit on the hard circuit board. If the processing unit is arranged in the housing 11, the welding pins 15 are used for transmitting the processing result obtained by the processing unit; the bonding pins 15 are used to transmit the differential signals obtained by the chip 12 if the processing unit is located outside the housing 11. The welding pins 15 may also be used to support the housing 11.
Of course, the circuit board 13 may also be a flexible circuit board, as long as the differential signal of the chip 12 can be output, and the object of the present invention can also be achieved.
FIG. 2c is a partial schematic view of a magnetic sensor according to an embodiment of the present invention. As shown in fig. 2b and 2c, the weak magnetic strengthening unit 14 includes a permanent magnet 141 and a magnetizer 142. The permanent magnet 141 is used for generating a magnetic field of the pre-magnetization weak magnetic mark and is made of a rare earth permanent magnet material such as neodymium iron boron, samarium cobalt or aluminum nickel cobalt, or made of a permanent magnet material such as sintered ferrite, bonded ferrite or injection-molded ferrite, or made of permalloy or silicon steel sheets. Two magnetic conduction arms 144 which are oppositely arranged are arranged on the magnetizer 142, the magnetic conduction arms 144 extend towards the medium to be detected, and an accommodating space for accommodating the chip 12 is formed between the two magnetic conduction arms 144. The chip 12 and the circuit board 13 are disposed in the accommodating space 143, and the sensing surface of the chip 12 is lower than the upper surface of the magnetic conductor 142, i.e., the sensing surface of the chip 12 is lower than the top end of the magnetic conductor arm 144, so that the chip 12 and the circuit board 13 are embedded in the accommodating space 143. The magnetizer 142 is overlapped with the permanent magnet 141, and the magnetizer 142 is located at a side close to the medium to be detected, and the magnetic arm 144 of the magnetizer 142 faces the medium to be detected, so that the opening of the accommodating space 143 faces the medium to be detected.
The magnetizer 142 has a high magnetic permeability, so that the magnetic lines of the magnetic field of the permanent magnet 141 can be transmitted along the matrix, that is, the matrix is transmitted to the medium to be detected along the two opposite magnetic guide arms 144, so as to magnetize the medium to be detected and enable the medium to have the magnetic field, so that the medium to be detected is magnetized on one hand, and the accommodating space 143 between the two opposite magnetic guide arms 144 forms a magnetic vacuum region on the other hand, thereby reducing the interference of other external magnetic fields on the chip 12, effectively suppressing or even eliminating noise interference such as electric signals or magnetic signals in the surrounding environment, and further improving the signal-to-noise ratio and sensitivity of the magnetic sensor.
Preferably, the magnetic arm 144 is perpendicular to the detection surface of the medium to be detected, so that the direction of the magnetic field generated by the permanent magnet 142 is perpendicular to the detection surface of the medium to be detected, which is more beneficial to pre-magnetizing the weak magnetic anti-counterfeit mark.
Although it is disclosed above that the magnetic conductor 141 includes two magnetic conductive arms 144, the magnetic conductor 141 of the present embodiment may be provided with only one magnetic conductive arm 144, and the accommodating space 143 for placing the chip 12 is provided next to the magnetic conductive arm 144. When the magnetic conduction device is used, the magnetic conduction arm 144 firstly slides over the anti-counterfeiting mark to pre-magnetize the weak magnetic anti-counterfeiting mark, and then the chip 12 slides over the anti-counterfeiting mark to detect the magnetic field of the weak magnetic anti-counterfeiting mark. Of course, the magnetic conductor 141 may be provided with three or more magnetic conductive arms 144 as long as the accommodating space 143 where the chip 12 is disposed next to the magnetic conductive arms 144.
As shown in fig. 2b, a ground terminal 18 is further provided on the housing 11, and the housing 11 is grounded via the ground terminal 18. The housing 11 is made of a non-magnetic material such as copper, aluminum, or an oxide thereof, or is made of plastic.
Fig. 2d shows a partial schematic view of another magnetic detecting magnetic sensor according to the embodiment of the present invention, as shown in fig. 2d, the outer circumference of the magnetizer 142 has the same size as the outer circumference of the permanent magnet 141, so that the magnetic lines of force of the magnetizer 142 are mainly concentrated right below the permanent magnet 141 to reduce the magnetic field strength around the permanent magnet 141. Of course, the outer dimension of the magnetizer 142 is smaller than the outer dimension of the permanent magnet 141, and the magnetic field strength around the permanent magnet 141 can be the same. Therefore, the magnetic field of the magnetizer 142 is restrained at the magnetic conduction arm 144 by the permanent magnet 141 as much as possible, the magnetic field strength of the position of the magnetic conduction arm 144 is enhanced, the pre-magnetization weak-magnetic anti-counterfeiting mark is facilitated, the influence of other external magnetic fields (the magnetic fields except the anti-counterfeiting mark) can be reduced, and the sensitivity of the magnetic detection magnetic sensor is improved. Therefore, in practical applications, a chip-type magnetic sensor in which the outer peripheral dimension of the magnetic conductor 142 is smaller than or equal to the outer peripheral dimension of the permanent magnet 141 is preferable.
FIG. 3 is a diagram illustrating a state of use of a magnetic sensor according to an embodiment of the present invention. The medium to be detected is a banknote 50, and a strong magnetic anti-counterfeiting mark and a weak magnetic anti-counterfeiting mark are arranged in the banknote 50. As shown in fig. 3, since the chip 12 is disposed in the concave portion 143, the magnetic conductive arm 144 concentrates the magnetic field B of the permanent magnet 141 toward the front end and the rear end (both right and left sides) of the chip 12. When the magnetic detection magnetic sensor 40 is scratched from the surface of the banknote 50, or when the banknote 50 is scratched from the surface of the magnetic detection magnetic sensor 40, the weak magnetic anti-counterfeiting mark is pre-magnetized by the magnetic field B of the permanent magnet 141, the pre-magnetized weak magnetic anti-counterfeiting mark generates a magnetic field which can be induced by the chip 12, the chip 12 induces the magnetic field of the weak magnetic anti-counterfeiting mark to obtain a differential output signal, the amplitude and waveform of the differential output signal correspond to the weak magnetic anti-counterfeiting mark, and the authenticity of the banknote 50 can be identified according to the amplitude and waveform of the differential output signal.
FIG. 4a is a diagram of a chip according to an embodiment of the invention. As shown in fig. 4a, the chip 12 includes a support 121, a pair of magnetically sensitive films 122 and pads 123, and the magnetically sensitive films 122 and the pads 123 are disposed on a surface of the support 121. The bonding pad 123 is electrically connected to the magnetically sensitive film 122, and the bonding pad 123 is used for electrically connecting the magnetically sensitive film 122 to a wiring such as the wiring board 13. The chip 12 formed by the magnetic sensitive film has small volume, easy integration and high sensitivity.
Specifically, the chip 12 includes two continuous and uninterrupted magnetic sensitive films 122a and 122b and three bonding pads 123a, 123b and 123c, where the first bonding pad 123a is disposed at the head end of the first magnetic sensitive film 122a, the second bonding pad 123b is disposed at the tail end of the first magnetic sensitive film 122a and the tail end of the second magnetic sensitive film 122b, and the third bonding pad 123c is disposed at the head end of the second magnetic sensitive film 122 b. The magneto-sensitive films 122a, 122b can be connected in a Wheatstone half-bridge circuit using the wiring board 13 and the pads 123a, 123b, 123 c. The chip 12 is magnetically induced to produce a differential output signal. Preferably, the magnetic field lines of the weak magnetic strengthening units 14 run perpendicular to the pinning direction of the magnetic sensitive films 122a and 122b to avoid the influence of the weak magnetic strengthening units 14 on the chip 12.
In this embodiment, the chip 12 may also include three or four or more magnetically sensitive films, that is, the chip 12 should include at least one pair of magnetically sensitive films and electrically connect the magnetically sensitive films to form a wheatstone half-bridge circuit or a wheatstone full-bridge circuit. The magnetic sensitive film 122 is a hall effect film, an anisotropic magnetoresistance film, a giant magnetoresistance film, a tunneling magnetoresistance film, a giant magnetoresistance film, or a giant hall effect film.
In addition, the magnetic sensitive film of the embodiment can adopt a continuous magnetic sensitive film or a discontinuous magnetic sensitive film. As shown in FIG. 4b, the magnetically sensitive film 122 includes a plurality of magnetically sensitive film segments 125, and the magnetically sensitive film segments 125 are electrically connected by conductors 126.
Fig. 4c is a partial structural diagram of another chip according to an embodiment of the invention. As shown in fig. 4c, n suppression units 127 for suppressing the demagnetizing field of the magnetic sensitive thin film 122 in a segmented manner are arranged in the length direction of the magnetic sensitive thin film 12, and the suppression units 127 are arranged on the surface and/or inside the magnetic sensitive thin film 122 at intervals, where n is an integer greater than or equal to 2. The suppressing unit 127 may be a slit, an electric conductor, a heating body, a heat insulator, or a hard magnet.
Fig. 5a is an exploded view of a magnetic sensor according to another embodiment of the present invention, and fig. 5b is a partial structural view of the magnetic sensor according to another embodiment of the present invention. As shown in fig. 5a, the magnetic detection magnetic sensor includes a housing 11, a chip 12, a circuit board 13, a field weakening unit 14, a processing unit (not shown in the figure), and a bonding pin 15. The structures of the housing 11, the chip 12, the circuit board 13, the processing unit and the bonding pins 15 are the same as those of the above embodiments, and are not described herein again. The present embodiment is different from the above-described embodiments in the structure of the weak magnetic reinforcing unit 14.
As shown in fig. 5b, the flux weakening unit 14 includes a permanent magnet 141 and a magnetizer 142, and the magnetizer 142 is stacked on the permanent magnet 142. The permanent magnet 141 is used for generating a magnetic field of the pre-magnetization weak magnetic mark and is made of a rare earth permanent magnet material such as neodymium iron boron, samarium cobalt or aluminum nickel cobalt, or made of a permanent magnet material such as sintered ferrite, bonded ferrite or injection-molded ferrite, or made of permalloy or silicon steel sheets. The magnetizer 142 is provided with a through hole 145, so that the magnetizer 142 forms a magnetizer with an annular structure. The accommodation space is formed in the through hole 145, and the chip 12 and the wiring board 13 are placed in the through hole 145. The action of the magnetizer 142 with the annular structure is similar to that of the magnetizer arm, the permeability of the magnetizer 142 is very high, and the magnetic lines of force of the magnetic field of the permanent magnet 141 can be transmitted along the matrix of the magnetizer, namely, the magnetic lines of force are transmitted to the medium to be detected through the matrix, so that the medium to be detected is magnetized and has the magnetic field, and the medium to be detected is magnetized; on the other hand, a magnetic vacuum region is formed in the through hole 145, so that interference of other external magnetic fields on the magnetic sensor can be reduced, noise interference such as electric signals or magnetic signals in the surrounding environment can be effectively inhibited or even eliminated, and the signal-to-noise ratio and sensitivity of the magnetic sensor can be improved.
It should be noted that the through hole 145 provided on the magnetic conductor 142 may also be replaced by a blind hole, that is, a concave pit is provided on the magnetic conductor 142, which can also achieve the object of the present invention.
Fig. 6 is a partial structural view of a magnetic sensor according to an embodiment of the present invention. As shown in fig. 6, the main difference between the present embodiment and the previous embodiment is: the weak magnetic strengthening unit 14 is disposed between the two magnetically sensitive films 122 of the chip 12. In fig. 6, an arrow indicates a pinning direction of the magnetically sensitive thin film 122. Preferably, the magnetic field lines of the weak magnetic strengthening units 14 run perpendicular to the pinning direction of the magnetic sensitive film 122 to avoid the influence of the weak magnetic strengthening units 14 on the chip 12 (if not perpendicular, the chip 12 is easily saturated by the influence of the weak magnetic strengthening units 14). In the present embodiment, the weak magnetic strengthening unit 14 may be a permanent magnet, a coil, or other components capable of generating a magnetic field. The weak magnetic strengthening unit 14 can be placed in any manner, for example, the N pole of the weak magnetic strengthening unit 14 is arranged on the side close to the medium to be detected, or the S pole of the weak magnetic strengthening unit 14 is arranged on the side close to the medium to be detected.
FIG. 7a is a cross-sectional view of a magnetic sensor for magnetic detection according to yet another embodiment of the present invention. As shown in fig. 7a, the magnetic detection magnetic sensor includes a housing 11, a chip 12, a circuit board 13, a field weakening unit 14, a processing unit (not shown in the figure), and a bonding pin 15. The other structures of the magnetic detection magnetic sensor except for the weak magnetic reinforcing unit 14 are the same as those of the above-described embodiment, and are not described again.
The flux weakening unit 14 comprises a magnetizer 142, a winding 147 and a power source (not shown), wherein the power source provides power to the winding 147, and the winding 147 is used for generating a magnetic field. The magnetizer 142 includes a magnetic conductive body 41 and two magnetic conductive arms 42, and the two magnetic conductive arms 42 are oppositely disposed on two sides of the magnetic conductive body 41. Each magnetic conductive arm 42 corresponds to a winding 147, and the winding 147 is sleeved outside the magnetic conductive arm 42. The magnetic conductor 142 causes the magnetic field S generated by the windings 147 to concentrate on the magnetic arms 42 and form a magnetic vacuum region in the receiving space between the magnetic arms 42. The chip 12 and the circuit board 13 are arranged in the accommodating space, and the sensing surface of the chip 12 faces to a medium to be detected. The magnetic field of the winding 147 passes through the magnetic guide arm 42, so that on one hand, the weak magnetic anti-counterfeiting mark is pre-magnetized; on the other hand, a magnetic vacuum area is formed in the accommodating space, so that the interference of other external magnetic fields on the magnetic sensor can be reduced, the noise interference of electric signals or magnetic signals and the like in the surrounding environment can be effectively inhibited or even eliminated, and the signal-to-noise ratio and the sensitivity of the magnetic sensor can be improved. Preferably, the magnetic field generated by the winding 147 is perpendicular to the sensing surface of the chip 12, which is more beneficial to pre-magnetization of the weak magnetic anti-counterfeiting mark and improves the magnetic vacuum of the accommodating space.
The magnetic conductive body 41 may further include a plurality of magnetic conductive arms 42, and the plurality of magnetic conductive arms 42 are symmetrically disposed along the periphery of the magnetic conductive body 41. Each magnetic conductive arm 42 corresponds to a winding 147, and each winding 147 is correspondingly sleeved outside one magnetic conductive arm 42. When the magnetic sensor is used, the chip 12 is arranged in the accommodating space, the sensing surface of the chip 12 faces to a medium to be detected, and the interference of other external magnetic fields on the magnetic sensor can be reduced, so that the noise interference of electric signals or magnetic signals and the like in the surrounding environment can be effectively inhibited or even eliminated, and the signal-to-noise ratio and the sensitivity of the magnetic sensor can be improved.
FIG. 7b is a cross-sectional view of a magnetic sensor for magnetic detection according to yet another embodiment of the present invention. As shown in fig. 7b, the field weakening detection magnetic sensor includes a case 11, a chip 12, a circuit board 13, a field weakening reinforcing unit 14, a processing unit (not shown in the figure), and a bonding pin 15. The other structures of the weak magnetic detection magnetic sensor except for the weak magnetic reinforcing unit 14 in this embodiment are the same as those in the above embodiments, and are not described herein again.
The flux weakening unit 14 comprises a magnetizer 142, a winding 147 and a power source (not shown), wherein the power source provides power to the winding 147, and the winding 147 is used for generating a magnetic field. The magnetizer 142 includes a magnetizer body 61 and a supporting portion 62 disposed at an end of the magnetizer body 61, the magnetizer body 61 and the supporting portion 62 form an i-shaped structure, and the winding 147 is sleeved (wound) outside the magnetizer body 61. The weak magnetic reinforcing unit 14 of the present embodiment does not form an accommodating space, and the chip 12 is disposed on the supporting portion 62. Specifically, the chip 12 is disposed on the surface of the circuit board 13, the circuit board 13 is disposed on the surface of the supporting portion 62, and the magnetic field B generated by the winding 147 is perpendicular to the sensing surface of the chip 12.
In this embodiment, the housing 11 may also be a shielding case, that is, the housing 11 is made of permalloy, ferrite or selenium steel sheet; or, the metal material or the nonmetal material is adopted for manufacturing, and the outer surface of the metal material or the nonmetal material is plated with a plating layer of nickel iron or permalloy.
Fig. 8a is an exploded view of a magnetic sensor according to yet another embodiment of the present invention. As shown in fig. 8a, the magnetic detection magnetic sensor includes a housing 11, a chip 12, a circuit board 13, a field weakening unit 14, a processing unit (not shown in the figure), and a bonding pin 15.
In this embodiment, a magnetic conductive hole 71 is formed on the housing 11, the chip 12, the circuit board 13, and the weak magnetic strengthening unit 14 are disposed in the housing 11, and the chip 12 is opposite to the magnetic conductive hole 71. The magnetic field of the anti-counterfeiting mark enters the shell 11 through the magnetic conduction hole 71 and is induced by the chip 12. Other structures of the present embodiment may adopt any of the structures of the above embodiments.
FIG. 8b is a cross-sectional view of another magnetic sensing magnetic sensor in accordance with an embodiment of the present invention. As shown in fig. 8b, the casing 11 is provided with a magnetic conduction hole 71, and the chip 12, the circuit board 13, and the weak magnetic reinforcing unit 14 are provided in the casing 11. The chip 12 is fixed on the circuit board 13, the chip 12 and the circuit board 13 are disposed in the accommodating space of the weak magnetic strengthening unit 14, and the chip 12 is opposite to the magnetic conducting hole 71.
FIG. 8c is a cross-sectional view of yet another magnetic sensing magnetic sensor in accordance with an embodiment of the present invention. As shown in fig. 8c, the casing 11 is provided with a magnetic conduction hole 71, and the chip 12, the circuit board 13, and the weak magnetic reinforcing unit 14 are provided in the casing 11. The circuit board 13 is fixed to the supporting portion 62 of the weak magnetic strengthening unit 14, the chip 12 is fixed to the circuit board 13, and the chip 12 is opposite to the magnetic conduction hole 71.
It should be noted that, in the above embodiments, different structures and use manners of the casing 11, the chip 12, the circuit board 13 and the weak magnetic strengthening unit 14 are respectively described, and in the actual use process, any combination of the different structures of the casing 11, the chip 12, the circuit board 13 and the weak magnetic strengthening unit 14 also belongs to the protection scope of the present invention.
The magnetic detection magnetic sensor provided by the embodiment comprises a weak magnetic strengthening unit, when a medium to be detected is detected, the magnetic strengthening unit generates a magnetic field perpendicular to a detection surface of the medium to be detected, so as to pre-magnetize a magnetic anti-counterfeiting mark, especially the weak magnetic anti-counterfeiting mark, the pre-magnetized weak magnetic anti-counterfeiting mark can generate a magnetic field, when a magnetic core passes through, a Wheatstone bridge in the chip induces the magnetized weak magnetic anti-counterfeiting mark and generates a differential output signal, the amplitude and the waveform of the differential output signal are in corresponding relation with the weak magnetic anti-counterfeiting mark in the medium to be detected, and the authenticity of the medium to be detected can be identified according to the amplitude and the waveform of the differential output signal. In addition, the weak magnetic reinforcing unit has good anti-interference capability, so that the reliability of the magnetic detection magnetic sensor can be improved.
It will be understood that the above embodiments are merely exemplary embodiments taken to illustrate the principles of the present invention, which is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.
Claims (21)
1. A magnetically detecting magnetic sensor, comprising:
the chip is used for sensing and detecting the magnetic anti-counterfeiting mark in the medium to be detected;
it is characterized in that the preparation method is characterized in that,
the chip is used for detecting the magnetic anti-counterfeiting mark in an induction way.
2. The magnetic detecting magnetic sensor according to claim 1, wherein a housing space is provided on the weak magnetic reinforcing unit, an open end of the housing space faces the medium to be detected, the chip is provided in the housing space, and a sensing surface of the chip faces the medium to be detected.
3. The magnetic detecting magnetic sensor according to claim 2, wherein the weak magnetic reinforcing unit includes:
a permanent magnet for generating a magnetic field for pre-magnetizing the magnetic marker;
the magnetizer is overlapped on the permanent magnet and comprises at least one magnetic conduction arm extending towards the medium to be detected, and the accommodating space is arranged close to the magnetic conduction arm.
4. A magnetic detecting magnetic sensor according to claim 3, wherein the magnetizer includes two magnetic conductive arms extending toward the medium to be detected, and the accommodating space is disposed between the two magnetic conductive arms.
5. A magnetic detecting magnetic sensor according to claim 3 or 4, wherein the magnetic conducting arm is perpendicular to the detection surface of the medium to be detected, so that the direction of the magnetic field generated by the permanent magnet is perpendicular to the detection surface of the medium to be detected.
6. A magnetic detecting sensor according to claim 3, wherein the permanent magnet is made of neodymium iron boron, samarium cobalt, alnico, ferrite, permalloy, or silicon steel sheet.
7. The magnetic detecting magnetic sensor of claim 2, wherein the receiving space is a blind hole or a through hole provided on the magnetic conductor.
8. The magnetic detecting magnetic sensor according to claim 1, wherein the weak magnetic reinforcing unit includes:
the winding is used for generating a magnetic field for pre-magnetizing the magnetic anti-counterfeiting mark;
a power supply for supplying electrical energy to the winding;
and the magnetizer enables the magnetic field generated by the winding to be vertical to the induction surface of the chip.
9. The magnetic detecting magnetic sensor of claim 8, wherein the magnetizer includes a magnetic conductive body and at least two magnetic conductive arms symmetrically disposed along a circumference of the magnetic conductive body;
the chip is arranged between the magnetic guide arms, and the induction surface of the chip faces to the medium to be detected;
each magnetic conduction arm corresponds to one winding, and each winding is correspondingly sleeved on the outer side of one magnetic conduction arm.
10. The magnetic detecting magnetic sensor of claim 9, wherein the magnetizer includes a magnetic conductive body and two magnetic conductive arms, and the two magnetic conductive arms are oppositely disposed at two sides of the magnetic conductive body.
11. The magnetic detecting magnetic sensor of claim 8, wherein the magnetic conductor includes a magnetic conductive body and a support portion disposed at an end of the magnetic conductive body, the winding is disposed outside the magnetic conductive body;
the chip is arranged on the supporting part.
12. A magnetic detecting magnetic sensor according to claim 1, wherein the chip comprises at least one pair of magnetically susceptible thin films and pads electrically connected to the magnetically susceptible thin films, the magnetically susceptible thin films being connected into a wheatstone bridge circuit by means of the pads and wires.
13. A magnetic detecting magnetic sensor according to claim 12, wherein each of said magnetically susceptible thin films is a continuous uninterrupted magnetically susceptible thin film; or,
each magnetic sensitive film comprises a plurality of magnetic sensitive film sections and a conductor connected with the magnetic sensitive film sections.
14. The magnetic detecting magnetic sensor according to claim 12, wherein n suppression units for suppressing the demagnetizing field of the magnetic sensitive thin film in a segmented manner are provided in the longitudinal direction of the magnetic sensitive thin film, the suppression units are provided at intervals on the surface and/or inside the magnetic sensitive thin film, wherein n is an integer not less than 2.
15. The magnetic detecting magnetic sensor of claim 14, wherein the suppression unit is a notch, an electrical conductor, a heating body, a thermal insulator, or a hard magnet.
16. The magnetic detecting magnetic sensor of claim 12, wherein the direction of the magnetic force lines of the weak magnetic reinforcing unit is perpendicular to the pinning direction of the magnetic sensitive thin film.
17. The magnetic detecting magnetic sensor according to claim 12, wherein the magnetic sensitive film is a hall effect film, an anisotropic magnetoresistive film, a giant magnetoresistive film, a tunneling magnetoresistive film, a giant magnetoresistive film, or a giant hall effect film.
18. The magnetic detecting magnetic sensor of claim 12, comprising a housing, a circuit board, a processing unit, and a soldering pin, wherein,
the circuit board is electrically connected with the chip and is used for transmitting the differential signal obtained by the chip;
the processing unit is used for distinguishing the anti-counterfeiting mark according to the differential voltage signal;
the chip and the circuit board are arranged in the shell; the processing unit is arranged in the shell or outside the shell;
the welding pins are electrically connected with the circuit board and used for transmitting signals and supporting the shell.
19. The magnetic sensing magnetic sensor of claim 18, wherein a magnetic via is provided on the housing, the chip being opposite the magnetic via.
20. The magnetic detecting magnetic sensor of claim 18, wherein the housing is made of copper, aluminum or an oxide thereof or plastic.
21. The magnetic detecting magnetic sensor of claim 18, wherein the housing is made of permalloy, ferrite or selenium steel; or, the metal material or the nonmetal material is adopted for manufacturing, and the chromium, the nickel iron or the permalloy plating layer is plated on the outer surface of the metal material or the nonmetal material.
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| CN201310034302.6A CN103971444A (en) | 2013-01-29 | 2013-01-29 | Magnetic sensor for magnetic detection |
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Application publication date: 20140806 |