JP3603872B2 - Magnetic sensor and banknote recognition device using it - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a magnetic sensor and a bill validator using the same.
[0002]
[Prior art]
In recent years, with the diversification and increase in the price of products sold in vending machines, ticket vending machines, and the like, banknote recognition devices that can use high-value banknotes other than 1,000 yen banknotes have been widely used. In particular, since the issuance of the 2,000-yen bill in July 2000, devices that can use high-value bills including the 2,000-yen bill are becoming common. On the other hand, with the advancement of OA equipment such as copiers and color printers, crimes in which counterfeit banknotes using these high-precision copying machines are being exercised are on the increase, and the identification ability of banknote identification devices is further improved. It is required to prevent crimes.
[0003]
In such a background, in a conventional bill identification device, a magnetic head is used as a sensor for detecting a characteristic of a bill for identification.
[0004]
[Problems to be solved by the invention]
However, such a conventional magnetic sensor is sensitive to a magnetic medium in close contact with the magnetic sensor, but has a certain thickness such as a banknote and has a magnetic characteristic on both sides. In addition, since the feature detection sensitivity is low, high-precision detection cannot be performed, and it has been difficult to improve the recognition accuracy of the bill validator.
[0005]
The present invention has been made to solve such a problem, and has as its object to provide a magnetic sensor having high sensitivity.
[0006]
[Means for Solving the Problems]
In order to achieve this object, a magnetic sensor according to the present invention is provided on an artificial lattice MR element provided on a front surface side of a substrate, and is mounted on a rear surface side of the substrate to derive a signal of the artificial lattice MR element. In a magnetic sensor including a wiring terminal, a magnet provided on the back surface side of the substrate, and a thin resin lid for protecting the artificial lattice MR element, the magnetic sensor includes a substrate and the wiring terminal. A holding body is formed by integrally sealing the substrate side with a resin, and the holding body has the magnet embedded therein so as to apply an auxiliary magnetic field in a direction perpendicular to the surface of the artificial lattice MR element. .
[0007]
This makes it possible to obtain a magnetic sensor having high sensitivity and capable of obtaining a stable output with respect to vibration and electrostatic discharge from the outside .
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
FIG. 1 is a sectional view of the magnetic sensor according to the first embodiment of the present invention.
[0009]
In FIG. 1, reference numeral 1 denotes an artificial lattice MR element formed on the surface of a ceramic substrate 2. As shown in FIG. 2, this artificial lattice MR element 1 has a nonmagnetic layer 3 made of Cu (copper) having a thickness of 10 ° (angstrom) to 30 ° and Ni (nickel) having a thickness of 20 ° to 40 °. ), And magnetic layers 4 formed of a mixture of Fe (iron) and Co (cobalt). It is important to stack 10 or more layers in bill identification. In the present embodiment, there are 15 layers.
[0010]
2 is a substrate formed of ceramic, and 5 is a protective film. As described above, in the artificial lattice MR element 1, the nonmagnetic layers 3 and the magnetic layers 4 are alternately stacked on the cross section, and when a magnetic field is applied in the vertical direction, the electric resistance between the magnetic layers changes. Therefore, a minute change in the magnetic field can be detected using this property.
[0011]
The multilayer film of the artificial lattice MR element 1 formed as described above is etched into the form shown in FIG. 3 to form a circuit. That is, the two artificial lattice MR elements 1a and 1b are connected in series, the connection point is connected to the conductor pattern 6a, and both ends are connected to the patterns 6b and 6c. Through holes 7a, 7b, 7c are connected to wiring terminals 8a, 8b, 8c (see FIG. 5), respectively.
[0012]
As described above, by arranging the magnetic medium sequentially before the two artificial lattice MR elements 1a and 1b, a change in magnetism can be detected with a simple circuit configuration.
[0013]
Returning to FIG. 1, reference numeral 8 denotes a wiring terminal for leading the signal of the artificial lattice MR element 1 to the outside, and is mounted on the back side of the substrate 2. And it is connected to the artificial lattice MR element 1 by a through hole 7. Reference numeral 9 denotes a holder, which integrally seals the substrate 2 and the wiring terminals 8 on the substrate 2 side with resin. Reference numeral 10 denotes a substantially rectangular concave portion that opens downward. Reference numeral 11 denotes a magnet having an outer shape that fits into the recess 10 and is embedded and mounted in the recess 10.
[0014]
The magnet 11 is located on the back side of the substrate 2 and applies an auxiliary magnetic field in a direction perpendicular to the artificial lattice MR element 1. The magnitude of the magnetic force is approximately 20 mT (millitesla). Good results can be obtained when the magnitude of the magnetic force is in the range of 15 mT to 30 mT. By applying an auxiliary magnetic field of this strength, it is possible to detect weak magnetism of magnetic printing applied to a banknote with high sensitivity.
[0015]
The magnet 11 is formed of a material in which ferrite magnetic powder is dispersed and mixed in a resin base or a rubber base. Therefore, processing becomes easy.
[0016]
Reference numeral 12 denotes a bill facing the artificial lattice MR element 1. In FIG. 1, the artificial lattice MR elements 1a and 1b are collectively expressed as an artificial lattice MR element 1. Similarly, the pattern 6 is a combination of the patterns 6a, 6b, 6c, the through hole 7 is a combination of the through holes 7a, 7b, 7c, and the wiring terminal 8 is the wiring terminals 8a, 8b, 8c. It is expressed collectively.
[0017]
As described above, the magnetic sensor 13 shown in FIG. 1 is housed in the resin case 15 and becomes the magnetic sensor 27. FIG. 4 is a partially crushed side view, FIG. 5 is a partially crushed front view, and FIG. 6 is an assembly view. 4 and 5, reference numeral 15 denotes a resin case, and reference numeral 16 denotes a thin resin cover that covers the opening 15a of the case 15. The lid 16 protects the artificial lattice MR element 1. Since the lid 16 is made of a liquid crystal polymer, the strength can be obtained even if it is thin. Therefore, the thickness is set to about 0.15 mm to minimize the decrease in sensitivity.
[0018]
The lid 16 can be mass-produced by injection molding, and does not need to be plated like a metal case to prevent corrosion and improve abrasion resistance, and can be configured at low cost.
[0019]
Reference numeral 17 denotes a hole formed on the side surface of the lid 16, which engages with a claw 18 provided on the case 15 to lock the lid 16 by snap fitting. Since both the case 15 and the lid 16 are made of resin, they can be easily attached with one touch by elastic deformation. Further, since there is no exposed conductive portion near the bill transport surface, electrostatic discharge is suppressed.
[0020]
Reference numeral 19 denotes a claw provided on the case 15, which is provided on the side opposite to the opening side 15 a and penetrates a hole 21 provided on the printed wiring board 20 so that the case 15 is elastically attached to the printed wiring board 20. It is locked. Reference numeral 22 denotes a boss provided integrally on the rear side of the case 15, and is firmly fixed to the printed wiring board 20 by screws 23. In FIG. 6, reference numeral 24 denotes a convex portion provided on the claw 19 side of the case 15 and is used for fitting and fixing the position in a concave portion 25 provided in the printed wiring board 20.
[0021]
28 is a gap formed between the holder 9 and the printed wiring board 20. The first circuit (amplifying circuit) into which a signal output from the artificial lattice MR element 1 is input is provided in the gap 28. Therefore, the wiring of a minute signal level can be shortened, which is a good measure against external noise. Reference numeral 26 denotes a groove provided on the boss portion 22 side of the case 15, and the wiring terminal 8 is inserted therein.
[0022]
FIG. 6 is an assembly view, in which the magnetic sensor 13 is housed in the case 15 and the lid 16 is covered. Then, the nail 19 is inserted into the hole 21 of the printed wiring board 20. The boss portion 22 is fastened to the printed wiring board 20 with a screw 23.
[0023]
As described above, the magnetic sensor 27 according to the present embodiment has high sensitivity because the artificial lattice MR element 1 is used. Further, since the magnet 11 for applying the auxiliary magnetic field in the direction perpendicular to the surface of the artificial lattice MR element 1 is provided, this magnetic sensor 27 can be used for a bill validator, and the recognition accuracy of the bill validator is improved. be able to.
[0024]
Further, since the magnet 11 is buried in the concave portion 10 formed in the holding body 9, the position of the magnet 11 is fixed, and a stable output against vibration or the like is obtained.
[0025]
Furthermore, since the holding body 9 is housed in the resin case 15, the intrusion of electrostatic discharge from the outside is suppressed, and the management of parts becomes easy.
[0026]
Further, since the wiring terminals 8 are fixed by the grooves 26, the insertion of the wiring terminals 8 into the printed wiring board 20 is facilitated.
[0027]
Next, the bill validator will be described. FIG. 7 is a cross-sectional view of the bill validator using the magnetic sensor 27 according to the present embodiment described with reference to FIGS. In FIG. 7, reference numeral 31 denotes an insertion slot for the bill 12, and a passage 32 for the bill 12 is connected to the insertion slot 31. The magnetic sensor 27 according to the present embodiment is mounted on the wall of the passage 32. The passage 32 is provided with a conveying means including a pulley 33 and a belt 34. Reference numeral 35 denotes a roller for holding the bill, and reference numeral 36 denotes an exit of the bill 12 provided at the end of the passage 32.
[0028]
FIG. 8 is a block diagram of a bill discriminating apparatus using the magnetic sensor 27 according to the present embodiment. In FIG. 8, the magnetic sensor 27 has two artificial lattice MR elements 1a and 1b having substantially the same performance connected in series on the substrate 2 and connected between the power supply 40 and the ground. The two artificial lattice MR elements 1a and 1b are arranged in this order in the traveling direction of the bill.
[0029]
The pattern 6a, which is a connection point between the artificial lattice MR elements 1a and 1b, is connected to the input of the amplification circuit 41. The output of the amplifying circuit 41 is input to a sample and hold circuit 42, and the output is connected to a discriminating circuit 45 in a microcomputer 44 via an A / D conversion circuit 43. A sampling signal circuit 46 is connected to the sample hold circuit 42 and the A / D conversion circuit 43. Reference numeral 47 denotes a memory in which the discrimination data of the bill 12 and the like are stored.
[0030]
The operation of the banknote recognition device configured as described above will be described below. First, the artificial lattice MR element 1a of the magnetic sensor 27 detects the magnetism of the magnetic substance attached to the banknote 12, and lowers the electrical resistance of the artificial lattice MR element 1a. Therefore, at this time, the voltage at the connection point 6a increases.
[0031]
Next, the magnetism of the magnetic material attached to the bill 12 is detected together with the artificial lattice MR elements 1a and 1b. At this time, the electric resistances of the artificial lattice MR elements 1a and 1b both decrease, and the voltage at the connection point 6a becomes half of the voltage of the power supply 40.
[0032]
Next, the magnetism of the magnetic material attached to the bill 12 leaves the artificial lattice MR element 1a and is detected only by the artificial lattice MR element 1b. Then, the electric resistance of the artificial lattice MR element 1a increases, the electric resistance of the artificial lattice MR element 1b decreases, and the voltage at the connection point 6a decreases.
[0033]
When the magnetism of the magnetic substance attached to the bill 12 leaves the artificial lattice MR element 1b, the electrical resistances of the artificial lattice MR element 1a and the artificial lattice MR element 1b both increase, and the voltage at the connection point 6a returns to the original state (power supply 40). Half of the voltage).
[0034]
As described above, a characteristic signal as shown in FIG. 9 is output from the magnetic sensor 27 based on the magnitude of the magnetism of the magnetic material attached to the bill 12. This signal is amplified by the amplifier circuit 41 and then input to the sample and hold circuit 42.
[0035]
The purpose of using the sample-and-hold circuit 42 is that the signal output from the magnetic sensor 27 is a pulse-like signal with a narrow width. This is to prevent this. Therefore, the peak value of the signal is held for a certain period of time by the sample and hold circuit 42 as shown in FIG. 10, and the reading by the A / D conversion circuit 43 is ensured. The sample and hold circuit 42 holds the maximum level of the signal. After a certain period of time, the signal is read by the A / D conversion circuit 43 and reset by the signal of the sampling circuit 46. It is necessary to hold the peak value for a certain period of time longer than the sampling period of the A / D conversion circuit 43. In FIGS. 9 and 10, the horizontal axis represents time (msec), and the vertical axis represents level (mV). Next, the magnetic signal of the bill 12 is converted into a digital signal by the A / D conversion circuit 43. Next, the authenticity of the bill 12 and the type of the bill 12 are determined by the determination circuit 45.
[0036]
As described above, in the present embodiment, since the magnetic sensor 27 using the artificial lattice MR element 1 is used, it is possible to realize a banknote recognition device with high recognition accuracy.
[0037]
In addition, since the magnetic sensor 27 using the artificial lattice MR element 1 is used, the sensitivity is high, and the inserted bill 12 can be identified even if the bill 12 is inserted face down.
[0038]
The determination by the determination circuit 45 is performed based on, for example, the magnitude of the maximum value of the signal near the predetermined position of the bill 12. In this case, a highly sensitive and precise feature of the bill 12 can be extracted by the magnetic sensor 27 using the artificial lattice MR element 1, so that a bill discriminating apparatus with high identification accuracy can be realized.
[0039]
Further, it is also possible to make an identification judgment based on a ratio between a local maximum value and a local minimum value of a signal near a predetermined position of the bill 12. In this case, since the ratio between the maximum value and the minimum value is used, it is a relative comparison and has a feature that it is hardly affected by the environment.
[0040]
In the determination, it is also possible to make an identification determination using the order in which the maximum value and the minimum value of the signal output level output from the magnetic sensor 27 occur. In this case, by utilizing the time axis and the level based on the order in which the signals are generated, a bill identification device with high identification accuracy can be realized.
[0041]
Further, the discrimination can be made using the difference between the position of the peak signal output from the magnetic sensor 27 on the banknote 12, the peak signal level at this time, and the signal output level at a predetermined position. In this case, by utilizing the position and level of the signal on the banknote 12, a banknote recognition device with high identification accuracy can be realized.
[0042]
By appropriately combining the above determination methods, the identification accuracy can be further improved.
[0043]
(Embodiment 2)
In the second embodiment, a magnetic sensor is formed using four artificial lattice MR elements, and a description will be given focusing on differences from the first embodiment. Parts corresponding to those in the first embodiment are denoted by corresponding reference numerals in the hundreds, and the description is simplified.
[0044]
FIG. 11 is a plan view of the magnetic sensor according to the second embodiment. A circuit is formed by etching the multilayer film of the artificial lattice MR element 1 described in the first embodiment with reference to FIG. 2 into the form shown in FIG. That is, the four artificial lattice MR elements 101a, 101b, 101c, and 101d are connected in series to form a serial connection, and the four connection points are connected to the conductor patterns 106a, 106b, 106c, and 106d, respectively. Are connected to wiring terminals 108a, 108b, 108c, 108d through through holes 107a, 107b, 107c, 107d, respectively. That is, they are symmetrically arranged on the ceramic substrate 102 and are bridge-connected.
[0045]
In this way, in FIG. 11, by arranging the magnetic medium sequentially in front of the four artificial lattice MR elements 101a, 101b, 101c, and 101d, a change in magnetism can be detected more precisely with a simple circuit configuration. be able to.
[0046]
1, the artificial lattice MR elements 101a, 101b, 101c, and 101d are collectively expressed as an artificial lattice MR element 1. In the same manner, the pattern 6 is a combination of 106a, 106b, 106c and 106d, the through hole 7 is a combination of the through holes 107a, 107b, 107c and 107d, and the wiring terminal 8 is the wiring terminals 108a, 108b, 108c and 108d. Is expressed collectively.
[0047]
FIG. 12 is a block diagram of a bill validator using a magnetic sensor 127 according to the second embodiment. This magnetic sensor 127 is the same as the magnetic sensor 27 described in the first embodiment except that four artificial lattice MR elements 101a, 101b, 101c, and 101d are formed.
[0048]
In the magnetic sensor 127, four artificial lattice MR elements 101a, 101b, 101d, and 101c having substantially the same performance are connected in series on the substrate 102, and patterns 106c and 106b of the four connection points are connected to the power supply 40 and the ground. The patterns 106a and 106d are connected to the input of the differential amplifier 141. The four artificial lattice MR elements 101a, 101c, 101b, and 101d are arranged in this order with respect to the traveling direction of the bill. The circuit configuration after the differential amplifier circuit 141 is the same as that in FIG. 8 in the first embodiment.
[0049]
The operation of the banknote recognition device configured as described above, which is different from that of the first embodiment, will be described below.
[0050]
That is, the magnetism of the magnetic material attached to the bill 12 is detected in the order of the artificial lattice MR elements 101a, 101c, 101b, and 101d. As in FIG. 8 in the first embodiment, the voltages at the connection points 106a and 106d sequentially change, and when the magnetism of the magnetic substance attached to the bill 12 leaves the artificial lattice MR element 101d, all the voltages are restored to the original values. Return to the state. FIG. 12 shows a method of detecting a voltage change between the connection points 106a and 106d, so that the influence when external magnetic noise is applied to the magnetic sensor 127 can be reduced.
[0051]
Note that the portions simplified in description here are the same as in the first embodiment.
[0052]
【The invention's effect】
As described above, the magnetic sensor of the present invention includes a substrate, an artificial lattice MR element provided on the surface side of the substrate for detecting a magnetic medium passing through the surface side of the substrate, and an artificial lattice MR element provided on the surface side of the substrate. In order to derive the signal of, a wiring terminal mounted on the back side of the substrate, a magnet provided on the back side of the substrate, and a thin resin lid for protecting the artificial lattice MR element are provided. In the magnetic sensor, the magnetic sensor forms a holding body by integrally sealing the substrate and the wiring terminal side of the wiring terminal with a resin, and the holding body has a structure with respect to the surface of the artificial lattice MR element. The magnet is buried so as to apply an auxiliary magnetic field in the vertical direction . An artificial lattice MR element is used.A thin resin lid for protecting the surface of the artificial lattice MR element is provided. The substrate side and resin The holding member sealed in, because the embedded magnets to add an auxiliary magnetic field in a direction perpendicular to the superlattice MR element surface, sensitive, vibration and stable against static electricity discharge from external A magnetic sensor capable of obtaining an output can be obtained.
[0053]
Therefore, if this magnetic sensor is used in a bill validator , the recognition accuracy of the bill validator can be improved.
[Brief description of the drawings]
1 is a side sectional view of a magnetic sensor according to Embodiment 1 of the present invention; FIG. 2 is a sectional view of an artificial lattice MR element; FIG. 3 is a plan view of the magnetic sensor; FIG. Partial crush side view of the magnetic sensor covered [FIG. 5], Partial crush front view [FIG. 6], same assembling drawing [FIG. 7] Cross-sectional view of a bill validator using the magnetic sensor of the present invention [FIG. 8] FIG. 9 is a signal diagram output from a magnetic sensor of the bill validator. FIG. 10 is a signal diagram output from a sample and hold circuit. FIG. 11 is a magnetic sensor according to Embodiment 2 of the present invention. FIG. 12 is a block diagram of a bill discriminating apparatus using a magnetic sensor according to the second embodiment.
REFERENCE SIGNS LIST 1 artificial lattice MR element 2 substrate 8 wiring terminal 9 holder 10 recess 11 magnet

Claims (7)

A substrate, an artificial lattice MR element provided on the surface side of the substrate for detecting a magnetic medium passing through the surface side of the substrate, and a substrate of the substrate for deriving a signal of the artificial lattice MR element . In a magnetic sensor including a wiring terminal mounted on a back surface, a magnet provided on the back surface side of the substrate, and a thin resin lid for protecting the artificial lattice MR element, the magnetic sensor includes the substrate And the substrate side of the wiring terminals are integrally sealed with resin to form a holder, and the holder is provided with the magnet so that an auxiliary magnetic field is applied in a direction perpendicular to the surface of the artificial lattice MR element. Embedded magnetic sensor. The magnetic sensor according to claim 1, wherein two artificial lattice MR elements are connected in series and arranged in parallel, and both ends and connection points of the series connection body are connected to wiring terminals, respectively. The magnetic sensor according to claim 1, wherein a recess is formed in the holding portion, and a magnet is embedded in the recess. A magnetic sensor, wherein the magnetic sensor according to claim 1 is housed in a resin case, wherein the case has an opening on the artificial lattice MR element side and a groove for holding a wiring terminal. 2. The magnetic device according to claim 1, wherein the four artificial lattice MR elements are connected in series in a ring shape and arranged in parallel with each other, and four connection points of the serially connected series connection body are respectively connected to wiring terminals. Sensors. A bill insertion slot, a passage connected to the insertion slot, the magnetic sensor according to claim 1 provided on a wall of the passage, an amplifier circuit connected to the magnetic sensor, and an output of the amplifier circuit. , An A / D conversion circuit connected to the output of the sample / hold circuit, and a determination unit connected to the output of the A / D conversion circuit. And a banknote recognition device having a circuit having a time constant longer than the sampling period of the A / D conversion circuit. 7. The bill validator according to claim 6, wherein a gap is provided between the printed wiring board on which the magnetic sensor is mounted and the holder, and an amplifier circuit is arranged in the gap.

Images