JP6718637B1 - Magnetic head for magnetic detection of paper sheets - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic head for sheet magnetic detection capable of reducing noise components appearing in a detection waveform and disturbance of the detection waveform. SOLUTION: A magnetic head 1 for magnetic detection of paper sheets, which is arranged so as to oppose a conveyance path 2 for conveying paper sheets P and is used for magnetic detection of the paper sheets P, and opposes the conveyance path 2. The first magnetic gap 3, the loop-shaped first magnetic circuit 4 in which the first magnetic gap 3 is interposed, the second magnetic gap 5 arranged inside the first magnetic circuit 4, and the second magnetic gap 5. An intervening loop-shaped second magnetic circuit 6, a circuit overlapping section 7 in which a part of the first magnetic circuit 4 and a part of the second magnetic circuit 6 overlap, and the circuit overlapping section 7 allows the first magnetic circuit 4 and A permanent magnet 8 for exciting the two magnetic circuits 6 and a detection coil 9 for detecting magnetism flowing in the second magnetic circuit 6 inside the first magnetic circuit 4 are provided. [Selection diagram] Figure 1

Description

The present invention relates to a magnetic head for magnetic detection of paper sheets used for magnetic detection of paper sheets.

A magnetic head for magnetic detection of paper sheets used for magnetic detection of paper sheets is known (for example, refer to Patent Documents 1 and 2). For example, as shown in FIG. 6, a paper sheet having a stripe pattern printed with magnetic ink is conveyed in a direction orthogonal to the stripe while the magnetic component of the paper sheet is connected to a differential detection circuit. When read by the magnetic head for magnetic detection, a waveform as shown in FIG. 7 is obtained.

There are two types of magnetic ink: a magnetic remnant type magnetic ink that retains magnetism when magnetized, and a non-magnetic residual type magnetic ink that retains magnetism when magnetized. When ink is detected without distinction, for example, as shown in FIG. 8, a magnetic gap 101 facing the transport path, a loop-shaped magnetic circuit 102 in which the magnetic gap 101 is interposed, and an exciting coil for exciting the magnetic circuit 102 are provided. A magnetic sheet 100 for magnetic detection of paper sheets is used, which is provided with 103 (or a permanent magnet) and a detection coil 104 for detecting the magnetism flowing in the magnetic circuit 102.

The detected waveform shown in FIG. 7 is an ideal waveform. When a similar magnetic component of the paper sheet is read by the conventional magnetic head 100 as shown in FIG. 8, as shown in (a) of FIG. 9, a noise component having a hump between the rising waveform and the falling waveform is obtained. N may appear, or the detected waveform may be significantly disturbed as shown in FIG. 9B. Since the noise component N and the disturbance of the detected waveform may cause erroneous detection, it is desirable to reduce them as much as possible.

The reason why the humped noise component N appears in the detected waveform is that the magnetic flux emitted by the magnetic component of the paper sheet reaches the detection coil 104 of the magnetic head 100 for magnetic detection of the paper sheet at irregular timing. To be Further, it is considered that the large disturbance of the detected waveform is caused by the strong magnetism emitted from the magnetizing magnet or the electric motor arranged in the vicinity of the magnetic head 100 for sheet magnetic detection.

JP, 2002-202353, A JP-A-63-88697

Therefore, an object of the present invention is to provide a magnetic head for paper sheet magnetic detection capable of reducing noise components appearing in the detection waveform and disturbance of the detection waveform.

The present invention has been made in view of the above circumstances in order to solve these problems, and the invention of claim 1 is arranged so as to face a conveyance path for conveying paper sheets, A magnetic head for magnetic detection of paper sheets used for magnetic detection of paper sheets, comprising: a first magnetic gap facing the transport path; and a loop-shaped first magnetic circuit in which the first magnetic gap is interposed. A second magnetic gap arranged inside the first magnetic circuit, a loop-shaped second magnetic circuit in which the second magnetic gap is interposed, a part of the first magnetic circuit and the second magnetic circuit. Only a part of the circuit that overlaps, an excitation unit that excites the first magnetic circuit and the second magnetic circuit in the circuit overlapping part, and a magnetism that flows in the second magnetic circuit inside the first magnetic circuit And a magnetic detecting means for detecting.
The invention of claim 2 is the magnetic head for magnetic detection of paper sheets according to claim 1, wherein the exciting means is a permanent magnet interposed in the circuit overlapping portion.
The invention according to claim 3 is the magnetic head for magnetic detection of paper sheets according to claim 1, wherein the exciting means is an exciting coil wound around the circuit overlapping portion.
A fourth aspect of the present invention is the magnetic head for magnetic detection of paper sheets according to any one of the first to third aspects, wherein the magnetic detection means is provided inside the first magnetic circuit and is provided with the second magnetic element. It is a detection coil wound around a circuit.
A fifth aspect of the present invention is the magnetic head for magnetic detection of paper sheets according to any one of the first to third aspects, wherein the magnetic detection means is arranged inside the first magnetic circuit and the second magnetic circuit. It is a magnetic detection element arranged in the gap.

According to the invention of claim 1, when the magnetic component of the paper sheet straddles the first magnetic gap, the magnetism (magnetic flux density) flowing through the first magnetic circuit and the second magnetic circuit changes, so that the second magnetic circuit is By detecting the flowing magnetism with the magnetism detecting means, it becomes possible to detect the magnetic component of the paper sheet. Further, since the magnetic detection means detects the magnetism flowing through the second magnetic circuit inside the first magnetic circuit through which the magnetism always flows (at least at the time of the detection operation), the first magnetic circuit functions as a magnetic shield, and the magnetic detection means. It is possible to reduce the magnetic noise that reaches the magnetic recording medium and to improve the detection accuracy of the magnetic head for magnetic detection of paper sheets.
According to the invention of claim 2, since the exciting means is a permanent magnet interposed in the circuit overlapping portion, not only can the electric circuit be simplified as compared with the case where the exciting coil is used for excitation, but a strong magnetic field can be obtained by selecting a rare earth magnet or the like. Can be flowed into the magnetic circuit.
According to the invention of claim 3, since the exciting means is the exciting coil wound around the circuit overlapping portion, adhesion of metal powder or the like can be suppressed as compared with the permanent magnet which is always in the excited state.
According to the invention of claim 4, since the magnetic detection means is the detection coil wound around the second magnetic circuit inside the first magnetic circuit, the existing detection circuit can be used to detect the magnetic component of the paper sheet. ..
According to the invention of claim 5, since the magnetic detection means is a magnetic detection element arranged in the second magnetic gap inside the first magnetic circuit, the magnetic detection element such as a Hall element or an MR element is used for paper sheets. The magnetic component of can be detected.

FIG. 3 is a side view of the magnetic head for sheet magnetic detection according to the first embodiment of the present invention. FIG. 2 is a waveform diagram in which magnetic components of a paper sheet are read by using the magnetic head for magnetic detection of paper sheets of FIG. 1. FIG. 6 is a side view of a magnetic head for sheet magnetic detection according to a second embodiment of the present invention. It is a side view of the magnetic head for paper sheet magnetic detection which concerns on 3rd Embodiment of this invention. It is a side view of the magnetic head for paper sheet magnetic detection which concerns on 4th Embodiment of this invention. It is a figure which shows the magnetic pattern of a paper sheet. It is a figure which shows the detection waveform (ideal waveform) of FIG. FIG. 11 is a side view of a magnetic head for magnetic detection of paper sheets according to a conventional example. (A) And (b) is a figure which shows the detection waveform of the magnetic head for paper sheet magnetic detection which concerns on a prior art example.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 is a magnetic sheet magnetic detection magnetic head of the first embodiment, and the magnetic sheet magnetic detection magnetic head 1 is opposed to a conveyance path 2 for conveying a paper sheet P such as a banknote. And is used for magnetic detection of the paper sheet P. The magnetic components of the paper sheet P include magnetic ink used for forgery prevention, metal threads, and the like. The paper sheets P are not limited to banknotes, and include gift certificates, cash vouchers, tickets, tickets, checks, and the like.

The magnetic head 1 for magnetic detection of paper sheets includes a first magnetic gap 3 facing the transport path 2, a loop-shaped first magnetic circuit 4 in which the first magnetic gap 3 is interposed, and a first magnetic circuit 4 inside the first magnetic circuit 4. Circuit duplication in which a second magnetic gap 5 is arranged, a loop-shaped second magnetic circuit 6 in which the second magnetic gap 5 is interposed, a part of the first magnetic circuit 4 and a part of the second magnetic circuit 6 overlap. The part 7, the permanent magnet 8 (exciting means) for exciting the first magnetic circuit 4 and the second magnetic circuit 6 in the circuit duplication part 7, and the magnetism flowing in the second magnetic circuit 6 inside the first magnetic circuit 4 are detected. And a detection coil 9 (magnetic detection means) that operates. In the following description, the conveyance direction of the paper sheet P is the X direction, the direction orthogonal to the front and back surfaces of the conveyed paper sheet P is the Z direction, and the X direction and the direction orthogonal to the Z direction are the Y direction.

The first magnetic circuit 4 and the second magnetic circuit 6 are configured by using a core member formed of a high magnetic permeability member (for example, permalloy). In this embodiment, a pair of F-shaped core members 10 are used. Specifically, each of the pair of core members 10 extends in the X direction so as to come closer to each other from the main body 10a along the Z direction and one end of the main body 10a, and the front end surfaces thereof have the first magnetic gap. The first arm portion 10b facing each other through the third arm portion 10c and the second arm portion 10c extending in the X direction so as to come closer to each other from the intermediate portion of the main body portion 10a, and the front end surfaces facing each other through the second magnetic gap 5c. With.

A flat non-magnetic member 11 (for example, non-magnetic stainless steel) is embedded in the first magnetic gap 3 so as not to hinder the smooth conveyance of the paper sheet P. Specifically, after adhering the non-magnetic member 11 between the first arm portions 10b of the pair of core members 10, the paper sheet contact surfaces of the first arm portion 10b and the non-magnetic member 11 are polished, The leaf P can be smoothly transported.

Since the second magnetic gap 5 is arranged inside the first magnetic circuit 4 and does not contact the paper sheet P, the second magnetic gap 5 may be in a void state without embedding a non-magnetic member.

The permanent magnet 8 has an S pole at one end in the X direction and an N pole at the other end in the X direction along the X direction. One end of the permanent magnet 8 in the X direction is joined to the inner surface of the lower end of one core member 10, and the other end of the permanent magnet 8 in the X direction is joined to the inner surface of the lower end of the other core member 10. As a result, the permanent magnet 8 can excite the first magnetic circuit 4 and the second magnetic circuit 6 in the circuit overlapping portion 7 where a part of the first magnetic circuit 4 and a part of the second magnetic circuit 6 overlap. It will be possible.

The detection coil 9 is wound around the second magnetic circuit 6 inside the first magnetic circuit 4, and detects the magnetism flowing in the second magnetic circuit 6 via the second magnetic gap 5. The detection coil 9 of the present embodiment is wound over the second arm portion 10c of the one core member 10, the second magnetic gap 5, and the second arm portion 10c of the other core member 10, It may be wound around one of the second arm portions 10c.

According to the magnetic head 1 for magnetic detection of paper sheets according to the first embodiment configured in this manner, as shown in FIG. 1, the magnetism generated from the permanent magnet 8 has two magnetic gaps 3 and 5 having the same magnetic gap. It branches into the magnetic circuits 4 and 6 and flows. Here, when the paper sheet P is conveyed along the conveyance path 2 and the magnetic component of the paper sheet P straddles the first magnetic gap 3, the magnetism (magnetic flux density) flowing through the first magnetic circuit 4 and the second magnetic circuit 6 is increased. ) Changes. For example, when the magnetic component of the paper sheet P straddles the first magnetic gap 3, the magnetism flowing through the first magnetic circuit 4 increases and the magnetism flowing through the second magnetic circuit 6 decreases. By detecting this magnetic change with the detection coil 9 wound around the second magnetic circuit 6, the magnetic component of the paper sheet P can be detected.

Further, since the detection coil 9 detects the magnetism flowing in the second magnetic circuit inside the first magnetic circuit 4 in which magnetism always flows, the first magnetic circuit 4 is made to function as a magnetic shield and the magnetism reaching the detection coil 9 is detected. Noise can be reduced and the detection accuracy of the magnetic head 1 for magnetic detection of paper sheets can be improved. For example, as shown in FIG. 2, it becomes possible to provide a magnetic head 1 for magnetic detection of paper sheets, in which a hump-shaped noise component is suppressed and a detected waveform close to an ideal waveform without large disturbance is obtained.

Further, in the first embodiment, since the permanent magnet 8 excites the first magnetic circuit 4 and the second magnetic circuit 6, not only the electric circuit can be simplified as compared with the case where the excitation coil is used, but also a rare earth magnet or the like is used. By selection, strong magnetism can be made to flow in the magnetic circuits 4, 6.

Further, in the first embodiment, since the magnetic change is detected by the detection coil 9 wound around the second magnetic circuit 6 inside the first magnetic circuit 4, the existing detection circuit is used to detect the magnetism of the paper sheet P. The component can be detected.

[Other Embodiments]
Next, magnetic heads 1B to 1D for sheet magnetic detection according to second to fourth embodiments of the present invention will be described with reference to FIGS. 3 to 5. However, with respect to the configuration common to the first embodiment, the same reference numerals as those of the first embodiment are used, and the description of the first embodiment may be cited.

[Second Embodiment]
As shown in FIG. 3, in the magnetic head 1B for sheet magnetic detection according to the second embodiment, instead of the detection coil 9, a magnetic detection element disposed in the second magnetic gap 5 inside the first magnetic circuit 6. 12 is different from the first embodiment.

According to the magnetic head 1B for magnetic detection of paper sheets of the second embodiment, the magnetic component of the paper sheet can be detected by using the magnetic detection element 12 such as a Hall element or an MR element. The same effect as can be obtained. Further, since the magnetic detection element 12 can be arranged in the second magnetic gap 5, the magnetic head 1B for magnetic detection of paper sheets can be made compact as compared with the case where the detection coil 9 is wound.

[Third Embodiment]
As shown in FIG. 4, the magnetic head 1C for sheet magnetic detection according to the third embodiment has an exciting coil 13 wound around the circuit overlapping portion 7 instead of the permanent magnet 8 in the first embodiment. It is different from the form. The magnetic circuits 4 and 6 of the third embodiment can be easily configured by using an E-shaped core member 10C instead of the F-shaped core member 10 of the first embodiment.

According to the magnetic head 1C for sheet magnetic detection of the third embodiment, the exciting coil 13 excites the first magnetic circuit 4 and the second magnetic circuit 6, and therefore, the same effect as that of the first embodiment can be obtained. can get. Further, since the exciting coil 13 is energized during the detection operation, it is possible to suppress adhesion of metal powder or the like as compared with the permanent magnet 8 which is always in the excited state.

[Fourth Embodiment]
As shown in FIG. 5, the magnetic paper 1D for magnetic detection of paper sheets according to the fourth embodiment includes a magnetic detection element 12 in place of the detection coil 9 and an exciting coil 13 in place of the permanent magnet 8. This is different from the first embodiment. Even with the magnetic head 1D for sheet magnetic detection of the fourth embodiment, the same effect as that of the first embodiment can be obtained. The magnetic circuits 4 and 6 of the fourth embodiment can be easily configured by using the E-shaped core member 10C as in the third embodiment.

The present invention is not limited to the above-described embodiment, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

1, 1B, 1C, 1D Magnetic head for magnetic detection of paper sheets 2 Conveyance path 3 First magnetic gap 4 First magnetic circuit 5 Second magnetic gap 6 Second magnetic circuit 7 Circuit duplication section 8 Permanent magnet (excitation means)
9 Detection coil (Magnetic detection means)
10 core member 10a body part 10b first arm part 10c second arm part 11 non-magnetic member 12 magnetic detection element (magnetic detection means)
13 Excitation coil (excitation means)
100 Paper Sheet Magnetic Detection Magnetic Head 101 Magnetic Gap 102 Magnetic Circuit 103 Excitation Coil 104 Detection Coil P Paper Sheet

Claims (5)

A magnetic head for magnetic detection of paper sheets, which is arranged to face a conveying path for conveying paper sheets and is used for magnetic detection of paper sheets,
A first magnetic gap facing the transport path,
A loop-shaped first magnetic circuit in which the first magnetic gap is interposed,
A second magnetic gap disposed inside the first magnetic circuit;
A loop-shaped second magnetic circuit in which the second magnetic gap is interposed,
A circuit overlapping portion in which a part of the first magnetic circuit and a part of the second magnetic circuit overlap,
Exciting means for exciting the first magnetic circuit and the second magnetic circuit in the circuit duplication section,
A magnetic head for magnetic detection of paper sheets, comprising magnetic detection means for detecting only the magnetism flowing in the second magnetic circuit inside the first magnetic circuit. The magnetic head for magnetic detection of paper sheets according to claim 1, wherein the exciting means is a permanent magnet interposed in the circuit overlapping portion. The magnetic head for sheet magnetic detection according to claim 1, wherein the exciting means is an exciting coil wound around the circuit overlapping portion. The sheet magnetism according to claim 1, wherein the magnetic detection means is a detection coil wound around the second magnetic circuit inside the first magnetic circuit. Magnetic head for detection. The sheet magnetism according to any one of claims 1 to 3, wherein the magnetic detection means is a magnetic detection element disposed inside the first magnetic circuit in the second magnetic gap. Magnetic head for detection.