JP2006127742A - Modular magnetic head for scanning magnetized strip or thread - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic head capable of supplying accurate output data. <P>SOLUTION: The core of a head for scanning a magnetized strip or thread is provided with two half cores 11 and 12 thin and long in a longitudinal direction and facing a horizontal direction. For each half core, a gap is formed in the longitudinal direction, and it is magnetically separated from the front end edges 16 and 15 of the other half core to be provided with parallel front end edges 15 and 16. Each half core is provided with a plurality of modular half core elements 20 arrayed in the longitudinal direction. Each modular half core element 20 has a front part 23 to constitute one front end edge part in the two half cores. The front part of the modular element belonging to one of the two half cores 11 and 12 is arranged in the longitudinal direction alternately with the front part of the modular element belonging to the other of the two half cores 12 and 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The invention relates to a magnetic head of the type defined in the preamble of claim 1. The magnetic head is intended to scan a code stored in a strip of magnetic material, in particular (but not exclusively) a security thread incorporated in a bank note.

  In banknotes, the security thread is arranged perpendicular to the larger side of the banknote and parallel to the smaller side of the banknote and extends the full width of the banknote. A known type of magnetic security thread can be made of a flexible and impermeable plastic material and consists of a support strip to which several regions of magnetic material such as iron oxide are attached. In order to store the code on the security thread (which clearly identifies the size or value of the banknote), different amounts of magnetic material may vary in thickness, density, or range of occupied areas, and the thread Applied to various zones.

  A recent device for verifying the authenticity of banknotes is to supply means for supplying banknotes in a direction substantially perpendicular to the magnetic security thread and to scan code stored in the security thread. And a scanning head having a “gap” that constitutes a sensing portion of the head.

  A known type of magnetic head comprises a core of magnetic material, which is a ferromagnetic metal plate and is composed of a pair of structures that are elongated in the longitudinal direction and have a substantially inverted C-shaped cross section. It is an open ring shape having a half core, and is a magnetic material core in which the rear end is in physical contact with each other in order to have magnetic continuity between the two cores. On the other hand, the front ends are spaced apart by inserting a thin sheet of magnetically non-conductive material (eg copper). As a result, the two half cores together constitute a ring that is magnetically opened at the front portion thereof by a longitudinal gap that forms the sensing portion of the head. On each half core is molded with a cover of electrically insulated material, coils are wound, and their heads are connected to respective pins located on the bottom. The whole part composed of the core and winding is buried in the synthetic resin in the screening container made of permalloy. As a result, only the front surface of the head with the gap protrudes from the shield. As is known, the passage of the magnetic security sled moving perpendicular to the gap generates a voltage that is made available at the pin to the coil by magnetic induction.

  Conventionally, a magnetic head is constructed by assembling two half cores having a length corresponding to the core of the head. This provides different punches for shearing and bending half core sheets and different molds for overmolding layers of plastic material that allow the half cores to be electrically isolated from their respective windings. Because it is necessary to do, considerable investment is required. The problem is particularly acute in the field of devices for verifying the authenticity of banknotes. In the above field, it is necessary to configure different heads each time due to the range defined by the various positions occupied by the security thread in different sized banknotes.

  It has also been proposed to produce half-cores by placing them side-by-side with another pair of modular elements that are aligned and faced laterally. The solution is that the security thread has passed through the cut between two pairs of modular elements arranged side by side, especially if the banknotes travel through the scanning device at a tilted position with respect to the longitudinal direction of the head. Sometimes it proves disadvantageous due to the fact that the electrical signal supplied to the output by the pin is weak or incomplete. To remedy this drawback, correlate and process the partial signals supplied by the various pins in order to obtain slightly complex electronics for the scanning device, i.e. data that can identify banknotes. There is a need to provide electronics that can.

  An object of the present invention is to produce a magnetic head capable of improving the above-mentioned drawbacks. In particular, it is required to produce a magnetic head capable of providing accurate output data in any length magnetic head in a simple and economical manner.

  These and other objects and advantages, which will be understood more clearly below, are achieved in accordance with the invention with a magnetic head as defined in the appended claims.

A description of preferred embodiments of the invention, but not limited thereto, will be given below with reference to the accompanying drawings.
Referring first to FIG. 1, the cores of the magnetic head 10 are 11 on the right and 12 on the left, which are elongated in the direction defined here as the longitudinal direction and have a pair of half cores facing each other laterally. Prepare.

  In this specification and claims, terms and expressions indicating position and orientation are intended to be relative to the longitudinal direction of the head. Accordingly, the expression “front side” indicates the side of the head facing the sensing portion.

  The two half-cores are generally C-shaped, opposed in cross-section, with respective rear edges 13, 14 in contact and respective front edges 15, 16 separated by a thin strip 17 of magnetically non-conductive material. Have Reference numerals 18 and 19 denote coils wound around the half cores and electrically insulated by a plastic member as will be described later.

  The schematic arrangement of the head shown in FIG. 1 is considered to be known as a whole. Therefore, in continuing the description of the specification, only those elements that are particularly relevant and interesting for the practice of the invention will be described in detail. For the manufacture of parts and elements not shown in detail, known types of magnetic head solutions may be mentioned.

  According to the invention, each half-core comprises a plurality of modular half-core elements 20 that are aligned with one another in the longitudinal direction. As shown in FIG. 2, each modular element 20 has a substantially C-shaped cross section, and is a rear portion 21 extending in the lateral direction, which constitutes the opposite half core portion, and is the same opposing modular. A rear part 21 having a free end edge 13 that contacts the free end edge 14 of the element 20, a middle part 22 substantially perpendicular to the rear part 21, and a front part having a portion 24 projecting longitudinally from one side of the middle part 22 Part 23.

  Therefore, the front part 23 is asymmetric with respect to a lateral surface passing through the centers of the rear part 21 and the intermediate part 22 (FIG. 3).

  FIG. 4 shows schematically the arrangement assembled and formed by the modular elements 20 in the head. Due to the shape of the modular element 20, two of those elements, 20a, 20b, belonging to different half-cores, are opposed to each other with the rear edges 13, 14 in contact with each other and arranged laterally. The protrusion 24 of one element (20a) protrudes oppositely in the longitudinal direction with respect to the protrusion 24 of the other element 20b. In other words, the front parts 23 of the modular elements of the half core 11 are staggered in the longitudinal direction, preferably with a half pitch, with respect to the front part 23 of the modular elements of the other half core 12. Each pair of modular elements 20a, 20b mounted side by side constitutes an open ring portion of the core of the head.

  As shown in FIGS. 7A and 7B, each modular element 20 forms a tubular portion 26 (in the illustrated example of a rectangular cross section) that includes an intermediate portion 22 and / or a rear portion 21 of the modular element 20 therein. It is inserted into the support member 25 made of plastic material and partially accommodated. One of the support members 25 is shown separately in FIGS. 5A and 5B. The cylindrical tubular portion 26 has a coil 18 (or 19) on the head portion that is electrically connected to a connection pin 27 protruding from the rear portion of the head (FIGS. 6A, 6B, and 7A, 7B). It is rolled up.

  In the preferred embodiment shown in the drawings, each support member 25 is of a modular type and is two similar supports that are capable of supporting modular half-core elements 20 that are adjacent to each other in the longitudinal direction and belong to the same half-core. A laterally adjacent support member having lateral connection means and seats 28 in the form of small indentations and protrusions for mechanical coupling to the member, and further supporting the modular element 20 belonging to the other half core Front connection means and seats 30, 31 in the form of small indentations and protrusions for mechanically connecting with each other. The front portions of the support members 25 are alternately arranged in the vertical direction with respect to the main body of the support member so as to expose the seats or the recesses 28 with which the small protrusions (not shown) protruding from the bottom surface of the horizontal surface portion 32 are engaged. A horizontal plane portion 32 is formed. The support member 25 further includes a front vertical plate portion 29 that forms a protrusion 30 and a recess 31 for mechanically connecting to the laterally opposite support member of the other half core. Preferably, the tubular portion 26 is inclined on the lateral surface and has two outer flanges 26a to contain the coil.

  The method for assembling the head according to the present invention is as follows. After the coil is wound around the cylindrical tubular portion 26 of the support member 25, the modular element 20 is passed through an opening 34 formed in the face of the support member with the intention of facing the centerline of the head. , Inserted into the support member. The certain connecting part between the intermediate part 22 and the rear part 21 remains inside the tubular part 26 of the support member. As shown in FIG. 1, the free end edge 13 of the modular element protrudes laterally from the tubular portion of the support member toward the centerline of the head. Since the front portion 23 of the modular element 20 has a lateral dimension that is greater than the lateral dimension at the opening 34 of the support member, the modular element is suspended in a stable manner on the support member at an intermediate stage of assembly (FIG. 7A). Maintained.

  The same operation is performed by inserting a plurality of modular elements 20 into the respective support members 25 provided with the coils 18 (or 19). Thereafter, some support members 25 are mechanically coupled by means of lateral connection means / seats 28 to obtain a first half-core group of a length suitable for the head to be manufactured. The foregoing operation is repeated to form a second half core group of the same length as the first. The two half core groups are then laterally connected to each other with a thin strip 17 of magnetically non-conductive material between them. The strip 17 advantageously has a series of small openings 35 for inserting the projections 30 into the recesses 31. Thereafter, as shown in FIG. 8, the assembly formed by the two half-core groups with the strip 17 interposed therebetween is placed in a conventional screening container 36 and is then used by experts in the field. As is known, it is partially immersed in the bonding resin to obtain a single block, which is then cut along line L with the core and gap counter electrodes appearing. The pin 27 is then connected to an electrical or electronic device that receives and processes the electrical signal generated in the coil by the passage of a magnetized strip or thread that slides sideways over the head.

  As can be appreciated, the present invention allows magnetic heads of any desired length to be manufactured in a modular fashion that solves the problems outlined at the outset of this specification.

  Due to the configuration of the modular element 20 (FIG. 4), any lateral line T is between the opposing lateral edges of the front part of at least one (20a or 20b) of the element parts of a pair of laterally aligned modular elements. Cross the head in a way that must be included. Each modular element is magnetically coupled to two modular elements adjacent in the longitudinal direction in the same half core. Thus, an elongated magnetized material (not shown), such as a banknote security thread, that passes laterally over the head along any horizontal line T1-T4 is always two It clearly intersects the front part of at least one modular element of one of the groups of half cores.

  In this regard, we do not want to be bound by any particular theory, but the tests performed by the Applicant have shown that the heads are at any point in their length due to the staggered arrangement of modular elements as described above. It shows that a clean electrical signal is always obtained at the pin of the coil excited by the magnetic flux due to the intersecting magnetized strips or threads. In particular, the scanned electrical signal is easily obtained even when the thread passes through a discontinuity point at the edge of two adjacent modular elements, as schematically shown by the lines T3, T4 in FIG. .

  The embodiments described and illustrated herein are to be regarded as exemplary embodiments of the magnetic head, and the present invention is not limited to the embodiments described above. As will be apparent to those skilled in the art, the present invention is capable of modifications relating to the shape and placement of parts and modifications relating to structural and functional details.

FIG. 1 is a cross-sectional view of a magnetic head according to the present invention. FIG. 2 is a perspective view of the modular element for producing the core of the head shown in FIG. 1 as seen from different angles. FIG. 3 is a perspective view of the modular element for producing the core of the head shown in FIG. 1 as seen from different angles. FIG. 4 is a view in the direction of arrow IV shown in FIG. 1, and is a schematic view in which the modular elements shown in FIGS. 2 and 3 of the head in the assembled state are arranged. FIG. 5A is a perspective view of the modular element support member of FIGS. 2 and 3 viewed from different angles and enlarged. FIG. 5B is a perspective view of the modular element support member of FIGS. 2 and 3 viewed from different angles and enlarged. FIG. 6A is a perspective view of the support member shown in FIGS. 5A and 5B, viewed from a different angle and enlarged, with the coil wound around the support member. FIG. 6B is a perspective view of the support member shown in FIGS. 5A and 5B, viewed from different angles and enlarged, with the coil wound. FIG. 7A is a perspective view seen from a different angle and enlarged with a coil wound around the support member shown in FIGS. 5A and 5B and a modular element inserted. FIG. 7B is an enlarged perspective view of the support member shown in FIGS. 5A and 5B, viewed from different angles, with the coil wound and the modular element inserted. FIG. 8 is a perspective view of the head according to the present invention in a partially assembled state.

Claims (10)

An open ring-shaped magnetic material core having two half cores (11, 12) elongated in the vertical direction and opposed to each other in the horizontal direction and having a substantially C-shaped cross section opposite to each other. The rear half edges (13, 14) that can come into contact with the rear end edges (14, 13) of the other half core (12, 11) and the magnetic gap to form a vertical gap that constitutes the head sensing unit. A magnetized strip or thread having a parallel front end edge (15, 16) magnetically separated from the front end edge (16, 15) of the other half core by a layer (17) of non-conductive material In the magnetic head for scanning,
Each of the half cores (11, 12) has a plurality of front portions (23) arranged in the vertical direction and capable of forming the respective portions of the front end edges (15, 16) in one of the two half cores. Comprising a modular half-core element (20),
The front part (23) of the modular half-core element (20) belonging to one (11, 12) of the two half-cores is a modular half-core element (20) belonging to the other (12, 11) of the two half-cores. Alternately arranged in the longitudinal direction with respect to the front part (23) of
A magnetic head characterized by that. Each modular half-core element (20) further has a rear end edge (13, 14) that can contact the rear end edge (14, 13) of the opposing modular element (20) forming part of the opposite half core. Forming a rear part (21) extending laterally with
The front part (23) has a part (24) projecting longitudinally from one side with respect to the rear part (21), so that in the assembled state,
The rear end edge (13) of each modular half-core element (20) is in contact with the rear end edge (14) of the modular half-core element (20) belonging to the opposite half-core arranged in a substantially lateral direction,
The protrusion (24) of each modular half-core element (20) protrudes in the longitudinal direction opposite to the protrusion (24) of the modular half-core element (20) belonging to the opposite half core, The front parts (23) of the modular half-core elements (20) belonging to are arranged alternately in the longitudinal direction with respect to the front part (23) of the modular half-core elements (20) belonging to the other of the two half cores,
The magnetic head according to claim 1.   The front portions (23) of the modular half-core elements (20) are staggered in the longitudinal direction at a substantially half pitch with respect to the front portions of the modular half-core elements (20) of the other half core (12). The magnetic head according to claim 1 or 2.   Each of the modular half-core elements (20) has a substantially C-shaped cross section and is obtained by cutting and bending from a single ferromagnetic metal. head.   Magnetic field according to any one of claims 1 to 4, wherein the front part (23) having a longitudinally or laterally projecting part (24) is asymmetric with respect to a cross-section passing through the rear part (21). head.   Each modular half-core element (20) forms at least one generally tubular portion (26) wound with a coil of electrical wire (18, 19) that can be associated with a magnetic flux passing through the modular half-core element (20). The magnetic head according to claim 1, wherein the magnetic head is partially accommodated in an electrically insulated support member (25).   Each modular half-core element (20) is partially housed in a respective electrically insulated support member (25), which is adjacent to the opposite half in the longitudinal direction on the same half-core (11 or 12). The first lateral connection means (28) for mechanically coupling the support member (25) to two similar support members (25) capable of supporting the modular half-core element (20) to which it belongs. 6. A magnetic head according to 6.   Each modular half-core element (20) is partially housed in an electrically insulated support member (25), which supports the modular half-core element (20) belonging to the opposite half-core and supports the side. The magnetic head according to claim 6 or 7, wherein a second front connection means (30, 31) for mechanically coupling the support member (25) to a similar support member (25) adjacent in the direction is formed.   Modular half-core element (20) according to any of the preceding claims. Electrically insulated support member (25) according to any of claims 6 to 8, which supports a modular half-core element (20) according to any of claims 1 to 5.

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