JP2020004021A - Magnetic detection device and magnetic detection method - Google Patents

Abstract

To provide a magnetic detection device and a magnetic detection method capable of detecting magnetic information of a printed matter conveyed by a metal drum body in a stable and highly accurate manner.SOLUTION: A magnetic detection device for detecting the magnetism of a printed matter includes: a metal drum body that rotates while holding the printed matter on a peripheral surface; a magnetic sensor that is provided facing the peripheral surface of the drum body and detects the magnetism of the printed matter; a storage part that stores an output of the magnetic sensor in a state where the drum body rotates at a first rotation speed and the printed matter is not held on the peripheral surface of the drum body as first difference calculation processing reference data; and a control part that obtains, as first detection data, an output of the magnetic sensor in a state where the drum body rotates at the first rotation speed and the printed matter is held on the peripheral surface of the drum body, and calculates magnetic data on the printed matter held on the drum body by subtracting the first difference calculation processing reference data from the first detection data.SELECTED DRAWING: Figure 8

Description

The present invention relates to a magnetic detection device and a magnetic detection method. More specifically, the present invention relates to a magnetic detection device and a magnetic detection method suitable for detecting the magnetism of a printed matter held on the peripheral surface of a rotating metal drum.

2. Description of the Related Art Conventionally, there has been known an inspection machine that prints a large number of small pieces arranged on a large-size sheet when printing paper sheets such as banknotes, and inspects the printed large-size sheet.

In addition, paper sheets such as banknotes are printed with magnetic information using magnetic ink containing a magnetic material to prevent counterfeiting.In the printing process of paper sheets, the presence or absence and quality of the printed magnetic information is checked. Need to be inspected.

Since the magnetic information printed on the printed matter is invisible to the naked eye, a magnetic sensor that detects magnetism is generally used for the inspection, and the magnetic information is acquired by the magnetic sensor. In order to perform stable and accurate inspection of magnetic information, it is necessary to reduce noise in magnetic detection by a magnetic sensor.

A first embodiment of Patent Document 1 discloses a magnetic information detecting device that detects magnetic information of a medium, and stores magnetic information regarding a transport belt as a noise component in a state where the medium is not transported in advance. In addition, there is disclosed a technique for reducing noise of magnetic information by subtracting a stored noise component from magnetic information of a medium being conveyed by a conveyance belt.

JP 2001-266205 A

However, the drum body such as the transfer cylinder of a large format sheet printing press is formed using a conductive material (electrical conductor, usually metal), so that magnetic information printed by the press is detected by a magnetic sensor. In this case, an eddy current is generated, and a magnetic field due to the eddy current, that is, an induced magnetic field is generated as noise, and a stable magnetic inspection cannot be performed. Further, since the intensity of the induction magnetic field increases with an increase in the rotation speed of the drum body, a flaw such as a flaw on the drum body or a dent on the surface of the drum body is clearly detected. In addition, the resin drum has poor processing accuracy and a large coefficient of thermal expansion, and therefore is not suitable for a large-size sheet inspection drum body that requires dimensional accuracy.

Inspection of magnetic ink printing on large-size sheets is preferably performed in a large-size sheet printing machine and performed in-line.However, a large-size sheet printing machine usually adjusts printing conditions by low-speed conveyance and finishes printing. Since the operation of increasing the transport speed is performed according to the situation, the magnetic inspection of the large format sheet requires means corresponding to a change in the printing speed, that is, the transport speed of the large format sheet.

On the other hand, in the magnetic information detecting device described in the first embodiment of Patent Document 1, only the magnetic information relating to the magnetic dust adhering to the transport belt can be deleted by the stored noise component. That is, information that is not synchronized with medium conveyance (belt movement) cannot be deleted. As described above, in the case of a magnetic inspection of a large-size sheet, an induced magnetic field noise is detected because a drum body containing a conductive material is used. Is a non-synchronized background noise. Therefore, the technology described in the first embodiment of Patent Document 1 cannot cope with induced magnetic field noise caused by the drum body.

The present invention has been made in view of the above situation, and provides a magnetic detection device and a magnetic detection method capable of detecting magnetic information of a printed material conveyed by a metal drum in a stable and highly accurate manner. It is intended to provide.

The present invention relates to a magnetic detection device for detecting the magnetism of a printed matter, comprising: a metal drum that rotates while holding the printed matter on a peripheral surface; and a magnetic drum that is provided to face the peripheral surface of the drum body. And the output of the magnetic sensor in a state where the drum body rotates at a first rotation speed and no printed matter is held on the peripheral surface of the drum body for a first difference calculation process. A storage unit for storing as reference data, and a first detection of an output of the magnetic sensor in a state where the drum body rotates at the first rotation speed and a printed material is held on a peripheral surface of the drum body. A control unit that obtains data as the data and calculates magnetic data related to the printed matter held on the drum body by subtracting the first difference calculation processing reference data stored in the storage unit from the first detection data. When Characterized in that it comprises a.

Further, according to the present invention, in the above-mentioned invention, the storage unit outputs the output of the magnetic sensor in a state where a printed material is not held on a peripheral surface of the drum body every time the rotation speed of the drum body changes. It is characterized in that it is stored as first difference calculation processing reference data.

Further, according to the present invention, in the above invention, the magnetic sensor detects an induction magnetic field of the drum body together with the magnetism of the printed matter.

Further, according to the present invention, in the above invention, the first difference calculation processing reference data includes magnetic data on the drum body.

Further, according to the present invention, in the above-mentioned invention, the storage unit may be configured so that the drum body, which does not hold a printed material on a peripheral surface, rotates at a plurality of rotation speeds different from the first rotation speed. A function of an output of the magnetic sensor corresponding to a rotation speed of the drum body calculated based on reference data which is an output of the sensor is stored, and the control unit holds a printed material on a peripheral surface based on the function. The output of the magnetic sensor when the unrotated drum body rotates at the second rotation speed is calculated as second reference data for differential calculation processing, and the output of the drum body rotating at the second rotation speed is calculated. The output of the magnetic sensor in a state where the printed matter is held on the peripheral surface is obtained as second detection data, and the second difference calculation processing reference data is subtracted from the second detection data to obtain the output. And calculates the magnetic data for the printed material is held on the arm member.

Further, according to the present invention, in the above invention, the storage unit stores the reference data.

The present invention is characterized in that, in the above invention, the control unit determines whether the printed matter has magnetism by comparing the calculated magnetic data on the printed matter with reference data for determination.

Further, according to the present invention, in the above invention, the printed matter held by the drum body is a large-sized sheet in which a plurality of small cut surfaces are arranged in a plurality of rows and a plurality of columns, and the control unit calculates the large-sized sheet. It is characterized in that it is determined whether or not one or more small cut surfaces have magnetism by comparing the magnetic data relating to the sheet with the reference data for determination in units of the small cut surfaces.

Further, in the present invention according to the above invention, the control unit may compare the calculated magnetic data on the large-sized sheet with the reference data for determination in the unit of the small cut surface to determine whether each of the small cut surfaces has magnetism. And determining whether the large-size sheet has magnetism by comparing the number of small cut surfaces determined to have magnetism with a predetermined threshold value.

Further, according to the present invention, in the above invention, the printed matter held by the drum body is a large-sized sheet in which a plurality of small cut surfaces are arranged in a plurality of rows and a plurality of columns, and the control unit calculates the large-sized sheet. The magnetic data on the sheet is divided into the small cut surfaces, and the magnetic data on two or more small cut surfaces are averaged.

Further, according to the present invention, in the above invention, the control unit averages magnetic data on a plurality of small cut surfaces in the entire large format sheet, in each of the same rows, or in each of the same columns. .

Further, according to the present invention, in the above invention, the control unit determines whether or not the two or more small cut surfaces have magnetism by comparing the averaged magnetic data with reference data for determination. And

Further, the present invention is a magnetic detection method for detecting the magnetism of a printed material by a magnetic sensor provided opposite to a peripheral surface of a drum body, wherein the drum body rotates at a predetermined rotation speed, and A difference calculation processing reference data storing step of storing an output of the magnetic sensor in a state where printed matter is not held on the peripheral surface as difference calculation processing reference data, and the drum body rotates at the predetermined rotation speed, and A detection data obtaining step of obtaining, as detection data, an output of the magnetic sensor in a state where a printed material is held on a peripheral surface of the drum body, and subtracting the difference calculation processing reference data from the detection data to obtain the drum. Calculating a magnetic data relating to the printed matter held on the body.

Also, in the present invention according to the above invention, the difference calculation processing reference data storing step stores the output detected by the magnetic sensor every time the rotation speed of the drum body changes as the difference calculation processing reference data. It is characterized by including the step of performing.

ADVANTAGE OF THE INVENTION According to the magnetic detection apparatus and magnetic detection method of this invention, the magnetic information of the printed material conveyed by a metal drum body can be detected stably and with high precision.

FIG. 2 is a schematic plan view illustrating an example of a large-sized banknote that is magnetically detected by the magnetic detection device according to the first embodiment. FIG. 3 is a schematic cross-sectional view of a test table provided in an experimental device manufactured by the present inventors. 2 shows the results of magnetic detection performed by a magnetic line sensor unit with a magnetic print medium placed on the test stand shown in FIG. 2, the detected image obtained on the left side, and the channel waveform on the broken line in the detected image on the right side. , Respectively. 3 shows how the induced magnetic field noise is removed when a magnetic printing medium is placed on the test stand shown in FIG. 2 and magnetic detection is performed. FIG. 2 is a schematic diagram of the magnetic detection device according to the first embodiment. FIG. 2 is a schematic plan view of the magnetic line sensor unit according to the first embodiment. FIG. 2 is a block diagram illustrating a configuration of a magnetic detection device according to the first embodiment. FIG. 3 is a diagram illustrating a control example of a rotation speed of a drum body according to the first embodiment. FIG. 9 is a block diagram illustrating a configuration of a magnetic detection device according to a second embodiment. FIG. 13 is a block diagram illustrating a configuration of a magnetic detection device according to a third embodiment. FIG. 14 is a schematic diagram illustrating an overview of a magnetic detection method (without determination processing) according to a third embodiment. FIG. 13 is a block diagram illustrating another configuration of the magnetic detection device according to the third embodiment. FIG. 13 is a schematic diagram illustrating an overview of a magnetic detection method (with determination processing) according to a third embodiment. It is a perspective schematic diagram of the printing apparatus of a large format banknote.

Hereinafter, preferred embodiments of a magnetic detection device and a magnetic detection method according to the present invention will be described with reference to the drawings.

Examples of the printed matter to which the present invention is applied include printed matter (hereinafter, also referred to as small pieces) such as banknotes (banknotes), checks, gift certificates, bills, forms, securities, card-like media, and small pieces of these. Can be applied to a large-size printed matter (hereinafter also referred to as a large-size sheet) in which a plurality of sheets are printed. Further, the substrate used for the printed matter targeted by the present invention is generally paper made of vegetable fiber, but for the purpose of improving durability, water resistance, security, etc., synthetic fiber is used as the material. Paper or a polymer sheet which is a sheet of synthetic resin may be used. Banknotes made from polymer sheets are called polymer banknotes. In the following, the present invention will be described with an example of a device and a method for bills.

Generally, printing of bills is performed on a large-size sheet on which a plurality of bills can be printed at the same time. Until a banknote is completed, a process of printing a common symbol on multiple banknotes, a process of inspecting the print quality of the symbol, a process of printing a different serial number for each banknote, and inspecting the print quality of the serial number And a step of cutting the large-sized sheet into bills, and a step of inspecting the cut bills (small pieces). In the following, the magnetic detection of banknotes according to the present invention will be described.However, the present invention relates to a process of inspecting the print quality of a symbol or serial number in a large format sheet and a print quality of a symbol or serial number in a small piece. And the process of inspecting

In addition, the symbol printing step and the banknote magnetic detection step according to the present invention may be performed by the same device or by different devices. Similarly, the serial number printing step and the banknote magnetic detection step according to the present invention may be performed by the same device or by different devices. For example, it may be performed by an apparatus including a printing unit that prints a symbol or a serial number and a magnetic detection device that detects magnetism of the symbol or the serial number. On the other hand, the detection may be performed by a magnetic detection device having no printing unit.

In the following, the present invention will be described by taking, as an example, a magnetic detection device for detecting the magnetism of a large-sized banknote, which is a device for printing a design or serial number for a large-sized banknote provided with a printing unit and a magnetic detection device.

<First embodiment>
The magnetic detection device according to the present embodiment is a magnetic detection device for a large-sized banknote on which a plurality of small pieces (banknotes) are printed vertically and horizontally, and is installed in a printing device for a symbol or a serial number of a large-sized banknote. Then, a magnetic image of the large bill held on the peripheral surface of the drum body of the printing device of the symbol or serial number is obtained and compared with the reference image.

As shown in FIG. 1, the large-sized banknote 110 in which magnetism is detected by the magnetic detection device according to the present embodiment is a large-sized printed matter (large-sized sheet) on which a plurality of small cut surfaces (banknote surfaces) 111 are printed vertically and horizontally. In addition, a symbol and / or serial number printed with magnetic ink is printed on each small cut surface 111 by a printing device. The serial number is a unique serial number for distinguishing banknotes one by one, and is composed of symbols such as letters and numbers. The information of the symbols themselves and the color information of those symbols are used. The banknotes are distinguished by these pieces of information.

When the visible light image of the large-sized banknote 110 is captured, the visible light image includes a pattern and / or a serial number printed with the visible light absorbing ink, and the visible light image prints the misalignment or fading thereof. Quality can be inspected. However, magnetism cannot be detected in a visible light image. Therefore, the magnetic detection device according to the present embodiment is configured to be able to acquire a magnetic image of the large format bill 110.

In this specification, a “magnetic image” refers to magnetic data acquired from a medium to be detected by a magnetic sensor, that is, an image based on the output of the magnetic sensor. The “output of the magnetic sensor” includes not only the output (magnetic data) of the magnetic sensor itself, but also general data (preferably image data) based on the output.

Here, first, the points of the present embodiment will be described.

The intensity of the induced magnetic field generated between the magnetic sensor and the metal (for example, aluminum) drum body increases as the rotation speed of the drum body increases, and sharply at the edge of the groove formed in the drum body. Increase. In addition, dents and scratches on the surface of the drum body are clearly detected. These are 100 times or more the magnetic signal of the large-sized bill 110, and have been the subject of the magnetic inspection of the large-sized bill 110.

The points of this embodiment that solve such problems are as follows.
(1) At a point in time when the rotation speed of the drum body becomes constant, a magnetic image (offset image) is acquired as reference data for difference calculation processing by a magnetic sensor in a state where the large format bill 110 is not conveyed and stored in the storage unit. After that, the large-sized banknote 110 is transported by the drum rotating at the rotation speed, and a magnetic image (detected image) is acquired as detection data by the magnetic sensor, and the difference calculation between the detected image and the preceding offset image is performed. Through the processing, magnetic data (target image) relating to the large-sized banknote 110 is obtained.
(2) The above process (1) is performed for each rotation speed of the drum body (each time the rotation speed changes).
(3) The offset image may be obtained in advance if the rotation speed of the drum body is the same.

In the above process (1),
Target image (data from which unnecessary background noise has been removed) = detected image-offset image detected image = magnetic detection signal of large bill 110 + induction magnetic field detection signal of drum body + magnetic dust detection signal offset image attached to drum body = The detection signal is the induction magnetic field detection signal of the drum body + the magnetic dust detection signal attached to the drum body.

Next, the state of generation of an induced magnetic field in the experimental device manufactured by the present inventors will be described with reference to FIGS.

As shown in FIG. 2, the test table 120 used was an aluminum plate 121 (10 mm thick) to which an iron screw 122 was fixed, and was placed on the aluminum plate 121. The two aluminum plates were welded to each other. And a magnetic printing medium 125 disposed on the aluminum plate 123. The magnetic printing medium 125 has a thickness of 10 mm.

The magnetic print medium 125 used is an experimental sample in which two large and small “500” characters are printed on a piece of paper with magnetic ink. The test table 120 is moved under the magnetic line sensor unit described below at 400 to 500 mm / sec. The magnetism was detected by the magnetic line sensor unit while moving horizontally, and a magnetic image was created from the output to obtain a detected image.

As a result, as shown in FIG. 3, in the detected image (with the magnetic printing medium), the induced magnetic field noise 126 caused by the edge of the aluminum plate 123 is large and is clearly detected. The detection signal 127 of the iron screw 122 is also detected. Further, the detection signal 128 of the welded portion 124 of the aluminum plate 123 is also slightly detected. On the other hand, the detection signal 129 of the character “500” on the magnetic print medium 125 is also detected, but is very weak.

Next, with reference to FIG. 4, a state of removal of induced magnetic field noise when detection is performed with the magnetic printing medium 125 placed on the test stand 120 will be described.

First, without disposing the magnetic printing medium 125 on the test stand 120, the magnetic detection is performed by the magnetic line sensor while moving the test stand 120 horizontally below the magnetic line sensor at the same speed as that of the detection image. A magnetic image was created from the output and used as an offset image.

As a result, as shown in FIG. 4, in the offset image (without the magnetic print medium), similarly to the detected image (with the magnetic print medium), the induced magnetic field noise 126 caused by the edge of the aluminum plate 123 is clearly detected. At the same time, the detection signal 127 of the iron screw 122 was detected, and the detection signal 128 of the welded portion 124 of the aluminum plate 123 was also slightly detected.

On the other hand, in the target image (difference image) obtained by subtracting the offset image from the detected image and amplifying, the induced magnetic field noise 126 caused by the edge of the aluminum plate 123, the detection signal 127 of the iron screw 122, and the aluminum plate 123 The detection signal 128 of the welded part 124 of the magnetic printing medium 125 could not be confirmed, and only the detection signal 129 of the character “500” of the magnetic print medium 125 could be clearly detected.

As described above, according to the present embodiment, the magnetic data relating to the large-sized banknote 110 from which unnecessary back noise (induction magnetic field noise) generated by the rotation of the metal drum is eliminated, and the large-sized banknote 110 to be conveyed is obtained. Magnetic information can be detected stably and with high accuracy.

Hereinafter, the configuration of the magnetic detection device 101 according to the present embodiment will be described.

As shown in FIG. 5, the magnetic detection device 101 according to the present embodiment is arranged such that metal drum bodies (hereinafter, simply “drums”) 10, 11, and 12 that convey large-sized bills 110 are opposed to the peripheral surface of the drum 11. A magnetic line sensor unit 20, a trigger 13 which is disposed inside the drum 11 and opposed to the magnetic line sensor unit 20 and detects the leading position of the large-size bill 110 conveyed by the drum 11, And a rotary encoder 14 connected to the

Each of the drums 10, 11, and 12 includes a cylindrical portion formed of metal (for example, aluminum), and has a surface of the cylindrical portion, that is, a peripheral surface (outer peripheral surface). Note that a part of the cylindrical portion in the circumferential direction may be missing. A holding mechanism (not shown) that holds the large-sized bill 110 is provided on the peripheral surface of each of the drums 10, 11, and 12, and is configured to be able to hold the large-sized bill 110 at a predetermined position on the peripheral surface. ing. Each of the drums 10, 11, and 12 is controlled by the magnetic detection device 101 to rotate at an arbitrary speed.

As shown in FIG. 6, the magnetic line sensor unit 20 includes a plurality of magnetic line sensors 21 arranged in a staggered manner in a main scanning direction (a direction orthogonal to the transport direction of the large format bill 110), and a plurality of magnetic lines. A housing 22 to which the sensor 21 is fixed, and a control board 23 provided in the housing 22 and controlling the magnetic line sensor 21 are provided, and detect the magnetism of the large format bill 110.

The magnetic line sensor unit 20 is arranged linearly in the axial direction of the drum 11. The detection width of the magnetic line sensor unit 20 in the main scanning direction is longer than the width of the peripheral surface of the drum 11, and magnetic information by magnetic ink printed on the large-size banknote 110 is detected on the entire surface of the large-size banknote 110.

Each magnetic line sensor 21 is a multi-channel sensor having a plurality of magnetic sensor elements arranged in a line in the main scanning direction, and outputs magnetic data acquired by each magnetic sensor element. The magnetic sensor elements included in all the magnetic line sensors 21 are arranged at an equal pitch in the main scanning direction.

As shown in FIG. 7, the magnetic detection device 101 includes a magnetic line sensor unit 20 including a plurality of magnetic line sensors 21, a personal computer 40 and a control circuit 50 as a control unit 30, a rotary encoder 14, a trigger 13, , Is provided.

The control circuit 50 is configured by a logic device such as an FPGA (Field Programmable Gate Array) and includes a data aggregation circuit 51.

The data aggregating circuit 51 digitally converts the output (magnetic data) of each magnetic line sensor 21, aggregates it into one image data per one large-sized bill 110, and outputs the image data to the personal computer 40.

The personal computer 40 monitors a rotation speed of the drum 11 based on a pulse signal from the rotary encoder 14, a pulse signal from the rotary encoder 14, a trigger signal from the trigger 13, and an output from the speed monitor 41. A data acquisition control unit 42 that controls the timing at which each magnetic line sensor 21 acquires magnetic data based on the rotation speed of the drum 11 that has been set, and an offset image described below as image data output from the data aggregation circuit 51. And a difference calculation unit 44 for performing a difference calculation process to generate a target image.

The storage unit 43 is generated from the output (magnetic data) of each magnetic line sensor 21 in a state where the drum 11 rotates at a predetermined rotation speed and the large bill 110 is not held on the peripheral surface of the drum 11. A magnetic image, that is, an offset image is stored as reference data for difference calculation processing. The offset image stored in the storage unit 43 is created based on magnetic data detected from a reference large-sized banknote properly printed with magnetic ink. This reference image is created based on magnetic data detected by each magnetic line sensor 21 of the magnetic detection device 101 from the viewpoint of effective removal of induction magnetic field noise and efficiency, but is generated by other magnetic sensors. It may be created based on the detected magnetic data.

The difference calculation unit 44 is generated from the output (magnetic data) of each magnetic line sensor 21 in a state where the drum 11 rotates at the predetermined rotation speed and the large bill 110 is held on the peripheral surface of the drum 11. The magnetic image, that is, the detected image is input from the data aggregation circuit 51 as detection data. Then, the difference calculation unit 44 performs a difference calculation process of subtracting the offset image stored in the storage unit 43 from the detected image input from the data aggregation circuit 51, and generates and outputs a target image. As described above, the target image is composed of magnetic data relating to the large-sized bills 110 (almost only the large-sized bills 110) from which unnecessary background noise such as induced magnetic field noise due to the rotation of the drum 11 has been removed.

Next, the operation of the magnetic detection device 101 according to the present embodiment and the processing flow of the magnetic detection method according to the present embodiment will be described with reference to FIG.

As shown in FIG. 8, first, the rotation speed of the drums 10 to 12 is gradually increased to a predetermined rotation speed n1 in a state in which the large format bill 110 is not conveyed by the drums 10 to 12 (drum acceleration step).

Next, in a state where the large-sized banknote 110 is not conveyed to the drums 10 to 12 rotating at the rotation speed n1, the magnetic line sensor unit facing the entire width of the peripheral surface of the drum 11 in synchronization with the timing of the output pulse of the rotary encoder 14. A predetermined number of lines of magnetic data are detected by 20, an offset image A is generated based on the output, and stored in the storage unit 43 (difference calculation processing reference data storage step).

Next, the plurality of large format bills 110 are sequentially conveyed by the drums 10 to 12 rotating at the rotation speed n1. Each large format bill 110 is conveyed at a predetermined position on the peripheral surface of each drum 10, 11, 12 by the holding mechanism of each drum 10, 11, 12. Then, the following processing is performed for each of the large format bills 110 that are sequentially conveyed. That is, from the timing when the leading position of the large format bill 110 reaches the trigger 13 and the trigger signal from the trigger 13 is received, the magnetic data is predetermined by the magnetic line sensor unit 20 in accordance with the timing of the output pulse of the rotary encoder 14. And the detected image A is generated based on the output (detected data acquisition step). Thereby, the detected image A is always obtained at the same position on the drum 11. Thereafter, a target image A of the large-sized banknote 110 held on the drum 11 is generated by subtracting the offset image A from the detected image A (difference calculation processing step).

Next, the rotation speed of the drums 10 to 12 is gradually increased to a predetermined rotation speed n2 in a state where the large format bill 110 is not conveyed by the drums 10 to 12 (drum acceleration step).

Next, in a state where the large format bill 110 is not conveyed to the drums 10 to 12 rotating at the rotation speed n2, the magnetic data is transmitted by the magnetic line sensor unit 20 to the predetermined number of lines in accordance with the output pulse timing of the rotary encoder 14. Is detected, an offset image B is generated based on the output, and stored in the storage unit 43 (difference calculation processing reference data storage step).

Next, the plurality of large format bills 110 are sequentially conveyed by the drums 10 to 12 rotating at the rotation speed n2. Each large format bill 110 is conveyed at a predetermined position on the peripheral surface of each drum 10, 11, 12 by the holding mechanism of each drum 10, 11, 12. Then, in the same manner as in the case of the rotation speed n1, the following processing is performed for each of the large format bills 110 that are sequentially conveyed. That is, from the timing when the leading position of the large format bill 110 reaches the trigger 13 and the trigger signal from the trigger 13 is received, the magnetic data is predetermined by the magnetic line sensor unit 20 in accordance with the timing of the output pulse of the rotary encoder 14. And the detected image B is generated based on the output (detected data obtaining step). Thereafter, a target image B of the large-sized banknote 110 held on the drum 11 is generated by subtracting the offset image B from the detected image B (difference calculation processing step).

Thereafter, if necessary, the above-described drum acceleration step, difference calculation processing reference data storage step, detection data acquisition step, and difference calculation processing step are repeated.

As described above, according to the magnetic detection device 101 according to the present embodiment and the magnetic detection method according to the present embodiment, unnecessary back noise such as induced magnetic field noise due to the rotation of the drum 11 does not depend on the rotation speed of the drum 11. Since the target image from which is removed can be acquired as magnetic data relating to the large-sized bill 110, the magnetic information of the large-sized bill 110 conveyed by the drum 11 can be detected stably and with high accuracy.

In addition, the storage unit 43 (difference calculation processing reference data storage step) stores the magnetic line sensor unit 20 in a state where the large format bill 110 is not held on the peripheral surface of the drum 11 every time the rotation speed of the drum 11 changes. Since the magnetic image (offset image) based on the output of the drum 11 is stored as the reference data for the difference calculation processing, the magnetic information printed on the large-size banknote 110 is stably and high-valued every time the rotation speed of the drum 11 changes. It can be detected with accuracy. In addition, since a more accurate offset image can be obtained as compared with a case where an offset image is acquired in advance, the magnetic information printed on the large-sized banknote 110 is more stably detected with higher accuracy. be able to.

As described above, from the viewpoint of improving the accuracy of the offset image, a plurality of offset images may be acquired while the drum 11 is rotating at a constant rotation speed, and an image obtained by averaging the offset images may be used. Good.

In the second embodiment of Patent Document 1, a noise sensor for detecting only a noise component on the transport belt is separately provided along the transport belt in addition to a sensor for magnetic detection of the medium. A magnetic information detecting apparatus for removing a noise component detected by a noise sensor from magnetic information of a medium containing a noise component detected by the sensor described in (1). However, in this device, noise may not be accurately removed due to performance mismatch such as output variation between the magnetic detection sensor and the noise sensor.

On the other hand, in the present embodiment, the magnetic line sensor unit 20 collects the magnetic data for creating the offset image and the magnetic data for creating the detected image. Unnecessary back noise can be effectively removed.

<Embodiment 2>
In the present embodiment, features unique to the present embodiment will be mainly described, and detailed description of contents overlapping with the first embodiment will be omitted. In the present embodiment and the first embodiment, members having the same or similar functions are denoted by the same reference numerals, and detailed description of the members will be omitted in the present embodiment.

Although magnetic ink is effective as a means for preventing forgery of paper sheets such as banknotes, on the other hand, it is easy to make mistakes in inserting ink in the printing process of large-sized banknotes, and it is necessary to inspect this. However, large-sized banknotes using magnetic ink cannot be inspected for print quality of magnetic ink even with the naked eye using room light, so a special method is needed to detect ink mis-insertion during the manufacturing process. It becomes. The present embodiment and Embodiment 3 to be described later are suitable for finding such a mistake in ink insertion in the process of manufacturing large-sized banknotes.

As illustrated in FIG. 9, in the magnetic detection device 102 according to the present embodiment, the personal computer 40 as the control unit 30 further includes a determination processing unit 45 that determines the presence or absence of magnetism of the large format bill 110 based on the target image. ing. In addition, the storage unit 43 stores a template image as determination reference data indicating an appropriate design or serial number printed by magnetic ink. The determination processing unit 45 determines whether or not the large-sized bill 110 has magnetism by comparing the target image regarding the large-sized bill 110 calculated by the difference calculation unit 44 with the template image. Thereby, the presence or absence of magnetic printing of the large format bill 110 can be inspected by the magnetic detection device 102. In detail, the target image and the template image are collated using a template matching method, and when a region where the similarity with the template image exceeds a predetermined threshold is present in the target image, the large format bill 110 is If it is determined that printing has been performed with the magnetic ink (normal), and there is no area in the target image in which the degree of similarity with the template image exceeds a predetermined threshold, the large-format banknote 110 is not printed with the magnetic ink (abnormal). ).

Here, the determination processing unit 45 compares one or more small cut surfaces 111 (preferably, one large format It may be determined whether or not all the small cut surfaces 111) of the bill 110 have magnetism. Thus, the magnetic detection device 102 can inspect whether or not the large-sized banknote 110 is magnetically printed in units of the small cut surface 111.

In addition, the determination processing unit 45 determines whether or not each of the small cut surfaces 111 has magnetism by comparing the target image regarding the large format bill 110 calculated by the difference calculation unit 44 with the template image in units of the small cut surfaces 111. At the same time, it may be determined whether or not the large-size banknote 110 has magnetism by comparing the number of the small cut surfaces 111 determined to have magnetism with a predetermined threshold value. In this case, due to the waving of the large-sized bill 110, the distance to the magnetic sensor element is different for each small cut surface 111, and a region where the output level from the magnetic line sensor unit 20 is high and a region where the output level is low are mixed in the large-sized bill 110 Even with this, the presence or absence of magnetic printing of the large format bill 110 can be inspected by the magnetic detection device 102. In detail, the determination processing unit 45 compares the target image regarding the large-sized banknote 110 calculated by the difference calculation unit 44 with the template image in units of the small cut surface 111 by the above-described template matching method to thereby obtain each small cut surface 111. It is determined whether or not the (large format bill 110) has magnetism, and the number of small cut surfaces 111 determined to have magnetism is counted. Then, the determination processing unit 45 compares the total number of the small cut surfaces 111 determined to have magnetism per one large format bill 110 with a predetermined threshold value, and when the total number exceeds the predetermined threshold value, 110 determines that printing has been performed with magnetic ink (normal), and when the total number of sheets is equal to or less than a predetermined threshold value, determines that the large-format banknote 110 has not been printed with magnetic ink (abnormal).

<Embodiment 3>
In the present embodiment, features unique to the present embodiment will be mainly described, and detailed description of contents overlapping with the first and second embodiments will be omitted. In the present embodiment and Embodiments 1 and 2, members having the same or similar functions are denoted by the same reference numerals, and detailed description of the members will be omitted in the present embodiment.

As shown in FIG. 10, in the magnetic detection device 103 according to the present embodiment, the personal computer 40 as the control unit 30 includes a division processing unit 46a and an averaging processing unit 46b.

As illustrated in FIG. 11, the division processing unit 46 a divides the target image regarding the entire large-sized banknote 110 generated by the difference calculation unit 44 into small cut surfaces 111, and generates a magnetic image (hereinafter, “small”) for each small cut surface 111. Cut image).

The averaging processing unit 46b averages two or more small cut images. As a result, a signal portion mainly caused by the magnetic ink remains and noise is reduced. Therefore, the averaged image is used to more accurately inspect the presence or absence of magnetic printing of two or more small cut surfaces 111. be able to. More specifically, the averaging processing unit 46b averages two or more cut images generated by the division processing unit 46a to generate and output one magnetic image (hereinafter, an average image).

The averaging processing unit 46b may average a plurality of small-section images over the entire large-sized banknote 110. As a result, noise is further reduced, so that the presence or absence of magnetic printing of the large format bill 110 can be inspected with higher accuracy using the averaged image. More specifically, the averaging processing unit 46b averages all the small-piece images (all small-piece images related to one large-size banknote 110) generated by the division processing unit 46a, and obtains one magnetic image (average image). ) May be generated and output.

As shown in FIG. 12, in the present embodiment, the personal computer 40 as the control unit 30 may further include a determination processing unit 46c. Further, the storage unit 43 may store a template image as reference data for determination indicating an appropriate design or serial number printed by magnetic ink.

As illustrated in FIG. 13, the determination processing unit 46c compares the average image generated by the averaging processing unit 46b with the template image stored in the storage unit 43, and thereby performs two or more small cut surfaces 111 (all small When the cut images are averaged, it is determined whether or not the large format bill 110) has magnetism. Thus, the presence or absence of magnetic printing of the two or more small cut surfaces 111 (or large bills 110 when all small cut images are averaged) can be more accurately inspected by the magnetic detection device 103. In detail, the average image and the template image are collated using the template matching method, and if there is a region in the average image having a similarity with the template image exceeding a predetermined threshold, two or more small cuts are obtained. The surface 111 (large-format bill 110 when all the small cut images are averaged) is determined to be printed (normal) with magnetic ink, and an area in which the similarity with the template image exceeds a predetermined threshold is included in the average image. If not present, it is determined that two or more small cut faces (large bill 110 when all small cut images are averaged) are not printed with magnetic ink (abnormal).

Further, as shown in FIG. 14, in the printing apparatus for large-size banknotes, the magnetic ink is not uniformly applied on the plate cylinder 132 due to the uneven application 131 a of the magnetic ink to the ink roller 131, and the gap between the plate cylinder 132 and the impression cylinder 133. It is also assumed that only the small cut surface 111 of a specific column or row of the large format bill 110 transported is not printed. In order to inspect such a coating unevenness 131a, the averaging processing unit 46b may average a plurality of small cut images for each same row or each same column. In detail, the averaging processing unit 46b averages the small slice images generated by the division processing unit 46a for each same row or each same column, and generates one magnetic image (average image) for each row or each column. May be. The magnetic detection device 103 may output an average image of each row or each column as shown in FIG. 10, or may output an average image of each row or each column in the determination processing unit 46 c as shown in FIG. 12. May be compared with the template image to determine whether the small cut surface 111 of each row or each column has magnetism.

In the second embodiment, the determination processing unit 45 compares the target image regarding the large-sized banknote 110 calculated by the difference calculation unit 44 with the template image in units of small cut surfaces 111 without dividing the target image into units of small cut surfaces 111. Has been described in which it is determined whether or not one or more small cut surfaces 111 or each small cut surface 111 has magnetism. However, the target image regarding the large format bill 110 calculated by the difference calculation unit 44 is divided into small cut surfaces 111. After the division, it may be determined whether or not one or more small cut surfaces 111 or each small cut surface 111 has magnetism. More specifically, in this case, the personal computer 40 as the control unit 30 further includes a division processing unit similar to the division processing unit 46a of the third embodiment. The division processing unit divides the target image of the entire large-sized banknote 110 generated by the difference calculation unit 44 into small cut surfaces 111, and divides the target image into one or more small cut surfaces 111 or a magnetic image (hereinafter referred to as a small Cut image). Then, the determination processing unit 45 compares each of the small-piece images generated by the division processing unit with the template image stored in the storage unit 43 by using the above-described template matching method, thereby obtaining one or more small-piece surfaces 111 or It is determined whether or not each small cutting surface 111 (large bill 110) has magnetism.

In the first to third embodiments, the case where the rotation speed of the drum 11 when acquiring the offset image is the same as the rotation speed of the drum 11 when acquiring the detected image, but the rotation speed before and after the rotation is obtained. An offset image interpolated from the obtained offset image may be used. More specifically, a plurality of magnetic images (hereinafter, referred to as “multi-images”) based on the output of the magnetic line sensor unit 20 in each state where the drum 11 that does not hold the large format bill 110 on the peripheral surface is rotating at a plurality of predetermined rotational speeds. Reference image) is prepared as reference data, and a function of the magnetic image based on the output of the magnetic line sensor unit 20 according to the rotation speed of the drum 11 is calculated based on these reference images, and the calculated function is stored in the storage unit 43. To memorize. Note that these reference images may also be stored in the storage unit 43. Further, based on the function, the control unit 30 rotates the drum 11 not holding the large format bill 110 on the peripheral surface at a predetermined rotation speed (however, excluding the plurality of predetermined rotation speeds at the time of generating the reference image). A magnetic image (offset image) based on the output of the magnetic line sensor unit 20 at this time is calculated as difference calculation processing reference data. A magnetic image (detected image) based on the output of the magnetic line sensor unit 20 in a state where the large bill 110 is held on the peripheral surface of the drum 11 rotating at the same rotation speed as the time of calculating the offset image by the difference calculation unit 44 Is obtained as detection data, and the offset data is subtracted from the detected image to calculate magnetic data (target image) related to the large-sized banknote 110 held on the drum 11. Accordingly, as long as the rotation speed of the drum 11 is within the range where the function is established, the offset image can be obtained without actually acquiring magnetic data by the magnetic line sensor unit 20 for any rotation speed. The time for acquiring images can be omitted, and the magnetic detection devices 101 to 103 can be operated more flexibly and efficiently.

In the first to third embodiments, the case where the printed matter is the large-sized banknote 110 in which the plurality of small cut surfaces 111 are arranged vertically and horizontally has been described. However, the printed matter is one in which only one small cut is arranged. The magnetic detection devices 101 to 103 may detect small pieces of magnetism one by one.

In this case, the printed matter may be cut from the magnetically printed large format bill 110, or may be magnetically printed on a small-sized substrate from the beginning.

Further, in the first to third embodiments, the case has been described in which the magnetic image obtained by imaging the output of the magnetic line sensor unit 20 is processed. However, the output of the magnetic line sensor unit 20 may be processed without being imaged. . For example, difference calculation processing reference data and detection data may be obtained from the peak value of each channel of the magnetic line sensor unit 20, and the difference calculation processing may be performed.

Further, in the first to third embodiments, the case has been described where the multi-channel magnetic line sensor unit 20 including the plurality of magnetic line sensors 21 is used as the magnetic sensor, but the magnetic sensor is one magnetic line sensor 21. It may output magnetic data of one channel.

The embodiments of the present invention have been described with reference to the drawings. However, the present invention is not limited to the above embodiments. Further, the configurations of the embodiments may be appropriately combined or changed without departing from the spirit of the present invention.

As described above, the present invention is a technique useful for detecting magnetic information of a printed matter conveyed by a metal drum.

10, 11, 12: drum body (drum)
13: trigger 14: rotary encoder 20: magnetic line sensor unit 21: magnetic line sensor 22: housing 23: control board 30: control unit 40: personal computer 41: speed monitor 42: data acquisition control unit 43: storage unit 44: Difference calculation units 45 and 46c: judgment processing unit 46a: division processing unit 46b: averaging processing unit 50: control circuit 51: data aggregating circuits 101, 102, 103: magnetic detection device 110: large-sized banknote 111: small cut surface (banknote) surface)
120: Test tables 121, 123: Aluminum plate 122: Iron screw 124: Welded part 125: Magnetic printing medium 126: Induction magnetic field noise 127: Detection signal of iron screw 128: Detection signal of welded part 129: Printed with magnetic ink Detection signal 131 of the character "500": ink roller 131a: uneven coating 132: plate cylinder 133: impression cylinder

Claims (14)

A magnetic detection device for detecting the magnetism of a printed matter,
A metal drum body that rotates while holding the printed matter on the peripheral surface,
A magnetic sensor that is provided facing the peripheral surface of the drum body and detects the magnetism of the printed matter;
A storage unit that stores an output of the magnetic sensor in a state where the drum body rotates at a first rotation speed and a printed material is not held on a peripheral surface of the drum body as first difference calculation processing reference data; When,
The drum body rotates at the first rotation speed, and acquires the output of the magnetic sensor in a state where a printed material is held on the peripheral surface of the drum body as first detection data, A control unit that calculates magnetic data on the printed matter held on the drum body by subtracting the first difference calculation processing reference data stored in the storage unit from the detection data. Magnetic detector. Each time the rotation speed of the drum body changes, the storage unit uses the output of the magnetic sensor in a state where no printed material is held on the peripheral surface of the drum body as the first difference calculation processing reference data. 2. The magnetic detection device according to claim 1, wherein the information is stored. The magnetic detection device according to claim 1, wherein the magnetic sensor detects an induced magnetic field of the drum body together with the magnetism of a printed matter. The magnetic detection device according to any one of claims 1 to 3, wherein the first reference data for difference calculation processing includes magnetic data on the drum body. The storage unit is based on reference data that is an output of the magnetic sensor in a state where the drum body that does not hold a printed material on the peripheral surface is rotating at a plurality of rotation speeds different from the first rotation speed. A function of the output of the magnetic sensor according to the calculated rotation speed of the drum body is stored,
The control unit, based on the function, the output of the magnetic sensor when the drum body that does not hold the printed material on the peripheral surface is rotated at a second rotation speed as the second difference calculation processing reference data With the calculation, the output of the magnetic sensor in a state where a printed matter is held on the peripheral surface of the drum body rotating at the second rotation speed is obtained as second detection data, and from the second detection data The magnetic detection device according to any one of claims 1 to 4, wherein magnetic data relating to the printed matter held on the drum body is calculated by subtracting the second reference data for difference calculation processing. The magnetic detection device according to claim 5, wherein the storage unit stores the reference data. The method according to claim 1, wherein the control unit determines whether the printed matter has magnetism by comparing the calculated magnetic data regarding the printed matter with reference data for determination. Magnetic detector. The printed matter held by the drum body is a large sheet in which a plurality of small cut surfaces are arranged over a plurality of rows and a plurality of columns,
The control unit determines whether or not one or more small cut surfaces have magnetism by comparing the calculated magnetic data on the large-sized sheet with the reference data for determination in units of the small cut surfaces. The magnetic detection device according to claim 7, wherein: The control unit determines whether or not each of the small cut surfaces has magnetism by comparing the calculated magnetic data on the large-sized sheet with the reference data for judgment in units of the small cut surfaces, and determines whether or not each of the small cut surfaces has magnetism. 9. The magnetic detection device according to claim 8, wherein whether the large-size sheet has magnetism is determined by comparing the determined number of small cut surfaces with a predetermined threshold. The printed matter held by the drum body is a large sheet in which a plurality of small cut surfaces are arranged over a plurality of rows and a plurality of columns,
7. The control unit according to claim 1, wherein the control unit divides the calculated magnetic data on the large-size sheet into the small cut surfaces and averages the magnetic data on two or more small cut surfaces. 8. The magnetic detection device as described in the above. The magnetic detection device according to claim 10, wherein the control unit averages magnetic data on a plurality of small cut surfaces in the entire large format sheet, in each of the same rows, or in each of the same columns. 12. The magnetic device according to claim 10, wherein the control unit determines whether the two or more small cut surfaces have magnetism by comparing the averaged magnetic data with reference data for determination. Detection device. A magnetic detection method for detecting the magnetism of a printed matter by a magnetic sensor provided opposite to a peripheral surface of a drum body,
A difference calculation processing reference data storing step of storing, as difference calculation processing reference data, an output of the magnetic sensor in a state where the drum body rotates at a predetermined rotation speed and a printed material is not held on a peripheral surface of the drum body; When,
A detection data acquisition step in which the drum body rotates at the predetermined rotation speed, and an output of the magnetic sensor in a state where a printed matter is held on a peripheral surface of the drum body as detection data,
A difference calculation processing step of calculating magnetic data on the printed matter held on the drum body by subtracting the difference calculation reference data from the detection data. The difference calculation processing reference data storing step includes a step of storing, as the difference calculation processing reference data, an output detected by the magnetic sensor every time the rotational speed of the drum body changes. Item 14. The magnetic detection method according to Item 13.

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